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Wintry/Severe/Normal Storm threat 12/19-21

deltadog03

By deltadog03,
in Southeastern States

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Smoked

Smoked

Posted
Posted

Positioning of the 12Z Euro does match up nicely with the 12Z para GFS which is encouraging. Euro is considerably stronger indicating a sub 1000 mb low off of the Outer Banks at around 140 hours out. As others have stated there is only marginal cold air available, so the strength and position of the high to the north will be a big player as to how much cold air gets locked in ahead of the strong and/or wraps around the backside as it deepens near the coast of NC. Next day or so of model runs will likely be telling if this is going to be a legit threat. 

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superjames1992

superjames1992

Posted
Posted

Yeah, Pack, the Euro ENS still mostly depicts a Miller B system.  It's basically identical to the 00z EPS mean, give or take a few miles.

 

Looking over the individual low placements, I don't think a single one agrees with the op.  Perhaps the operational's higher resolution is allowing it to see something the lower-resolution ensembles are missing, though probably not.

 

FWIW, the control run takes the low through central GA up over RDU and then just north of Norfolk.  It's a Miller A, but it was a Miller B last night.

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Webberweather53

Webberweather53

Posted
Posted

2 of the top 4 CIP's 5h analogs...just saying...I wish I could post the EuroWx snow map which some people feel like is a realistic snow map  :whistle:

 

Edit:  The Dec,2002 ice storm is in the analog set too.  I didn't check all of them, just ones that I remembered.

 

accum.19880108.gif

 

accum.19820115.gif

 

 

If the snowpack across the northern tier was at least at climatology, if not greater, we'd easily be talking about wintry weather here up to the caliber of those events, & possibly even down to the I-20 corridor, but this isn't likely, IMO, and even though we have observed winter storms with less snow to our north, it's pretty rare (at least since 2000 anyways) to see a winter storm here in NC without the southern edge of the snowpack at least down through the I-90 corridor...

The general average of the southern extent of the snowpack according to what I've observed in the US preceding winter storms here in NC is the I-70 corridor (which is slightly better than climatology) & it never hurts to have snow on the ground over the Appalachians...

The differing shades of blue are directly related to frequency, darker hues= higher frequency of occurrence (in this case, the location of the southern edge of the US snowpack)

US-Snow-cover-edge-NC-Snows-1-day-lag-10

 

 

A dismal snowpack like this more than likely isn't going to cut it...

gfs_asnow_us_11.png

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franklin NCwx

franklin NCwx

Posted
Posted

ENS says the Op run was on crack, looks more NW than the 0z ENS run. LOL

Edit: It's to far west for the DC crew. Crazy runs today.

it's the same as the 0z until it gets to eastern nc then it's farther west than 0z. The control is now a miller a that blasts up thru 95 compared to the miller b it had last night. Ens mean is still a miller b.
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superjames1992

superjames1992

Posted
Posted

it's the same as the 0z until it gets to eastern nc then it's farther west than 0z. The control is now a miller a that blasts up thru 95 compared to the miller b it had last night. Ens mean is still a miller b.

 

Yeah, the fact that the control shifted from a solid Miller B last night to a Miller A today has me wondering if the op might not be totally on crack, though I'm admittedly reaching.  Granted, it's a Miller A that does no good for anyone outside of the mountains because the track is inland, but it's a Miller A, nevertheless.

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msuwx

msuwx

Posted
Posted

Yeah, the 12z Euro ensemble mean is essentially right on top of the 0z ensemble mean. Very similar, Miller B track (one weakening low in KY/ WV, one taking over near ILM). Only real difference (in the time periods it impacts the Carolinas) is the 12z is 2mb weaker than the 0z run. 

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Smoked

Smoked

Posted
Posted

Kind of a random question, but TWC has Greensboro at 46/31 with R/S showers on 12/20...has Durham at 46/31 but with just rain. What gives G-boro the chance of snow but not Durham? They're the same temp, only only ~50 miles apart. 

 

Could be the timing/intensity of precipitation at each location and/or the depth of cold air just above the surface. 50 miles further east closer to the coast can make it considerably more difficult to maintain cold enough air several thousand feet above the surface to allow snow to make it to the surface.

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burgertime

burgertime

Posted
Posted

 

Yeah, the 12z Euro ensemble mean is essentially right on top of the 0z ensemble mean. Very similar, Miller B track (one weakening low in KY/ WV, one taking over near ILM). Only real difference (in the time periods it impacts the Carolinas) is the 12z is 2mb weaker than the 0z run. 

