Potential 3-5 day thaw coming

[Ginx snewx]

Donnie Baseball and Matt Rodgers schooling JB

If, by his comment that the "back of winter is broken" he means the worst cold in absolute terms will be past, I agree. If, however, he believes the remainder of winter will see temperatures average above normal with little or no snowfall prospects, I disagree.

IMO, the upcoming thaw that should set in around mid-month +/- a few days will last 1-2 weeks. Previously, forecasts that each period of moderation would mark the end of the winter proved incorrect on several occasions. Similarly, the cold anomalies that accumulated have shattered numerous "warm winter" forecasts.

I suspect that any "end of winter" forecasts will meet a similar fate to the earlier ones this time around. In fact, it would not surprise me if much of the northern half of the U.S. (including New England, the Great Lakes region, southern Ontario, southern Quebec, and Middle Atlantic region) is colder than normal at the end of February into the start of March, along with some opportunities for snowfall. Ultimately, winter will yield to spring. But before then, I expect that there will be some additional highlights.

I'm looking at the European ensembles this morning, Don, and it seems like they are limiting this "Feb Thaw" to about a week and that your assessment here is looking really good.

[CoastalWx]

Everything about that map looks mediocre, though, for a wintry pattern in SNE: the NAO block is much too east-based, the EPO manifests itself more of an Aleutian ridge which leads to lower heights in the west, and the SE ridge is getting out of control.

0z GFS was a torch in the long range:

This isn't too unusual for February in a strong Niña however...both 1988-89 and 1954-55 saw the trough shift into the west for most of February.

It's pretty mediocre for maybe your area on south. The point was that even that setup would be enough for an overrunning or miller b scenario if it were to happen. You can see what I mean by looking at the mass fields.

Notice the boundary south of sne, high pressure building in from the Canadian prairies and low pressure moving into the central high plains. Storm track looks like classic Nina with storms riding fromTX through the OH valley, so we will need some ridging in the poles to help out. Whether it is some sort of EPO or NAO. It also may be a case where we shouldn't rush things. IOW pattern might take a bit to cool down.

[Typhoon Tip]

I thought I would start a thread on the longer term pattern development...beyond next week's storms threats.

This is probably not what winter enthusiasts want to see in the title of the thread, but its time to face the very real possibility of a decent thaw and period of milder weather before going back intot he winter pattern. All ensemble guidance is beginning to hone in on a long wave pattern that supports a much milder regime over the CONUS...we'll try to get to New England specifics in a bit...but here are the GFS super ensemble analog guidance for day 8 (Feb 13)

Notice how there is a lot of troughing going on over Alaska and also in the PNA region. The ridging has been pushed well southwest of the optimal position for delivering cold into the CONUS. The leftover cold and lower height are still hanging on over the northeast US.

Now lets roll the analog dates forward 4 days:

The developing ridge in the SW US has now pushed well into the middle of the country and east of the Mississippi. Virtually zero arctic air to be found in the CONUS as the low heights over the PAC NW is mainly modified Pacific air.

Now another 4 days forward and we are in full torch mode on the composite.

But notice how the NAO and the EPO have just become to look more favorable on the last composite...the ensemble mean actually shows something similar which would spell the end of the milder period and begin dumping cold back into the CONUS...perhaps in the Feb 20-25 period. This could be the beginning of our winter finale over the late Feb to mid March period.

The latest MJO forecast is in good agreement amongst the model ensemble guidance as well with a strong wave headed into phase 6 out of the circle of death. Phase 6 supports a PV well north as seen in this DJF composite of above avg amplitude phase 6 waves from RaleighWx's page:

However, if you remember from earlier in the season when we were first predicting cold in early December, you might recall that phase 6 was decent in December. Well its not so good later in the winter as this February-only composite for phase 6 shows:

You can it basically supports a torch in the eastern US.

