029
FXUS01 KWBC 080817
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
416 AM EDT WED OCT 08 2008
VALID 12Z WED OCT 08 2008 - 00Z FRI OCT 10 2008
THERE WILL BE TWO SIGNIFICANT WEATHER FEATURES TO AFFECT THE LOWER
48 BY FRIDAY. THE FIRST IS ASSOCIATED WITH UPPER LEVEL
TROUGHING... CURRENTLY MOVING ACROSS THE MISSISSIPPI VALLEY WHERE
AT THE SURFACE... PRECIPITATION CURRENTLY STRETCHES FROM THE GULF
COAST TO THE GREAT LAKES. THIS BROAD AREA OF PRECIPITATION WILL
MOVE EAST OVER THE NEXT TWO DAYS... WITH HEAVIER RAINFALL TOTALS
OCCURRING OVER THE SOUTH DUE TO THE PRESENCE OF THUNDERSTORMS.
THESE RAINS WILL BE BENEFICIAL AS THEY WILL IMPACT THE HEART OF AN
ONGOING DROUGHT ACROSS THE SOUTHEAST. THE SOUTHERN SURFACE FRONTAL
SYSTEM WILL MOVE TO THE CAROLINA COAST BY THURSDAY NIGHT AND IS
THEN EXPECTED TO STALL... PERHAPS PROLONGING THE THREAT OF
RAINFALL OVER THE SOUTHEAST. THE OTHER FRONTAL SYSTEM... NEAR THE
GREAT LAKES... IS EXPECTED TO SLOWLY DISSIPATE WEDNESDAY NIGHT...
THEREBY PRODUCING LESS OVERALL RAIN FOR LOCATIONS NORTH OF THE
MASON DIXON LINE. THE GREATEST CHANGE IN AIRMASS BEHIND THESE TWO
SYSTEMS WILL BE SOMEWHAT LOWER DEWPOINTS AFTER THE FRONTS MOVES
THROUGH.
OUT WEST...A HIGHLY ANOMALOUS UPPER LEVEL TROUGH IS EXPECTED TO
DROP INTO THE WESTERN CONUS BY THIS WEEKEND... BRINGING A DRASTIC
CHANGE IN WEATHER. TODAY WILL BE COOLER ACROSS THE WEST BEHIND A
COLD FRONT... HOWEVER... THERE WILL BE LITTLE TO NO PRECIPITATION
TO SPEAK OF. THE UPPER TROUGH WILL BEGIN TO DIG INTO THE WEST ON
THURSDAY... BRINGING IN THE COLDEST AIR OF THE SEASON. HIGH
TEMPERATURES WILL BE ON A STEADY DOWNWARD TREND INTO THE
WEEKEND... FALLING AT LEAST 20 DEGREES BEHIND THE FRONT BY
THURSDAY... COMPARED TO TODAY. PRECIPITATION WILL EXPAND DURING
THE DAY ON THURSDAY... IMPACTING THOSE FROM WASHINGTON AND OREGON
TO MONTANA...WYOMING AND THE DAKOTAS. THE GREATEST IMPACT IN TERMS
OF PRECIPITATION... THROUGH THURSDAY... IS FORECAST TO OCCUR OVER
THE NORTHERN ROCKIES INTO THE HIGH PLAINS... AS STRONG WEST TO
SOUTHWEST FLOW PROVIDES IDEAL CONDITIONS FOR UPSLOPE ACROSS THE
HIGHER TERRAIN. SNOW LEVELS WILL FALL AND PORTIONS OF WYOMING ARE
EXPECTED TO SEE THE FIRST SIGNIFICANT SNOW STORM OF THE SEASON.
AS THE UPPER TROUGH MOVES IN... EXPECT WINDS TO INCREASE...
ESPECIALLY THROUGH PASSES AND ALONG REGIONS OF HIGHER TERRAIN. AT
LEAST THROUGH FRIDAY MORNING... THE MOISTURE SOURCE FOR THIS STORM
WILL BE RATHER LIMITED AS AN OLD FRONT ACROSS THE GULF OF MEXICO
WILL PREVENT SIGNIFICANT MOISTURE FROM MOVING NORTH THROUGH THE
PLAINS AND INTO THE NORTH CENTRAL U.S. SO... ALTHOUGH
PRECIPITATION WILL BE SIGNIFICANT... IT DOES NOT APPEAR TO BE THE
WORST CASE SCENARIO FOR AN UPPER TROUGH OF THIS MAGNITUDE COMPARED
TO IF THE GULF WERE COMPLETELY OPEN FOR BUSINESS... AGAIN... AT
LEAST THROUGH FRIDAY MORNING.
OTTO
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