 

 

Could be the timing/intensity of precipitation at each location and/or the depth of cold air just above the surface. 50 miles further east closer to the coast can make it considerably more difficult to maintain cold enough air several thousand feet above the surface to allow snow to make it to the surface.

 

 

Thanks for taking the time to post today your input is always appreciated. 

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Webberweather53

Webberweather53

Posted
Posted

Kind of a random question, but TWC has Greensboro at 46/31 with R/S showers on 12/20...has Durham at 46/31 but with just rain. What gives G-boro the chance of snow but not Durham? They're the same temp, only only ~50 miles apart. 

 

 

50 miles often makes a gigantic difference in these kind of NW gradient events (which are usually coupled w/ CAD, & this also assumes that there actually is going to be wintry precip here, which may not occur, but assuming there is), climatologically speaking, because of it's location, the depth of the CAD wedge when it develops is typically quite a bit deeper over Greensboro than in the Triangle, at least enough to have a higher retention against the latent heat of freezing which in concert w/ warm air advection in the mid-levels, are the mechanisms that erode the wedge. Thus, Greensboro can withstand & come away with more (re)-freezing precipitation in this kind of set-up, whereas areas like Durham & Raleigh can merely get clipped or miss out entirely. Last March is a great example...

accum.freezing.20140307.gif

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Ollie Williams

Ollie Williams

Posted
Posted

 From RNK

HAZARDOUS WEATHER OUTLOOKNATIONAL WEATHER SERVICE BLACKSBURG VA351 PM EST MON DEC 15 2014ALLEGHANY NC-SURRY-STOKES-ROCKINGHAM-CASWELL-WILKES-YADKIN-WYTHE-PULASKI-MONTGOMERY-CARROLL-FLOYD-CRAIG-ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-PATRICK-FRANKLIN-BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-APPOMATTOX-BUCKINGHAM-HALIFAX-CHARLOTTE-351 PM EST MON DEC 15 2014THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTHCAROLINA...NORTHWEST NORTH CAROLINA...CENTRAL VIRGINIA...SOUTHCENTRAL VIRGINIA...SOUTHWEST VIRGINIA AND WEST CENTRAL VIRGINIA..DAY ONE...THIS AFTERNOON AND TONIGHT.HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME..DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.THERE IS A CHANCE FOR SNOW OR A WINTRY MIX FRIDAY NIGHT INTOSATURDAY NIGHT.

And todays 3pm Discussion..

 

HIGH PRESSURE WILL THEN PASS ACROSS THE GREAT LAKES THURSDAY
NIGHT...AND THEN BUILD SOUTHWARD ACROSS THE MID ATLANTIC ON FRIDAY
TO WEDGE AGAINST THE EASTERN FACE OF THE APPALACHIANS. AS THE HIGH
BUILDS IN...WE WILL NOTICE WINDS SHIFTING INCREASINGLY
NORTHEASTERLY...WHICH WILL DRAW COOLER AIR INTO OUR AREA FROM NEW
ENGLAND. THE OTHER MAJOR FEATURE WE WILL SEE TAKE SHAPE ON FRIDAY IS
THE PASSAGE OF A LARGE UPPER LEVEL TROUGH FROM THE ROCKIES EASTWARD
ACROSS THE PLAINS. THIS TROUGH WILL SUPPORT DEVELOPMENT OF A LOW
PRESSURE SYSTEM ALONG THE TEXAS COAST THAT WILL PUSH EAST NORTHEAST
FRIDAY NIGHT AND SATURDAY. THIS LOW PRESSURE SYSTEM WILL BE A MAJOR
FACTOR IN OUR WEATHER FOR THE COMING WEEKEND...LIKELY BRINGING
WINTER STORM CONDITIONS TO PORTIONS OF OUR AREA.

WEATHER FORECAST MODELS ARE IN BETTER AGREEMENT WITH ONE ANOTHER
TODAY CONCERNING THIS SYSTEM...BUT HAVE NOTICEABLY SHIFTED IN THE
TRACK THAT THE STORM IS EXPECTED TO FOLLOW. MOST CONSISTENT OVER THE
PAST COUPLE DAYS HAS BEEN THE ECMWF...AND HAVE STEERED THE LONG-
RANGE FORECAST IN ITS FAVOR THIS AFTERNOON...ALONG WITH THE SIMILAR
CANADIAN MODEL. HOWEVER...UNCERTAINTY STILL REMAINS AND HAVE NOT
COMPLETELY BOUGHT INTO THE ECWMF/CANADIAN SOLUTIONS AS THE 15/12Z
RUNS HAVE SHIFTED THE LOW EAST FROM THE PREVIOUS RUNS...WITH THE LOW
NOW EXPECTED TO PASS NORTHEAST ALONG THE COAST RATHER THAN FURTHER
INLAND.

