Friday February 8th Storm Potential

[Edge Weather]

The ECMWF starts to develop a low on Thursday at 114 hrs along the Alabama Gulf Coast, then moves the low through Georgia, the Carolinas, Virginia, and to the Delmarva, as it phases with a clipper dropping down from Canada and through Ohio.  It is nearly fully phased as it reaches the Delmarva on Friday morning at 132 hrs, and then it is fully phased as it reaches just south of Long Island at 138 hrs has a 988mb low.  As it moves across the Delmarva, it takes a path across Cape May, and then along coastal NJ.  At 144 hrs the low is located over Eastern Massachusetts as a 984mb low.  It then stalls the low out there and moves it slowly east on Friday night.  Total precip amounts are about 1.75 inches throughout our area.  It looks as if the precip could start as snow in northern sections on Friday morning, with a quick hit possible before the precip turned to rain, and then possibly back to snow before ending in most sections, with wrap around moisture depicted as snow here late on Friday.  However, a 100-150 mile shift eastward of this system and a slightly quicker deepening and this could be snow for everyone.  The Euro ensemble mean does appear that it may be about 100 miles further east, as at 144 hrs the ensemble mean has the low about 100 miles further east, about 50 miles to the east of Cape Cod, but I only have access to it at 144 hrs, so maybe those with the 6 hrs ensembles can shed some light.  The model had already indicated the possibility of a big storm in this time frame earlier in the week, so this is quite interesting. This morning's control run is in basically perfect agreement with the operational run, but is even slightly stronger with the low. 

[Edge Weather]

Ensemble member P010 from the 6z GFS is very close to the same solution, but not as deep with the low. 

[PB GFI]

You don't want the euro to verify. It's a rain storm. You don't snow on the backside of departing lows that move to you re NE. You dry out. Very different from Xmas 02 or jan 2011 So hope the euro is weaker and further east. Not a set up you wana see

[Edge Weather]

You don't want the euro to verify. It's a rain storm. You don't snow on the backside of departing lows that move to you re NE. You dry out. Very different from Xmas 02 or jan 2011 So hope the euro is weaker and further east. Not a set up you wana see

 

Well, even with this exact solution, people to the north and west start and end as snow.  It depicts snow on the back side because it has massive wrap around as the low continues to intensify and stalls out over Eastern Massachusetts.  It is still 5+ days away.  If it shifts even 100 miles further east and deepens just a bit quicker, most of us have a massive snowstorm.  The ensembles appear that they may be slightly east already, hard to tell though, but at 144 hrs the ensembles are definitely 100 miles further east, but don't have access to 138 hrs when we need it.

[NEG NAO]

there is not going to be a storm along the coast that intensifies - the indicies don't support it - both the NAO and PNA are forecasted to be close to neutral the end of this week or slightly negative or positive

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml

[MJO812]

there is not going to be a storm along the coast that intensifies - the indicies don't support it - both the NAO and PNA are forecasted to be close to neutral the end of this week or slightly negative or positive

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml

 

Euro has support from the ensembles which is really interesting. The one thing I have to say is that the Euro has bombed out way too many storms this season. None which have verified.

[NEG NAO]

Euro has support from the ensembles which is really interesting. The one thing I have to say is that the Euro has bombed out way too many storms this season. None which have verified.

exactly - still in this progressive pattern there may be a storm that develops down south but unless the indicies start cooperating its going to be more of this progressive unorganized pattern we are in so any storm will not have the chance to wind up and intensify coming up the coast..............

[MJO812]

exactly - still in this progressive pattern there may be a storm that develops down south but unless the indicies start cooperating its going to be more of this progressive unorganized pattern we are in so any storm will not have the chance to wind up and intensify coming up the coast..............

 

I agree with you

[Edge Weather]

exactly - still in this progressive pattern there may be a storm that develops down south but unless the indicies start cooperating its going to be more of this progressive unorganized pattern we are in so any storm will not have the chance to wind up and intensify coming up the coast..............

 

HM has been talking a lot recently in the Philly forum about how he did not believe the Lake cutter scenario for this storm I believe and how there would be more Pacific energy interacting soon, and he gave sound reasoning for both. 

[jm1220]

I wouldn't count on it, as long as we have an unfavorable NAO we'll continue to have these unimpressive clipper failures, or raging cutters. There's no support for a bombing low near us, period.

[MJO812]

I wouldn't count on it, as long as we have an unfavorable NAO we'll continue to have these unimpressive clipper failures, or raging cutters. There's no support for a bombing low near us, period.

 

MJO is about to get favorable for us. Maybe they will help us out. HM in the Philly thread was talking about how this storm might not be a GLC and track further south and east due to the clippers suppressing the pattern.

