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February 12-13 Storm, Part III: Trilogy ends and then Obs thread soon!

stormtracker

By stormtracker,
in Mid Atlantic

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HM

HM

Posted
Posted

GFS precip is kinda weird on the western flank when the model is off OC

The GFS is blowing up some sick W. Atlantic convection which works in-tandem with the dry-conveyor belt. This could be a reason it is limiting QPF in your area, but I am guessing.

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Deck Pic

Deck Pic

Posted
Posted

same almost every winter...the models are flawed, including euro, to give DC snow and snow amounts that are totally inconsistent with climo and their OWN advertised longwave patterns...It is hard to snow in DC even in a good pattern..and Resolution will do nothing to stop it....LWX will have like their 100th bust in the last 4 years....

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usedtobe

usedtobe

Posted
Posted

look like 4" for me and then sleet and then rain

 

next

Matt, the run is bizarre, It's gotten wetter but I don't understand why the deformation zone doesn't have heavier precip or why when the low pulls east the 850 temps are slow to respond.  A closed 500 with a low winding up offshore should be wetter. 

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Deck Pic

Deck Pic

Posted
Posted

Matt, the run is bizarre, It's gotten wetter but I don't understand why the deformation zone doesn't have heavier precip or why when the low pulls east the 850 temps are slow to respond.  A closed 500 with a low winding up offshore should be wetter. 

 

yes...both this run and the euro look goofy....I believe the GFS is closest to being correct...I'd be surprised if I see more than 2-3" from this storm before I mix...

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swimmatte

swimmatte

Posted
Posted

DCA

 

THU 06Z 13-FEB     -2.9    -4.9    1021    96 100    0.16    555 539
THU 12Z 13-FEB     -1.3    -0.4    1011    97 99      0.42    551 542
THU 18Z 13-FEB      0.9     0.3    1001    99 99       0.14    543 543
FRI 00Z 14-FEB       0.9    -0.8      998    94 98       0.15    536 538
FRI 06Z 14-FEB      -0.8     0.0    1000    88 21       0.01    537 537 

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Ian

Ian

Posted
Posted

To be fair, LWX hasn't even put out a warning yet with snow total ranges.. I don't see how this can be ascribed to them as a bust no matter what happens.

people are giving them a hard time for that but i think today's models show it's pretty wise.. perhaps could hoist out west tho.

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

Matt, the run is bizarre, It's gotten wetter but I don't understand why the deformation zone doesn't have heavier precip or why when the low pulls east the 850 temps are slow to respond.  A closed 500 with a low winding up offshore should be wetter. 

 

It does look kind of unusual.  Just looking at the low track and nothing else, one might think that's pretty good.  But the thermals go to pot.  It is certainly wetter.

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HM

HM

Posted
Posted

The surface high extends westward into the mid-level confluence over the N. Mid Atlantic before cyclonic flow takes over with nor'easter. The high did its job and is being overused here as a reason. The problems are with the mid-level lows 850-700 track/wind etc.

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Ian

Ian

Posted
Posted

It does look kind of unusual.  Just looking at the low track and nothing else, one might think that's pretty good.  But the thermals go to pot.  It is certainly wetter.

the trough starts to go negative pretty early tho .. the pass is fine

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Deck Pic

Deck Pic

Posted
Posted

people are giving them a hard time for that but i think today's models show it's pretty wise.. perhaps could hoist out west tho.

 

yeah...caution is good.. and I am not blaming them entirely...it is our reliance on models in DC that lead us to bust so much...I hate to be right, but I am right...models almost NEVER trend to snowier solutions....

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miller.b.time

miller.b.time

Posted
Posted

Updated Heavy Snow disco from WPC:

 

