954
FXUS01 KWBC 170856
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
455 AM EDT THU SEP 17 2009
VALID 12Z THU SEP 17 2009 - 00Z SAT SEP 19 2009
THE SOUTHERN STREAM FLOW FROM THE SOUTHWEST...ACROSS THE SOUTHERN
PLAINS...LOWER MISSISSIPPI VALLEY AND INTO THE SOUTHEASTERN U.S.
WILL CHANGE ONLY SLOWLY THIS FORECAST PERIOD. SURFACE TO UPPER
LEVEL CIRCULATIONS IN THIS FLOW WILL REMAIN REMOVED FROM THE MORE
ENERGETIC NORTHERN STREAM FLOW MOVING FROM THE NORTHEASTERN
PACIFIC...EASTWARD ACROSS THE PACIFIC NORTHWEST...CANADA AND INTO
THE NORTHEASTERN U.S. SUBSEQUENTLY...EXPECT A WET WEATHER PATTERN
TO PERSIST IN THIS SOUTHERN STREAM FLOW WHERE MOISTURE VALUES WILL
REMAIN ABOVE NORMAL. TWO DISTINCT CIRCULATION CENTERS WILL
DOMINATE THIS FLOW OVER THE NEXT FEW DAYS. THE PRIMARY
CIRCULATION IS THE PERSISTENT SURFACE TO UPPER LEVEL SYSTEM IN THE
VICINITY OF THE SOUTHERN PLAINS/LOWER MISSISSIPPI VALLEY. THIS
SYSTEM HAS BEEN ACROSS THIS REGION FOR ALL OF THIS WEEK...AND WILL
PERSIST INTO FRIDAY BEFORE WEAKENING AS IT BECOMES INCREASINGLY
ELONGATED. SHOWERS AND THUNDERSTORMS WILL PERSIST FROM THE
SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY AND
SOUTHEAST...WITH HEAVY PRECIPITATION AMOUNTS POSSIBLE. RECENT
HEAVY RAINS WITH THIS SYSTEM HAVE SATURATED THE SOIL ACROSS
PORTIONS OF THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI
VALLEY...LEADING TO THE CONTINUED THREAT OF FLOODING ACROSS THESE
REGIONS OVER THE NEXT FEW DAYS. THE SECOND SOUTHERN STREAM
CIRCULATION CENTER IS EXPECTED TO MOVE SLOWLY SOUTHEASTWARD FROM
THE DESERT SOUTHWEST INTO THE SOUTHERN HIGH PLAINS. THIS SYSTEM
WILL ENHANCE LARGE SCALE LIFT FROM THE FOUR CORNERS
REGION...SOUTHEASTWARD THROUGH NEW MEXICO AND INTO SOUTHWEST
TEXAS....SUPPORTING POTENTIAL FOR ADDITIONAL SHOWER AND
THUNDERSTORM ACTIVITY ACROSS THESE REGIONS.
THE AMPLIFIED/ENERGETIC NORTHERN STREAM FLOW ACROSS CANADA WILL
PUSH A STRONG COLD FRONT SOUTHEASTWARD INTO THE GREAT LAKES AND
NEW ENGLAND FRIDAY...SOUTHWARD INTO THE MID ATLANTIC AND OHIO
VALLEY REGION BY EARLY SATURDAY. THIS FRONT WILL NOT BE A
SIGNIFICANT PRECIPITATION PRODUCER...BUT WILL USHER A COOL AUTUMN
LIKE AIRMASS SOUTHEASTWARD ACROSS THE NORTHEASTERN QUARTER OF THE
NATION BY THE BEGINNING OF THE WEEKEND.
THE OPPOSITE WILL TRUE TEMPERATURE WISE ACROSS A LARGE PORTION OF
THE WESTERN U.S. FROM CALIFORNIA...EASTWARD ACROSS THE GREAT BASIN
AND INTO THE NORTHERN TO CENTRAL HIGH PLAINS. ABOVE NORMAL
TEMPERATURES ARE EXPECTED ACROSS THESE REGIONS OVER THE NEXT
SEVERAL DAYS.
ORAVEC
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