[easternsnowman]

Well, even with this exact solution, people to the north and west start and end as snow.  It depicts snow on the back side because it has massive wrap around as the low continues to intensify and stalls out over Eastern Massachusetts.  It is still 5+ days away.  If it shifts even 100 miles further east and deepens just a bit quicker, most of us have a massive snowstorm.  The ensembles appear that they may be slightly east already, hard to tell though, but at 144 hrs the ensembles are definitely 100 miles further east, but don't have access to 138 hrs when we need it.

euro 5 days out has not been too good lately.

[Edge Weather]

From HM in the Philly forum, posted on January 31:

 

If the modeling is mishandling the Tropical Pacific (if, really?!?! lol) then it makes sense that they are gradually bringing on the phase 1 WPO signal that transitions into a cold PNA signal mid-month.

1. The +WPO anomaly should retrograde based on the IO forcing and stratospheric trends (IO forcing more important). This needs to be watched for FUTURE stratospheric warmings. I'm telling you guys, this won't be as easy as last year's "downwelling cool upper stratospheric +AO signal." I could see another quick bottom-up warming from a wave 1 amplification and the initiation could be during the consolidation process of the IO wave--EA MT response (along with the N PAC low in tandem).

2. The long range ensemble means are useless when you have a rapidly revolving polar vortex with each member disagreeing on its position and speed...the average will look dumb. My advice is to supplement PV placement with Spag Plots and climo of Pacific Factors.

3. The Central Pacific forcing is still very much dominating the N Pac pattern with an equatorial KW shooting across the E PAC and a few RW heading into the western Pacific. This has broadened the area of forcing, strengthened the Hadley Cell here and extended the Pacific Jet. The anticyclone reached the Dateline a few days ago and is firmly entrenched. The upper low that breaks off to the East will supply the STJ in a few days to the CONUS.

 

You shouldn't worry about IO forcing. This time of year, the IO forcing basically brings a PNA pattern. The Feb 5-10 period is the TNH hangover with a slowly retrograding +WPO and displaced PV into Quebec, albeit brief displacement. The southern stream will become even more active next week, despite the -AAM tendency currently. This is a bit of a climo lag type of thing from the current regime in place.

I could see a substantial RNA develop 2/20-3/5 once we consolidate the wave into the IO early Feb and propagate into phase 4-5 (I think it will take some time for the C PAC to fully relax). However, I also expect the AO might try to go negative. It is quite possible (help me for saying this) that the Midwest sees a turn-around here late winter-early spring. A strong analog showing up is 1975 which brought a major April snowstorm to the Chicago area. This is just speculation because I'm still unsure about the stratosphere right now. My gut says March isn't a simple blowtorch this year / +AO.

There has been a MRG and KW in the IO leading the African Pulse as the MJO begins to make the transition into the Indian Ocean. There have been upper lows propagating poleward, slowly, from N. Africa into India / Himalayas. The question is: how long will it take for the Pacific convection to subside and the focus to become the IO? The longer the subsiding takes, the longer the anticyclone stays in place at the Dateline and subsidence stays over Indonesia (both are important for anchoring an Aleutian-PNA system). I agree with Mike that the MJO signal should go into the circle of death (because it really is a distorted signal at this point) and possibly remain in the 1-2-3-4 octants for a good chunk of Feb.

 

GFS shows a solid 110-120 knot jet slamming into the SW US 2/6-2/8 with no polar vortex retreat.

The first two "clippers" are real clippers, embedded entirely within the continental air mass / northern stream. The 2/5-2/7 systems are Pacific Origin technically and have a little more southern stream to work with. The next PV revolution southward comes on 2/10.

 

How will it play out?!?!?

 

Edit: naturally the post-truncation GFS becomes phase-happy which is complete nonsense. The -30c air behind the Arctic Cold front will push through quickly missing the southern wave as that trails behind leading to a potential snow event. I don't think this will be an inland runner. The only thing keeping me from being more confident is the lack of an appreciable -NAO; otherwise, I'd be calling for a KU.

[Weathergun]

The OP Euro is likely too amplified. But on every model the airmass is moderates too much, ahead of this storm.

[Edge Weather]

I have a question in to HM now asking whether he was specifically speaking of this potential.  I am sure he was talking about this coming weekend, just not sure if it was this day specifically, or the next one on Monday.  I will let you know if he responds. 

[jm1220]

MJO is about to get favorable for us. Maybe they will help us out. HM in the Philly thread was talking about how this storm might not be a GLC and track further south and east due to the clippers suppressing the pattern.

Well, we saw 2 weeks ago a low that was initially progged to be a cutter end up a minor clipper. There are reasons why we need a good NAO to have a real shot at a major snow event-it slows the upper air pattern down and allows for a favorable track for us. Without the blocking we had, 2010-11 would have been a disaster. Could it happen? Sure, but our odds are definitely against it given how progressive the pattern is. There's way too much chaos with multiple vorts whenever a storm does come near us, which screws it up and shears it out, and there's nothing to stop a storm that does phase from cutting.

