January Pattern and Storm Discussion II

[MillerA]

GSP disco:

 

 

Long term /Friday through Monday/... as of 330 am Tuesday...a complicated weather pattern is emerging Friday through Sat and the models are displaying varying solutions. There is some good run to run consistency in the European model (ecmwf) and the GFS is fairly close to the overall trends...however enough of a difference exists with respect to to the potential wedge setup Friday and the evolution of the warm air advection precipitation...that a general blend of these two models was used to generate the weather grids. The surface temperatures were crafted after the European model (ecmwf)/S low level thickness pattern...while the middle to upper level thermal and mass fields were based more on the GFS. Overall confidence is low to average. The main concern early Friday will be for the -fzra potential across the NC mountains...northern fhills and northern Piedmont. The GFS is has a more defined wedge in place than the European model (ecmwf)...yet both models show little in the way off strong cross isobaric flow. This gives the impression The Wedge will be fairly easy to break down with the incoming deep trough dynamics. This will leave a short window of time by the way 12z and 16z where surface temperatures will be low enough to support -fzra. Overall amounts will not be that great and measurable ice generally confined north of i40 in the higher elevations. Enough to make roads slick however. With an advancing warm front...surface temperatures will warm above freezing at all locales by noon and a changeover to all rain will occur until the evening. Maximum temperatures will be tricky with the precipitation dragging...cloud cover and warm air advection...but for now believe maxes about 10 degrees f below normal seems reasonable. A very strong trough axis pushes into the mountains Friday night and Ushers in an Arctic airmass. Temperatures in the h92-850 mb layer will drop to around -11 c by 12z Sat across the northern NC mountains both the GFS and the European model (ecmwf) show an accompanying layer of high relative humidity Friday night and along with the strong dynamical vertical velocities...snow ratios should be pretty high. Snowfall amounts could amount to several inches across the northern mountains by the time the snow ends around noon. Maximum temperatures for Sat will still be about 10-12 degrees below normal.

[GaWx]

The 6Z GFS is even colder than the 0Z GFS. It appears to have a longer duration of ZR. It still isn't too big of a deal just yet, but it has been looking colder with each run in the CAD areas. Will this colder trend continue for several more runs? If so, those areas may have a rather substantial event with which to deal on 1/25. Will continue to monitor closely as 72 hours is still enough time for pretty significant changes and analogs/climo are somewhat worrisome.

[FallsLake]

RAH thinks the storm will be south. I think we definitly have a storm to track. Here we go again.... 

 

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 230 AM TUESDAY...

A LATE WEEK COLD AIR DAMMING EVENT AND POTENTIAL WINTER STORM FOR
PORTIONS OF OUR REGION...

A LARGE SPREAD IN THE MODEL SOLUTIONS CONTINUE AFTER THE LATEST
00Z/22 JANUARY 13 MODEL RUN CONCERNING THE LATE WEEK COLD AIR
DAMMING (CAD) EVENT AND NOW POTENTIAL WINTER STORM ALONG THE EAST
COAST INCLUDING PORTIONS OF CENTRAL NC. THE SPREAD IN THE
TRACK/TIMING/STRENGTH OF THE DEVELOPING LOW PRESSURE SYSTEM APPEARS
TO BE RELATED TO THE INTERACTION WITH THIS DEVELOPING SYSTEM WITH
THE NORTHERN (POLAR JET) OVER THE GREAT LAKES INTO NEW ENGLAND
FRI-SAT. JUST AS WE SUSPECTED 24 HOURS AGO... THE MODELS WERE HAVING
MAJOR DIFFICULTY IN FORECASTING THE POTENTIAL CAD EVENT FOR OUR
REGION FRIDAY (TRACKING THE AFOREMENTIONED STORM SYSTEM NE DEEP INTO
THE MODIFIED ARCTIC AIR MASS) TO OUR NORTH... PUTTING OUR REGION IN
THE WARM SECTOR. WE DID NOT BUY INTO IT AND WE STILL DO NOT.