As mentioned above, the pattern should come to end though fairly swiftly as the MJO wave is forecasted to go robustly into phase 7 and phase 8. Both of which support a much favorable Pacific pattern and a return to arctic cold to the CONUS. So while its possible we get pretty mild, it shouldn't be a long lived spell. I know Don Sutherland was pointing this out as well a few days ago in his thread on the main wx side. The NAO is also quite possibly going to come back into a favorable state as well, so we could see a pretty nice pattern set up in both oceans after we rid ourselves of this milder one.

The caveats:

-Ensembles show a pretty strong PV NE of Hudson Bay...more so than the analog composite would suggest. This can keep some sneaky cooler air into New England so we might only get a modified version of the milder look and still even sneak a few snow threats out of it with pseudo overrunning type storms.

-Ensembles have really struggled in the medium to long range over the arctic and especially with the NAO. NAO could build back and retrograde a ridge from Scandanavia sooner than what is modeled which wouldn't be terribly uncommon. That might push the PV SE more and cool off the northeast...particularly SE Canada and New England despite the ugly Pacific pattern.

- Low level cold might hang on tougher than the mid-levels in this set up.

Ballz of steel, ma-man, balls of steel bringing that talk 'round deez parts.

Ha ha, I made a post 10 days ago about many of these same ideas and was met immediately with strong opposition - as though I had crept through a bedroom window and stolen the first born child (oh, they stopped short of making the rebuttals personal but I could tell they didn't like me for it at the time). But, I even annotated some graphics showing teleconnectors converging on a warm signal then - funny how those statistics part of those ideas don't garner as many post responses

I have a Met buddy who said, "I am sick of snow. If this ended tomorrow and we lurched into an early spring, I couldn't be happier" (outside of this immediate community of enthusiasts and Meteorologist, I am finding this attitude burgeoning). This is the same cat that was wishing on chaos two weeks before. We were talking, there always something that happens to stop the snow pack from getting out of control. I have never seen it higher than 40" - that 1996, just before THAT season's f-up leveled down to 0 in a matter of days off of 2 southerly gale events to 60+ DPs! This year...there are spot totals out there, but most are around 30-35 before yesterdays matting took place. It appears just eye-balling that despite never going above 33F during yesterdays 12 hours of light rain, we are settled down to 27 or so". Not bad, but far from what this pattern could have been. There were at least 3 events in this 40 days stretch where the totals wound up significantly less than was conceptualized off of veracious forecasting efforts (not wishcasting by any means). Those probably atone for 20" total of missed because of permutations on the fly - in a way, this season f'ing up began actually during those events, and will culminate the f-up by run at sunny days pushing 55. Bye-bye snow pack!

If that happens that is...

Having said all that, although your analysis is very good, we can vary the interpretation within reasonably objective analysis depending on what data sourcing we use. Take the overnight teleconnectors from CPC for example. The NAO is modestly positive beginning now at some ~+.7 SD, but we see a rather concerted descent taking place, dropping the mean down to nearly 0.0 before the members mop-end into dischord over where the index will be 2 weeks from now. Nearing D15, about 2/3rds of the members are above 0.0 (averaging ~+.5 so not really alarmingly a warm signal by any means), while 1/3 are negative (also only modestly so). The overall modality over the next 15 days, however, is for dropping NAO. This is actually more discerned at CDC, but I have come to find via years of experience that the CDC index values are less useful for ferreting out periods of pattern change (it actually makes sense when one considers that CPC deal only with mid level geopotential anomalies, where as the CDC uses only low level mass flux anomalies - the mid levels (as we know) drives the surface features in the 101 sense of things).

At the end of the day, ...for now the NAO is not alarmingly throwing off an warm signals, and in fact the opposite, flagging some cool insert into at least the NE CONUS.

The PNA is a dagger in the heart of the enthusiasts. Both the CPC and CDC hammer the -PNA to the beat of the deepest expression of the cold season thus far. You don't really want that in February when the sun is making gains every day. About this latter factor, the sun on a sunny day - even a cold one - in middle February can eat snow packs. I recall one afternoon over BARE ground while at UML a high temeprature of 60F on a near calm sunny afternoon with the 850mb temperature of 32F. That was all sun doing that. Particularly if there is dark debris embedded in the snow you can see this destruction happen. Snow banks become "shard" in appearance, and the trunks of trees in deep ambient snow develop doughnut moats on the south side. I have noticed over the years that this sun-factor of fighting albedo to incur damage on snow really thresholds over on or about February 10th. The difference in sun-eat ability is noticeably different between Feb 5th and the 15th. If you are a winter weather enthusiast, you don't want a 21 member GFS heavily concerted drop to -1.5SD when the sun is seasonally introducing spring.

