Winter Outlook 2024-2025

[40/70 Benchmark]

2 hours ago, qg_omega said:

First call tonight?

How is your call for a incredibly warm winter going?

I think most would agree that I have no issue owning a wrong forecast (or hedge), so I'm not sure what your point is. I think my seasonal idea looks pretty good.

[40/70 Benchmark]

Back to Regularly Scheduled "Cold & Dry" First Half of January

Weekend Storm No Longer Anticipated Due to Sudden Reversal of Trends

It became apparent early on Sunday that there was a definitive trend amongst all guidance to no longer hold back southern stream energy. 

 

 

This would subsequently afford it the opportunity to phase, at least to some degree, on Friday with a descending parcel of northern stream energy. 

 

 

Thus fostering the development of a significant winter storm this weekend. 

 

 

 

The thought process was that this type of a trend being evident across all guidance to varying degrees within 4 days of the potential phase was definitive evidence that guidance had an adequate handle on the southern stream evolution. Thus the likelihood of at least an eventual partial phase was relatively high, which is what led the conclusion that an impactful winter storm was likely. However, as turns out, guidance in fact did not yet have an accurate portrayal of the southern stream.

 

Southern Stream Holding Back Eliminates Phasing Prospects

It became evident by early Tuesday morning that the expectation that the southern stream energy would eject early enough to link up with the northern parcel would be incorrect, as guidance began to rapidly reverse that trend. 

 

 

This reversal is likely at least partially due to models keying on on seperate northern stream piece of energy that would disrupt the western CONUS ridge at the precise time that it was to assist in triggering the downstream phasing and coalescing of energy that would facilitate the development of the east coast storm next weekend.

 

 

Ironically enough, this outcome is very similar to the original expectation from late last week that the first half of January would remain cold and dry.

 

 

Although it is rare for trends in guidance to completely reverse once within 3-4 days of lead time, it is not impossible, and the assumption of Eastern Mass Weather that this would not be case in this instance proved incorrect.

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Cold January with Notable Lack of Major Snowfall Poised to Continue

Frigid Arctic Chill to Arrive on the Heels of Slight Snow Chance Sunday Night

Although the month of January has evolved somewhat colder than anticipated thus far, the chilly temperatures have not translated to much in the way of snowfall.

 

This was not entirely unexpected given that the Eastern Mass Weather Winter Outlook called for most of the above average monthly allotment of snowfall to come between January 21 and February 4th, however, there is a considerable amount of doubt as to whether that will in fact be the case.

 

Frigid Onset to Second Half of January Largely Unaccompanied by Snowfall

The latter half of January looks to begin in much the same manner that the first half evolved, with the exception of the fact that the airmass early next week will be the coldest of the season thus far. The combination of west coast ridging and blocking within the NAO domain will send the polar vortex on yet another journey southward during the coming weekend as it descends out of James bay and into southeast Canada. At the same time, a weak wave of low pressure will pass offshore on Sunday night out ahead of the leading edge of the arctic airmass.

 

 

 

While the bulk of the precipitation will remain offshore, it is not out of the realm of possibility that an inch or two of snowfall, perhaps up to 3" in some localized areas, could fall over especially the southeastern third of the region before it moves away and the arctic siege begins on Monday.

 

Thereafter, the cold will moderate thoroughot the latter half of the week as the vortex begins to lift away over the Canadian maratimes.

 

Then the final third of the month will represent a period of transition, as the polar blocking relinquishes its grip and the Pacific blocking reasserts itself. This will present an opportunity for a more significant storm system, as is the case with any period of mass flux.

High Latitude Realignment to be Accompanied by Latter January Storm Possibility

The expectation last fall was for the month of January to predominately feature plenty of high latitude blocking on the Pacific side that would be accompanied by a strong polar vortex, and thus a dearth of blocking over the arctic. However, while the polar vortex has in fact been appreciably strong, it has remained fairly uncoupled with the troposphere, which has allowed blocking within the NAO domain to remain rather prevalent, regardless. 

 

This may ultimately prove to be a case of delayed rather than denied, as there are signs that the appreciably strong polar vortex will begin to grow more coupled from the stratosphere down through the troposphere. What this will entail is a reconfiguration of the pattern in that the arctic will begin to neutralize (rising AO & NAO), while the greater heights reconfigure from the Atlantic to the Pacific side (descending EPO/WPO, ascending PNA).  A hemispheric realignment of this magnitude will represent the type of mass flux and teleconnection modularity that will enhance the likelihood of the development of a major winter storm. This is evident on the Atlantic side.

 

 

And the Pacific side between approximately January 23-25.

 

 

While this is in accordance with the January 21-February 3 window identified last fall for a heightened risk of a major winter storm, ensemble support continues to be relatively meager, and a track out to sea remains the most likely outcome.

 

 

Thereafter, the pattern moderates somewhat over the final third of the month, while also ostensibly becoming more conducive to increased snowfall throughout the forecast area.