WE AGREE WITH THE CURRENT HPC GUIDANCE IN SUPPORT OF THE COLDER AND
MORE SUPPRESSED STORM TRACK. JUST HOW FAR SUPPRESSED THE SYSTEM
VERIFIES STILL DEPENDS ON THE INTERACTION WITH THE POLAR JET.
THEREFORE... THE STORM TRACK IS OF LOW CONFIDENCE RIGHT NOW... AND
MAY NOT CHANGE UNTIL 24-48 HOURS OUT. IF THE 00Z/EC OR UKMET WERE TO
VERIFY... THERE WOULD BE WINTER STORM CONDITIONS OVER AT LEAST THE
PIEDMONT AND POSSIBLY DEEP INTO THE PIEDMONT OF OUR REGION FRIDAY
INTO FRIDAY NIGHT.

HOWEVER... THERE IS HIGH CONFIDENCE IN A DEVELOPING COLD AIR DAMMING
EVENT WHICH WILL HAVE STRONG RAMIFICATIONS ON THE TEMPERATURES
DURING THE SAID PRECIPITATION EVENT EXPECTED LATE WEEK. WE WILL
TREND BACK COLDER AGAIN (AS WE DID LAST NIGHT) WITH THE FORECAST FOR
THIS SYSTEM. IN FACT... THE ARCTIC AIR MASS THAT IS FORECAST TO BE
IN PLACE OVER OUR REGION THURSDAY NIGHT INTO FRIDAY WILL BE THE
COLDEST IN 2 SEASONS... AND WILL BE VERY DRY AS WELL. MOS GUIDANCE
STILL SUGGESTS DEW POINTS IN THE SINGLE DIGITS AND LOWER TEENS BY
12Z FRIDAY... WITH ACTUAL TEMPERATURES WELL BELOW FREEZING.
THEREFORE... WHEN THE DEVELOPMENT OF PRECIPITATION OCCURS FRIDAY
(GFS QUICKER AND EC SLOWEST)... THERE WILL BE CONCERN AND POTENTIAL
FOR A WINTERY MIXTURE. IF HPC VERIFIES WITH THE FORECAST OF THE
1033+ MB SURFACE HIGH (ARCTIC AIR) DOWN THE EASTERN SEABOARD
(FAVORABLE POSITION AND STRENGTH FOR SIGNIFICANT CAD DEVELOPMENT)...
WITH THE COLDEST AIR MASS IN TWO SEASONS IN PLACE BEFORE THE
PRECIPITATION DEVELOPS... THERE WOULD BE HIGH POTENTIAL FOR P-TYPE
ISSUES.

THE SURFACE HIGH IS FORECAST TO BE PROGRESSIVE AND SHIFT OFFSHORE
DURING FRIDAY. HOWEVER... WAA/ISENTROPIC LIFT ASSOCIATED WITH THE
APPROACHING LOW PRESSURE ALOFT SHOULD BE SIGNIFICANT ENOUGH GENERATE
A CAD EVENT. HPC ALSO FAVORS THE APPROACHING LOW PRESSURE TO
TRACK/REDEVELOP OVER SOUTH CAROLINA OR FAR SOUTHERN NORTH CAROLINA
(ALONG THE STRONG BAROCLINIC ZONE) LATE FRIDAY... THEN MOVE UP THE
COAST. THIS WOULD BE A MILLER B TYPE LOW AND ALONG WITH THE CAD WITH
VERY COLD DRY AIR ALREADY IN PLACE... THERE SHOULD BE A FAIRLY LARGE
P-TYPE TRANSITION ZONE WITH THE POTENTIAL FOR SNOW AND SLEET TO
FREEZING RAIN AT LEAST FOR THE PIEDMONT DAMMING REGION. THE
CONTINUED LARGE SPREAD IN SOLUTIONS WILL TAKE TIME TO IRON OUT...
BUT THIS STORM SYSTEM HAS PLENTY OF POTENTIAL GIVEN THE TRENDS
TOWARD A MORE SOUTHERN STORM TRACK... MILLER B TYPE LOW... AND AN
ANTECEDENT VERY COLD DRY AIR MASS IN PLACE "BEFORE" THE
PRECIPITATING DEVELOPS. HPC CURRENTLY FAVORS THE LATEST EC AND
UKMET... BUT ONLY WITH LOW CONFIDENCE. TAKEN LITERALLY... GIVEN THE
EXTENT OF THE CAD AND THE MILLER B STORM TRACK (OVER SC AND FAR
EASTERN NC)... PARTIALS SUPPORT SIGNIFICANT SNOW/SLEET AND EVEN SOME
FREEZING RAIN IN THE PIEDMONT DAMMING REGION MID DAY FRIDAY INTO
FRIDAY NIGHT. QPF POTENTIAL SUGGESTS HIGH END ADVISORY INTO LOW END
WINTER STORM CONDITIONS. WE WILL NOT GO THAT FAR GIVEN THE LOW
CONFIDENCE THIS FAR OUT.