As a quick side note on the recent operational GFS depictions: There is a one whopper of a temperature gradient setting up across the CONUS. along and N of 40N there is some mighty cold. Right around 40 N or just south of there by a click or two there is on average 42DM of thickness gradient packed into about 200 miles, S of which there are values as high as 568DM over Texas. That could mean 83F at Dallas while it is near 0 at Tower MN. All of this is in the la-la range of the GFS run, granted, but I just though it interesting that sort of depiction has been emanating from the deterministic run as of late.

What could compensate this PNA: A) Said neutralization of the NAO, which is actually more negative than that if one just uses the ESRL/PLD values - but that is never a good idea to just use one source when several avail. the EPO is forecast to spend 5 or 6 days spiking to over +1SD, but then resumes a neutral-negative appeal smartly by D7 crash. The question here with me is whether it spends enough time in positive mode to have impact on the temperature distributions? My immediate guess is some, but not a whole helluva a lot. The predominating signal is neutral negative, and seeing it smartly reacquire that signal after D7 is probably more telling. It seems a sub-conclusion here is more more of the same for this winter thus far, and that is the polar field indices really trying to establish proxy on the pattern, including temperature and to some degree (no pun intended) the precipitation anomaly distributions.

The AO is a real wild card. Rumor has it that the ECMWF ensemble stratospheric guidance are flashing a SSWE. I have been pinging the CDC's monitoring source daily, and though there are some warm nodes spanning the last several weeks, none of these are propagating in nature - a key characteristic leading -AO response. Nonetheless, we shall have to see if the ECMWF ensembles are correct, and whether this emerges shortly here and indeed begins propagating. If so, the AO will tank near the end of this month; or depending on when the emergence/propagation really happens, usually 20 days post those occurrences. That of course does not include the time period in question, but it is on the table for the season as a whole.

All in all your analysis is spot on, but this just offers a slightly different take based on these other discrete sources. So taken for what it's worth .... Could we end up colder along and N of 40N? I think that is a distinct possibility, though far from certain. One thing is for certain, should we establish all that gradient, that will only help the enthusiast should storms move through.

[ORH_wxman]

John, good post. I do agree that there is a chance we could stay a bit cooler in terms of anomalies than further SW and W into the midwest/plains. I think I mentioned that exact scenario at the end of my original post....we could get some colder air bleeding down from Quebec if the setup is right. Hard to say exactly how that shakes out yet. There is a pretty potent Scandanavian ridge that develops and its not uncommon at all to see that retrograde into the NAO region....its not currently progged to do that, but we could end up seeing that as we get closer. It would certainly help in pushing the gradient a bit further south.

[Typhoon Tip]

John, good post. I do agree that there is a chance we could stay a bit cooler in terms of anomalies than further SW and W into the midwest/plains. I think I mentioned that exact scenario at the end of my original post....we could get some colder air bleeding down from Quebec if the setup is right. Hard to say exactly how that shakes out yet. There is a pretty potent Scandanavian ridge that develops and its not uncommon at all to see that retrograde into the NAO region....its not currently progged to do that, but we could end up seeing that as we get closer. It would certainly help in pushing the gradient a bit further south.

Yes, exactly - in fact, it wouldn't sound absurd to me at all if some astute poster went so far as to say these teleconnectors outright signal wedge cold like that, as well as overrunning (Scott )

ha ha, yea you.

Anyway, the 00z ECM has at least one day of balm ...maybe 2, then a polar high and cold crash nearing D10 la la range.

