108
FXUS01 KWBC 230817
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
417 AM EDT TUE SEP 23 2008
VALID 12Z TUE SEP 23 2008 - 00Z THU SEP 25 2008
A VIGOROUS COLD FRONT THAT IS CURRENTLY OVER THE DAKOTAS AND SPANS
BACK INTO COLORADO HAS ALREADY PROVEN TO BE A SIGNIFICANT WEATHER
PRODUCER AND WILL CONTINUE TO YIELD MORE STORMY CONDITIONS ON
TUESDAY AND WEDNESDAY. THIS CYCLONE HAS SEVERAL FACTORS WORKING IN
ITS FAVOR. THE FIRST THING THAT JUMPS OUT IS THE STARK CONTRAST IN
THE TWO AIR MASSES. OUT AHEAD OF THE FRONT...IN THE WARM
SECTOR...TEMPERATURES WILL BE WELL INTO THE 70S AND 80S WITH VERY
HIGH DEW POINTS. BEHIND THE COLD FRONT...THE DEW POINTS PLUMMET
AND THE TEMPERATURES IN THE COLD SECTOR ARE EASILY 10-15 DEGREES
COOLER. SECONDLY...THE LONGWAVE TROUGH IS RELATIVELY
BROAD...SPANNING THE NORTHWEST QUADRANT OF THE CONUS. WITHIN THE
UPPER LEVEL TROUGH...THERE ARE SEVERAL POCKETS OF ENERGY
PROPAGATING EASTWARD AND ENABLING FURTHER AMPLIFICATION OVER THE
NORTHERN PLAINS. ALL THE WHILE...MOISTURE WILL CONTINUE TO GET
ENTRAINED INTO THIS SYSTEM. THE PRECIPITATION SHIELD WILL SPAN
MORE THAN 1000 MILES IN LENGTH FROM MANITOBA TO EASTERN COLORADO.
HOWEVER...THE HEAVIEST ACCUMULATIONS ARE EXPECTED OVER MINNESOTA
AND WISCONSIN...WHICH ARE ALSO LIKELY SUSPECTS FOR SEVERE
THUNDERSTORM DEVELOPMENT.
SOUTHEAST...CURRENTLY OFF THE CAROLINA COAST...THERE IS A BROAD
AREA OF INVERTED TROUGHING AT THE SURFACE WITH THE REMNANTS OF A
FRONTAL BOUNDARY JUST OFF SHORE. CLOCKWISE CIRCULATION AROUND THE
SURFACE HIGH WILL CONTINUE TO STIMULATE ONSHORE OVER THE CAROLINAS
AND FLORIDA...RESULTING IN SCATTERED SHOWERS/THUNDERSTORMS ALONG
THE SEABOARD. CONVECTION WILL BEGIN TO PERCOLATE AS THE DAYTIME
TEMPERATURES BEGIN TO CLIMB. ADDITIONALLY...A MID LEVEL LOW OFF
THE CAROLINA COAST WILL DEVELOP ON TUESDAY AND CLOSE OFF BY
WEDNESDAY...AN INDICATION THAT THE COASTAL LOW AT THE SURFACE
WILL STRENGTHEN AND CONVECTION WILL GET BETTER ORGANIZED.
ELSEWHERE...A PACIFIC CYCLONE IS CLOSING IN ON BRITISH
COLUMBIA...AND WILL CONTINUE TO INTENSIFY INTO WEDNESDAY. THIS
MATURE LOW PRESSURE SYSTEM WILL BEGIN TO ENHANCE ONSHORE FLOW INTO
WESTERN CANADA AND WASHINGTON STATE ON TUESDAY...WITH SCATTERED
RAINS REACHING THE OLYMPIC PENNINSULA BY TUESDAY EVENING. WHILE
THE LION'S SHARE OF THE PRECIPITATION WILL FALL NORTH OF THE
U.S./CANADIAN BORDER...THIS SYSTEM WILL BRING COOLER AND CHILLY
CONDITIONS TO THE PACIFIC NORTHWEST. OTHERWISE...SOUTHERN TEXAS
AND NORTHEASTERN MEXICO CAN ANTICIPATE MORE SHOWERS AND
THUNDERSTORM THIS FORECAST PERIOD...AS A BATCH OF PERTURBED
WEATHER MOVES WESTWARD INTO THE REGION. THIS RAINFALL MAY IMPACT
THE EASTERN PORTION OF THE RIO GRANDE.
SZATANEK
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