GIVEN THE DISAGREEMENT IN THE MODELS AND FORECASTERS... WE WILL ONLY
TREND TOWARD THE "POTENTIAL" FOR A WINTER STORM... BUT HIGHLIGHT THE
COLDER CAD CONDITIONS AS LIKELY FOR LATE WEEK. THIS WOULD BE
FOLLOWED BY ADDITIONAL COLD DRY AIR LATE IN THE WEEKEND... BEFORE A
WARM UP NEXT WEEK.

SENSIBLE WEATHER...

INCREASING CLOUDS AND COLD THURSDAY NIGHT. LOWS IN THE 20S. A CHANCE
OF A WINTERY MIX (SNOW/SLEET TO FREEZING RAIN/RAIN PIEDMONT)... AND
A CHANCE OF COLD RAIN ELSEWHERE FRIDAY. HIGHS IN THE 30S W-N AND 40S
E-S. PRECIP MAY END AS WINTERY MIX FRI NIGHT... LOWS IN THE 20S TO
LOWER 30S SE. BREEZY AND COLD SAT-SUN. HIGHS IN THE 30S TO LOWER 40S
SE. LOWS 15-25 FAR SE.

&&
 

[John1122]

06z GFS is very light on QPF but supports some freezing rain for Eastern TN and NC, especially north of 40.

[DaculaWeather]

Birmingham is having a hard time believing temperatures that are 6 standard deviations below normal...

 

THE MOST PUZZLING PART OF THIS FORECAST PACKAGE...AS IT HAS BEEN FOR THE LAST FEW DAYS...IS THE TEMPERATURE GUIDANCE OVER THE NEXT 5-7 DAYS.  MODELS ARE STRUGGLING MIGHTILY WITH HOW COLD IT WILL BE AT NIGHT AND HOW WARM IT MAY GET EACH DAY. 

I DON'T THINK I'VE EVER SEEN A 6 STD IN THE ENSEMBLE GUIDANCE...AND COUPLE THAT WITH A 20 DEGREE RANGE IN THE GFS ENSEMBLES THURSDAY AND THURSDAY NIGHT...WE COULD

GET THINGS HANDED TO US COME VERIFICATION TIME. WON'T MAKE ANY MAJOR CHANGES RIGHT NOW AND HOPE FOR SOME BETTER GUIDANCE WITH UPCOMING MODEL RUNS.

[DaculaWeather]

Birmingham is having a hard time believing temperatures that are 6 standard deviations below normal...

 

THE MOST PUZZLING PART OF THIS FORECAST PACKAGE...AS IT HAS BEEN FOR THE LAST FEW DAYS...IS THE TEMPERATURE GUIDANCE OVER THE NEXT 5-7 DAYS.  MODELS ARE STRUGGLING MIGHTILY WITH HOW COLD IT WILL BE AT NIGHT AND HOW WARM IT MAY GET EACH DAY. 