THE SHIFT IN TRACK KEEPS OUR AREA FURTHER AWAY FROM THE WARM AIR
WRAPPING AROUND THE LOW...WHICH NOW INTRODUCES A STRONGER POTENTIAL
FOR SNOW AND SLEET FURTHER EAST...POSSIBLY TO INCLUDE THE
SOUTHSIDE...AS COLDER AIR IS DRAWN ACROSS OUR AREA TOWARD THE LOW
CENTER. ALSO SEE A POSSIBILITY OF REDUCED PRECIPITATION FOR OUR AREA
AS THUNDERSTORM ACTIVITY DEVELOPING ALONG THE GULF COAST MAY ABSORB
SOME OF THE MOISTURE RIDING NORTHWARD INTO THE MID ATLANTIC. AT ANY
RATE...THE FORECAST FOR THIS SYSTEM IS FAR FROM SET IN STONE...AND
ADDITIONAL CHANGES/ADJUSTMENTS ARE LIKELY OVER THE NEXT COUPLE OF
MODEL RUNS.

THE LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT OUR AREA MAINLY FROM
THE PREDAWN HOURS OF SATURDAY THROUGH LATE SATURDAY EVENING. AS THE
LOW MOVES AWAY SATURDAY NIGHT...WINDS WILL SHIFT NORTHWESTERLY...
RESULTING IN LINGERING UPSLOPE SNOW SHOWERS ACROSS THE WESTERN
RIDGES...WHILE CLEARING CONDITIONS CAN BE EXPECTED FURTHER EAST.
HIGH PRESSURE WILL BEGIN TO SETTLE ACROSS OUR AREA LATE SUNDAY
EVENING.

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Jon

Jon

Posted
Posted

FWIW the 12z EPS Euro probability of 24hr accum of 1" snow is worse than the 00z by a pretty good bit, especially in the foothills probabilities dropped 10, 20, some places 30%+ by my estimations...only difference in the 12z is it sprayed 0-10% probabilities over the east part of the state, where it had been previously 0%....DC is brushed by 99.99% probabilites whereas the 0z had them near 70ish%, huge increase in the size of the 99.99% probability over VA/WVA border encompasing the entire border they share.

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Webberweather53

Webberweather53

Posted
Posted

On SV it looks like the low is in the gulf.....but northern stream is def. interacting so it's all strung out. Maps on SV are just those multicolored 5h maps so it's always hard to find a center. 

 

Those maps are colored 500mb heights overlaid w/ mean sea level pressure, so it actually is showing where the model "thinks" the actual center should be... The UKMET is ever so slightly north & west of the ECMWF's solution from yesterday

 

GZ_D5_PN_120_0000.gif

 

ecmwf_T850_us_7.png

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burgertime

burgertime

Posted
Posted

Those maps are colored 500mb heights overlaid w/ mean sea level pressure, so it actually is showing where the model "thinks" the actual center should be... The UKMET is ever so slightly north & west of the ECMWF's solution from yesterday

 

 

 

 

 

Thanks. Wish SV would just do either a vort map for the Ukie or go with a regular surface map. 

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FallsLake

FallsLake

Posted
Posted

RAH staying conservative with this weekends storm (which they should...)

 

AT THIS POINT WITH THE SOUTHERN STREAM SYSTEM YET TO REACH THE
PACIFIC COAST AND WITH LIMITED CONFIDENCE WE ARE HESITANT TO BUY
INTO ANY GIVEN SOLUTION. IT IS WORTH NOTING THAT THE EC COULD
SUPPORT SOME WET SNOW ACROSS THE INTERIOR PIEDMONT BUT THIS
SCENARIO IS AN OUTLIER AT THIS POINT. WITH BOUNDARY LAYER
TEMPERATURES JUST ABOVE FREEZING AND THE NEED FOR DYNAMICAL COOLING
TO SUFFICIENTLY COOL THE PROFILE...THIS APPEARS UNLIKELY AT THIS
TIME. IT IS MUCH MORE LIKELY THAT A CHILLY RAIN WITH TEMPS IN THE
30S. IT ALSO APPEARS THAT ANY THUNDERSTORM THREAT WOULD BE
SUPPRESSED TO THE IMMEDIATE COASTAL AREAS.

 

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Jon

Jon

Posted
Posted

Ends up really weird with a partially phased system. Two big pieces of energy...one heading just south of NC and the other north west of it heading east.  

welp...para still wins that run, GFS is god awful. Next time it shows something amazing for NC remind me that it's the GFS.

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