758
FXUS01 KWBC 172101
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
500 PM EDT WED SEP 17 2008
VALID 00Z THU SEP 18 2008 - 12Z FRI SEP 19 2008
MUCH OF THE NATION WILL BE PRECIPITATION-FREE THROUGH FRIDAY AS A
BULK OF THE UPPER-LEVEL ENERGY WILL REMAIN NORTH OF THE
U.S./CANADIAN BORDER. THIS SHOULD PROVIDE SIGNIFICANT RELIEF TO
THOSE AFFECTED BY RIVER FLOODING CAUSED BY THE REMNANTS OF
HURRICANE IKE AS IT WILL BE DRY THROUGH THE REMAINDER OF THE WORK
WEEK. THE UPPER-LEVEL PATTERN FOR THE NEXT 60 HOURS WILL CONTINUE
TO CONSIST OF TROUGHING OVER THE EASTERN HALF OF THE
NATION...WHILE A RIDGE REMAINS STRONG OVER THE WESTERN TIER. BY
FRIDAY MORNING...A CLOSED UPPER LOW WILL BEGIN TO FIGHT THE RIDGE
UPSTREAM AS IT MOVES INTO NORTHERN CALIFORNIA.
THE PRIMARY FOCUS OF MEASURABLE RAINFALL WILL BE ACROSS THE
SOUTHEASTERN U.S. COAST STRETCHING FROM THE OUTER BANKS OF NORTH
CAROLINA SOUTHWARD INTO THE SUNSHINE STATE. A FRONTAL BOUNDARY
CURRENTLY OFFSHORE OF THE SOUTHEAST WILL REMAIN QUASI-STATIONARY
WHILE SLOWLY DRIFTING OFFSHORE BY THURSDAY EVENING. THIS SURFACE
FRONT COMBINED WITH A WARM...MOIST AIR MASS WILL HELP PROVIDE THE
FOCUS FOR SCATTERED SHOWERS AND THUNDERSTORMS. FARTHER TO THE
NORTH...CONDITIONS WILL BECOME MORE INDICATIVE THAT AUTUMN IS JUST
AROUND CORNER AS A COOL DOME OF HIGH PRESSURE WILL FILL IN OVER
THE NEW ENGLAND STATES BY EARLY FRIDAY. VERY COOL OVERNIGHT
TEMPERATURES WILL BE COMMONPLACE THURSDAY NIGHT OVER THE INTERIOR
NORTHEAST AS CALM WINDS COMBINED WITH CLEAR SKIES WILL MAXIMIZE
THE RADIATIONAL COOLING EFFECT. IN FACT...TEMPERATURES WILL
APPROACH THE FREEZING MARK AND EVEN PUSH INTO THE 20S UP IN MAINE.
A FREEZE WATCH IS ALREADY IN EFFECT ACROSS THE INTERIOR NORTHEAST
IN ANTICIPATION OF THE FREEZING OVERNIGHT TEMPERATURES EXPECTED.
WITHIN THE EASTERN EXTENT OF THE RIDGE IN THE WEST...ANOMALOUSLY
WARM TEMPERATURES WILL HIT THE NORTHERN HIGH PLAINS AND EASTWARD
THROUGH THE DAKOTAS OVER THE COURSE OF THE NEXT COUPLE OF DAYS.
THE HIGH PRESSURE ALOFT WILL WARM THE AIR COLUMN SUFFICIENTLY TO
BRING TEMPERATURES CLOSE TO THE 90 DEGREE MARK ON THURSDAY AND
FRIDAY. THIS MARKS A 15 TO 20 DEGREE DEPARTURE FROM CLIMATOLOGY.
A SLOWLY MOVING CLOSED LOW OVER THE EASTERN PACIFIC WILL
EVENTUALLY MOVE INTO NORTHERN CALIFORNIA BY FRIDAY MORNING. THIS
SYSTEM WILL HELP INCREASE THE CLOUD COVER AND BRING A SLIGHT
CHANCE OF SHOWER ACTIVITY LATER IN THE DAY ON FRIDAY.
MEANWHILE...THE RIDGE UPSTREAM OVER THE INTERMOUNTAIN WEST WILL
HOLD STRONG AS THE TROUGH APPROACHES FROM THE WEST COAST.
RUBIN-OSTER
GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV
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