196
FXUS01 KWBC 172018
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
418 PM EDT SAT OCT 17 2009
VALID 00Z SUN OCT 18 2009 - 12Z MON OCT 19 2009
AN UPPER TROUGH ACROSS THE EASTERN THIRD OF THE NATION HAS KEPT
TEMPERATURES WELL BELOW NORMAL...WHILE A SERIES OF SURFACE COASTAL
LOWS CONTINUE TO IMPACT THE MID-ATLANTIC AND COASTAL NEW ENGLAND.
AS AN ANOMALOUSLY COLD AIR MASS HAS SETTLED IN PLACE THE PAST
SEVERAL DAYS...MUCH OF THE MOISTURE BEING STEERED INLAND FROM THE
COASTAL ATLANTIC WATERS IS BEING CONVERTED TO A LIGHT TO MODERATE
SNOWFALL ACROSS THE NORTHERN APPALACHIANS AND PORTIONS OF THE
INTERIOR NORTHEASTERN U.S. ALTHOUGH...AS THIS SYSTEM SLOWLY TRACKS
TO THE NORTHEAST...MUCH OF THE PRECIPITATION WILL BE CONSTRAINED
TO THE COASTAL REGIONS WHERE TEMPERATURES ARE FORECAST TO BE
CHILLY...BUT ABOVE FREEZING...THUS SUPPORTING RAIN AND POSSIBLY A
RAIN/SNOW MIX FARTHER INLAND. IN ADDITION TO THE COOL AND
UNSETTLED WEATHER WILL BE BREEZY CONDITIONS...ESPECIALLY ALONG THE
COASTAL SHORES. AN EXPANSIVE SURFACE RIDGE TO THE NORTH COMBINED
WITH THE STRENGTHING AXIS OF LOW PRESSURE OVER THE ATLANTIC WILL
ENHANCE THE PRESSURE GRADIENT ALLOWING FOR GUSTY WINDS THE NEXT
COUPLE OF DAYS.
THE OTHER PORTION OF THE U.S. WHICH CAN EXPECT PRECIPITATION THE
NEXT COUPLE OF DAYS IS ACROSS THE WESTERN TIER STATES. THE FIRST
SYSTEM IS CURRENTLY PUSHING INTO THE PACIFIC NORTHWEST WHERE AN
ENHANCED ONSHORE FLOW HAS SUPPORTED MODERATE TO HEAVY RAINFALL
ALONG THE OLYMPIC MOUNTAIN RANGE. THIS AXIS OF PRECIPITATION WILL
GRADUALLY WEAKEN IN TIME AS IT CROSSES THE HIGHER TERRAIN OF THE
INTERIOR WEST. IN ADDITION...THE UPPER-LEVEL DISTURBANCE
RESPONSIBLE FOR THE UNSETTLED CONDITIONS WILL TAKE A MORE WEST TO
EAST TRACK...THEREFORE KEEPING THE COLDER AIR AND THE HEAVIER
PRECIPITATION TO THE NORTH OF THE U.S./CANADIAN BORDER.
A MORE SIGNIFICANT UPPER TROUGH WILL DIVE SOUTHEASTWARD INTO
NORTHERN CALIFORNIA BY EARLY MONDAY HELPING SPREAD WIDESPREAD
RAINFALL FROM WASHINGTON STATE SOUTHWARD INTO THE SAN
FRANCISCO/OAKLAND BAY AREA. THIS WILL ADD FURTHER PRECIPITATION TO
THE REGION WHERE HEAVY RAINFALL IMPACTED MUCH OF CALIFORNIA LESS
THAN SEVEN DAYS AGO. UNTIL THEN...FAIR CONDITIONS WILL PERSIST
OVER THE REGION WITH WIDESPREAD 70S IN THE FORECAST AND MUCH
WARMER CONDITIONS TO THE SOUTH ACROSS THE DESERT SOUTHWEST.
A LARGE SURFACE DOME OF HIGH PRESSURE ACROSS THE OZARKS IS
PROMOTING TRANQUIL CONDITIONS OVER MUCH OF THE PLAINS AND
MISSISSIPPI RIVER VALLEY. THE NEARLY CLOUDLESS SKIES AND CALM
WINDS WILL ENHANCE OVERNIGHT COOLING ALLOWING FOR LOWS TONIGHT TO
APPROACH THE FREEZING MARK AS FAR SOUTH AS THE TENNESSEE RIVER
VALLEY. MANY OF THE LOCAL FORECAST OFFICES ACROSS THE REGION HAVE
PLACED THEIR WARNING AREAS IN FREEZE WATCHES/WARNINGS FOR THE
ANTICIPATED COLD TEMPERATURES. THIS SURFACE ANTICYCLONE WILL
EVENTUALLY EDGE EASTWARD REACHING THE EAST COAST BY MONDAY ONCE
THE COASTAL SYSTEM DEPARTS OFFSHORE.
RUBIN-OSTER
GRAPHIC AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page