February 1-3 Storm

[am19psu]

As most of you are aware, there is a potent shortwave progged to come out of the Southern Rockies early next week. Rather than focusing on someone's backyard, this thread will focus on the synoptic pattern as a whole.

To start, before the system even gets going, there will be an Arctic high riding down the lee of the Rockies, bringing extremely cold air all the way down to Central TX. Even ensemble guidance is progging in a 1048mb high over Montana. Given that airmass to the north, overrunning precipitation will be widespread across the Southern Plains through the Lower Mississippi Valley. The first forecast challenge will be where the rain/snow/ice lines set up.

The GFS shows the 850 0C line across OKC, while the Euro brings it farther south. However, since the Euro is a more amplified solution, the deformation zone is farther north, getting wintry precip all the way up to Omaha. Both the GFS and Euro ops are more amplified than their respective ensemble means. With less amplificaiton, you'd see less warm advection on the front side and more wintry precip all down toward the Red River and into the Ozarks, which are all rain in the op models.

The low pressure will then head WNW into the OH Valley, with widespread p-type issues on the front side and heavy snow likely on the backside of the low as it makes a beeline for Cincinnati or Columbus or even Charleston, WV.

This has the potential to be a pretty big deal in the Midwest, with a band of 8-12" snows possible on the northwest side of the surface low track.

Once reaching the Appalachians, energy will transfer to the coast with Miller B cyclogenesis occurring near the Delmarva. As mentioned before the op models are much more amplified than their ensemble members. If the op models verify, cyclogenesis won't occur until nearly Montauk Point, but I'd rather go with ensemble suite at this time.

That would favor another snowstorm across New England and possibly NYC - similar to 1/11-12 event.

What can go wrong with my forecast? Just about everything. With no NAO block in place, expect solutions to be scattered over the next few days. Some will show a lakes cutter as massive cold advection across the Plains causes the 500mb trough to go negative tilt and take the surface low toward DTW. Or, if the polar vortex is stronger than current models indicated, it could just as easily suppress everything and send the surface low out to sea.

This is a high bust potential forecast. Feel free to post your thoughts here.

[DaculaWeather]

One of my questions would be... what's keeping the cold air so far west?

[wxmx]

One of my questions would be... what's keeping the cold air so far west?

The main average longwave trough is over the Rockies...there's some ridging out east.

[SnowBerg]

This has the potential to be a pretty big deal in the Midwest, with a band of 8-12" snows possible on the northwest side of the surface low track.

Once reaching the Appalachians, energy will transfer to the coast with Miller B cyclogenesis occurring near the Delmarva. As mentioned before the op models are much more amplified than their ensemble members. If the op models verify, cyclogenesis won't occur until nearly Montauk Point, but I'd rather go with ensemble suite at this time.

This is a high bust potential forecast. Feel free to post your thoughts here.

The last three 00Z/12Z GFS runs have been remarkable consistent (could be consistently wrong, of course). Here is the 12Z run's corresponding map to the one you have above from last night's run:

The main difference is the low is about 4mb stronger. I'll feel better about this late Saturday or early Sunday once the upper air is better sampled and in the model initialization. Definitely one to watch.

[easternsnowman]

It looks like the latest models have a good event further south into philly area also.

[am19psu]

It looks like the latest models have a good event further south into philly area also.

Yeah, it's really a question of when and where the low reforms off the coast. Obviously, the earlier it occurs, the better off Philly and DC will be.

[am19psu]

The last three 00Z/12Z GFS runs have been remarkable consistent (could be consistently wrong, of course). Here is the 12Z run's corresponding map to the one you have above from last night's run:

The main difference is the low is about 4mb stronger. I'll feel better about this late Saturday or early Sunday once the upper air is better sampled and in the model initialization. Definitely once to watch.

Yeah, if current trends hold, IL/IN/OH could be in for a significant snow storm. This would be the first good one of the year for you guys, no?

[SnowBerg]

Yeah, if current trends hold, IL/IN/OH could be in for a significant snow storm. This would be the first good one of the year for you guys, no?

In terms of having a strong cyclone, yes. We've had over 28 inches of snow here (already more than normal for the season), but most of it has come with clipper systems, and almost all have them have come straight down with little wind to speak of. We had a 7" snow and 5" snow in December. In many ways that has been great (especially wrt snow measurement), but I'm ready for something to really crank up.

[am19psu]

Pending the Euro ensembles, I still like the less amplified GFS/GEM solutions for next week's evolution moreso than the amplified European given the current ensemble member guidance. If those solutions pan out, everyone north of the Ohio River should be in good shape.

