FXUS61 KPBZ 021649
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1149 AM EST WED DEC 2 2009
.SYNOPSIS...
A DEEPENING STORM SYSTEM WILL BRING RAIN TO THE REGION LATER TODAY
AND INTO EARLY THURSDAY. COLDER AIR WILL MOVE IN FOR THE END OF
THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATE MORNING UPDATE TO REFRESH WORDING. OTHERWISE GRIDS LOOK TO BE
IN GOOD SHAPE. DEEPENING SFC LOW WILL SLOWLY MOVE UP THE TN AND
LOWER OHIO VALLEY TODAY. LOW WILL WIND UP AS UL ENERGY DIGS INTO W
KY THIS AFTERNOON. WITH TRACK OF LOW...WARMER AIR WILL MOVE UP THE
EASTERN US AS MUCH COLDER AIR DIGS INTO THE N GREAT LAKES AND
UPPER MIDWEST. IT WILL TAKE A BIT OF TIME TO MOISTEN THE LOWER
ATMOSPHERE...BUT EXPECT ALL LOCATIONS TO SEE RAIN BY LATE
AFT/EARLY EVE. LOCATIONS NORTH OF I-80 WILL STAY DRY THE LONGEST.
SFC WINDS WILL INCREASE THIS AFTERNOON IN RESPONSE TO TIGHTENING
SFC PRES GRADIENT. VERY STRONG WINDS...AROUND 2000FT AND ABOVE ARE
EXPECTED LATE THIS MORNING AND THROUGH THE AFT AS 85H LOW MOVES
INTO THE OHIO VALLEY. WILL ISSUE A WIND ADVISORY FOR MY RIDGE
COUNTIES OF W MD AND N WV.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
DIFFERING SOLUTIONS ON TRACK OF LOW TONIGHT WITH NAM BEING FURTHER
WEST THAN GFS. THE TRACK OF THE SFC LOW WILL BE IMPORTANT FOR THE
LOCATION OF TONIGHTS DRY SLOT. THE NAM SOLUTION WOULD BRING THE
DRY SLOT THROUGH THE REGION THIS EVENING WHILE THE GFS SOLUTION
KEEPS THE DRY SLOT WELL EAST OF THE AREA. WILL LEAN TOWARD THE GFS
SOLUTION AS IT IS CLOSER IN AGREEMENT WITH 21Z SREF/12Z ECMWF.
RAIN WILL CONTINUE INTO EARLY THU MORNING. SFC LOW CONTINUES TO
DEEPEN TONIGHT AND ALSO SPEED UP AS UL WAVE MOVES QUICKLY THROUGH
W PA. BACK EDGE OF RAIN SHOULD REACH PIT CLOSE TO 12Z THU AND
CLEAR THE NORTH BY LATE THU MORNING.
MUCH COLDER AIR WILL MOVE IN BEHIND EXITING SYSTEM ON THU. WIND
DIRECTION IS NOT OPTIMAL FOR LES THU AND LL THICKNESS NOT COLD
ENOUGH UNTIL LATE IN THE DAY TO SUPPORT ALL SNOW. EXPECT TO SEE
SNOW FIRST ON THE HIGHEST ELEVATIONS AS 85H TEMPS DROP BELOW -3 BY
LATE AFTERNOON. MID LEVEL WIND DIRECTION HAS MORE OF A WESTERLY
COMPONENT WHICH WILL BE MORE CONDUCIVE TO UPSLOPE PRECIP THU AND
ACROSS THE FAR NORTH. WILL KEEP IN CHC FOR SHOWERS ACROSS MOST OF
THE REGION THU BUT THIS MAY BE OVERDOING IT. THIS WILL HAVE TO BE
ADDRESSED IN LATER FORECASTS.
STRONG CAA CONTINUES INTO FRIDAY BUT MID LEVEL WINDS BEGIN TO GO
MORE SOUTHWESTERLY AND 50H LOW REMAINS WELL NORTH OF THE REGION.
THIS WILL CONTINUE THE RISK FOR UPSLOPE SNOW SHOWERS BUT WILL NOT
PROVIDE A SHOT AT LES. EXPECT PLENTY OF CLOUDS AND COLD TEMPS
FRIDAY WITH THE STRONG MID LEVEL CAA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
COLDER PATTERN WILL CONTINUE FOR THE REMAINDER OF THE LONG TERM
PERIOD. HOWEVER LARGE SFC HIGH WILL PROVIDE A MAINLY DRY PERIOD AS
WELL.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
LOW PRESSURE EMERGING FROM THE DEEP SOUTH WILL CONTINUE TO PUSH
MOISTURE WITH GRADUALLY LOWERING CEILINGS OVER UPPER OHIO VALLEY
PORTS TODAY. LIGHT PRECIP OVER ZZV AND MGW IN THE LATE MORNING
WILL ALSO SPREAD QUICKLY NORTHWARD.
CONDITIONS WILL DETERIORATE TO IFR THIS EVENING WITH SURFACE
INCREASING OUT OF THE SOUTHEAST TO ABOUT A SUSTAINED 10, WITH
GUSTS NEAR 20KT. WIND ALOFT WILL INCREASING SIGNIFICANTLY AS LOW
LEVEL JET ON THE FLANK OF THE LOW PROGRESSES NORTHWARD...WILL THUS
INCLUDE LOW LEVEL WIND SHEAR IN TAFS FOR ALL PORTS DURING THE
EVENING HOURS.
RESTRICTIONS WILL CONTINUE INTO THURSDAY AS THE LOW DIGS NORTHEASTWARD.
POST SYSTEM COLD ADVECTION WILL MAINTAIN AREAS OF MVFR STRATOCUMULUS
ACROSS THE REGION INTO THE WEEKEND. HIGH PRESSURE IS PROGGED TO
CROSS THE REGION SUNDAY WITH MAINLY DRY/VFR CONDITIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR MDZ001.
OH...NONE.
PA...NONE.
WV...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ023-041.
&&
$$