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSIONNWS WEATHER PREDICTION CENTER COLLEGE PARK MD451 PM EST TUE FEB 11 2014VALID 00Z WED FEB 12 2014 - 00Z SAT FEB 15 2014...SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY TO SOUTHEAST AND ALONGTHE EAST COAST...  A WINTER STORM WITH HIGH SOCIETAL IMPACT IS IMMINENT ACROSS THESOUTHERN TIER OF THE COUNTRY AND VERY LIKELY TO PROCEED UP THEEAST COAST ON WED AND THURS... ESSENTIALLY EXTENDING FROM THELOWER MS VALLEY TO NEW ENGLAND OVER THE THREE DAY PERIOD.A WELL-DEFINED SHORTWAVE TROUGH EMBEDDED WITHIN THE SOUTHERNSTREAM IS FORECAST TO MOVE OUT ACROSS TX/OK THISEVENING...REACHING THE LOWER MS VALLEY BY TOMORROW MORNING WHILESPURRING THE DEVELOPMENT AND THE EAST-NORTHEASTWARD TRACK OF ASURFACE LOW ALONG A STALLED FRONTAL BOUNDARY OVER THE NORTHERNGULF.  INCREASING LOW LEVEL SOUTH-SOUTHWESTERLY FLOW WILL AFFORDSTRONG ISENTROPIC LIFT OVER A COLD ARCTIC SURFACE HIGH NOSING INTOTHE REGION...WITH ADDITIONAL LIFT AFFORDED BY THE RIGHT-ENTRANCEREGION OF THE UPPER JET.  THIS WILL SET THE STAGE FOR ASIGNIFICANT AND POTENTIALLY PARALYZING ICE STORM FOR PORTIONS OFTHE SOUTHEASTERN U.S.  WHILE AT LEAST SOME ICE ACCUMULATIONS CANBE EXPECTED ALONG A WIDE SWATH STRETCHING FROM NORTHEASTERN TX TOEASTERN NC THROUGH DAY 1...THE AREAS MOST LIKELY TO SEESIGNIFICANT ACCUMULATIONS OF A QUARTER-INCH OR MORE ARE CENTEREDACROSS NORTHERN LA/SOUTHERN EASTERN AR INTO W-CENTRAL MS...ANDMORE NOTABLY FROM E-CENTRAL AL TO SOUTHERN EASTERN NC...INCLUDINGNORTHERN-CENTRAL GA AND CENTRAL SC.  ACROSS THIS LATTER REGIONTHERE IS A HIGH RISK FOR ICE ACCUMULATIONS OF AT LEAST AQUARTER-INCH...WITH POTENTIALLY MUCH HEAVIER AMOUNTS BY WEDEVENING.  FURTHER TO THE NORTH...A SMALLER SWATH OF HEAVY SNOWS ISPOSSIBLE...WITH THE THREAT FOR ACCUMULATIONS OF 8-INCHES OR MORETHROUGH WED EVENING MAINLY CONFINED TO NORTHEASTERN GA...UPSTATESC AND SOUTHWESTERN NC.WHILE THE MODELS GENERALLY AGREED ON THIS SCENARIO UNFOLDINGACROSS THE SOUTH...THE FORECAST BECOMES MORE MURKY ON DAYS 2-3. CONCEPTUALLY THE MODELS ALL SHARE SIMILAR IDEAS...AS THEAFOREMENTIONED SOUTHERN STREAM WAVE PHASES WITH A NORTHERN STREAMTROUGH DROPPING SOUTHEASTWARD OUT OF THE NORTHERN HIGH PLAINS ANDINTO THE LOWER MS/TN VALLEYS BY TOMORROW EVENING...THIS WILL SPURTHE DEVELOPMENT OF A LOW ALONG THE SOUTHEAST COAST THAT ISFORECAST TO TRACK NORTHEASTWARD ALONG THE MID ATLANTIC COAST WEDNIGHT-THU AND THEN ALONG THE NORTHEAST COAST THU NIGHT-FRI MORNINGAS THE PHASED TROUGH ASSUMES A NEGATIVE TILT AND LIFTS ALONG THECOAST.   WITH THIS SYSTEM THE POTENTIAL FOR WIDESPREAD DISRUPTIVESNOW/ICE ACCUMULATIONS ALONG THE MID ATLANTIC TO THE NORTHEASTREMAINS...HOWEVER DETAIL DIFFERENCES PERSIST IN THE MODELS THATLOWER CONFIDENCE IN THE PLACEMENT AND MAGNITUDE OF SNOW/ICEACCUMULATIONS.  FURTHER COMPLICATING THE FORECAST ARE RUN-TO-RUNDIFFERENCES IN THE MODELS WHICH HAVE SIGNIFICANT IMPACTS ONTHERMAL PROFILES AND AMOUNTS.  THE NCEP MODELS REMAIN SLOWER THANTHE ECMWF/UKMET TO CLOSE OFF A LOW AT 500MB AND IN TURN ARE FASTERTO LIFT THE SYSTEM ALONG THE COAST AND IN TURN ARE LIGHTER WITHAMOUNTS AND/OR PAINT THEIR HEAVIER ACCUMULATIONS FURTHER TO THEEAST.  THE UKMET/ECMWF ON THE OTHER HAND HAVE BOTH TRENDED ALITTLE SLOWER...WRAPPING MORE WARM AIR FURTHER INLAND THAN THEIRPREVIOUS RUNS...SHIFTING THE RAIN/SNOW LINE FURTHER TO THEWEST...RESULTING IN LIGHTER ACCUMULATIONS ALONG THE COASTAL PLAINSWITH A TIGHTER ACCUMULATION GRADIENT ALONG THE PIEDMONT BACK INTOTHE MOUNTAINS.  WHILE THE MODELS CONTINUE TO WORK OUT THEIRDIFFERENCES...AN INTERMEDIATE SOLUTION...BUT ONE MORE CLOSELY TIEDTO THE UKMET/00Z ECMWF...WAS FOLLOWED THROUGH THE DAY 2-3PERIODS....WHICH IS REFLECTED IN THE HIGHER PROBABILITIES FORHEAVY SNOW CENTERED ALONG AND WEST OF THE I-95 CORRIDOR THROUGHTHE CENTRAL-NORTHERN MID ATLANTIC INTO THE NORTHEAST.  MEANWHILESIGNIFICANT ICING WILL STILL BE POSSIBLE EARLY ON IN THE DAY 2PERIOD ACROSS PORTIONS OF CENTRAL SC TO SOUTHEASTERN VA.
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Ian