[MJO812]

Well, we saw 2 weeks ago a low that was initially progged to be a cutter end up a minor clipper. There are reasons why we need a good NAO to have a real shot at a major snow event-it slows the upper air pattern down and allows for a favorable track for us. Without the blocking we had, 2010-11 would have been a disaster. Could it happen? Sure, but our odds are definitely against it given how progressive the pattern is. There's way too much chaos with multiple vorts whenever a storm does come near us, which screws it up and shears it out, and there's nothing to stop a storm that does phase from cutting.

 

 

Until the PNA and NAO are favorable, all we will have to look forward to are clippers.

[Weathergun]

One reason why MJO the may not be that helpful this week, is that appears to be speeding quickly across phase 8 and into phase 1 appears not be a cold phase in February:

 

[Edge Weather]

From a meteorologist in the New England Forum:

 

We'll see it slow down at the end of this week. Once that PV moves west, the flow will become more amplified. That may mean a cutter near the 10th-12th or so, but then we'll start seeing more storms coming out of the sw an srn plains towards mid month. Of course it means not every storm may give us snow...but the regime does change. It certainly won't be as cold, and we'll have more storms I think. Nobody can say for sure this far out if it will be a snowy.

[MJO812]

Low down south at 102 hours

 

http://mag.ncep.noaa.gov/Image.php?model=gfs&area=namer&param=850_temp_mslp_precip&cycle=12ℑ=gfs%2F12%2Fgfs_namer_102_850_temp_mslp_precip.gif

[Edge Weather]

12z GFS is taking a major turn toward the 0z ECMWF.  It has a disturbance along the Gulf coast, moving into Georgia and the Carolinas at 114 hrs.  with a weak clipper in the Great Lakes.  The GFS had nothing in the Carolinas on the previous run, now it has heavy rain there and some snow in our area from the clipper.

[Edge Weather]

Low near Hatteras with heavy rain down there and a beautiful high situated over Ontario and Quebec.  It just misses the phase, but man was this a huge step toward the EC.

[PB GFI]

Theres a good chance the euro is over amplifying the sysyem. I would wait to see if the euro even sees thid at 12 z. The ensembles r slightly weaker than the op. I wouldnt take one run as gospel

[Allsnow]

The flow is to progressive and we have not had phasing all winter between southern and northern stream systems. I expect this to be no different

[Edge Weather]

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

1047 AM EST SUN FEB 03 2013

VALID 12Z WED FEB 06 2013 - 12Z SUN FEB 10 2013

...WINTER RETURNING TO THE INTERMOUNTAIN WEST AND CENTRAL PLAINS

FRIDAY TO SUNDAY...

...SYNOPSIS...

WE CONTINUE IN AN OSCILLATING PATTERN OF DRY AND SEASONABLY COLD

WEATHER ANCHORED BY LOW HEIGHTS IN THE EAST...FOLLOWED BY PERIODS

OF PROGRESSIVE FLOW AND A NORTHWARD SURGE OF WET AND VERY WARM

WEATHER THAT BETTER RESEMBLES EARLY SPRING. THE CURRENT DAY 3-7

FORECAST FEATURES THE LATTER...WITH THE DOMINANT FEATURE BEING A

PROGRESSIVE DEEP TROUGH THAT REACHES THE INTERMOUNTAIN WEST AND

CENTRAL U.S. BY NEXT WEEKEND. A NOTEWORTHY SYSTEM MAY ALSO OCCUR

ALONG THE EAST COAST DURING THE TRANSITION PERIOD LATE IN THE WORK

WEEK. THE 00Z ECMWF INDICATES THE POSSIBILITY OF A SIGNIFICANT

STORM...BUT CURRENT THINKING IS THAT A LESSER STORM MOVING QUICKLY

OUT TO SEA IS THE MORE LIKELY SCENARIO.

...MODEL CHOICE...