 

However, this does not appear to be a favorable pattern for major east coast snowstorms, and the similarities of the pattern thus far to some seasons that have managed to largely avoid snowfall across the area with surgical precision can not be denied.

 

 

 

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Plowable Snowfall Possible for Large Portion of Southern New England Sunday Evening into Early Monday

Weak Storm System Appears To Track Closer to Region

Synoptical Overview:

This weekend a parcel of energy will begin to be steered around the approaching polar vortex that will supply the bout of arctic chill next week.

 

It will then round the base of the vortex and turn up the coast, however, the primary difference from yesterday is that it now appears as though it will track closer to the region to the region as it passes offshore early Monday.

 

 

The obvious implication of this is that it would have a slightly greater impact on the forecast area overnight Sunday and into early Monday morning relative to expectation yesterday, and thus slightly more snowfall.

 

Expected Storm Evolution:

A separate, lead system will traverse the area overnight Saturday, with precipitation falling primarily in the form of rainfall and some mixed precipitation in the higher terrain.

 

 

The follow up energy, which is the system of interest, then overspreads the area on Sunday evening with snowfall across the majority of the area, and rain over the cape and islands,

 

 

Snowfall may be slightly heavier over the deep interior, as well as the immediate coast during the peak of the event due to mid level and low level frontogenesis.

The low level convergence along the coast will be in association with the coastal front, which will begin over the immediate north shore, Boston area and interior southeastern Mass Sunday evening, before drifting southeastward overnight.

 

 

 

The other area of potential banding will be attributable to some mid level deformation just to the northwest of the mid level low track, across the northwest Connecticut hills and into Worcester county.

 

Any rain and mixed precipitation over the cape and islands will transition over to snowfall, as the system begins to pull away during the wee hours of Monday morning.

 

 

The last of the snowfall should exit the cape prior to midday.

 

First Call:

 

 

Final Call will be issued on Saturday-

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Final Call for Quick Hitting Sunday Night Snows

Slightly Heavier Amounts Expected

Synoptic Overview:

Currently a parcel of energy is beginning to veer around the approaching polar vortex that will supply the bout of arctic chill next week.

 

It will then continue to round the base of the vortex and turn up the coast throughout tonight and into tomorrow. There is no deviation to this portion of the forecast rationale. 

 

However, there is one subtle change from First Call issued Thursday that does have fairly significant ramifications for the Final Call. Note that the position of the approaching polar vortex was over James Bay in the above guidance from Thursday, as compared to today's output posted below, which has the vortex slightly further to the north, and more over bodily over Hudson's Bay as opposed to James Bay, Canada.

 

The implication of this further north position of the polar vortex is that ir would afford slightly more space for the energy rotating around its southern periphery and up the east coast to amplify and intensify slightly faster before exiting the area.

 

 

This would result in somewhat heavier snowfall than indicated in the First Call.

 

Expected Storm Evolution:

Snowfall should breakout outcross the region late Sunday afternoon and early evening from southwest to northeast. Precipitation may commence as a mix along the south coast, and rainfall across extreme coastal southeastern Mass, the cape and islands.

 

The low will begin to intensify more rapidly as it passes off shore later Sunday evening, which will cause heavier bands of snow to develop, especially just to the northwest of the nascent mid level lows. Where exactly the most intense and persistent banding develops will dictate which locales receives localized heavier amounts of snowfall, however the annotation below provides the best estimate.

 

Any residual mixed precipitation and rainfall will transition to snow before precipitation ends during the pre-dawn hours of Monday morning, as the system pulls away into the Gulf of Maine.

 

 

Final Call:

 

First Call Issued Thursday, January 16th @ 10PM:

 

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Snowfall Forecast for Quick Hitting Sunday Night Snows Largely Successful 

Minor Forecast Discrepancies

Here is the Final Call for last night's fast moving winter storm (right) versus what actually transpired (left) in terms of total snowfall accumulations.

 

While the forecast overall was fairly representative, the most persistent banding ended up being over the Berkshires into southern Vermont, as opposed to northern Worcester country into southern New Hampshire. Additionally, slightly less snowfall fell versus the expectation over the eastern half of the region due to the slower arrival of the colder air relative to modeling, thus 4-7" would have been more appropriate versus the 5-8" range that was utilized.

 

Final Grade: B

 

[H2Otown_WX]

On 1/20/2025 at 3:42 PM, 40/70 Benchmark said:

 

 

Snowfall Forecast for Quick Hitting Sunday Night Snows Largely Successful 

Minor Forecast Discrepancies

Here is the Final Call for last night's fast moving winter storm (right) versus what actually transpired (left) in terms of total snowfall accumulations.

