FXUS61 KPBZ 091044
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
544 AM EST WED DEC 9 2009

.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM WILL CROSS THE GREAT LAKES TODAY.
PRECIPITATION WILL COMPLETE A CHANGE TO ALL RAIN AND BECOME LESS
WIDESPREAD BUT WINDY CONDITIONS MAY BE EXPECTED. MUCH COLDER
TEMPERATURES WILL MOVE OVER THE REGION TONIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
HAVE MAINTAINED WINTER WEATHER ADVISORY FOR AREAS EAST OF FKL TO
IDI AS SOME POCKETS OF WINTRY MIXED PRECIP CONTINUE. THE WARNING
FOR INDIANA AND GARRETT HAS BEEN DROPPED DUE TO RISING
TEMPERATURES AND LIGHTENING PRECIP. PRECIP WILL BE CHANGING TO
RAIN OVER THE NEXT FEW HOURS IN THE ADVISORY. 

OTHER PROBLEM OF THE DAY IS OF WIND WITH THIS STRONG LOW PRESSURE
SYSTEM. HAVE EXPANDED/SIMPLIFIED WIND ADVISORIES FOR FULL DAY
COVERAGE AS PER EXPECTED MIXING WITH CONVECTION AND CONTINUED
DOWNSLOPE ACCELERATIONS.

DRY SLOT SHOULD END THE HEAVIEST RAIN BY, OR SHORTLY AFTER
DAYBREAK. HOWEVER, LINE OF SHOWERS ALONG THIS SYSTEMS COLD FRONT
IS ALSO EXPECTED...WITH THAT FEATURE WILL COME THE BEST CHANCE OF
SOME WIND GUSTS NEAR 55 MPH.

STRONG WIND WILL CONTINUE TO WORK ACROSS THE REGION WEDNESDAY
NIGHT...THUS WILL KEEP THE WIND ADVISORY FOR EASTERN COUNTIES
THROUGH THE NIGHT FOR NOW. REMAINING PRECIP WILL CHANGE TO SNOW
SHOWERS...WITH UPSLOPE AND LAKE ENHANCED SNOW SHOWERS LIKELY.
WITH THE FLOW W/SW...THINK ACCUMS WILL REMAIN UNDER ADVISORY
CRITERIA.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
WINDS AND PRECIP WILL GRADUALLY DIMINISH THURSDAY INTO FRIDAY AS
HIGH PRESSURE BUILDS INTO THE REGION FROM THE SOUTHWEST. MUCH
COLDER AIR WILL WORK ACROSS THE REGION...APPROXIMATELY 10-15
DEGREES BELOW NORMAL. WITH 10-20 MPH WINDS CONTINUING THURSDAY
NIGHT INTO FRIDAY...WIND CHILL TEMPERATURES WILL FALL TO AROUND
ZERO THURSDAY NIGHT FOR THE LOWLANDS...AND ZERO TO 10 BELOW FOR
THE HIGHER ELEVATIONS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SURFACE HIGH PRESSURE WILL SLIDE ACROSS THE REGION ON SATURDAY. A 
WEAK SYSTEM WILL BRING AN INCREASE IN MOISTURE AND A SMALL CHANCE OF 
SNOW SHOWERS SATURDAY NIGHT AND EARLY SUNDAY. THE NEXT SYSTEM 
APPROACHING FROM THE WEST EARLY NEXT WEEK WILL BRING SLIGHT CHANCE 
POPS TO THE UPPER OHIO VALLEY LATE MONDAY INTO TUESDAY.

TEMPERATURES ARE EXPECTED TO BE A FEW DEGREES BELOW NORMAL FOR MUCH 
OF THE EXTENDED PERIOD.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO DEEPEN AS IT TRACKS FROM THE MID MS 
VALLEY INTO THE GREAT LAKES TODAY. WIDESPREAD MVFR CONDITIONS CAN BE 
EXPECTED TO PERSIST OVERNIGHT AND INTO THE MORNING HOURS...WITH 
OCCASIONAL IFR CONDITIONS IN HEAVIER PRECIPITATION. A MIX OF 
SNOW...FREEZING RAIN...AND SLEET AT FKL AND DUJ SHOULD CHANGE OVER 
TO ALL RAIN BY 12Z. WIDESPREAD RAIN SHOULD MOVE OUT OF THE AREA
BY EARLY AFTERNOON...WITH ANY LEFTOVER PRECIPITATION CHANGING
OVER TO SNOW BY 00Z. CONDITIONS ARE EXPECTED TO SLOWLY TREND TO
VFR TONIGHT.

WINDS WILL ALSO BE AN ISSUE AT ALL SITES. A LOW LEVEL INVERSION WILL 
KEEP STRONG WINDS FROM MIXING DOWN TO THE SURFACE FOR THE REST OF 
THE OVERNIGHT HOURS AND INTO THE MORNING...BUT RADAR WIND PROFILER 
SHOWS THAT 50 KT WINDS ARE ONLY 2-3 KFT OFF THE SURFACE. HAVE 
INCLUDED LOW LEVEL WIND SHEAR AT ALL SITES UNTIL THE COLD FRONT 
PASSES...AT WHICH TIME THESE WINDS SHOULD BEGIN TO MIX DOWN TO THE 
SURFACE. WIND GUSTS TO 40 KT AT ALL SITES WEDNESDAY AFTERNOON AND 
EVENING MAY STILL BE A CONSERVATIVE ESTIMATE...WITH THE POSSIBILITY 
OF 50 KT GUSTS NOT OUT OF THE QUESTION.

WINDS WILL GRADUALLY DIMINISH ON THURSDAY. GENERALLY VFR CONDITIONS 
IS EXPECTED AS HIGH PRESSURE BUILDS IN FRIDAY AND MOVES EAST ACROSS 
THE REGION DURING THE WEEKEND.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR MDZ001.
OH...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR OHZ039>041-
     048>050-057>059-068-069.
PA...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ007-008-013-
     014-020-021-029-031.
     WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR PAZ009-015-016-022-
     023-030-032.
     WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR PAZ008-
     009-015-016.
WV...WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR WVZ001>004-012-
     021-022.
     WIND ADVISORY UNTIL 6 AM EST THURSDAY FOR WVZ023-041.

&&

$$