425
FXUS01 KWBC 250900
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
500 AM EDT FRI SEP 25 2009
VALID 12Z FRI SEP 25 2009 - 00Z SUN SEP 27 2009
MUCH OF THE PRECIPITATION DURING THE NEXT COUPLE OF DAYS WILL BE
IN RESPONSE TO A STRONG CLOSED UPPER LOW POSITIONED ACROSS THE
CENTRAL PLAINS. THIS PARTICULAR WEATHER SYSTEM HAS ALREADY BEEN
RESPONSIBLE FOR A LATE SUMMER SNOWFALL EVENT ACROSS PORTIONS OF
COLORADO AND WYOMING EARLIER THIS WEEK. AS THE WORK WEEK
CONCLUDES...TWO SEPARATE AXES OF PRECIPITATION WILL IMPACT THE
EASTERN HALF OF THE NATION. THE WEAKER BATCH OF RAINFALL WILL BE
IN ASSOCIATION WITH THE UPPER LOW WHICH WILL REMAIN
QUASI-STATIONARY OVER NEBRASKA/KANSAS ON FRIDAY BEFORE EVENTUALLY
EJECTING EASTWARD. IN ADVANCE OF THE DYNAMIC LOW CENTER...A
SLOW-MOVING FRONTAL BOUNDARY CURRENTLY PLACED ACROSS THE CENTRAL
GULF COAST AND EDGING NORTHWARD INTO THE TENNESSEE RIVER VALLEY IS
ANOTHER FOCUS FOR SHOWERS AND THUNDERSTORMS. WHILE THE ACTIVITY
WILL BE MORE WIDESPREAD IN NATURE...IT WILL BE DIFFICULT TO
PINPOINT THE PRECISE LOCATIONS OF HEAVIER RAINFALL GIVEN THE
STRONGEST DYNAMICS ALOFT REMAINS TO THE WEST.
BY THE START OF THE WEEKEND...THIS QUASI-STATIONARY CLOSED LOW
WILL EJECT EASTWARD AND HELP SPREAD THE HEAVIER AXIS OF
PRECIPITATION EASTWARD INTO THE MID-ATLANTIC REGION. AS THIS
OCCURS...A CHANGE IN THE CONDITIONS WILL IN STORE ACROSS THE EAST
COAST. AS THE WEATHER HAS BEEN MILD AND RATHER MUGGY MUCH OF THIS
WEEK...THE FRONTAL PASSAGE WILL BRING MUCH COOLER WEATHER TO THE
REGION BY THE LATTER HALF OF THE WEEKEND. HIGHS ON SUNDAY ACROSS
MUCH OF THE MID-ATLANTIC WILL LINGER IN THE 60S.
A RIDGE OF HIGH PRESSURE ACROSS THE WESTERN U.S. WILL KEEP
CONDITIONS RATHER QUIET AS MUCH OF THE ACTIVE WEATHER SITS EAST OF
THE ROCKIES. WARM TEMPERATURES WILL PREVAIL ACROSS MUCH OF THE
REGION WITH THE HOT SPOTS ACROSS THE DESERT LOCALES AS WELL AS
OVER THE INTERIOR VALLEYS OF CALIFORNIA. BOTH LOCATIONS WILL
APPROACH AND EXCEED THE TRIPLE DIGIT MARK WITH COOLER WEATHER
EXPECTED AS ONE INCHES CLOSER TO THE COASTLINE. THE ABOVE NORMAL
TEMPERATURES WILL CONTINUE THROUGHOUT THE WEEKEND AS THE UPPER
RIDGE REMAINS LOCKED IN PLACE.
RUBIN-OSTER
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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