598
FXUS61 KPBZ 280713
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
313 AM EDT WED MAY 28 2025
SYNOPSIS
RAIN FAVORING NORTHERN WEST VIRGINIA AND WESTERN PENNSYLVANIA
WILL CONTINUE TODAY BEFORE A BRIEF PERIOD OF DRY AND WARMER
WEATHER DEVELOPS THURSDAY. PROBABILITIES ARE INCREASING IN
SEEING ANOTHER ROUND OF RAIN SHOWERS FRIDAY AND SATURDAY WHILE
TEMPERATURE FALLS WELL BELOW AVERAGE. LOOK FOR MORE SUMMER LIKE
TEMPERATURE TO DEVELOP NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- RAIN WILL CONTINUE TODAY WITH LOW PROBABILITY THUNDERSTORMS
POSSIBLE DURING THE AFTERNOON.
- HIGHEST RAINFALL AMOUNTS WILL BE EAST OF I-79 BUT ARE UNLIKELY
TO LEAD TO FLOODING ISSUES.
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WEAK WARM, MOIST ADVECTION AROUND 700MB COMBINED WITH WEAK JET
ASCENT WILL BE THE PRIMARY DRIVER OF EARLY MORNING PRECIPITATION
THAT FAVORS LOCATIONS EAST OF I-79 AND NOTABLY THE HIGHER
TERRAIN. THOUGH UNCERTAINTY IS INCREASING BASED ON OVERNIGHT
RADAR TRENDS, THE EXPECTATION IS FOR MORE WIDESPREAD LIGHT RAIN
SHOWERS DEVELOPING IN THE LATE MORNING TO EARLY AFTERNOON PERIOD
AS THE UPPER LEVEL SHORTWAVE TROUGH APPROACHES FROM THE WESTERN
GREAT LAKES.
HI-RES MODELING SUGGESTS SOME HEATING MAY OCCUR IN THE LATE
AFTERNOON HOURS NEAR THE I-70 CORRIDOR AFTER THE MID-LEVEL WARM
FRONT LIFTS NE AND PRIOR TO THE APPROACH OF THE OCCLUDED SURFACE
FRONT. SOME INSTABILITY GENERATION COULD LEAD TO ISOLATED
EVENING THUNDERSTORMS, BUT DESPITE STRONG SHEAR, MEAGER CAPE
VALUES SHOULD MITIGATE A SEVERE THREAT. OVERALL, LIMITED
INSTABILITY AND WEAKER FORCING PRECLUDES FLASH FLOOD CONCERNS
IN SPITE OF 90TH PERCENTILE PWATS. MEAN HREF QPF ONLY EXCEED 1"
OVER THE WV HIGHER TERRAIN, WITH 90TH PERCENTILE OUTCOMES STILL
BELOW 2"; GIVEN DRIER ANTECEDENT CONDITIONS AND THE LONGER
DURATION OF ACCUMULATION, THIS FURTHER EXEMPLIFIES THE LOW FLOOD
RISK.
PASSAGE OF THE OCCLUDED FRONT AS THE UPPER TROUGH AXIS LIFTS NE
WILL LEND TO A GENERALLY DRY OVERNIGHT PERIOD, THOUGH AN
ISOLATED SHOWER/SPRINKLE FROM WEAK SHORTWAVES WITHIN THE ZONAL
FLOW CAN'T BE RULED OUT.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- DRY WEATHER AND BRIEF WARMING EXPECTED THURSDAY.
- PATTERN SHIFT WITH NEXT LOW PRESSURE SYSTEM STARTING FRIDAY.
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QUASI-ZONAL TO SOUTHWEST FLOW OVER SURFACE HIGH PRESSURE WILL
GENERALLY SUPPORT DRY WEATHER AND SEASONABLE TEMPERATURE
THURSDAY. HOWEVER, GIVEN LITTLE CHANGE IN BOUNDARY LAYER
MOISTURE FROM WEDNESDAY, AN ISOLATED AFTERNOON SHOWER CAN'T BE
RULED OUT THURSDAY DUE TO EMBEDDED VORT ADVECTION IN THE SW FLOW
THAT GLOBAL MODELS MAY HAVE MORE DIFFICULTY IN RESOLVING.
