932
FXUS01 KWBC 080853
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
452 AM EDT THU OCT 08 2009
VALID 12Z THU OCT 08 2009 - 00Z SAT OCT 10 2009
AN ACTIVE WEATHER PATTERN IS IN STORE FOR MUCH OF THE UNITED
STATES OVER THE NEXT FEW DAYS DUE TO CLASHING OF UNSEASONABLY WARM
AND COLD AIRMASSES OVER THE LOWER 48. THE WESTERN END OF A FRONT
THAT MOVED ACROSS THE EASTERN U.S. ON WEDNESDAY CURRENTLY
SEPARATES A VERY HUMID... MOISTURE LADEN AIRMASS TO ITS SOUTH OVER
SOUTH TEXAS AND GULF COAST REGIONS FROM COOLER AND DRIER AIR TO
THE NORTH. LOW LEVEL SOUTHERLY FLOW ACROSS THE BOUNDARY IS ALREADY
PRODUCING POCKETS OF STEADY RAINFALL FROM THE TEXAS PANHANDLE TO
THE MIDDLE MISSISSIPPI VALLEY. THE APPROACH OF A BROAD UPPER LEVEL
TROUGH FROM THE SOUTHWEST WILL INCREASE LOW LEVEL SOUTHERLY FLOW
OUT AHEAD OF THE TROUGH FROM THE CENTRAL TO THE EASTERN U.S. IN
ADDITION TO INCREASING RAINFALL COVERAGE. FLOOD AND FLASH FLOOD
WATCHES HAVE BEEN POSTED FROM TEXAS... NORTHEASTWARD INTO INDIANA
DUE TO THE EXPECTED HEAVY RAIN.
A LARGE AREA OF WIDESPREAD HEAVY RAIN IS EXPECTED TO LAST THROUGH
THE DAY TODAY FROM NORTHWEST TEXAS INTO THE OHIO VALLEY WITH BROAD
2 TO 4 INCH TOTALS POSSIBLE THROUGH FRIDAY MORNING. RAINFALL WILL
SHIFT EAST ON FRIDAY AS THE FRONT AND UPPER TROUGH SLIDE EAST...
THOUGH AMOUNTS SHOULD DIMINISH RELATIVE TO THE CENTER OF THE
COUNTRY. THE EXCEPTION TO THIS WILL BE FOR LOCATIONS ACROSS EAST
TEXAS INTO LOUISIANA WHERE A STALLED FRONT AND GREATER MOISTURE
AVAILABILITY COULD STILL POSE A HEAVY RAIN THREAT.
REGARDING TEMPERATURES... ALTHOUGH EVERYONE BEHIND A SECONDARY
COLD FRONT CURRENTLY MOVING THROUGH THE CENTRAL U.S. WILL
EXPERIENCE BELOW AVERAGE TEMPERATURES... MAJOR DEPARTURES ARE
ANTICIPATED WITH A REINFORCING SHOT OF ARCTIC AIR DUE TO ARRIVE
INTO THE LOWER 48 TONIGHT. THIS REINFORCING BLAST WILL SLIDE DOWN
THE EAST SIDE OF THE NORTHERN AND CENTRAL ROCKIES LEAVING BEHIND
30 TO 40 DEGREE DEPARTURES FROM THE AVERAGE MAX TEMPERATURE ACROSS
THE NORTHERN TO THE CENTRAL HIGH PLAINS.
OTTO
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