 

While the forecast overall was fairly representative, the most persistent banding ended up being over the Berkshires into southern Vermont, as opposed to northern Worcester country into southern New Hampshire. Additionally, slightly less snowfall fell versus the expectation over the eastern half of the region due to the slower arrival of the colder air relative to modeling, thus 4-7" would have been more appropriate versus the 5-8" range that was utilized.

 

Final Grade: B

 

You're pretty hard on yourself man. You schooled professional forecasters.. 5-8 vs 4-7 be damned.

[40/70 Benchmark]

 

Some Light Snow Possible Mid Week

Primarily Northern Sections

Synoptic Overview:

On Tuesday, a modest northern stream parcel of energy will emerge out of a split flow and eject over a western-biased PNA ridge, and into the Great Lakes.

 

This clipper system will then resume more of an east-southeast track around the base of the departing polar vortex that will take it into New York State on Tuesday night.

 

The system is likely to have limited room for amplification given the combination of cut-off energy over the southwestern CONUS in association with the southern branch, as well as a PNA ridge that is both fairly meager and western biased.

 

 

Potential Storm Tracks:

The forecast modest degree of amplification of this clipper system means that it is likely to track at least somewhat to the north of southern New England, rather than bodily through the region, as modeled by the GFS model, which would imply several inches of snowfalls similar to the last storm.

 

The Canadian guidance tracks the system significantly further to the north, across northern New England, and produces little if any snow across the area.

 

 

While the European model represents somewhat of a compromise solution in which the storm tracks just to the north of the area, across southern Vermont and New Hampshire. 

 

This scenario would yield perhaps an inch or two of snow north of the Mass pike and most especially north of route 2, which may represent the most viable solution. The southern track of the GFS is the least preferred outcome at this time. 

Stay tuned for an update on Tuesday if necessary.

First Call:

 

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Mixed Results Concerning January Forecast & Look Ahead to Potentially More Eventful February

Paradoxical Warmer & Snowier Regime Possible Moving Forward

January 2025 Review

The main premise for the January 2025 portion of the winter outlook was that a potent -WPO/+PNA couplet would fuel a January 2022 like mismatch from the Maritime Content forcing that has been so prevalent over the course of the last several years. 

 

 

This portion of the forecast worked out about as well as it possibly could have, as the MJO did indeed make it into the west-central Pacific to trigger the anticipated extra tropical Pacific response. 

 

Note that the MJO did not travel through phase 8 this month, as it did during the analog month of January 2022.  

 

However, its extensive journey through phase 1 represents a trivial difference considering the similarities in the two adjacent phases.

 

Thus the predominate tropical forcing of the two months was highly analogous, as forecast, but there were some important differences within the polar domain that ultimately biased the month significantly colder relative to forecast.

Nuances of the Polar Vortex Lead Forecast Astray

January 2025 was forecast to feature a very strong polar vortex (PV) and consequently, a +AO and NAO in the mean, much like January 2022 (.85, 1.08 mean monthly AO/NAO). Here is the polar vortex composite from January 2022, with the stratosphere pictured on top, and the tropospheric PV on the bottom.

 

 

Now here is the PV composite from January 2025 for comparison.

 

 

The vortex is of considerable intensity and reasonably well centered over the pole, however, note that it is neither perfectly aligned or coupled down through the troposphere, where the vortex is slightly weaker and more displaced away from the NAO domain. This allowed for high latitude blocking to prevail in this region, as evidenced by both the monthly NAO activity:

 

And the 500mb composite.

 

This clearly resulted in a much colder than forecast month, especially over the Ohio River Valley and southeastern half of the country.

 

 

 

 

The forecast across New England was not impacted as adversely (Normal to +2 forecast versus Normal to -2 reality) as the rest of the eastern US due to decreased correlation with the NAO, which is where the error was.

 

 

And ironically enough, less snowfall than anticipated, as the very suppressed pattern resulted in an even drier month than forecast.

 

The error was primarily within the NAO domain, as the AO behaved in a more volatile manner and looks to finish the month approximately near neutral to somewhat positive.

 

Now as the month of January draws to a close, the MJO will approach the Maritime continent, as high latitude blocking abates and the pattern modifies. While this will undoubtedly mean the end of the uncharacteristically and historic wintry weather to the south, that will not necessarily the case for the northeast.

 

February 2025 Preview: "Warmer and Snowier"

There are no major changes to the original forecast philosophy for February 2025. Here are the original thoughts from early November, which remain valid.

 

February Analogs: 2011, 2008, 2000, 1999,1972

The polar vortex should begin the month very strong, but watch for a potential SSW from about mid month onward.

The pace of moderate storms should increase for the first time all season, just as the warmer weather returns in February, however, a notable difference from many recent months of February is that it should not be prohibitively warm so as to entirely preclude some appreciable snowfall across the majority of the region. The month should finish 1 to 3F above average with near normal to perhaps just below normal snowfall. Northern New England should see above normal snowfall as the cold air source lurks close by in southeastern Canada, which will produce several front-end snowfall for much of southern New England and perhaps even into the northern mid Atlantic at times.