Ian

Posted
Posted

yeah...caution is good.. and I am not blaming them entirely...it is our reliance on models in DC that lead us to bust so much...I hate to be right, but I am right...models almost NEVER trend to snowier solutions....

In this range especially. Too soon 2.11 0z Euro.. too soon. 

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twax1

twax1

Posted
Posted

SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...

NORTHERN STREAM SHORT WAVE IS DIVING SOUTHEAST OVER MONTANA WHILE
SOUTHERN STREAM TROUGH IS PUSHING ACROSS THE SOUTHWESTERN US THIS
AFTERNOON PER LATEST WATER VAPOR LOOP. PHASING OF THESE PIECES OF
ENERGY REMAINS AN ISSUE AS IT AFFECTS THE TRACK OF THE SURFACE LOW
AND PLACEMENT OF THE LOW LEVEL THERMAL GRADIENT...WITH THE ECMWF
CONTINUING TO BE THE WETTEST/WARMEST/SLOWEST AND FARTHEST WEST. THE
NAM IS THE MOST PROGRESSIVE...BUT THE GFS HAS THE LOWEST QPF.
PREFERENCE IS THE TRACK OF THE GFS...HOWEVER...SINCE THIS IS A
SOUTHERN STREAM DOMINATE STORM WITH THE SURFACE LOW ORIGINATING OVER
THE GULF OF MEXICO...THE QPF LOOKS WELL ON THE LOW SIDE...AND HAVE
INCREASED QPF TO MORE OF A BLEND OF ECMWF/GFS/WPC. SNOW RATIOS WILL
START OUT BETWEEN 11:1 AND 12:1 NEAR THE I-95 CORRIDOR WITH UP TO
15:1 TO THE WEST AS ANTECEDENT CONDITIONS WILL BE COLD. AS WARM NOSE
PUSHES IN ACROSS THE EAST...SNOW RATIOS WILL LOWER...ESPECIALLY AS
SLEET THEN RAIN MIXES GENERALLY ALONG AND EAST OF I-95. POTENTIAL
FOR HEAVY SNOW BANDING EXISTS ESPECIALLY IN SWATH ON NORTHERN SIDE
OF 700MB FGEN FORCING WHERE NEGATIVE EPV INSTABILITY SITS JUST ATOP
FORCING IN THE 700-600 MB LEVEL ON A CROSS-SECTION. AT THIS
TIME...THIS BANDING POTENTIAL LOOKS TO SET UP TO THE WEST OF I-95 ON
A CORRIDOR FROM NEAR CHO TO IAD TO N/NE MD. MAXIMIZED OMEGA IN
DENDRITIC GROWTH LAYER WILL ALSO SUPPORT HIGH SNOW
RATES...ESPECIALLY LATE WED NIGHT INTO THURS MORNING. SNOW TOTALS
LOOKING IMPRESSIVE WITH OVER A FOOT POSSIBLE ACROSS THE BLUE RIDGE
DUE TO INITIALLY UPSLOPE COMPONENT WITH THIS STORM SYSTEM. WILL
LIKELY BE SOME TUNING OF THE SNOW AMOUNTS AS THE STORM NEARS...AND
WILL MAINTAIN WATCH FOR NOW WITH CONTINUED UNCERTAINTY. THE EDGES
REMAIN MOST QUESTIONABLE DUE TO POTENTIAL RAIN/SLEET/SNOW LINE
ACROSS METRO AREAS AND SOUTHERN MARYLAND...AND ALSO WITH THE
LOCATION OF THE CUTOFF ON THE WESTERN SIDE OF THE SNOW BANDS TOWARD
WESTERN MARYLAND/EASTERN WV.

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

yeah...caution is good.. and I am not blaming them entirely...it is our reliance on models in DC that lead us to bust so much...I hate to be right, but I am right...models almost NEVER trend to snowier solutions....

 

I see what you're saying, but don't totally agree.  I don't think that reliance on models by forecasters (or us, or anyone else) causes more busts.  I think they know what issues the models may have, what the biases are, etc., and take that into account.  I cannot blame LWX or any other forecast outlet for issuing a watch and giving a heads-up at what could be a very disruptive event, when essentially every single major piece of guidance has been screaming for a high potential for warning-criteria snows.  We may mix or change over but it still looks very likely will be that level of snowfall through Thursday morning.

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