[CoastalWx]

Yes, exactly - in fact, it wouldn't sound absurd to me at all if some astute poster went so far as to say these teleconnectors outright signal wedge cold like that, as well as overrunning (Scott )

ha ha, yea you.

Anyway, the 00z ECM has at least one day of balm ...maybe 2, then a polar high and cold crash nearing D10 la la range.

I mentioned this in the other thread that this delicate balance of having the cold wedge in here, just before low pressure crosses over or just of sne, can be observed on the GFS op. It seems like just a slight adjustment in the heights up by the EPO and NAO region have a big impact in the sensible wx in sne.

It's 100 miles from people claiming the winter '10/'11 lives on...or people like Ray and Kevin going rafters as the snowpack melts away. That's the gradient that we could be talking around here....potentially anyways.

[Organizing Low]

the 12z GFS looked better compared to yesterdays 12z i thought.....much briefer and less threatening out west.

[Typhoon Tip]

My snow pack is taking a major beating today... We are nearing 40F and the near full sun feels hot - and the snow level just dropped 3" since this morning where I estimated 27" - if we did this every day we'd be down to mud in a week.

Wow, so much power laying it down, yet so tenuous is its residence.

[Organizing Low]

My snow pack is taking a major beating today... We are nearing 40F and the near full sun feels hot - and the snow level just dropped 3" since this morning where I estimated 27" - if we did this every day we'd be down to mud in a week.

Wow, so much power laying it down, yet so tenuous is its residence.

oh ya

it will be gone in a blink if the conditions are ripe.

[donsutherland1]

Great discussion and analysis, Will. Hopefully, before the onset of the thaw, Tuesday's event will prove a little colder and snowier than presently modeled.

[40/70 Benchmark]

I'm glad Will made this thread, even though weenies hate it. It's the reality we face, with the possibility that the snowpack around here has peaked.

Snowpack has def. peaked.....a little earlier than it had to, since the epic model fail for last night and now the bomb falling by the way-side.

Feb 1969 lives on.

[Clinch Leatherwood]

Snowpack has def. peaked.....a little earlier than it had to, since the epic model fail for last night and now the bomb falling by the way-side.

Feb 1969 lives on.

http://forecast.weather.gov/product.php?site=NWS&&format=CI&version=1&glossary=0&highlight=off&issuedby=BOX&product=RWR

Two days now of a big thaw here with maybe three coming Monday. Joyce says after this week the jet goes flat, I agree the days of "snowmageddon" are done. We may get more snowstorms but the epic month is done.

People are trusting models at day ten to give a temp picture when they've been too cold at 48 hrs for a week.

One station not a mountain below or at freezing at 1pm. Torch!

[weatherMA]

http://forecast.weat...BOX&product=RWR

Two days now of a big thaw here with maybe three coming Monday. Joyce says after this week the jet goes flat, I agree the days of "snowmageddon" are done. We may get more snowstorms but the epic month is done.

People are trusting models at day ten to give a temp picture when they've been too cold at 48 hrs for a week.

One station not a mountain below or at freezing at 1pm. Torch!

Get the mower ready.

[ORH_wxman]

Get the mower ready.

Not long until he has it out.

[Organizing Low]

man this really is the only place one can wallow in the pity of a thaw.

all other regions: i welcome the thaw and cant wait for spring!

whats up with that, we still have 2 more months of winter here, lets try and keep this to a minimum.

[ORH_wxman]

man this really is the only place one can wallow in the pity of a thaw.

all other regions: i welcome the thaw and cant wait for spring!

whats up with that, we still have 2 more months of winter here.

Well we have a ways to go in winter compared to areas further south...the climo really tightens the noose on the gradient in late February and March.

Luckily, I think most signs are that we get back to more wintry type pattern toward the end of the month after this milder period. Hopefully we can mitigate the thaw a bit with some sneaky cold air from the PV in E Canada. We'll have to wait and see. We get a nice arctic blast after the Tuesday event....then its a lot of questions after that moves out.

[Organizing Low]

Well we have a ways to go in winter compared to areas further south...the climo really tightens the noose on the gradient in late February and March.