"SWFE"....AKA "Southwest Flow Events-

 

 

 

While there is currently little support for a major stratospheric warming during the month of February, research implies that there is a threat from mid month into March. While the signal is not as strong as it was in recent analog years, such as 2018 and 2023, there are two reasons why this month should not be nearly as warm as other recent months of February, regardless of whether the PV remains of considerable intensity. First of all, the guidance is in fairly strong agreement that the MJO will traverse the MC phases at a very low amplitude.

 

 

In fact, the ECMWF actually implies that the wave will dissipate, however, it is expected to persist at a relatively low amplitude through the MC phases given the ECMWF's proclivity to underestimate the amplitude of waves in this region over the last several years. Secondly, seasonal guidance continues in strong agreement with the Eastern Mass Weather February 2025 forecast H5 composite, which implies that the PV will remain close enough for southern Canada to remain fairly cold.

 

 

The general pattern is also supported across ensemble guidance in the medium to longer range.

 

 

 

This rather close proximity of the PV to the CONUS is illustrated well by the forecast for both the EPO and WPO to remain negative, which will act to keep Canada fairly cold given the developing positive NAO working in conjunction with the fact that the cold air thus far this season has beeb biased towards the western hemisphere.

 

 

This will undoubtedly supply some cold enough antecedent air masses for an increase in wintry precipitation across the region relative to January, especially given that elevating heights across the southeastern US courtesy of a persistent RNA pattern will ensure more precipitation will make it up the coast.

 

 

 

 It is this agglomeration of factors that will foster the "warmer and (somewhat) snowier" February pattern. What is slightly more nebulous is whether or not the cold pattern will return. Certainly the coldest weather of the season has already been observed, however, there are some subtle suggestions that the transition to spring will not be swift.

 

Possible Colder Pattern Resumes Late Month

The development of the prevalent RNA pattern for the month of February is very high confidence, as it is well supported by the passage of the MJO though the MC phases of 4, 5 and 6.

 

 

Thereafter, there is evidence to support the progression of the MJO into phase 7.

 

 

This may imply a return of the western CONUS ridging that had been very prevalent throughout the first half of this winter season.

And any potential warming of the polar stratosphere would also likely mean a return of at least some degree of high latitude blocking to end the season, as well.

 

 

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Final Call for early Wednesday AM Light Snows

No Changes to the Forecast

Synoptic Overview:

The forecast rationale from First Call on Saturday is unchanged. A fast moving,  modest parcel of northern stream energy will move through central New England during the predawn hours of Wednesday morning.

 

 

This track is indeed most similar to the scenario modeled by European guidance last weekend, as anticipated.

 

Expected Storm Evolution:

Snowfall should break out after midnight, primarily to the north of the Mass turnpike and especially the route 2 region.

 

 

The snow will grow steadiest near the New Hampshire and Vermont border by approximately 4am.

 

 

And thankfully will be winding down by the morning commute, however, it is advised to allow for some extra time north of Boston, nonetheless.

 

 

Final Call:

There are no changes to the forecast snowfall map.

 

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Final Call for early Wednesday AM Light Snows

No Changes to the Forecast

Synoptic Overview:

The forecast rationale from First Call on Saturday is unchanged. A fast moving,  modest parcel of northern stream energy will move through central New England during the predawn hours of Wednesday morning.

 

 

This track is indeed most similar to the scenario modeled by European guidance last weekend, as anticipated.

 

Expected Storm Evolution:

Snowfall should break out after midnight, primarily to the north of the Mass turnpike and especially the route 2 region.

 

 

The snow will grow steadiest near the New Hampshire and Vermont border by approximately 4am.

 

 

And thankfully will be winding down by the morning commute, however, it is advised to allow for some extra time north of Boston, nonetheless.

 

 

Final Call:

There are no changes to the forecast snowfall map.

 

[40/70 Benchmark]

Strong Forecast for Wednesday AM Light Snows

The forecast from this morning verified very well overall, with just some minor discrepancies.

 

 

 

The heaviest amounts of 3"+ were slightly east of forecast over the northern Berkshires and southern Vermont, and the 1-2" area extended slightly further south than it should have over western Massachusetts.

 

Final Grade: A

[40/70 Benchmark]

 

Guidance Finally Converging on Expected Major Late Winter Stratospheric Disruption

Early Analysis Concerning What this May Entail

Guidance Nods to Climo Based Research

It was decided upon completion of the preliminary polar analysis, published on August 11th, that the Eastern Mass Weather primary polar analog for the 2024-2025 season would be 2022-2023. It was then further elucidated in the publication of the Winter Outlook on November 12th, why these seasonal parallels, which include very similar strength westerly QBO values occurring near solar max during modest cool ENSO, made a major late winter disruption of the polar vortex significantly more likely relative to climatology.