I DON'T THINK I'VE EVER SEEN A 6 STD IN THE ENSEMBLE GUIDANCE...AND COUPLE THAT WITH A 20 DEGREE RANGE IN THE GFS ENSEMBLES THURSDAY AND THURSDAY NIGHT...WE COULD

GET THINGS HANDED TO US COME VERIFICATION TIME. WON'T MAKE ANY MAJOR CHANGES RIGHT NOW AND HOPE FOR SOME BETTER GUIDANCE WITH UPCOMING MODEL RUNS.

[buncombe]

Is the Bham discussion referring to the variance between the models rather than deviations from normal?  Seems variance is more likely.

[John1122]

Birmingham is having a hard time believing temperatures that are 6 standard deviations below normal...

 

THE MOST PUZZLING PART OF THIS FORECAST PACKAGE...AS IT HAS BEEN FOR THE LAST FEW DAYS...IS THE TEMPERATURE GUIDANCE OVER THE NEXT 5-7 DAYS.  MODELS ARE STRUGGLING MIGHTILY WITH HOW COLD IT WILL BE AT NIGHT AND HOW WARM IT MAY GET EACH DAY. 

I DON'T THINK I'VE EVER SEEN A 6 STD IN THE ENSEMBLE GUIDANCE...AND COUPLE THAT WITH A 20 DEGREE RANGE IN THE GFS ENSEMBLES THURSDAY AND THURSDAY NIGHT...WE COULD

GET THINGS HANDED TO US COME VERIFICATION TIME. WON'T MAKE ANY MAJOR CHANGES RIGHT NOW AND HOPE FOR SOME BETTER GUIDANCE WITH UPCOMING MODEL RUNS.

 

JKL also spoke of models having a hard time with temps. They discounted the NAM entirely, saying it's too warm and said the GFS likely was too.

[DaculaWeather]

This loop http://www.daculaweather.com/4_nh_wv_loop.php you can see exactly how far south the cold has come... and not far enough. You can also see the western ridge getting smashed by the pacific flow. You'll also notice nothing out east to keep things bottled up.

[burgertime]

Personally I'm not excited about this one really at all. That being said the Euro does drop snow across much of NC, EPS control run does as well. I suppose this could be one of those tricky little storms the problem is like with most with these types of tracks I question how much moisture can really wring out to help us. Euro has more QPF than other models, if we get better trends in our favor than great but again I'm not holding my breath over it. 

[WilkesboroDude]

NWS Blacksburg biting...

  Latest models have trended colder with this system suggesting a good portion of the quantitative precipitation forecast may be snow or sleet b4 changing to freezing rain. At this time think we will be looking at Winter Weather Advisory conditions Friday. Would need a bit more quantitative precipitation forecast...or...for all of the precipitation to fall as freezing rain in order to justify a watch/warning sort of concern. At the very least...this will be a concern for schools/dot/travel interests as the ground will be frozen allowing for easy accumulation for whatever winter ptype occurs.

[nchighcountrywx]

Raysweather still feels like this will be winter's coldest week.

 

As we start the wrap up with winter into the last 30 days of solid meteorological winter, this week gives us a solid week of winter with another great weekend of winter outdoorsman sportsmen activities of both nordic and alpine sking:

 

http://www.averyweather.com/Forecast/Beech+Mountain

 

[FallsLake]

NWS Blacksburg biting...

  Latest models have trended colder with this system suggesting a good portion of the quantitative precipitation forecast may be snow or sleet b4 changing to freezing rain. At this time think we will be looking at Winter Weather Advisory conditions Friday. Would need a bit more quantitative precipitation forecast...or...for all of the precipitation to fall as freezing rain in order to justify a watch/warning sort of concern. At the very least...this will be a concern for schools/dot/travel interests as the ground will be frozen allowing for easy accumulation for whatever winter ptype occurs.