[gil888]

Pending the Euro ensembles, I still like the less amplified GFS/GEM solutions for next week's evolution moreso than the amplified European given the current ensemble member guidance. If those solutions pan out, everyone north of the Ohio River should be in good shape.

I'm thinking NYC and BOS are ok with this one, but DC is in trouble if they want a lot of snow. Better model agreement for now, but the CAD on the east side of the Appalachians needs to be present and not get scoured out like a few models are forecasting. I'll feel better after the Euro locks in I think there is also the potential for a decent severe weather outbreak for AR/MS/LA as well as the storm winds up initially. At least the active weather pattern will continue!

[ORH_wxman]

The ECMWF ensemble mean is pretty amplified like the OP run. It would get the mixing line up to about Boston. It doesn't mean a whole lot yet, but something to watch. The overall pattern is pretty hostile for a coastal storm. The cold air might be strong enough to force a little bit of secondary coastal cyclogenesis, but we probably won't see the deep upper level lows off the east coast like we've seen in the past few events. But who knows, this winter has been crazy and defying a lot of typical climo.

[A-L-E-X]

The ECMWF ensemble mean is pretty amplified like the OP run. It would get the mixing line up to about Boston. It doesn't mean a whole lot yet, but something to watch. The overall pattern is pretty hostile for a coastal storm. The cold air might be strong enough to force a little bit of secondary coastal cyclogenesis, but we probably won't see the deep upper level lows off the east coast like we've seen in the past few events. But who knows, this winter has been crazy and defying a lot of typical climo.

Most people think it is a "correction" for the collective screwing we had in the late 80s-early 90s and late 90s. At this point, I think a huge rainstorm would be much more dangerous than another snowstorm here.

[gil888]

The ECMWF ensemble mean is pretty amplified like the OP run. It would get the mixing line up to about Boston. It doesn't mean a whole lot yet, but something to watch. The overall pattern is pretty hostile for a coastal storm. The cold air might be strong enough to force a little bit of secondary coastal cyclogenesis, but we probably won't see the deep upper level lows off the east coast like we've seen in the past few events. But who knows, this winter has been crazy and defying a lot of typical climo.

No this definitely looks more like overrunning with a weaker low. Models are in a better agreement but I don't trust them with this storm yet--farther north and west than the last one, but how far? Too many large changes (save maybe the GFS, and let's face it the GFS isn't the Euro) to feel like I have a good handle on this situation. ah the perils of 5-6 day forecasts...

[Terpeast]

Going by the GFS runs only, I would be concerned about icing in the DC area. Lots of cold air in place aided by the snowpack and the E canadian PV, but the sfc/upper low tracks to the west of the area as an inland/apps runner. 850-700 thicknesses may appear to be warm enough for rain in DC, but the first blue 1000-850 thickness runs right throough DC and a bit south, raising the potential for sleet or freezing rain after an initial dose of a little snow if this pans out.

[Srain]

Looks like a wide spread winter storm to me. Much of the CONUS well see something from this 'event'…it's good to see some discussion on the main page for a change...

[armyftball]

These overall storm threads are a lot more interesting to me than whether its going to hit my backyard.

THIS is meteorology.

[Ian]

These overall storm threads are a lot more interesting to me than whether its going to hit my backyard.

THIS is meteorology.

yes.. good idea.

[am19psu]

There's lots of mixing issues on this particular run of the GFS, but I wouldn't worry too much about it... yet. The ensemble guidance agrees with ops, but both the GFS and Euro have had a warm bias this winter. The track of the surface low wasn't terribly different, so I'd still guess that north of the Ohio River is looking at decent snow out of this run.

[Roger Smith]

I have the feeling that the models are moving this storm too far north -- the eventual track may be closer to BNA-CRW-DCA.

This is a very large expanse of cold air moving down behind the clipper system and there are 1-3 ft snowpacks generally in place now north of about 38N. This is why I find the easy rebound of thickness a bit difficult to visualize on the models, and also a more southerly track could produce a more intense storm. There will be blizzard conditions from CO across KS and parts of OK into nw AR, s MO and w KY during the formative stages, and heavy freezing rain from s/c AR into w TN and parts of s/c KY. Snowfall across the plains states in regions mentioned could be 10-15 inches in places, trending to near 20 inches in parts of IN-OH.

Expecting this storm to run into a wall of cold air with a narrow mixed precip zone, so this is an early call for a major snowstorm Feb 2-3 across most of the northeast and OV with potential for 15-30 inches of snow in some parts of PA, NJ, NY and southern New England. I think the mixing zone will be across VA and MD south of BWI, DE and extreme southern NJ with potential for significant snow during the duration of the event.

