993
FXUS61 KPBZ 090835
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
435 AM EDT WED JUL 9 2025
SYNOPSIS
A SURFACE FRONT WILL MEANDER ACROSS THE REGION THROUGH THE WEEK
AND INTO THE WEEKEND, MAINTAINING DAILY SHOWER AND THUNDERSTORM
CHANCES.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:
- STALLED BOUNDARY ALONG THE PA/WV BORDER KEEPS MOST CONVECTION
SOUTH OF PITTSBURGH TODAY.
- DAYTIME HIGHS TOP OUT JUST ABOVE NORMAL.
---------------------------------------------------------------
LATEST SURFACE ANALYSIS SHOWS A PSEUDO-STATIONARY BOUNDARY
PARKED ALONG THE PA/WV BORDER, WHICH WILL SERVE AS THE FOCAL
POINT FOR ANY CONVECTIVE DEVELOPMENT TODAY ONCE INSTABILITY
INCREASES WITH DIURNAL HEATING. INCREASED MID AND UPPER LEVEL
CLOUD COVERAGE WILL PERSIST THROUGH THE PERIOD WITH INCREASED
MOISTURE ADVECTION AHEAD OF AN APPROACHING MID-LEVEL SHORTWAVE.
THE CLOUD COVERAGE THAT HAS INCREASED OVER THE COURSE OF THE
NIGHT HAS MITIGATED ANY WIDESPREAD FOG DEVELOPMENT THIS MORNING,
AND DO NOT ANTICIPATE THE NEED FOR ANY ADVISORIES AT THIS TIME.
MODELS, ANALOGS, AND MACHINE LEARNING GUIDANCE ARE ALL IN
AGREEMENT WITH MINIMAL STRONG/SEVERE POTENTIAL WITH ANY
CONVECTION TODAY. T HIS WOULD BE LIMITED TO PORTIONS OF
NORTHERN WEST VIRGINIA, WHERE THERE IS BETTER
INSTABILITY/STRONGER UPDRAFT POTENTIAL, AND POTENTIAL FOR
LOCALIZED HEAVY RAINFALL, BUT THE OVERALL THREAT IS LOW.
SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- BETTER COVERAGE OF SCATTERED STORMS THURSDAY AS BOUNDARY LIFTS
BACK NORTH.
- SLIGHTLY ABOVE NORMAL TEMPERATURES CONTINUE.
----------------------------------------------------------------
CONVECTION FADES THIS EVENING, WITH THE OVERNIGHT PERIOD LARGELY
DRY ACROSS THE REGION. ON THURSDAY, A CROSSING SHORTWAVE TROUGH
WILL PUSH THE AFOREMENTIONED BOUNDARY NORTH AGAIN AS A WARM
FRONT, RESULTING IN SLIGHTLY MORE DIURNAL CONVECTIVE COVERAGE.
RELATIVELY WEAK CAPE PROFILES AND RELATIVELY LOW SHEAR SUGGEST A
MINIMAL SEVERE THREAT. LATEST MSU-CLP AND CIPS GUIDANCE DOES NOT
HINT AT MUCH POTENTIAL AT ALL FOR SEVERE CONVECTION OR FLOODING
IN THE PERIOD.
LONG TERM /FRIDAY THROUGH TUESDAY/
KEY MESSAGES:
- STALLED BOUNDARY LINGERS INTO THE WEEKEND AT LEAST WITH
CONTINUED DAILY RAIN CHANCES, CURRENTLY HIGHEST SUNDAY.
- LOW RAIN CHANCES NEXT WEEK AS PATTERN UNCERTAINTY INCREASES.
- CONTINUED NEAR TO ABOVE-NORMAL TEMPERATURE.
-------------------------------------------------------------------
ON FRIDAY, A WAVE OF LOW PRESSURE ALONG THE BOUNDARY MAY PUSH IT
BACK SOUTH OF PITTSBURGH, PERHAPS TOWARDS THE MASON-DIXON LINE. THIS
WOULD KEEP HIGHER DIURNAL SHOWER/STORM CHANCES ACROSS OUR SOUTHERN
ZONES. PRECIPITABLE WATER REMAINS ELEVATED NEAR AND SOUTH OF THE
BOUNDARY, WITH A REASONABLE RANGE OF 1.3 TO 1.6 INCHES, SO LOCALLY
HEAVY RAINFALL WILL REMAIN POSSIBLE.
MORE ORGANIZED SURFACE LOW PRESSURE LIKELY LIFTS ACROSS THE WESTERN
GREAT LAKES ON SATURDAY, WHICH WOULD PUSH THE BOUNDARY BACK NORTH,
BEFORE A POTENTIAL COLD FRONTAL PASSAGE SATURDAY NIGHT OR SUNDAY.