I agree, the issue with this setup is the cold ground. This last event was never really a problem for the roads (..except during the snow fall & some black ice). This system has the potential to cause a lot of problems even with just a little precip. The in-famious 1" snow fall in Raleigh a few years back shut the whole city down because the snow stuck to the frozen pavement and then turned to ice. I would think even with a Winter Weather Advisory amount of precip would/could be worse than many of our winter events.

[NCSNOW]

Personally I'm not excited about this one really at all. That being said the Euro does drop snow across much of NC, EPS control run does as well. I suppose this could be one of those tricky little storms the problem is like with most with these types of tracks I question how much moisture can really wring out to help us. Euro has more QPF than other models, if we get better trends in our favor than great but again I'm not holding my breath over it. 

Hard to bet against back to back euro operational runs inside 5 days, espeacilly considering it's ensembles have been tooting this horn since Saturday and still continue to be in lock step. Hopefully this will trend in alot of folks favor so we all can enjoy atleast a couple of days of true winter sceneary before the annual 3-5 month heatwave locks back in.

[POWERSTROKE]

Anybody hoping for ZR deserves a week long power outage. I'd rather have 33 and rain.

 

 

I will take it.  Been without power for 9 days due to ice before

[packbacker]

0z Nogaps shifted from central NY at the 12z run yesterday to central NC at the 0z run.

I do agree with Burger though, we are getting sucked in and this seems prime to disappoint our area.

[WhiteoutWX]

I think I-40 north has a shot at some frozen. The usual screwzones will likely be left out.

[Poimen]

let's see what the 12Z guidance offers today...I suspect we'll see some definite trends in one direction or the other.

[strongwxnc]

You would hope so Sir. However, as has been stated many times around here, trends can and will happen up till the system is coming in.  But yes, I hope the 12 runs began to line up one way or another.

let's see what the 12Z guidance offers today...I suspect we'll see some definite trends in one direction or the other.

[rduwx]

0z Nogaps shifted from central NY at the 12z run yesterday to central NC at the 0z run.

I do agree with Burger though, we are getting sucked in and this seems prime to disappoint our area.

 

 

I was out of town over the weekend and have to admit I haven't been following this that closely but so far I don't see anything to get real excited about for the RDU area.  Is it possible to see some snow or ice out of this?  Sure, but I don't believe it will amount to much.

[mackerel_sky]

Saw on TWC map for Thu.,that a cold front was dropping down from the N,backdoor-like thru NC.This will get the fresh cold air in before the system gets here.That seems better because I thought we were relying on the stale cold to hold on from today.

[packbacker]

I was out of town over the weekend and have to admit I haven't been following this that closely but so far I don't see anything to get real excited about for the RDU area.  Is it possible to see some snow or ice out of this?  Sure, but I don't believe it will amount to much.

I will say I would bet the GFS is wrong though, the northern stream is just crushing the southern energy. The Euro has a much better chance of trending north than staying where it's at. But we could still see a minor event out of this. Not buying the extreme 2ft+ of snow it had for Boston on the 0z run, although would love to watch that unfold. You would have to think this would be a good event for the MA/NE, they haven't had squat all winter.

[eyewall]

For an extended ZR event you would need a solid CAA feed as remember it can be self-limiting due to latent heat release due to the ice accrual itself. Either way this may be a bit of a mess but so far I am not expecting a major event.

[jmundie]

For those of you who haven't experienced a minor event with cold ground - it's a fun experience. Almost two years ago in Nashville - high temp of 23 when snow moved in. It immediately stuck to everything. Roads did melt for about 15 minutes but then turned into sheets of ice/snow. This started at 3:30 pm. Interstate traffic was gridlocked until midnight. All for 2 inches of snow.

