***A SIGNIFICANT EAST COAST WINTER STORM TO BRING HAZARDOUS WINTER
TRAVEL CONDITIONS FROM SOUTHEAST TO NEW ENGLAND THROUGH FRIDAY.
WORST CONDITIONS EXPECTED ALONG THE IMMEDIATE EASTERN SEABOARD
FROM THE CAROLINAS TO MAINE. BITTERLY COLD TEMPERATURES AND
DANGEROUS WIND CHILLS TO PERSIST INTO THE WEEKEND***
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DISCUSSION...
THE NEVER-ENDING FRIGID AIR MASS ACROSS THE EASTERN PORTION OF THE
COUNTRY WILL BE REINFORCED OVER THE NEXT COUPLE DAYS AND THRIVE
THROUGH THE UPCOMING WEEKEND. A SPLIT FLOW UPPER TROUGH WITH SHORT
WAVES NEAR THE UPPER MS VALLEY AND FRONT RANGE OF THE
CENTRAL/SOUTHERN ROCKIES WILL DIG OFF TO THE SOUTH AND EAST. THE
SOUTHERN MOST FEATURE WHICH WILL ARRIVE TO THE CENTRAL GULF COAST
TONIGHT AND WILL INTERACT WITH SUBTROPICAL MOISTURE OVER THE GULF
OF MEXICO TO ALLOW PRECIP TO FLOURISH IN THE ESTABLISHED COLD
SECTOR. THIS SHOULD OCCUR OVERNIGHT INTO WED MORNING ACROSS
SOUTHEAST GA AND PORTION OF THE FL PANHANDLE INTO THE NORTHERN FL
PENINSULA, WHERE THERMALS SUGGEST NOT ONLY THE POTENTIAL FOR SNOW
BUT PERHAPS A HIGH END ICING EVENT. CONTINUED COLD ADVECTION FROM
THE NORTH COMBINED WITH LARGE SCALE LIFT AHEAD OF THE SHORT WAVE
TROUGH AND A PRONOUNCED INVERTED SURFACE TROUGH EXTENDING FROM THE
MAIN SURFACE LOW NEAR THE BAHAMAS TO THE SOUTHEAST COAST. THUS
FROM TUES TO WED EVENING, EXPECT FREEZING RAIN POTENTIAL FROM FL
EASTERN PANHANDLE/NORTHERN PENINSULA THROUGH SOUTHEAST GA INTO
EASTERN SC/SERN NC WITH SNOW ACCUMULATIONS POSSIBLE FROM THE
NORTHERN FL PENINSULA THROUGH SOUTHEAST GA INTO EASTERN SC/SERN
NC.
THE ACTION THEN SHIFTS WED NIGHT THROUGH THURS FROM EASTERN NC UP
THROUGH COASTAL/VERY EASTERN DELMARVA INTO THE NORTHEAST. THE
SOUTHERN STREAM SHORT WAVE DEPARTS THE SOUTHEAST TO BEGIN PHASING
WITH A SURFACE LOW LIFTING NORTH OVER THE WESTERN ATLANTIC AND
STILL WELL OFFSHORE OF THE EAST COAST. HOWEVER BACK UPSTREAM...
ENOUGH INFLUENCE FROM THE NORTHERN STREAM SHORT WAVE NEAR THE
GREAT LAKES TO APPALACHIANS SHOULD DRAW MOISTURE AND THE WESTERN
FRINGE OF THE LARGE PRECIP SHIELD INTO THE EASTERN PORTION OF THE
NORTHEAST. THUS THE HEAVY SNOWFALL AXIS APPEARS LIKELY TO TAKE
SHAPE FROM NERN NC/SERN VA ALONG THE MID-ATL COAST OR JUST
OFFSHORE INTO EASTERN LONG ISLAND AND UP THROUGH ALL OF EASTERN
NEW ENGLAND. FINALLY FROM THURS EVENING THROUGH FRI, EXPECT THE
BACK END OF THE INTENSE PHASED CYCLONE TO ENCOMPASS NORTHERN NEW
ENGLAND WITH ADDITIONAL SNOWFALL AMOUNTS.
THE OVERALL TREND WITH THE 12Z GUIDANCE IS A SLIGHT WESTWARD JOG
WITH MOST ITEMS INCLUDING THE CRITICAL QPF, THOUGH THE NAM APPEARS
TO BE OVER-ZEALOUS IN THE COLD SECTOR, AND WPC FOLLOWED WPC QPF.
CONCERNING PTYPE AND THERMALS A BLEND OF THE GFS, ECMWF, BOTH
GLOBAL MEANS AND NAM WERE USED THROUGH THE ENTIRE FORECAST PERIOD,
A SOLID DIVERSIFIED ENSEMBLE APPROACH.
Credit: Weather Prediction Center
By
/ January 3, 2018 