262
FXUS01 KWBC 232057
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
457 PM EDT WED SEP 23 2009
VALID 00Z THU SEP 24 2009 - 12Z FRI SEP 25 2009
A LARGE CLOSED UPPER LEVEL LOW CURRENTLY SITTING OVER THE CENTRAL
HIGH PLAINS IS FORECAST TO WOBBLE ABOUT ITS CURRENT POSITION AS
THE WEEKEND APPROACHES. TEMPERATURES WELL BELOW AVERAGE EXIST
BENEATH THE UPPER LOW... WITH THE GREATEST DEPARTURES IN PLACE
FROM CENTRAL COLORADO TO WESTERN KANSAS. ALTHOUGH THE UPPER LOW
WILL NOT MOVE MUCH... THE AIRMASS WILL MODIFY AND TEMPERATURES
WILL APPROACH CLOSER TO AVERAGE ON FRIDAY. LIGHT SNOW IS STILL
POSSIBLE OVER THE HIGHER ELEVATIONS OF THE COLORADO ROCKIES...
MAINLY ABOVE 7500 FT AS MOISTURE CONTINUES TO WRAP AROUND THE
WESTERN SIDE OF THE UPPER LOW. SCATTERED RAIN SHOWERS AND PERHAPS
A THUNDERSTORM CAN BE EXPECTED ACROSS THE FRONT RANGE INTO THE
PLAINS.
A QUASI-STATIONARY BOUNDARY AT THE LEADING EDGE OF THE COLDER AIR
WILL HELP IN GENERATING RAIN AND THUNDERSTORMS ALONG THE FRONT AND
ACROSS SOUTHERN AND EASTERN TEXAS AS LOW LEVEL FLOW OVERRIDES THE
BOUNDARY. UPPER LEVEL ENERGY IS EXPECTED TO WRAP AROUND THE UPPER
LOW AND IMPACT PORTIONS OF THE MIDWEST INTO MINNESOTA WITH
POTENTIALLY HEAVY RAIN AS A NARROW AXIS OF HIGHER MOISTURE WORKS
NORTH JUST AHEAD OF THE UPPER LOW.
ACROSS THE NORTHEAST... MOSTLY SCATTERED SHOWERS AND THUNDERSTORMS
WILL CONTINUE AHEAD OF A COLD FRONT CURRENTLY DROPPING THROUGH THE
REGION. A SECONDARY SURGE OF COLDER AIR WILL REACH THE NORTHEAST
BY THE END OF THE WEEK ACCOMPANIED BY A LARGE DOME OF HIGH
PRESSURE WHICH WILL DROP TEMPERATURES ACROSS THE MID ATLANTIC AND
NORTHEAST BELOW AVERAGE FRIDAY INTO SATURDAY.
THE NORTHWEST WILL SEE A COLD FRONTAL PASSAGE STARTING EARLY
TOMORROW MORNING AS A POTENT FRONT MOVES ASHORE. GIVEN THAT THIS
REGION INTO SOUTHWESTERN CANADA HAS BEEN WELL ABOVE AVERAGE FOR
THIS TIME OF YEAR... TEMPERATURES ACROSS THE REGION ARE ONLY
EXPECTED TO FALL TO NEAR NORMAL BY THE END OF THE WEEK. WITH LOTS
OF DRY AIR PRESENT ACROSS THE NORTHWEST... PRECIPITATION SHOULD
REMAIN MOSTLY CONFINED TO COASTAL BRITISH COLUMBIA.
OTTO
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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