Area Forecast Discussion
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000
FXUS61 KPBZ 300832
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
432 AM EDT WED JUL 30 2014

.SYNOPSIS...
SHOWER CHANCES TODAY AS ANOTHER WEAK DISTURBANCE MOVES THROUGH THE
BROAD LOW PRESSURE SYSTEM. TEMPERATURES WILL BEGIN TO MODERATE
TOWARD NORMAL BY LATE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A FEW THUNDERSTORMS LINGER NORTH OF THE AREA AS OF ABOUT 06Z.
THESE DEVELOPED EARLIER ALONG THE NOSE OF A RELATIVELY WEAK H5
JET MAX. AS WE PROGRESS FURTHER INTO THE EARLY MORNING HOURS...THESE
THUNDERSTORMS SHOULD CONTINUE TO WANE WITH LACK OF SUFFICIENT
INSTABILITY AND WITH THE UPPER LEVEL JET DIMINISHING. THUS...HAVE
DECREASED POPS NORTH OF I80 OVER THE NEXT SEVERAL HOURS.

MOSTLY CLEAR SKIES PERSISTING AS MID-LEVEL CLOUDS MOVING IN FROM
THE NW ARE DISSIPATING AS THEY ENCROACH. LLVL DEWPOINT DEPRESSIONS
REMAIN SUFFICIENT ENOUGH TO CURTAIL ANY WIDESPREAD FOG
DEVELOPMENT...HOWEVER A FEW SHELTERED AREAS COULD SEE SOME PATCHY
FOG THIS MORNING.

CURRENT WATER VAPORY LOOP SHOWS AN UPPER LEVEL VORT DROPPING SOUTH
THROUGH THE WRN GREAT LAKES. THIS QUICK MOVING DISTURBANCE WILL
GENERATE SCATTERED SHOWERS TODAY AS IT PIVOTS AROUND THE EXPANSIVE
LOW PRESSURE SYSTEM STILL RESIDING NEAR JAMES BAY. STEEPENING
LLVL LAPSE RATES AND DEEPER MOISTURE AVAILABILITY WILL HELP FUEL
CONVECTIVE SHOWER DEVELOPMENT. HOWEVER...INSTABILITY OVERALL IS
STILL LACKING WITH VERY LITTLE CAPE IN THE CHARGE SEPARATION
LAYER. WILL KEEP THE MENTION OF THUNDER OUT OF THE FORECAST FOR
THIS AFTERNOON.

SHOWER CHANCES DISSIPATE QUICKLY THIS EVENING AS THE WAVE PULLS
AWAY TOWARDS SUNDOWN. SEVERAL HI-RES MODELS INDICATING A SECONDARY
WAVE OF PRECIPITATION OVERNIGHT INTO THURS MORNING ASSOCIATED WITH
ANOTHER UPPER LEVEL TROF AXIS SWINGING THROUGH. THIS FEATURE IS
CORROBORATED AMONG THE MORE BROAD SOLNS OF THE 00Z NAM AND GFS.
THE DEEPER MOISTURE WILL REMAIN CLOSE TO THE UPPER LOW ACROSS OUR
NORTH...THIS WILL BE THE AREA THAT IS THE FOCUS OF SLGT AND CHC
POPS THROUGH ABOUT 12Z.
TAX

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
SHOWERS WILL DIMINISH THIS EVENING AS THE SHORTWAVE TROUGH EXITS
TO THE EAST. MEANWHILE THE LONGWAVE WILL PIVOT EAST AND WEAKEN AS
THE MAIN JET CORE MIGRATES FURTHER BEYOND INFLECTION POINT OF THE
FRONT SIDE OF THE TROUGH AS A SECOND WEAK SHORTWAVE TRANSITIONS
THROUGH THE FLOW THURSDAY MORNING/EARLY AFTERNOON. THIS DISTURBANCE
SHOULD ONLY IMPACT NORTHERN ZONES AS THE LONGWAVE LIFTS TO THE NORTH.

FLOW ALOFT WILL SWITCH TO THE SOUTHWEST ON FRIDAY AND ALLOW FOR DEEPER
MOISTURE TO ADVECT NORTH. THIS ALONG WITH A SHORTWAVE PASSING
ACROSS THE REGION ON FRIDAY WILL RESULT IN SCATTERED
SHOWERS/THUNDERSTORMS FRIDAY AFTERNOON AND EARLY EVENING...WITH
THE BEST CHANCES ACROSS THE RIDGES AND SOUTHEASTERN PORTIONS OF
THE FORECAST AREA WHERE THERE WILL BE BETTER UPPER LEVEL SUPPORT.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MOISTURE ADVECTION WILL CONTINUE OVERNIGHT FRIDAY AND SATURDAY BUT
RECENT MODEL RUNS HAVE NOT SHOWN THE BEST CONTINUITY IN REGARDS TO
TIMING THE NEXT SHORTWAVE TO PASS THROUGH AND HELP SUPPORT
ACTIVITY SO HAVE OPTED TO LEAVE CHANCE POPS IN THE FORECAST FOR
BOTH SATURDAY AND SUNDAY AFTERNOONS UNTIL GUIDANCE SHOWS BETTER
RUN TO RUN CONTINUITY WITH THE FEATURE. DRY CONDITIONS ARE
FORECAST BY NEXT MONDAY AS OPERATIONAL RUNS SHOW THE LONGWAVE
PATTERN BECOMING MORE ZONAL...BUT REMAIN CAUTIOUSLY OPTIMISTIC IN
FINALLY BREAKING THE PATTERN AS MODELS HAVE BEEN FAIRLY
INCONSISTENT IN PROGGING THIS OVER THE PAST 10 OPERATIONAL RUNS.


&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
VFR CONDITIONS PREVAIL UNDER MAINLY CLEAR SKIES. HOWEVER...ANOTHER
AREA OF CLOUDS WILL SWING THROUGH FROM THE NORTHWEST WITH THE NEXT
UPPER LEVEL WAVE. WILL KEEP IN A VFR FORECAST FOR MOST PORTS ON
WEDNESDAY. THE EXCEPTION WILL BE AT FKL AND DUJ WHERE MVFR CIGS
WITH SHOWERS ARE POSSIBLE WITH THE PASSAGE OF A WEAK SURFACE
BOUNDARY WEDNESDAY AFTERNOON.

OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
NO WDSPRD RSTRNS EXPD.

&&

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

&&

$$






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