030
FXUS01 KWBC 222038
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
438 PM EDT TUE SEP 22 2009
VALID 00Z WED SEP 23 2009 - 12Z THU SEP 24 2009
A VERY AMPLIFIED UPPER LEVEL PATTERN HAS SET UP ACROSS THE LOWER
48 WITH A DEEP CLOSED LOW OVER THE CENTRAL PLAINS AND A LARGE
BLOCKING UPPER RIDGE OVER THE PACIFIC NORTHWEST. THE UPPER LOW
OVER THE PLAINS IS NOT FORECAST TO MOVE MUCH THROUGH THURSDAY...
WHICH WILL KEEP THE CENTRAL AND SOUTHERN PLAINS INTO THE CENTRAL
AND SOUTHERN ROCKIES... WELL BELOW AVERAGE WITH REGARDS TO
TEMPERATURE. COUNTERCLOCKWISE FLOW AROUND THE LOW IN THE LOWER AND
MID LEVELS OF THE ATMOSPHERE WILL TRANSPORT MOISTURE NORTHWARD
ALONG THE ASSOCIATED COLD FRONT... WITH SOME SPREADING WESTWARD
INTO THE HIGH PLAINS. THE ANOMALOUSLY COLD AIR OVER COLORADO
SHOULD GIVE THE REGION ITS FIRST SNOW OF THE SEASON. SNOW
ACCUMULATIONS EXCEEDING 6 INCHES ARE EXPECTED INTO COLORADO
ROCKIES... MAINLY EAST OF THE CONTINENTAL DIVIDE WITH LESSER BUT
STILL NOTEWORTHY AMOUNTS ALONG THE PALMER DIVIDE. SNOW SHOULD PICK
UP LATER TONIGHT AND LAST INTO THE DAY TOMORROW.
THE COMBINATION OF A SLOW MOVING COLD FRONT ACROSS THE WESTERN
GULF AND ABUNDANT MOISTURE WILL AID IN PRODUCING PERSISTENT RAIN
AND EMBEDDED THUNDERSTORMS FROM THE LOWER MISSISSIPPI VALLEY AND
ALONG THE TEXAS GULF COAST INTO EASTERN MEXICO. THESE RAINS WILL
BE BENEFICIAL TO A SEVERE DROUGHT ONGOING ACROSS SOUTH TEXAS.
THE REST OF THE WEST INTO THE NORTHWEST WILL STAY WARM AND DRY
UNDER THE PRESENCE OF THE BLOCKING UPPER LEVEL RIDGE AS THE WORK
WEEK WANES. THE GREATEST POSITIVE DEPARTURE FROM MAX TEMPERATURES
WILL EXIST OVER SOUTHWESTERN CANADA UNTIL A RATHER STRONG COLD
FRONT MOVES INTO THE REGION WEDNESDAY NIGHT. PRECIPITATION SHOULD
REMAIN CONFINED TO COASTAL BRITISH COLUMBIA WITH ONSHORE FLOW.
THE EASTERN U.S. WILL REMAIN SOMEWHAT UNSETTLED THROUGH
THURSDAY... SOUTH OF A COLD FRONT APPROACHING FROM CANADA. WITH
MOISTURE ALREADY IN PLACE... WEAK UPPER LEVEL DISTURBANCES WILL
AID IN PRODUCING WET WEATHER FROM THE SOUTHEAST INTO NEW ENGLAND
WITH AN ONSHORE COMPONENT TO THE LOW LEVEL WIND LIKELY FOCUSING
LOCALLY HEAVIER RAINFALL ACROSS THE COASTAL CAROLINAS.
OTTO
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