Would not be surprised if we start seeing greater development night of Feb 2-3 offshore as we get closer to the time, due to new moon energy peak (Feb 3 03z) and possible 970-975 mb low south of LI towards benchmark. Given the way this winter has gone and the pattern last winter, each storm feeds off the snow-cover of the previous one and this could be a huge event.

[SnowGoose69]

I have the feeling that the models are moving this storm too far north -- the eventual track may be closer to BNA-CRW-DCA.

This is a very large expanse of cold air moving down behind the clipper system and there are 1-3 ft snowpacks generally in place now north of about 38N. This is why I find the easy rebound of thickness a bit difficult to visualize on the models, and also a more southerly track could produce a more intense storm. There will be blizzard conditions from CO across KS and parts of OK into nw AR, s MO and w KY during the formative stages, and heavy freezing rain from s/c AR into w TN and parts of s/c KY. Snowfall across the plains states in regions mentioned could be 10-15 inches in places, trending to near 20 inches in parts of IN-OH.

Expecting this storm to run into a wall of cold air with a narrow mixed precip zone, so this is an early call for a major snowstorm Feb 2-3 across most of the northeast and OV with potential for 15-30 inches of snow in some parts of PA, NJ, NY and southern New England. I think the mixing zone will be across VA and MD south of BWI, DE and extreme southern NJ with potential for significant snow during the duration of the event.

Would not be surprised if we start seeing greater development night of Feb 2-3 offshore as we get closer to the time, due to new moon energy peak (Feb 3 03z) and possible 970-975 mb low south of LI towards benchmark. Given the way this winter has gone and the pattern last winter, each storm feeds off the snow-cover of the previous one and this could be a huge event.

I'm thinking the same thing about the first system being more south....the 500mb setup from 72-96 hours over the Plains is ugly and to me is not conducive to a system that will be able to ramp up and run that far northward...I think there may be a transfer to the coast a bit earlier than the GFS has been trying to show.

[tmagan]

I have the feeling that the models are moving this storm too far north -- the eventual track may be closer to BNA-CRW-DCA.

This is a very large expanse of cold air moving down behind the clipper system and there are 1-3 ft snowpacks generally in place now north of about 38N. This is why I find the easy rebound of thickness a bit difficult to visualize on the models, and also a more southerly track could produce a more intense storm. There will be blizzard conditions from CO across KS and parts of OK into nw AR, s MO and w KY during the formative stages, and heavy freezing rain from s/c AR into w TN and parts of s/c KY. Snowfall across the plains states in regions mentioned could be 10-15 inches in places, trending to near 20 inches in parts of IN-OH.

Expecting this storm to run into a wall of cold air with a narrow mixed precip zone, so this is an early call for a major snowstorm Feb 2-3 across most of the northeast and OV with potential for 15-30 inches of snow in some parts of PA, NJ, NY and southern New England. I think the mixing zone will be across VA and MD south of BWI, DE and extreme southern NJ with potential for significant snow during the duration of the event.

Would not be surprised if we start seeing greater development night of Feb 2-3 offshore as we get closer to the time, due to new moon energy peak (Feb 3 03z) and possible 970-975 mb low south of LI towards benchmark. Given the way this winter has gone and the pattern last winter, each storm feeds off the snow-cover of the previous one and this could be a huge event.

Not a big fan of snowpack significantly altering storm track, after all, we had a 20+" inch snowpack across parts of the mid-Atlantic and southern New England in January 1996, and this occurred.

[Srain]

The signals are becoming a bit stronger for a severe weather event for E TX, LA, MS in the warm sector prior to the Arctic boundary passing. There may well be a 30 to 40 degree drop after the frontal passage in the Southern Plains. This has all the makings of a major winter season storm with widespread affects for much of the US, IMO. Two Winter RECON missions are scheduled for the Pacifc on Sunday and Monday to sample that Pacific storm as it is dropping S along the W Coast.

[Jet-Phase]

I noticed that the 2003 PDII was one of the analogs listed. The latest NAM reminds me of the 2 part system where the first one came through a couple of days before the main event. The strong banana-looking Highs look very simila ralong with the moisture source and where the battle lines are for this to be more easterly track.

[wxmx]

A little off topic, but related. The Rio Grande Valley and half MX is looking at it's most severe and damaging cold blast since 1989, according to the 12z GFS...

[am19psu]

A little off topic, but related. The Rio Grande Valley and half MX is looking at it's most severe and damaging cold blast since 1989, according to the 12z GFS...