Luckily, I think most signs are that we get back to more wintry type pattern toward the end of the month after this milder period. Hopefully we can mitigate the thaw a bit with some sneaky cold air from the PV in E Canada. We'll have to wait and see. We get a nice arctic blast after the Tuesday event....then its a lot of questions after that moves out.

very true about the south, i understand that for sure.

yeah im just focusing on the fresh cold thats going to move in after the tuesday event.

lets see what happens after that, but first step is to get this post MW blizzard stale air out of here pronto.

[Clinch Leatherwood]

man this really is the only place one can wallow in the pity of a thaw.

all other regions: i welcome the thaw and cant wait for spring!

whats up with that, we still have 2 more months of winter here.

I love all weather. I love spring more than any other season, longer days, more sun.

You guys are all talking about a potential thaw when it's 40+ now, and was in the 50s yesterday. Thaw is here.

Already the canal is full of bikers and roller bladers.....

46 here weenies out everywhere

[Baroclinic Zone]

I love all weather. I love spring more than any other season, longer days, more sun.

You guys are all talking about a potential thaw when it's 40+ now, and was in the 50s yesterday. Thaw is here.

Already the canal is full of bikers and roller bladers.....

46 here weenies out everywhere

Yup, 45F here. Wearing shorts outside since 45F is the new 60F given where we've been this winter.

[CoastalWx]

It does feel nice out, but a little preliminary to claim winter is over and high sun angle torching everything. It's the beginning of February and we've had plenty of days where snow sticks to everything once it starts to fall. The sun angle argument is weak imo.

[Baroclinic Zone]

It does feel nice out, but a little preliminary to claim winter is over and high sun angle torching everything. It's the beginning of February and we've had plenty of days where snow sticks to everything once it starts to fall. The sun angle argument is weak imo.

Sun angles been getting higher since mid-Dec.

[ORH_wxman]

I love all weather. I love spring more than any other season, longer days, more sun.

You guys are all talking about a potential thaw when it's 40+ now, and was in the 50s yesterday. Thaw is here.

Already the canal is full of bikers and roller bladers.....

46 here weenies out everywhere

Well today is a temporary thaw...esp down in your area. But we'll see how it feels in 3-4 days.

The real thaw is not until next week.

[weatherMA]

41F here with cloudy skies. Thats like 5 or 6 above normal. Not a torch.

[CoastalWx]

Sun angles been getting higher since mid-Dec.

Sure it gets stronger, but people act like it's a mid April sun because it's in the low 40s. We'll how that sun angle feels a few days from now.

[Baroclinic Zone]

41F here with cloudy skies. Thats like 5 or 6 above normal. Not a torch.

I think ORH average for this time of year is around 32F so to be 9F over would be pretty substantial.

[Baroclinic Zone]

Sure it gets stronger, but people act like it's a mid April sun because it's in the low 40s. We'll how that sun angle feels a few days from now.

mid to upper 40's for just about all of SE MA/ S RI/ S CT.

[CoastalWx]

mid to upper 40's for just about all of SE MA/ S RI/ S CT.

That only enhances my argument.

Next week is when a true "break" may happen, but the duration and strength is up in the air for sure.

[OSUmetstud]

mid to upper 40's for just about all of SE MA/ S RI/ S CT.

44 here. beautiful though...the icy layer on top of the snowpack will keep from too much damage being done.

I actually think this is my record lifetime SWE on the ground.

[weatherMA]

I think ORH average for this time of year is around 32F so to be 9F over would be pretty substantial.

Fair enough. TWC tells me I average 34F (so +7), but not sure how accurate that is.

Splitting hairs though. Today is above normal but +6 or +9, not a torch.

[Baroclinic Zone]

That only enhances my argument.

Next week is when a true "break" may happen, but the duration and strength is up in the air for sure.

No doubt, but today is a prime example of what happens when you don't have arctic air around. Usually when we have a system blow through it gets cold on the back side. Not with this one. 850's are running at -3F and we are in the upper 40's. Looks like the NAM and GFS are busting about 10F too cold right now with 2m temps.