[DaculaWeather]

http://www.daculaweather.com/4_hpc_extended_disco.php

 

 

 

CROSS THE EAST...USED A COMBINATION OF THE 18Z GEFS MEAN/00Z(YESTERDAY) UKMET FOR THE LOW MOVING TOWARD THE OHIO VALLEY ONFRIDAY...WITH THE SLOWER 12Z ECMWF AND FASTER 12Z GFS FURTHER FROMTHE CONSENSUS BUT STILL PLAUSIBLE SOLUTIONS.  THE LARGE ARRAY OFSOLUTIONS APPEARS PARTIALLY RELATED TO HOW NORTHERN STREAM FLOWCROSSING THE GREAT LAKES INTERACTS WITH THE APPROACHING SYSTEM. BY FRIDAY NIGHT...THE LOW SHOULD BEGIN TO REFORM NEAR THEBAROCLINIC ZONE OVER THE CAROLINA PIEDMONT BEFORE CONSOLIDATINGWITH THE PARENT LOW NEAR THE NORTHEAST COAST.  THE SUBFREEZINGANTECEDENT CONDITIONS AHEAD OF THE LOW'S APPROACH FAVORS ASIGNIFICANT SWATH OF FREEZING AND FROZEN PRECIPITATION...WITH THETIMING/AMOUNTS STILL SOMEWHAT UNCLEAR BASED ON THE LARGE SOLUTIONSPREAD...BUT PRESENTLY APPEARS MOST LIKELY FROM THE TENNESSEERIVER VALLEY/APPALACHIANS/CAROLINA FOOTHILLS AND PIEDMONTNORTHWARD INTO NEW ENGLAND FRIDAY AND SATURDAY.

[GaWx]

Folks,

The southern extent of the ZR keeps getting further south in GA. The 18z 1/21 GFS had gotten down to Cumming/Gainseville. The 0z 1/22 GFS had reached all of the way down to Marietta with a tiny amount (~.01") The 1/22 6z GFS is all of the way down to the southside of Atlanta at the airport with a tiny amount while it gives Marietta nearly .10". It is mainly about the colder trends right now as the models play catch-up with the intensity of the cold, dry air that will be in place initially. All of this is being shown without the aid of cold easterly winds. The modeled winds are still SE and, yet, there is some ZR that is trending further south. Imagine how much more significant this could get if the runs start showing ZR locking east winds as well as heavier precip. With the potential event still 78 hours out, there's still plenty of time for this to evolve. Analogs and climo are keeping me on my toes with this threat.

By the way, KATL hasn't received measurable ZR in two years. Also, KATL hasn't experienced a winter event that was mainly ZR in a good bit longer than that as I recall. I'll check the records when I get the chance.

[HKY_WX]

with a slp this far north, it's inevitable there will be a changeover. euro looks like snow to sleet/freezing rain for most of northern NC.

[packbacker]

Well the 6z GEFS has about 7/12 members with snow into NC.

[packfan98]

Many of the 6z individual ensemble members offers some in the SE snow.  I think the trend south will remain for the next 48 hours.  Will it tick north in the last 24 hours before the storm? Probably.  I also think the trend to slightly colder temperatures will continue as well (this has historically been the case leading up to an event).  Just enough to give the NC Crew in the I-85/40 corridors some hope.  Maybe the biggest question mark will be how much moisture will there be?  Anyway, I'm all in for model watching. Not too optimistic that I'll actually see a significant amout of winter weather though.

 

http://raleighwx.americanwx.com/models/gfsensemble/members/06zsnowf090.html

[weatherheels]

with a slp this far north, it's inevitable there will be a changeover. euro looks like snow to sleet/freezing rain for most of northern NC.

You'd have to be right.   I'm shocked at how low the high temperatures are progged to be on Friday with a slp projected to be north of us.  I guess we all know how hard it is to get that lower level cold pushed out once it gets wedged in. Looks like it could be one of those days where we dont get above freezing here in the Triad.