379
FXUS01 KWBC 200823
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
422 AM EDT TUE OCT 20 2009
VALID 12Z TUE OCT 20 2009 - 00Z THU OCT 22 2009
THE COMBINATION OF SEVERAL FACTORS WILL LEAD TO A BUSY WEATHER
PATTERN FOR THE CENTRAL AND SOUTHERN U.S. INTO MIDWEEK. FIRST... A
STRONG UPPER LEVEL DISTURBANCE NEAR THE SIERRA NEVADA MOUNTAINS
THIS MORNING IS EXPECTED TO TRACK EASTWARD... REACHING THE
SOUTHERN PLAINS ON WEDNESDAY. IN ADDITION... SOME OF THE MOISTURE
ASSOCIATED WITH TROPICAL STORM RICK IN THE EASTERN PACIFIC WILL BE
TRANSPORTED ACROSS MEXICO INTO THE SOUTHERN PLAINS AHEAD OF THE
UPPER TROF ALONG WITH MOISTURE FROM THE GULF OF MEXICO LEADING TO
ANOMALOUSLY HIGH LEVELS OF AVAILABLE MOISTURE THROUGHOUT THE
CENTRAL AND SOUTHERN U.S. IN ADDITION... COLD AIR OVER SOUTH
CENTRAL CANADA AND THE NORTH CENTRAL U.S. WILL SURGE SOUTHWARD
BEHIND A COLD FRONT BEGINNING TONIGHT... MAKING IT INTO NORTHERN
MEXICO BY THURSDAY MORNING.
TEMPERATURES AT THE SURFACE ACROSS THE COLORADO FRONT RANGE ARE
EXPECTED TO BECOME COLD ENOUGH TO SUPPORT AN ACCUMULATING SNOW...
WITH SEVERAL INCHES POSSIBLE BEGINNING TONIGHT. HIGHER
ACCUMULATIONS CAN BE EXPECTED INTO THE ELEVATED TERRAIN...
ESPECIALLY WITH NORTHEASTWARD FACING MOUNTAIN SLOPES. WIDESPREAD
SIGNIFICANT RAIN WITH COLD... GUSTY NORTHERLY WINDS BEHIND THE
FRONT CAN BE EXPECTED ACROSS PORTIONS OF THE CENTRAL PLAINS WITH
WIDESPREAD CONVECTION AND DRENCHING RAINS SOUTH OF THE FRONT
ACROSS THE SOUTHERN PLAINS.
ELSEWHERE ACROSS THE COUNTRY... AFTER A COLD START FOR FOLKS EAST
OF THE APPALACHIANS... SOUTHERLY FLOW ON THE BACKSIDE OF A SURFACE
RIDGE WILL ALLOW A WARMING TREND INTO MID WEEK FOR THE EAST.
CONDITIONS WILL BE RAIN FREE EXCEPT PERHAPS FOR THE EASTERN
FLORIDA PANHANDLE WHERE EASTERLY LOW LEVEL FLOW WILL KEEP THE
THREAT OF SHOWERS PRESENT.
AFTER A PLEASANT DAY TODAY... THE PACIFIC NORTHWEST WILL
EXPERIENCE DETERIORATING CONDITIONS BEGINNING EARLY WEDNESDAY WITH
THE APPROACH OF AN OCCLUDED CYCLONE FROM THE PACIFIC. SINCE
TEMPERATURES BEHIND THE FRONT WILL NOT BE ALL THAT DIFFERENT FROM
CURRENT CONDITIONS... THE BIGGEST IMPACT FROM THIS SYSTEM OTHER
THAN INCREASED CLOUDS WILL BE UPSLOPE DRIVEN RAIN AND MOUNTAIN
SNOW FOR THE CANADIAN ROCKIES. TOTAL RAINFALL AMOUNTS ARE EXPECTED
TO BE ON THE LIGHT SIDE FOR THIS ARE OF THE COUNTRY GIVEN THE TIME
OF YEAR.
OTTO
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