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FXUS01 KWBC 210822
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
322 AM EST FRI NOV 21 2008
VALID 12Z FRI NOV 21 2008 - 00Z SUN NOV 23 2008
ANOMALOUSLY COLD AIR REMAINS ACROSS MUCH OF THE EASTERN HALF OF
THE UNITED STATES AS A LARGE DOME OF SURFACE HIGH PRESSURE SETTLES
IN OVER THE REGION. CURRENTLY...THE AREA OF HIGH PRESSURE RESIDES
OVER THE NORTHERN PLAINS WHERE SINGLE DIGIT TEMPERATURES OVERNIGHT
ARE WIDESPREAD WITH EVEN SOME READINGS APPROACHING BELOW ZERO.
WHILE SUCH OVERNIGHT LOWS ARE NOT RECORD BREAKING...THEY DO MARK A
10 TO 15 DEGREE DEPARTURE FROM CLIMATOLOGY FOR THE MIDDLE TO END
OF NOVEMBER. AS THIS SURFACE RIDGE TRACKS TOWARD THE SOUTH AND
EAST...THIS WILL HELP KEEP TEMPERATURES WELL BELOW NORMAL ACROSS
MUCH OF THE EAST COAST. IN FACT...MANY READINGS ARE MORE
REMINISCENT OF TEMPERATURES DURING THE SEASON OF WINTER THAN THE
MIDDLE OF AUTUMN. DESPITE ABUNDANT CLOUD COVER EXPECTED ACROSS THE
OHIO VALLEY AND MID-ATLANTIC...ENOUGH COLD AIR WILL BE ADVECTING
FROM THE NORTHERN TIER TO PROMOTE OVERNIGHT TEMPERATURES INTO THE
UPPER TEENS TO LOWER 20S FRIDAY NIGHT. SUBFREEZING TEMPERATURES
ARE EVEN EXPECTED TO EXTEND AS FAR SOUTH AS THE FLORIDA PANHANDLE.
THE GENERAL NORTHWESTERLY TO NORTH-NORTHWESTERLY FLOW AT THE
SURFACE ACROSS THE NORTHEAST WILL PROMOTE WIDESPREAD LAKE EFFECT
SNOWS FOR MUCH OF THE NEXT COUPLE OF DAYS. AS THE WINDS START TO
TURN MORE SOUTHERLY BY SATURDAY AFTERNOON IN ADVANCE OF THE NEXT
STORM SYSTEM...THE LAKE EFFECT PRECIPITATION SHOULD WIND DOWN
ACROSS THE UPPER GREAT LAKES BY THIS TIME. FARTHER AWAY FROM THE
LAKES...MUCH OF THE APPALACHIAN MOUNTAIN RANGE CAN ALSO EXPECT
LIGHT TO MODERATE SNOW SHOWER ACTIVITY AS AN UPSLOPE FLOW WILL
CONTINUE ALONG THE ELEVATED TERRAIN.
AN UPPER-LEVEL DISTURBANCE CURRENTLY MOVING THROUGH THE UPPER
INTERMOUNTAIN WEST WILL EVENTUALLY CROSS INTO THE PLAINS BY FRIDAY
EVENING BEFORE NOSING SOUTHEASTWARD INTO THE MIDDLE MISSISSIPPI
VALLEY. THIS BATCH OF ENERGY WILL HELP SPAWN A MIXTURE OF RAIN AND
SNOW SHOWERS IN CLOSE PROXIMITY TO A WARM FRONTAL BOUNDARY. THIS
FRONT SHOULD HELP BRING MILDER AIR TO THE NORTHERN TIER AS DAYTIME
TEMPERATURES TO START THE WEEKEND WILL BE AT LEAST 10 TO 15
DEGREES WARMER THAN THEY WILL BE ON FRIDAY.
THE WEATHER ACROSS THE PACIFIC NORTHWEST WILL REMAIN UNSETTLED AS
A SERIES OF UPPER-LEVEL TROUGHS CONTINUE TO BOMBARD THE REGION.
WHILE THE BEST ATMOSPHERIC DYNAMICS WILL REMAIN NORTH OF THE
U.S./CANADIAN BORDER...A MOIST ONSHORE FLOW WILL HELP PROMOTE
NUMEROUS SHOWERS ACROSS THE REGION WITH HIGHER ELEVATION SNOWS AS
THE COLD AIR ALOFT ARRIVES WITH THE WEATHER SYSTEM.
RUBIN-OSTER
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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