THERE REMAINS ENSEMBLE DISAGREEMENT ON HOW THIS COULD PLAY OUT,
PARTICULARLY WITH THE TIMING. FOR NOW, SUNDAY APPEARS TO HAVE BETTER
RAIN CHANCES THAN SATURDAY, AND GIVEN THE FROPA UNCERTAINTY, THE
SECOND HALF OF THE WEEKEND ALSO HAS GREATER HIGH TEMPERATURE
UNCERTAINTY. NBM 10TH TO 90TH PERCENTILE SPREADS EXCEED 10 DEGREES
FOR MOST OF THE REGION, WITH POSSIBLE MAX VALUES RANGING FROM AROUND
80 TO THE LOWER 90S. SEVERE POTENTIAL WILL DEPEND ON TIMING AS WELL,
WITH ENSEMBLE SOUNDINGS AND MACHINE LEARNING ADVERTISING AT LEAST
LOW-END POTENTIAL - FORECAST DEEP SHEAR REMAINS ON THE LOW SIDE,
LIMITING ORGANIZED CONVECTION POTENTIAL. LOCALIZED HEAVY RAIN
REMAINS POSSIBLE AS WELL.
UNCERTAINTY THEM PROPAGATES INTO NEXT WEEK. ELEVATED 500MB HEIGHTS
AND ZONAL FLOW ALOFT ARE MOST LIKELY, KEEPING TEMPERATURES NEAR TO
ABOVE NORMAL, BUT DIFFERENCES IN DISTURBANCES IN THAT FLOW
REQUIRE LOW-END POPS FOR BOTH MONDAY AND TUESDAY.
AVIATION /08Z WEDNESDAY THROUGH SUNDAY/
THERE IS STILL SOME UNCERTAINTY REGARDING THE AREAL COVERAGE AND
DEGREE OF INTENSITY FOR FOG FORMATION THIS MORNING. FACTORS FAVORING
FOG INCLUDE ENOUGH BOUNDARY LAYER MOISTURE, VERY LIGHT WIND, AND A
PERIOD OF CLEARER SKIES FOSTERING STRONG RADIATIONAL COOLING.
FACTORS THAT COULD LIMIT FOG INCLUDE THE INFLUX OF MID-HIGH LEVEL
CLOUDS OVERNIGHT AHEAD OF THE NEXT SHORTWAVE AND ITS TIMING TO
DISRUPT COOLING PROCESSES. CLOUD COVER HAS REMAINED OVER EASTERN
OHIO, ALLOWING FOR SOME RADIATIVE COOLING TO OCCUR OVER WESTERN PA
AND PARTS OF NORTHERN WV. THIS HAS RESULTED IN THE DEVELOPMENT OF
RIVER VALLEY FOG.
THE FOLLOWING TERMINALS HAVE A HIGHER LIKELIHOOD OF OBSERVING FOG:
FKL, DUJ, LBE, AND MGW. THERE IS A MODERATE CHANCE FOR PIT/AGC
SINCE THE RIVER VALLEY FOG DEVELOPMENT HAS BEEN SLOWER AND CLOUD
COVER WILL REACH THIS AREA SOONER THAN THE EASTERN TERMINALS.
THERE IS A LOWER PROBABILITY FOR FOG AT BVI/HLG SINCE THESE
TERMINALS WILL SOON HAVE CLOUD COVER.
DIURNAL HEATING/MIXING WILL ERODE ANY FOG/LOW STRATUS BY 14Z, WITH
VFR EXPECTED THE REST OF THE DAY. SHORTWAVE MOVEMENT IS LIKELY TO BE
DISPLACED TOO FAR NORTH/SOUTH TO GENERATE PRECIPITATION, HOWEVER,
THERE IS A LOW PROBABILITY (30%) FOR A SHOWER BETWEEN 18Z-00Z AT ZZV
AND MGW. FOLLOWING SUNSET, THE PROBABILITY FOR A RAIN SHOWER
DECREASES.
OUTLOOK...
A WEAKLY FORCED BUT WARM/HUMID ENVIRONMENT IS FAVORED
THROUGH THE END OF THE WEEK THAT WILL ALLOW FOR INTERMITTENT PERIODS
OF SHOWERS/THUNDERSTORMS; CONFIDENCE IS LIKELY TO BE LOWER ON TIMING
VARIOUS ROUNDS OF PRECIPITATION AS WELL AS THE RESULTANT CIG/VIS
IMPACT THEY COULD HAVE DURING THE MORNING HOURS.
MORE SIGNIFICANT UPPER LEVEL AND SURFACE BOUNDARY MOVEMENT APPEARS
TO ARRIVE OVER THE WEEKEND THAT WILL CREATE A MORE FOCUSED AND
BETTER TIMED PERIOD FOR CONVECTION AND RESTRICTION DEVELOPMENT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...88
AVIATION...FRAZIER/LUPO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page