THE MODELS ARE SIMILAR IN WAVE SPACING AND TIMING DURING THE

DEVELOPING PROGRESSIVE FLOW WHICH RUNS FROM THE CENTRAL PACIFIC

ACROSS NORTH AMERICA. THIS MAKES IT RELATIVELY EASY TO IDENTIFY

THE STRONG OR WEAK OUTLIERS...AND MAKE A FORECAST NEAR THE MIDDLE

OF THE SPREAD. IN DOING THIS...THE SURFACE FORECASTS WERE

PARTICULARLY USEFUL...AND WE CHOSE MODELS THAT MET OUR

EXPECTATIONS FOR THE RESPECTIVE INTENSITIES OF A LOW OVER NEW

ENGLAND ON FRIDAY AND ANOTHER OVER THE CENTRAL PLAINS ON

SATURDAY/SUNDAY. THE MOST NOTABLE OUTLIER WAS THE 00Z

ECMWF...WHICH FORMS MORE OF A CLASSIC NOR'EASTER ON FRIDAY. THIS

RESULTS FROM A LOW THAT ORIGINATES OVER THE NORTHERN GULF OF

MEXICO AND TAKES A CLASSIC TRACK AROUND THE SOUTHERN END OF THE

APPALACHIANS AND UP THE EAST COAST. THE LOW MAY FORM IN THE

NORTHERN GULF AS A RESULT OF ENERGY CURRENTLY DIGGING TOWARD

MEXICO. THE ECMWF...HOWEVER...WAS SUBSTANTIALLY DEEPER THAN ALL

OTHER MODELS WITH AN UPSTREAM TROUGH THAT PICKS UP THIS FEATURE

AND ALLOWS THE EAST COAST CYCLOGENESIS TO OCCUR. ALTHOUGH A

HANDFUL OF ECMWF ENSEMBLE MEMBERS DO THE SAME THING...THE ECMWF

ENSEMBLE MEAN IS LESSER AMPLIFIED. THE PATTERN THIS WINTER HAS

TENDED TO PROMOTE PROGRESSIVE SYSTEMS THAT ARE FARTHER OUT TO SEA

BEFORE THEY INTENSIFY. THE GFS RUNS...ALONG WITH THE

UKMET...CONTINUE TO SUPPORT THIS NOTION...WITH EMPHASIS ON A

NORTHERN STREAM SHORWAVE AND ASSOCIATED SURFACE LOW WHICH GAINS

STRENGTH AS IT EXITS NEW ENGLAND FROM WEST TO EAST. WHILE THE

ECMWF SOLUTION IS NOT IMPOSSIBLE...THERE IS NOT ENOUGH OF AN

ESTABLISHED TREND TO GIVE IT MUCH WEIGHT IN THE FORECAST.

BACK TO THE WEST...WE DID GIVE THE ECMWF AND EC ENSEMBLE MEAN MORE

WEIGHT AS THE GFS RUNS AT 00Z AND 06Z WERE SLOWER AND SOMEWHAT

DEEPER THAN CONSENSUS.

...IMPACTS...

LOCALLY HEAVY RAIN IS POSSIBLE ALONG THE IMMEDIATE GULF COAST DAYS

3/4. HEAVY RAIN WILL BECOME MORE LIKELY ON DAY 7 WITH CYCLOGENESIS

AND A PACIFIC FRONT TAPPING INTO GULF MOISTURE OVER THE

CENTRAL/SOUTHERN PLAINS AND ADJACENT MISSOURI/MISSISSIPPI VALLEYS.

ON THE BACK SIDE OF THE SYSTEM...WINTER WEATHER INCLUDING HEAVY

SNOW IS POSSIBLE FROM THE INTERMOUNTAIN WEST INTO THE CENTRAL

PLAINS. AS WE TRANSITION TO ANOTHER BRIEF PERIOD OF SOUTHWEST

UPPER FLOW AND SOUTHERLY LOW LEVEL FLOW ACROSS THE SOUTHEASTERN

HALF OF THE COUNTRY...TEMPERATURES AGAIN WARM TO WELL ABOVE

AVERAGE FOR BOTH MAX AND MIN TEMPERATURES.

BURKE

[NEG NAO]

this is what happens when the NAO is slightly positive or close to neutral  and the PNA not positive enough - GFS has the right idea

 

http://raleighwx.americanwx.com/models/gfs/12zgfs850mbTSLPp06126.gif

[PB GFI]

We get one or 2 shots mid month. Thats when we get STJ influence. And by then the NAO should b neg. Dont knw what that leads too but thats gona b the best we gona get

[SACRUS]

GFS was closer to the ecm for the 8th-9th storm potential.  It'll be interesting to see the the GEFS and euro later this afternoon.  

 

The lakes cutter remains a consistent signal on most guidance for the 10-12th.

[Edge Weather]

this is what happens when the NAO is slightly positive or close to neutral  and the PNA not positive enough - GFS has the right idea

 

http://raleighwx.americanwx.com/models/gfs/12zgfs850mbTSLPp06126.gif

 

Well, I guess it might very well have the right idea on this run, but keep in mind that it had no rain over the Carolinas on the previous run, just 6 hours ago, where it now has heavy rain.  One more big shift like that in 6 hours and we end up with the Euro solution.  Not saying it will happen, but you have to admit that the GFS just made one massive change. 

[NEG NAO]

Well, I guess it might very well have the right idea on this run, but keep in mind that it had no rain over the Carolinas on the previous run, just 6 hours ago, where it now has heavy rain. One more big shift like that in 6 hours and we end up with the Euro solution. Not saying it will happen, but you have to admit that the GFS just made one massive change.

what is the trigger to intensify it and phase it ???