571
FXUS61 KPBZ 041924
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
324 PM EDT SAT JUL 4 2009
SYNOPSIS
LOW PRESSURE FROM MISSOURI MOVING THROUGH SOUTHERN WEST VIRGINIA
LATE TONIGHT MAY SPREAD A FEW LIGHT SHOWERS AS FAR NORTH AS
INTERSTATE 70 LATE TONIGHT AND SUNDAY MORNING. MIDWEST HIGH
PRESSURE WILL THEN PROVIDE DRY CONDITIONS AND SEASONABLE
TEMPERATURES INTO WEDNESDAY.
NEAR TERM /THROUGH SUNDAY/
RECENT BLEND OF SREF MODEL AND GEFS MODEL RUNS CONTINUE TO SHOW
THE MISSOURI CENTERED LOW PRESSURE SYSTEM ONLY HAVING A SLIGHT
CHANCE OF SPREADING LIGHT SHOWERS ACROSS PARTS OF THE UPPER OHIO
VALLEY SOUTH OF I-70 LATE TONIGHT INTO SUNDAY.
THE REST OF THE UPPER OHIO VALLEY SHOULD BE DRY ALTHOUGH A
PREVIOUS NAM MODEL RUN HAD SUGGESTED A POST SYSTEM CONVERGENCE
ZONE HAD A SLIGHT CHANCE OF INITIATING SHOWERS SUNDAY AFTERNOON.
FORECASTED TEMPERATURES CLOSER TO WARMER NAM MOS VALUES.
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/
JUDGING FROM RECENT SREF MODEL RUNS...EXPECT THE UPPER OHIO VALLEY
TO BE DRY THIS PERIOD ALTHOUGH AGAIN THE OPERATIONAL NAM MODEL RUN
SUGGESTS FRONTAL-TYPE BANDS MOVING THROUGH MONDAY AND TUESDAY
AFTERNOONS THAT COULD INITIATE SHOWERS. THE ONE ON TUESDAY LOOKS
PARTICULARLY POTENT AS IT COULD BE ASSOCIATED WITH A TRAVELING
SHORT-WAVE TROUGH IN NORTHEAST FLOW ALOFT AND NAM HAS SURFACE DEW
POINTS ABOVE 60 TO CAUSE INSTABILITY. HOWEVER WITH MOST OTHER SREF
MEMBERS NOT SHOWING THIS SCENARIO AND HAVING SURFACE DEW POINTS
NO HIGHER THAN MID 50S...ELECTED TO GO THE MAJORITY OF SREF MODEL
MEMBERS AND KEEP IT DRY.
FORECASTED TEMPERATURES CLOSER TO WARMER NAM MOS VALUES.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
MAJORITY OF GEFS MODEL MEMBERS SHOW A ZONAL JETSTREAM SHIFTING
NORTHWARD LATE WEEK SO EXPECT TEMPERATURES TO WARM THIS PERIOD AS
INDICATED BY HPC GUIDANCE AND GFS MOS...WHICH HAS A SOONER WARM
UP.
STILL TOO DIFFICULT TO TIME ANY SHOWER INITIATING SHORT-WAVE
TROUGHS OR OTHER FACTORS SO MAINTAINED DRY FORECAST UNTIL LATE
FRIDAY OR SATURDAY.
AVIATION /19Z SATURDAY THROUGH THURSDAY/
EXPECT PREVALENT VFR CONDITIONS ACROSS THE UPPER OHIO VALLEY THIS
PERIOD.
JUDGING FROM RECENT SURFACE SATELLITE AND RADAR DATA...EXPECT VFR
ALTOCUMULUS TO SPREAD ACROSS THE SOUTHERN TWO THIRDS OF THE UPPER
OHIO VALLEY TONIGHT INTO SUNDAY MORNING.
BASED ON RECENT SREF MODEL RUNS...THE LOW PRESSURE SYSTEM PASSING
SOUTHEASTWARD THROUGH SOUTHERN WEST VIRGINIA TONIGHT STILL HAS A
SLIGHT CHANCE OF SPREADING MVFR SHOWERS AS FAR NORTH AS I-70 AND
SO KZZV AND KMGW MAY BE AFFECTED THEN. THOSE TWO SITES MAY BE THE
ONLY ONES TO BE AFFECTED BY MVFR FOG SUNDAY MORNING.
SURFACE WINDS WILL BE WESTERLY 6-10 KTS TODAY AND BECOME LIGHT
AND VARIABLE TONIGHT THEN BECOME SOUTHEASTERLY NEAR 5 KTS DAYTIME
SUNDAY.
PBZ WATCHES/WARNINGS/ADVISORIES
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
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