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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 170830
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
430 AM EDT FRI MAY 17 2013

.SYNOPSIS...
STALLED FRONT WILL REMAIN SOUTH OF THE AREA THROUGH MOST OF
SATURDAY. FRONT WILL SHIFT NORTHWARD SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
DEWPOINT BOUNDARY IS PROVIDING A VERY DIFFERENT WEATHER STORY TO
THE NORTH AND TO THE SOUTH. SOUTH OF THE BOUNDARY...A LARGE AREA
OF STRATUS HAS DEVELOPED UNDER WHICH THERE ARE AREAS OF FOG. SOME
OF THE FOG IS DENSE...BUT APPEARS TO BE RATHER PATCHY. NORTH OF
THE BOUNDARY...SKIES ARE CLEAR AND NO FOG HAS FORMED. THE DRIER
AIR TO THE NORTH IS ATTEMPTING TO MOVE SOUTHWARD...BUT IS NOT
MAKING MUCH HEADWAY. HIGH PRESSURE...OVER THE GREAT LAKES...WILL
PROVIDE A PUSH SHORTLY AFTER DAWN. THE DRIER AIR WORKING IN
CONJUNCTION WITH SUNSHINE WILL ERODE THE STRATUS/FOG FROM NORTH TO
SOUTH.

HIGH PRESSURE WILL REMAIN PARKED OVER THE GREAT LAKES...WHILE THE
PRESSURE FRONT SITS OVER THE MID ATLANTIC. WITH NO REAL WAVES OF
ENERGY TO PIN CONVECTION ON...THINK THAT ANY ACTIVITY WOULD
DEVELOP OVER THE FAR SOUTH IN THE AREA OF HIGH TDS.

TEMPS WILL CONTINUE TO BE WARM.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
FOR TONIGHT INTO SUNDAY...GENERAL AGREEMENT THAT BOUNDARY WILL
PUSH NORTHWARD BUT AGAIN DISAGREE ON TIMING AND STRENGTH OF
POSSIBLE SHORTWAVES. CONTINUE THE PREVIOUS TRENDED TOWARD NAM
SOLUTION WITH HIGHEST SHOWER CHANCES ACROSS THE SOUTH AND RIDGES
THROUGH THE WEEKEND UNTIL SUNDAY.

TEMPERATURES A COMPROMISE BETWEEN 21Z SREF AND GFS MOS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MODEL AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN IS BEGINNING TO
IMPROVE...AT LEAST THROUGH DAY 6 BEFORE THERE ARE GLARING
DIFFERENCES. IN GENERAL...UPPER LEVEL RIDGING WILL CONTINUE TO
AMPLIFY OVER THE EASTERN HALF OF THE CONUS AS A CUTOFF LOW DEVELOPS
OVER THE NORTHERN PLAINS. THIS LOW WILL SLOWLY MAKE IT`S APPROACH
THROUGH THE PERIOD...HELPING TO SWING AN ASSOCIATED FRONT ACROSS THE
REGION BY LATE WEDNESDAY/EARLY THURSDAY. HOWEVER...DIFFERENCES STILL
REMAIN IN THE AMOUNT OF CONVECTIVE ACTIVITY THERE WILL BE IN THE
WARM SECTOR SUNDAY THROUGH WEDNESDAY AS DIFFERENT SHORTWAVES MOVING
THROUGH THE UPPER LEVEL FLOW ARE TIMED DIFFERENTLY FROM RUN TO RUN.
TO TAKE INTO ACCOUNT THESE DIFFERENCES...OPTED TO REMAIN
CONSERVATIVE WITH POPS UNTIL LATE TUESDAY BEFORE INCREASING CHANCES
IMMEDIATELY AHEAD OF THE COLD FRONT. TEMPERATURES WERE ALSO KEPT
BELOW MOS GUIDANCE...ESPECIALLY ON TUESDAY AND WEDNESDAY AS AMPLE
MOISTURE AND CLOUD COVER WILL LIKELY KEEP TEMPERATURES FROM REACHING
THE MID 80`S SUGGESTED.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
A FAIRLY ABRUPT DEWPOINT DISCONTINUITY SNAKES THROUGH NORTHEASTERN
OHIO TO JUST SOUTH OF KBTP AND JUST NORTH OF KIDI. ALL OF THIS
SITES SOUTH OF THIS ARE LIKELY TO EXPERIENCE AT LEAST SOME FOG
THROUGH THE EARLY MORNING HOURS. IN PARTICULAR...LIFR CONDITIONS
IN FOG/STRATUS ARE LIKELY AT KZZV...KHLG...AND KMGW THROUGH
MORNING. BECAUSE SURFACE MOISTURE IS SLIGHTLY LOWER AROUND
KPIT...JUST MVFR VIS WAS CARRIED. BY ROUGHLY 13Z...DIURNAL MIXING
SHOULD INCREASE AND MIX OUT FOG EVERYWHERE...WITH VFR CONDITIONS
EXPECTED AT ALL TERMINALS AFTER THAT TIME. FRIES

.OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/...
GENERAL VFR SHOULD CONTINUE UNTIL SATURDAY AFTERNOON WHEN INCRSG
MSTR AND INSTABILITY SPPRT PCPN CHCS AND RESTRICTIONS...WHICH ARE
EXPECTED TO PERIODICALLY CONT THROUGH TUESDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$