This is the first winter I've really paid attention to it, but do you think it's going to happen this time? I've been bullish on the two cold shots, but they never materialized down to the Rio Grande.

[Srain]

This is the first winter I've really paid attention to it, but do you think it's going to happen this time? I've been bullish on the two cold shots, but they never materialized down to the Rio Grande.

The trends today suggest that it may well be. We've been watching this pattern for so long (before the 17th) it's crazy. That said, the GFS coming onboard regarding the colder air certainly raises an eyebrow in our part of the world. 2meter temps are in the upper teens in my area.

[am19psu]

I think you'd come up with a pretty decent forecast right now if you took the average of the Top 5 CIPS analogs right now. That'd put snow down from OKC all the way to Caribou.

http://www.eas.slu.edu/CIPS/ANALOG/thumbnails.php?reg=EAST&model=GFS212&fhr=120&flg=new&map=COSN&sort=FINAL

The southern extent of the snow is obviously still the difficult part of the forecast. I'd favor it being farther south than currently progged, relying on the seasonal warm bias of the GFS and Euro.

[wxmx]

This is the first winter I've really paid attention to it, but do you think it's going to happen this time? I've been bullish on the two cold shots, but they never materialized down to the Rio Grande.

I think it will this time...if there's not too much energy dragging in the backside of the trough that undercuts the cold high (like the GGEM), hard freezes down to the Rio Grande and south are high probability in my book. Probably not -9C 850mb temps like the GFS, but -6C like the Euro look very possible (mid 20s for surface and 3 days of lows below freezing are my forecast for the region)

[Srain]

HPC Final Update:

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

129 PM EST SAT JAN 29 2011

VALID 12Z TUE FEB 01 2011 - 12Z SAT FEB 05 2011

..WIDESPREAD MAJOR WINTER STORM TO IMPACT THE PLAINS TO THE

NORTHEAST THIS WEEK...

LATEST MODELS AND ENSEMBLE MEANS MAINTAIN A STRONG MEAN RIDGE FROM

THE ERN PAC NWD THRU THE PERIOD ALTHOUGH SOME CHANGES IN SHAPE

OCCUR AS SHRTWVS ROUND THE RIDGE. ASSOC POSITIVE HGT ANOMALIES

ARE FCST TO BE STRONGEST OFF THE PAC NW COAST BY D+8. FAIRLY

CONSISTENT WITH TELECONNECTIONS RELATIVE TO THIS FEATURE...

GUIDANCE DISPLAYS AN ELONGATED MEAN TROF FROM ERN CANADA SWWD.

ONE OR MORE INSTANCES OF FLOW SEPARATION WITHIN THIS MEAN TROF

WILL CONTINUE TO ADD TO TYPICAL DETAIL UNCERTAINTIES.

WITH THE MAJOR STORM SYSTEM FCST TO TRACK NEWD FROM THE PLAINS TUE

ONWARD... MODELS AND ENSEMBLES HAD BEEN SHOWING SIGNIFICANT SPREAD

AND CONTINUITY CHANGES RECENTLY BUT OVER THE PAST 24 HRS APPEAR TO

BE STARTING TO CONVERGE TOWARD A COMMON SOLN THOUGH SOME

TRACK/TIMING DIFFS REMAIN. GFS RUNS HAVE STABILIZED OVER THE PAST

DAY WHILE THE 12Z AND NEW 00Z ECMWF RUNS HAVE ADJUSTED STEADILY

EWD FROM THE 00Z/28 RUN THAT HAD DEFINED THE WRN SIDE OF THE SOLN

ENVELOPE. MEANWHILE THE UKMET IS ON THE FASTER SIDE OF THE SPREAD

OVER THE ERN STATES AND BY EARLY THU THE CANADIAN BECOMES SLOWER

THAN THE GUIDANCE AVERAGE OFF THE NERN COAST. THE 00Z GEFS/12Z

ECMWF ENSEMBLE MEANS PROVIDE A GOOD COMPROMISE FOR TRACK/TIMING

AND ALSO FOLLOW PREVIOUS CONTINUITY EXTREMELY WELL... SO THEIR

SOLNS ARE RECOMMENDED FOR THIS SYSTEM.

WITH UPSTREAM FLOW THE GFS COMPARES LEAST FAVORABLY TO ENSEMBLE

CLUSTERING AND MOST OTHER MODELS. THE GFS FEEDS A LOW CONFIDENCE

WRN CANADA SHRTWV INTO THE MEAN TROF OVER THE WEST BY WED AND IS

RELATIVELY FAST/AMPLIFIED WITH ENERGY EJECTING ACROSS THE

CNTRL-ERN STATES BY DAYS 5-7 THU-SAT. BY LATE IN THE FCST THE

GEFS MEAN ALSO BECOMES RATHER AMPLIFIED WITH ITS ERN CONUS TROF.