Here is a brief excerpt for review:

"Given that the QBO analog of 2020-2021 took place near solar minimum, the early January 2021 SSW  is of least relevance as a viable analog occurrence this season. However, the February 2023 SSW, which is a better solar analog, lends more support to a later season potential polar vortex disruption along the lines of March 1971 and 2000. This notion is supported by research on high solar, westerly QBO seasons, which lends credence to the late winter/early spring displacement scenario".

 

 

 

"The postulation of a modestly disturbed polar vortex during the month of December, followed by a recovery during the middle portion of the winter, prior to a more substantial displacement of the polar vortex during either February or March is well supported by research on moderate, basin-wide La Niña events taking place near a solar maximum with a westerly QBO. Such an evolution would also be consistent with the 2022 type of preferred mismatch during January 2025, which would be Pacific driven (-WPO/-EPO and/or +PNA and accompanied by a fairly strong polar vortex (+AO/NAO)".

However, despite a wealth of research supporting the notion of a late season disruption of the polar vortex, as of late Monday evening guidance did not have any such suggestion. That has since changed.

 

Potential Stratospheric Warming Analog

Both the European and the GFS have come into strong agreement on a polar vortex split in the vicinity of February 10th, where as one half of the polar vortex is sent into southeastern Canada, which would act to eventually supply cold air to the northeastern US.

 

 

This represents a significant deviation from the displacement of the polar vortex that took place during the primary polar analog of February 2023, which sent the polar vortex careening onto the other side of the globe. Additionally, an extreme RNA pattern ensured that whatever cold was able to load over the CONUS was heavily biased west.

 

February 2008 featured a similar displacement, which focuses pedestrian cold values over the north and deep interior.

 

Perhaps a more viable analog to what is modeled to transpire in the stratosphere later this month is the February 2018, during which the polar vortex actually remained on this side of the globe.

 

There is still plenty of time to monitor and glean greater insight as to how exactly this stratospheric disruption will evolve, but in the mean time, enjoy the reprieve in the form of a moderation in temperatures before winter storm prospects increase by mid month. The caveat being that this milder interlude will be heralded in by 1-3" of snowfall on Sunday night given that the current air mass is of arctic origin. These are type of southwest flow events (SWFEs)/warm air advection events that identified in the Winter Outlook as the type of precipitation events that would predominate the month of February.

 

 

Sunday night's light snowfall will rapidly melt during a very pleasant Monday.

 

 

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Messy Thursday on Tap This Week

First & Final Call 

Synoptic Overview:

The first in a long line of northern stream systems will travel the atmospheric conveyor and arrive in region during the day on Thursday. Given that this northern stream jet is so prevalent and the flow so fast, none of these storms will be particularly strong and they will all be fast moving.

 

 

Expected Storm Evolution:

Snowfall looks to break out after the AM commute on Thursday throughout the vast majority of the region, as it will begin my mid morning southwest and later morning northeast.

 

 

Snowfall will mix and change over to sleet and rain to the south of the Mass pike and near the coast during the afternoon prior to ending, as a warming WSW flow aloft will accompany the storm system into the region. 

 

 

There could be hazardous period of glaze over northern Connecticut, southern portions of the Berkshires and Worcester hills.

 

FIRST & FINAL CALL:

 

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First Call for Weekend Snowfall

Several Inches Likely OverNight Saturday Into Sunday 

Synoptic Overview:

The next in a succession of northern stream impulses will approach the area this weekend.

 

The primary difference with this system relative to many of the disturbances that we have dealt with this season is that looks to be intensifying on approach, as opposed to shearing out.

 

 

This is due at least in part to the Alaskan ridge growing in amplitude, which in turn lowers heights downstream and allows the wave to "dig" a bit on approach.

 

Expected Storm Evolution:

Snow looks to break out early in the evening on Saturday from southwest to northeast, and the precipitation shield will have overspread the entire region prior to midnight.

 

Snowfall will mix with sleet and rain along the south coast and especially the cape and islands during the predawn hours on Sunday, with a complete change to to rain likely over the outer cape and Nantucket island.

 

The heaviest amounts should occur in bands that will set up to north of the track of the developing mid level low during this time, along and north of the Mass pike.

 

 

Precipitation should begin to taper off Sunday AM, and wind down as snowfall everywhere by midday Sunday.

 

FIRST CALL:

 

 

Final Call will be issued on Saturday.

 

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Verification for Messy Thursday

Fairly Strong Forecast

Here is the reality versus the forecast for the messy Thursday, weak storm system that impacted the region yesterday.

 

The mid level warmth was slightly more aggressive than implied in the forecast, so the 1-3" area would have been better represented by a coating to 2" range, and the 2-4" maximum area to the north should have been 1-3". The slight glaze did indeed materialize towards the end of the event across a large majority of the area, as expected. 

Final Grade: A-

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Final Call for Weekend Snows 

No Major Changes to Forecast

Synoptic Overview:

There are no significant changes to the synoptic forecast overview from First Call on Thursday.

