163
FXUS01 KWBC 181924
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
324 PM EDT SUN OCT 18 2009
VALID 00Z MON OCT 19 2009 - 12Z TUE OCT 20 2009
AS ONE AMPLIFIED UPPER TROUGH SLOWLY MOVES OFFSHORE INTO THE
CANADIAN MARITIMES...ANOTHER ONE WILL BEGIN TO IMPACT THE UNITED
STATES...THIS TIME ACROSS THE DESERT SOUTHWEST. IN BETWEEN THESE
TWO WEATHER SYSTEMS...A LARGE AREA OF RIDGING ALOFT WILL PROMOTE
FAIR CONDITIONS ACROSS THE CENTER OF THE NATION. HOWEVER...BY
TUESDAY MORNING...CONDITIONS ARE FORECAST TO DETERIORATE ACROSS
THE NORTHERN PLAINS AND UPPER MIDWEST AS THE FRONTAL BOUNDARY
ASSOCIATED WITH THE WESTERN SYSTEM BEGINS TO DROP SCATTERED
PRECIPITATION TO THE REGION.
CURRENTLY...THE MAIN FEATURE IMPACTING THE NATION ON SUNDAY IS THE
AREA OF LOW PRESSURE JUST OFF THE NEW ENGLAND COAST. THE LAST...IN
A SERIES OF SURFACE CYCLONES IMPACTING THE NORTHEASTERN U.S. IS
HELPING STEER A STEADY FLOW OF ATLANTIC MOISTURE INTO THE UPPER
MID-ATLANTIC AND COASTAL NEW ENGLAND STATES. THIS HAS HELPED
PRODUCE WIDESPREAD RAIN SHOWERS TO THE REGION WITH EVEN A MIXTURE
OF RAIN AND SNOW FARTHER INLAND AS A COLD AIR MASS HAS REMAINED IN
PLACE. THE SHOWER ACTIVITY SHOULD WIND DOWN ACROSS THE NORTHEAST
BY EARLY MONDAY MORNING IN TIME TO START THE NEW WORK WEEK. IN THE
WAKE OF THIS SYSTEM...AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE
WILL DROP INTO THE EASTERN THIRD OF THE U.S. PROMOTING IMPROVING
WEATHER FOR NEXT WEEK. IT WILL ALSO SUPPORT ANOMALOUSLY COOL
TEMPERATURES OVERNIGHT WITH WIDESPREAD LOWS TONIGHT RANGING FROM
THE UPPER 20S TO THE MID 30S ACROSS MANY AREAS EAST OF THE
MISSISSIPPI RIVER. CONSEQUENTLY...A SLEW OF FREEZE WARNINGS AND
FROST ADVISORIES HAVE BEEN ISSUED BY MANY OF THE LOCAL FORECAST
OFFICES.
ALL EYES WILL TURN TO THE WEST AS A STRONG UPPER TROUGH DROPS DOWN
INTO NORTHERN CALIFORNIA AND EVENTUALLY INTO THE DESERT SOUTHWEST
LATE MONDAY NIGHT AND INTO TUESDAY. LIGHT TO MODERATE RAIN SHOWERS
ARE FORECAST TO PUSH INLAND BY THE START OF THE MORNING RUSH HOUR
ON MONDAY ACROSS NORTHERN CALIFORNIA. AS THE SYSTEM EDGES SOUTH
AND EAST...THE PRECIPITATION AMOUNTS SHOULD DIMINISH...WITH THE
BEST COVERAGE ALONG THE FAVORED TERRAIN OF THE INTERIOR MOUNTAIN
WEST. BY TUESDAY MORNING...TEMPERATURES WILL DROP BELOW FREEZING
ACROSS PORTIONS OF THE CENTRAL AND NORTHERN ROCKIES WHICH WILL
PROMOTE LIGHT TO MODERATE SNOWFALL. FOR MORE INFORMATION ON THE
POTENTIAL FOR THE EXPECTED SNOWS...PLEASE READ THE HPC HEAVY SNOW
AND ICING DISCUSSION AT
WWW.HPC.NCEP.NOAA.GOV/DISCUSSIONS/QPFHSD.HTML.
RUBIN-OSTER
GRAPHIC AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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