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Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 2140Z Feb 24, 2015)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
440 PM EST TUE FEB 24 2015

VALID 00Z WED FEB 25 2015 - 00Z SAT FEB 28 2015


...SRN PLAINS/LOWER MS VALLEY TO THE SOUTHERN
APPALACHIANS/SOUTHEAST/MID-ATL...

A VERY COMPLEX FORECAST FOR THE SOUTHERN TIER OF THE COUNTRY ON
WED AND THURS.... AS AN ACTIVE SRN BRANCH WITH GULF OF MEXICO AND
SUBTROPICAL MOISTURE INTERACTS WITH POLAR AND ARCTIC HIGH PRESSURE
FOR THE THREAT OF EXTENSIVE WINTER WEATHER. 
 
A CLOSED MID TO UPPER LOW OVER AZ/NM WILL EJECT OUT IN THE SRN
PLAINS/LOWER MS VALLEY ON WED AND PROGRESS ALONG THE FAST SRN
BRANCH INTO THE SOUTHEAST LATE WED INTO THURS. THIS SYSTEM SHOULD
BEGIN TO TAP A BRIEF BUT ANOMALOUS SURGE IN LL MOISTURE FROM THE
GULF OF MEXICO WITH PWS AOA 1 TO 2 TIMES ABOVE STANDARDIZED
ANOMALIES. THIS MOISTURE WILL OVERRUN A FORMING BAROCLINIC ZONE
NEAR THE CENTRAL GULF COAST AND MODEL THERMAL PROFILES SUGGEST
POSSIBLE STREAK OF HEAVY SNOW AND NARROW TRANSITION ZONE FROM NERN
TX TO NRN GA/SRN APPALACHIANS... WITH THE HEAVIEST FROZEN PRECIP
ACROSS NERN TX/SRN AR/NRN MS/AL INTO NRN GA. AS A SURFACE LOW
DEVELOPS AND ARRIVES TO JUST OFFSHORE OF THE FL PANHANDLE LATE
WED... THIS LOW WILL JUMP TO THE CAROLINAS COAST BY THURS MORNING.
THIS SHOULD RESULT IN A POTENTIALLY DECENT DYNAMIC COOLING REGIME
FROM NRN GA/ERN TN THROUGH NC/SRN VA AND PERHAPS FARTHER NORTH.
THIS ENTIRE FCST SOUND FAIRLY STRAIGHT FORWARD... HOWEVER A DECENT
AMOUNT OF SPREAD EXISTS WITH THE GUIDANCE. THE CLEAR TREND OVER
THE PAST 24 HRS IS A CONTINUE TREND TO THE NORTH WITH THE
EXTENSION OF THE DEVELOPING PRECIP SHIELD. THE 12Z NAM/09Z SREF
MEAN ARE AN ACTUAL CLEAR OVER-AMPLIFIED SOLUTION... WHILE THE
GFS/ECMWF ARE MORE SUBDUED. WPC BOUGHT THE NORTHWARD TREND BUT
REMAINED CONSERVATIVE IN RELYING CLOSE TO THE GLOBAL DUO OF THE
GFS/ECMWF THROUGHOUT. THIS MEANS DRAWING SNOW FARTHER NORTH INTO
PARTS OF THE TN VALLEY/APPALACHIANS AND MID-ATL REGION. THIS FCST
REMAINS FLUID ESPECIALLY THURS FOR A REGION SUSCEPTIBLE TO ANY
WINTER WEATHER INVOLVING AN ACTIVE SRN STREAM... PLENTY OF
MOISTURE AND ARCTIC AIR.    

...UPPER MIDWEST INTO MID MS VALLEY...

UPPER HEIGHT FALLS ACCOMPANYING AN ALBERTA CLIPPER WILL ARRIVE
INTO THE NRN PLAINS/UPPER MIDWEST AND MID MS VALLEY WED INTO
THURS. THIS SHOULD RESULT IN MDT TO HEAVY UPSLOPE SNOW FROM THE
NRN TO CENTRAL ROCKIES... WHILE A STRIPE OF LIGHT TO MDT
OVERRUNNING AND DYNAMICALLY DRIVEN SNOW WILL BE POSSIBLE FROM THE
DAKOTAS INTO IA AND WRN IL/NRN MO. WPC FOLLOWED A BLEND OF THE
GUIDANCE FOR THE HEAVY SNOWFALL PROBS... ESPECIALLY ACROSS IA.

...NEW ENGLAND...

A POWERFUL NRN STREAM SHORT WAVE TROUGH MOVING ACROSS THE GREAT
LAKES TUES INTO WED WILL EVENTUALLY HELP INDUCE A LOW OFFSHORE OF
SRN NEW ENGLAND. THIS LOW FORMING WED MORNING WILL DEEPEN RAPIDLY
WHILE LIFTING TO THE NORTH/NNW WITH BACKING FLOW. THIS SHOULD
RESULT IN A ZONE OF HEAVY DEFORMATION/DYNAMIC COOLING SNOWFALL
FROM PARTS OF SRN NEW ENGLAND UP THROUGH THE ERN PORTION OF MAINE.
WPC GENERALLY FOLLOWED A 12Z BLEND OF THE GUIDANCE FOR THE HEAVY
SNOW PROBS.

...CO/NM ROCKIES DAYS 2-3...

ON THURS AND FRI STEADY UPPER HEIGHT FALLS OUT WEST ALONG WITH
SEVERAL SHORT WAVE IMPULSES DIVING THROUGH THE INTER-MOUNTAIN WEST
WILL COMBINE WITH A MAMMOTH RIDGE OF ARCTIC HIGH PRESSURE FOR
STEADY AND STRONG AT TIMES UPSLOPE/OROGRAPHIC SNOW ACROSS THE
CENTRAL/SRN ROCKIES WITH SOME OVERRUNNING OUT INTO THE SRN PLAINS.
THE BULK OF THE ACTION ON THURS WILL OCCUR ACROSS THE CO ROCKIES
AND EAST SLOPES OF THE SANGRE DE CRISTO RANGE ACROSS SERN CO/NERN
NM. THE ACTION SHIFTS SOUTH INTO SRN CO/NRN NM ON FRI... WHILE
SOME LIGHTER OVERRUNNING SNOW WILL BE POSSIBLE INTO THE TX/OK
PANHANDLES.

MUSHER