The next in a succession of northern stream impulses is approaching the area this weekend.

 

The primary difference with this system relative to many of the disturbances that we have dealt with this season is that it is actually intensifying slightly on approach, as opposed to shearing out.

 

 

This is due at least in part to the Alaskan ridge growing in amplitude, which in turn lowers heights downstream and allows the wave to "dig" a bit on approach.

 

Expected Storm Evolution:

Snowfall will overspread this area quickly this evening from west-southwest to east-northeast, rapidly becoming heavy over southwestern New England, where very heavy bands become established later this evening.

 

 

This will represent one potential area of somewhat higher snowfall totals across the region.

 

 

Some mixing with rain over the outer cape and islands will cut down on accumulations in those locales.

 

The other area of subtle enhancement will be to the north, as the banding to the south weakens a bit as it translates eastward, and the best lift focuses north Sunday morning. This will become evident in radar imagery as the morning progresses and echoes over especially the south half of the area rapidly weaken.

 

 

However, snowfall will be more tenacious to the north of the developing m id level low, throughout the route two region, which will prolong the storm and allow this area to catch up a bit with the southern zone of enhancement.

 

Drier air will end the snowfall more quickly to the south, as any rain rapidly transitions back to snowfall before ending on the cape and islands early Sunday afternoon.

 

 

Final Call:

 

First Call Issued Thursday February 6th.

 

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Forecast for Weekend Snows Too Aggressive 

Dry Air Mitigating Factor

Clearly the forecast for this weekend's snows was not one of the better efforts from Eastern Mass Weather,  as the 6-10" and 5-8" forecast ranges ended up verifying as 5-8" and 3-6".

 

The short answer as to why this was the case is that the encroachment of the drier air from the south, as discussed in the Final Call, was both faster and more aggressive than expected. 

 

 

This acted to essentially put an end to accumulating snowfall by around dawn on Sunday, as opposed to lingering throughout much of the morning.  There were some subtle warning signs amongst guidance that snowfall could be a slightly less prolific than forecast as a direct result of less proficient snow growth.

Lift and Moisture Less Than Ideally placed Within Snow Growth Region

Here is data derived from the NAM forecast sounding for Lawrence, MA during yesterday's

storm.

 

Note how the maximum area of lift and moisture was not colocated with the -12 to -18c snow growth region, which is the ideal thermal range within the atmosphere for moisture and lift to combine for the optimal production of snow flakes, which of course accumulate the most efficiently. While this data was considered, it was obviously not weighted heavily enough into the forecast. The reason forecasting is so difficult is because not only is it incumbent on the forecaster to complete an exhaustive review of the data, but its also crucial to determine how heavily two weight each piece of data and when to disregard.

 

Final Grade: C+

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Active Pattern Set to Continue into Mid Month 

Tropics & The Pole Initially Conflict

There were two assertions made by Eastern Mass Weather with respect to the month of February, and the fact that they have both come to fruition is making for some challenging forecasts with respect to storm tracks because they reality is that they both conflict with one another.

Maritime Continent Forcing to Remain Prevalent Throughout First Half of Month

Currently the MJO is in phase 6 and approaching phase 7 at a fairly strong amplitude, both of which tend to favor lower heights in the west and greater heights in the east.

 

Note the shift to the east of the east coast ridging and the building of higher heights in the west, which serves as a prelude to the changes that will grow more prevalent beyond mid month.

 

While intuitively one may suggest that this promotes in inland track of east coast cyclones, that is not always the case, as is the cast with storm number one on Tuesday.

 

Note that the system is forecast to pass south of the area and out to sea. despite the east coast ridge. However, if there were more of a trough on the east coast, the wave could potentially "dig" more, which could allow it to amplify and track further up the coast. Thus the more precise way to articulate this is that Maritime continent forcing is simply more unfavorable for major east coast winter storms because the east coast ridging that it promotes is hostile in a multitude of ways. However, tropical forcing does not operate in a vacuum, and there other global influences that can dictate the pattern. Namely, the higher latitudes.

Ensuing Polar Vortex Split Will Play A Role

 In addition to a return to Maritime continent forcing and west coast troughing, the other Eastern Mass Weather postulation that is coming to fruition this month is a major disruption of the polar vortex, which will take place early this week. 

 

 

Not only will the disjointed polar vortex lobe supply antecedent cold air masses in advance of storm systems, but it will also act to foster the development of higher heights around the pole, which will only grow more prominent and represent added resistance to inland tracks towards mid month. While this next storm system on Thursday is an example of Maritime continent forcing mitigating an east coast storm opportunity via higher heights allowing for a more inland track, the aforementioned antecedent cold will also be evident. There is likely to be a few inches of snowfall across at least the interior prior to ending as sleet and rain.