TELECONNECTIONS RELATIVE TO THE ERN PAC MEAN RIDGE FAVOR HOLDING

DOWNSTREAM NEGATIVE HGT ANOMALIES FARTHER WWD THAN INDICATED BY

THE GEFS MEAN AT THAT TIME. MEANWHILE UNCERTAINTY WITH EXACTLY

HOW FLOW WILL EVOLVE OVER THE SWRN CONUS/NWRN MEXICO FAVORS

GREATER WEIGHTING OF ENSEMBLE MEANS VERSUS ONE INDIVIDUAL MODEL

RUN. THE 00Z ECMWF COMPARES BETTER TO ENSEMBLE MEANS THAN THE GFS

BUT THE ECMWF MAY BECOME TOO DEEP WITH ITS NWRN MEXICO CLOSED LOW

BY DAY 6 FRI IN LIGHT OF SOME FCST HGT ANOMALIES REACHING 3-4

STDEVS BELOW NORMAL.

THE DAYS 3-5 TUE-THU FCST STARTS WITH A BLEND OF THE 00Z GEFS/12Z

ECMWF ENSEMBLE MEANS TO REFLECT PREFERENCES WITH THE SYSTEM

AFFECTING THE ERN HALF OF THE CONUS. THIS SOLN COMPARES WELL TO

OTHER GUIDANCE IN PRINCIPLE WITH STRONG HIGH PRESSURE BUILDING

OVER THE CNTRL-WRN STATES. DAYS 6-7 FRI-SAT USE A 70/30 BLEND OF

THE 12Z ECMWF MEAN/00Z ECMWF AS THE ECMWF MEAN COMPARES BETTER TO

TELECONNECTIONS THAN THE GEFS MEAN. MINORITY WEIGHTING OF THE 00Z

ECMWF PROVIDES A LITTLE ADDED DETAIL WHILE DOWNPLAYING ITS LOWER

CONFIDENCE ATTRIBUTES.

MORNING PRELIM UPDATES BLEND EQUAL AMOUNTS OF 00Z GFS AND ECMWF

ENSEMBLE MEANS. THIS SIMPLIFICATION RESULTS IN THE SAME PATTERNS

OF THE PREVIOUS OVERNIGHT BLENDS.

...AFTERNOON UPDATE...

NEW 12Z GFS IS MORE PROGRESSIVE WITH THE MID LEVEL TROF AFTER DAY

4 WED THAN PRIOR RUNS AND OTHER MODELS AND ITS ENS MEAN. 12Z

CMC/UKMET AND ENS MEANS REMAIN PREFERRED. NO CHANGES TO AFTERNOON

FINALS FROM PRIOR HPC PRELIM PROGS.

EXPECT A BROAD HEAVY SNOW SWATH FROM THE CENTRAL PLAINS EAST AND

NORTHEAST NORTH OF THE OH RIVER AND MASON DIXON LINE TUESDAY INTO

WEDNESDAY WITH VERY FAVORABLE UPPER LEVEL JET COUPLING. HEAVY

RAINS SOUTHWARD ACROSS THE LOWER MS AND TN VALLEYS TUESDAY AND

WEDNESDAY.

WITH MASSIVE HIGH PRESSURE PUSHING DOWN THRU THE PLAINS WITH TEH

COLDEST AIR DAMMED AGAINST THE ROCKIES EXTREME COLD WILL SET INTO

THE PLAINS WITH NEGATIVE ANOMALIES NEAR OR BELOW 30 DEGREE

DEPARTURES FROM NORMAL YIELDING A HUGE AREA OF NEAR AND BELOW ZERO

TEMPERATURES READINGS DAY AND NIGHT TUESDAY AND WEDNESDAY.

CONSIDERABLE COLD AIR WILL SPILL OVER THE ROCKIES INTO THE GREAT

BASIN AND TO THE WEST COAST WITH TEMPERATURES WELL BELOW NORMAL

INTO LATE WEEK.

RAUSCH/ROSENSTEIN

[am19psu]

There's very little difference between the GFS/ECM/GEFS/ECENS. Working out the p-type issues will remain tricky, but it's highly likely places like St Louis, Champaign, Indianapolis, and Columbus see a major snowfall out of this storm. The I-95 corridor, except maybe BOS, will probably see too much warming to get a significant snow, but interior sections that have been in a "snow hole" have another shot this week.