THE DEVELOPMENT AND DEEPENING OF A LOWER OHIO RIVER VALLEY UPPER
TROUGH WILL OCCUR THURSDAY EVENING INTO FRIDAY, SHIFTING SLOWLY
EASTWARD THROUGH THE PERIOD. THIS TROUGH SHOULD SPUR SURFACE
CYCLOGENESIS (WHICH MAY BE AIDED BY ONGOING CONVECTION) THAT
LOOKS TO DEEPEN SLIGHTLY AND TRACK GENERALLY ENE. VARIABILITY IN
THE UPPER TROUGH DEPTH AND SURFACE LOW POSITIONING CONTINUES TO
LOWER CONFIDENCE IN THE TIMING AND AREAL COVERAGE OF THE
ASSOCIATED RAINFALL FOR THE UPPER OHIO RIVER VALLEY. THE MAIN
FOCUS IN MESSAGING IS THAT THIS PERIOD WILL SIGNAL A SHIFT
TOWARDS EASTERN CONUS TROUGHING THAT FAVORS PERIODIC
PRECIPITATION CHANCES AND FALLING TEMPERATURE.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPERATURES CONTINUE THIS WEEKEND, WARMING NEXT
WEEK
- LIGHT RAIN SHOWERS FAVORED SATURDAY
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ENSEMBLE MEANS HAVE CONTINUED THEIR TREND TOWARD FAVORING DEEPER
AND SLIGHTLY SLOWER EASTERN CONUS TROUGHING THAT WILL CREATE
PERIODS OF RAIN SHOWERS SATURDAY WITH LIMITED HEATING. SEEING
SOME CONSENSUS ON MID-DAY 850MB TEMPS AROUND 7 DEGREES C LEAD TO
A MORE BEARISH TEMPERATURE FORECAST FOR SATURDAY (LEANING TOWARD
EUROPEAN MODEL MEANS AND LOCAL STUDIES). THIS NW FLOW PATTERN
LIKELY WILL FAVOR GREATER CLOUD COVER THAN MODEL MEANS SUGGEST
AS WELL AS MORE SCATTERED PRECIPITATION, WHICH WOULD FURTHER
LIMIT DIURNAL HEATING SATURDAY.
THE MODEL CONSENSUS IS FOR THE UPPER TROUGH AXIS TO BE EAST OF
THE REGION BY SUNDAY, ALLOWING FOR DRIER WEATHER AND SLIGHT
TEMPERATURE IMPROVEMENTS. CONFIDENCE RAISES SIGNIFICANTLY FOR
EARLY NEXT WEEK TO SEE LARGE HEIGHT RISES AND POTENTIAL RIDGE
DEVELOPMENT THAT LENDS TO ABOVE NORMAL TEMPERATURE AS EARLY AS
MONDAY THAT PERSISTS MUCH OF THE WEEK. IF THIS PATTERN DEVELOPS,
LOOK FOR SUMMER-LIKE TEMPERATURE READINGS BY MID WEEK BUT ALSO
THE POTENTIAL FOR RIDGE BREAKDOWNS THAT COULD LEAD TO A SEVERE
WEATHER OUTBREAK.
AVIATION /07Z WEDNESDAY THROUGH SUNDAY/
IFR CEILINGS COVER ROUGHLY WESTERN HALF OF AREA AND HAVE
STRUGGLED INTO THE EAST DUE TO SOUTHEAST FLOW AND DOWNSLOPING
OFF THE RIDGES, WITH LOCAL GUSTS OF 25-30 KNOTS. FLOW SHOULD
WEAKEN AND TURN MORE SOUTHERLY AND ALLOW THE IFR CEILINGS TO
SPREAD INTO THE REST OF THE TAF SITES DURING THE MORNING.
RAIN AND EMBEDDED HEAVIER SHOWERS SHOULD INCREASE DURING THE
MORNING AS A SHORT WAVE TROUGH MOVES QUICKLY FROM KENTUCKY INTO
THE UPPER OHIO RIVER VALLEY BY MIDDAY HOURS. PERSISTENT RAIN MAY
RESULT IN MVFR TO LOCALLY IFR VISIBILITIES AS WELL.
EXPECT PRECIPITATION TO TAPER OFF AND BECOME MORE SPOTTY SHOWERS
THIS AFTERNOON WHICH SHOULD RESULT IN IMPROVEMENTS IN VISIBILITY
BUT IFR TO MVFR CEILINGS LIKELY TO PERSIST INTO TONIGHT.
ANY BREAKS IN THE CLOUDS WITH MOIST CONDITIONS AND LIGHT WINDS
WOULD RESULT IN FOG FORMATION SO SIGNIFICANT IMPROVEMENTS IN
RESTRICTIONS ARE NOT LIKELY UNTIL THURSDAY.
OUTLOOK...
UPPER TROUGH REMAINS IN PLACE ON FRIDAY WITH REINFORCING UPPER
TROUGH DIGGING ACROSS AREA ON SATURDAY. MAINLY VFR CEILINGS
EXPECTED BOTH DAYS WITH PERIODS OF MVFR CONDITIONS IN SHOWERS
LIKELY. NORTHWEST WIND GUSTS ON SATURDAY IN THE 25 TO 30 KNOT
RANGE ARE EXPECTED.
HIGH PRESSURE BUILDING IN SUNDAY SHOULD RESULT IN VFR AND MAINLY
CLEAR CONDITIONS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...FRAZIER
NEAR TERM...FRAZIER
SHORT TERM...FRAZIER
LONG TERM...FRAZIER
AVIATION...CRAVEN
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