 

Cold will become more prevalent and there will be added resistance to inland tracks of low pressure systems as the month of progresses. A potentially major storm next weekend looks to at least deposit several inches of snowfall across the area prior to any mix or change to sleet and rainfall.

 

 

Beyond mid month tropical forcing will begin to augment the building of heights near the pole as the MJO approaches phase 8.

 

Stay tuned for First Call for the Thursday system tomorrow night and more update on the potential weekend system throughout the week.

 

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First Call for Probable Major Holiday Weekend Mess 

Snow to Potentially Extended Icing & Rain

Messy Thursday AM commute to Serve as Prelude to Weekend

Although it is certainly not a significant storm, the weak system moving through tonight into tomorrow AM is timed to unfortunately coincide with the morning commute, thus is advised to allow for extra time.

 

Snowfall accumulations will range mostly between a coating and an inch, with some spots near the Vermont and New Hampshire border near 2" before a change to a bit of ice and rain. Then the focus shifts to this weekend, which is destined for more significant travel disruptions.

Synoptic Overview:

This weekend, a southern stream wave will begin to interact with a lobe of the polar vortex pinned to the south of a potent -NAO block.

 

The combination of antecedent elevated east coast heights attributable to the Maritime continent phases of the MJO and the -NAO block being positioned sufficiently north as to allow a partial midwest phase will maintain enough eastern ridging to allow for an inland track of the low. 

 

 

This will delay the transfer of the mid level low to the coast until the system reaches a very high latitude, which will ensure that snowfall will be limited across much of the region. However, once the system progresses far enough to the east, the it will begin to be influenced initially at the surface by confluence due to the tandem of the -NAO block and the potent 50/50 low. 

 

Precisely how quickly this occurs will crucial to whether or not a portion of the area receives a significant ice storm on Sunday.

 

Expected Storm Evolution:

Precipitation will break overspread the region as snowfall from southwest to northeast on Saturday evening.

 

 

After a few inches of snowfall, precipitation will rapidly transition to some ice and rain to the south of the Mass turnpike by midnight late Saturday evening.

 

The transition will quickly over spread the remainder of the region by daybreak, after several inches of snowfall. It is at this point that an extended period icing may occur across the deep interior, as the confluent flow to the north retards the retreat of the antecedent cold.

 

 

Then precipitation may change to rainfall across the vast majority of the day on Sunday for at least a brief period, due to the inland track of the primary mid level low.

 

However, later in the afternoon, as the surface low potentially transfers to the coast, colder air may once again be advected from the northeast down the coast, which would reintroduce icing issues across especially interior northeastern Mass over through the eastern slopes of the Worcester hills.

 

Stay tuned for an important update on Friday night or Saturday morning, given that some modifications to the forecast will likely be necessary as details of this evolution become clearer.

 

FIRST CALL:

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Final Call for Messy Holiday Weekend Storm

Snow to Rain Near the Coast & Significant Ice Inland

Synoptic Overview:

The larger synoptic scale overview remains unchanged from Wednesday's First Call.

This weekend, a southern stream wave will begin to interact with a lobe of the polar vortex pinned to the south of a potent -NAO block.

 

The combination of antecedent elevated east coast heights attributable to the Maritime continent phases of the MJO and the -NAO block being positioned sufficiently north as to allow a partial midwest phase will maintain enough eastern ridging to allow for an inland track of the low. 

 

 

This will delay the transfer of the mid level low to the coast until the system reaches a very high latitude, which will ensure that snowfall will be relatively limited across much of the region. However, once the system progresses far enough to the east, it will begin to be influenced initially at the surface by confluence due to the tandem of the -NAO block and the potent 50/50 low. 

 

 It now appears as though the surface low will redevelop on the coast quickly enough so that a portion of the area receives a significant, albeit manageable ice storm on Sunday.  

 

Expected Storm Evolution:

Precipitation will overspread the region as snowfall from southwest to northeast on Saturday evening.

 

 

 

After a few inches of snowfall, precipitation will rapidly transition to some ice and rain to the south of the Mass turnpike after midnight early Sunday morning.

 

 

The changeover will slow somewhat as it works into northern areas by mid day due to increased resistance from confluence. However, the potent primary mid level low to the west will ultimately win the battle and snowfall will give way to ice.

 

 

And then eventually rain, outside of perhaps northern Worcester country during the afternoon.

However, towards evening the surface low will transfer to the coast, which will re-advect colder air from the northeast down the coast. This would reintroduce icing issues across especially interior northeastern Mass over through the eastern slopes of the Worcester hills.

 

In fact, precipitation may even change back to snowfall prior to ending entirely later Sunday evening.

 

 

FINAL CALL:

 

 

First Call issued Wednesday, February 12 @ 830pm:

 

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Major Storm Threat Next Week Likely to Yield More Bark Than Bite

Recurrent Pattern Renders Major New England Strike Unlikely 

Tropical Constructive Interference with Pole Triggers Major Storm Threat

Last weekend it was explained that the MJO would be moving out of the Maritime Continent, which is where it currently is as this weekend's system tracks inland, and into phase 8 towards mid month.

 

The implication of this is that the tropics would begin to constructively interfere with the disturbed polar domain from approximately mid month onward.

 

Guidance has began to reflect this, as ridging begins to build out west behind a departing Pacific wave that is forecast to eventually phase with one of the split polar vortex lobes. beneath the negative NAO block.

 

 

Guidance is in good agreement on the overall pattern next week, which bares striking similarities to a major storm threat from January

Redux of January PNA Ridge Structure Likely to Yield Similarly Flawed Phase

The modeled 500mb pattern on the European ensemble mean at first glance appears immensely ominous next week, which is why many media outlets have already began to sound the alarms on a "historic blizzard" potential. 

 

However, there is ample reason to doubt that this system will phase proficiently enough with the southern stream wave moving up the coast to impact the forecast area in a major way. Note the similarity in the forecast position of the PNA ridge next week in the above image to that which preceded the major storm threat of January 11th.

 

This has been a very prevalent feature in the seasonal mean, which may at least partially explain the relative absence of major snowfalls across the region despite the relative cold temperatures.

In the instance of the storm threat from last month, there was a significant amount of guidance that phased the systems very well, which yield a blizzard throughout the forecast area. However, that of course did not happen, as the phase was very "ragged" and the region ended up with a light to moderate snowfall. There is strong ensemble consensus in this pattern taking shape once again, as the GFS and Canadien ensemble mean both strongly supported the previously posted European ensemble mean.

 

This lends support to the notion that the storm system next week is unlikely to affect the region with anything more than a light to moderate snowfall, given that the position and orientation of the ridge out west is likely to hinder the eventual phasing attempt over the eastern US.

Stay tuned for a potential First Call on Monday night-

 

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Strong Messy Weekend Forecast

Here is the Eastern Mass Weather Final Call versus reality.

 

 

 

The snowfall forecast was very good, however, ice should have been stressed. more over Connecitcut as opposed to northern Worcester country, since low level cold was tenacious enough to prolong sleet over central Mass.

 

Final Grade: A

 

[Prismshine Productions]

 

Strong Messy Weekend Forecast

Here is the Eastern Mass Weather Final Call versus reality.       The snowfall forecast was very good, however, ice should have been stressed. more over Connecitcut as opposed to northern Worcester country, since low level cold was tenacious enough to prolong sleet over central Mass.  

Final Grade: A

 

Well done Ray

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Thursday Storm Threat by the Wayside as Expected

Potentially One More Storm Threat to Close the Month

Some Light Nuisance Snows Possible Thursday Across Outer Cape & Islands

On Friday Eastern Mass Weather asserted why there was unlikely to be major winter storm impacting the region on Thursday. Similarities were noted between the modeled pattern over the western CONUS and other instances throughout the season that have greatly inhibited the ability of the streams to sufficiently phase and for energy to turn the corner and come up the coast.

The most prominent comparison was made between the forecast position of the PNA ridge next week (now tomorrow) in the above image to that which preceded the major storm threat of January 11th.

 

The placement of this ridge has been a consistent feature in the seasonal mean, which may at least partially explain the relative absence of major snowfalls across the region despite the relative cold temperatures.

Short term guidance with respect to the near miss tomorrow is no different.

 

 

 

 

The nuance pointed out in the large scale pattern is why a blizzard is not on the table, but the small vortex over southeastern Canada is why a portion of the area is not going to be able to muster a moderate snowstorm. 

 

 

 

As it stands, the outer cape and islands may muster as much as 1-3" of snow tomorrow, but the balance of the region will one relegated to flurries. Then the weekend finally begins to warm up before we await the next potential storm threat to close the month of February.

 

One Final Threat to Close Out an Active Month of February

There is telconnector support for a storm system represented by increased modularity within the polar domain (transition across NAO and AO) in the vicinity of the turn of the month.

 

 

This is also evident on all three major ensemble camps, but what is apparent is that all three ensemble suites have the position of the western ridge right near the coast, which is where it has been for the vast majority of the season.

 

 

Thus in the interim, any deterministic solutions implying major coastal cyclogenesis are likely to be in error, as they have been all season. Coastal development will likely be moderate with any major development likely to be either further down the coast, or in this instance more likely on the coast or just inland.

[RUNNAWAYICEBERG]

When does the work start for next winter?

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13 hours ago, RUNNAWAYICEBERG said:

When does the work start for next winter?

June

[H2Otown_WX]

We here at Eastern Mass Weather feel we are long overdue for a 200" season

[RUNNAWAYICEBERG]

1 hour ago, H2Otown_WX said:

We here at Eastern Mass Weather feel we are long overdue for a 200" season

We here in western ct need a 20”+ event next winter…

[Prismshine Productions]

Predication:

We start off torchy, big backend winter

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