469
FXUS61 KPBZ 041755
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
155 PM EDT MON MAY 4 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST.
KEY MESSAGES
1) SHOWER AND THUNDERSTORM CHANCES INCREASE THIS EVENING AND
TONIGHT
2) ACTIVE WEATHER PATTERN EXPECTED THROUGH THE WEEKEND
3) FROST POSSIBLE THURSDAY NIGHT
DISCUSSION
KEY MESSAGE 1...
THE LATEST MESOANALYSIS SHOWS DIURNAL INSTABILITY BEGINNING TO
INCREASE IN THE WARM SECTOR ACROSS THE MIDWEST AND LOWER OHIO
VALLEY REGIONS. LOW SURFACE DEW POINTS CONTINUE TO HINDER
DESTABILIZATION, THOUGH EXPECT SOME MOIST ADVECTION LATER THIS
AFTERNOON AND EVENING IN SW FLOW AND AN APPROACHING LOW LEVEL
JET. ML CAPE IS STILL EXPECTED TO BE LIMITED ACROSS THE UPPER
OHIO VALLEY REGION (GENERALLY LESS THAN 750 J/KG,) THOUGH JET
ASCENT AND A CROSSING SHORTWAVE SHOULD SPARK SCATTERED SHOWERS
AND THUNDERSTORMS LATE THIS AFTERNOON INTO TONIGHT. THERE IS A
BRIEF WINDOW LATE THIS AFTERNOON AND EARLY EVENING FOR STRONG
STORMS WITH 30-35 KT OF SHEAR ON THE NOSE OF THE JET, THOUGH
THIS POTENTIAL SHOULD WANE THIS EVENING AS THE LIMITED
INSTABILITY DIMINISHES.
ELEVATED INSTABILITY AND THE CROSSING SHORTWAVE SHOULD STILL
MAINTAIN SOME SHOWERS/STORMS OVERNIGHT.
KEY MESSAGE 2...
THE FOCUS WILL SHIFT TO AN APPROACHING COLD FRONT ON TUESDAY,
AS IT SINKS SLOWLY SOUTH TOWARD THE REGION. THE FLOW ALOFT IS
NEARLY PARALLEL TO THE FRONT, SO EXPECT ONLY A SLOW
PROGRESSION. SHOWER/STORM CHANCES WILL INCREASE FROM THE NW
THROUGH THE DAY, BUT SHOULD MAINLY BE CONFINED NORTH OF PIT
MOST OF THE DAY. SHEAR AND INSTABILITY IS EXPECTED TO BE EVEN
MORE LIMITED THAN TODAY, WITH ML CAPE LESS THAN 500 J/KG AND
LIMITED SHEAR. WARM AIR ALOFT SHOULD ALSO LIMIT BUOYANCY,
LIMITING ANY SEVERE WEATHER POTENTIAL. MORE WIDESPREAD SHOWERS
AND EMBEDDED THUNDERSTORMS ARE EXPECTED TUESDAY EVENING INTO
WEDNESDAY AS THE FRONT SLOWLY DROPS SOUTH ACROSS THE REGION.
A WAVE OF LOW PRESSURE IS PROGGED TO TRACK ALONG THE FRONT ON
WEDNESDAY AS IT STALLS ACROSS THE OHIO VALLEY AND CENTRAL PA,
MAINTAINING MORE SHOWERS AND ISOLATED THUNDERSTORMS. IT SHOULD
TURN MUCH COOLER NORTH OF THE FRONT WEDNESDAY, WITH HIGHS
AROUND 10 DEGREES BELOW AVERAGE. THE FRONT SHOULD PROGRESSES
FURTHER OUT OF THE REGION THURSDAY AS THE FLOW TURNS MORE WNW,
THOUGH IT SHOULD STILL BE IN CLOSE ENOUGH PROXIMITY TO MAINTAIN
SHOWER CHANCES.
THE UPPER OHIO VALLEY REGION IS THEN PROGGED TO BE UNDER A
BROAD UPPER TROUGH THROUGH THE WEEKEND. A SERIES OF SHORTWAVES
ROTATING THROUGH THE TROUGH WILL THEN KEEP PERIODIC SHOWER
CHANCES IN THE FORECAST.
KEY MESSAGE 3...
THERE IS SOME POTENTIAL FOR FROST THURSDAY NIGHT, THOUGH THIS
WILL BE HIGHLY DEPENDENT ON THE AMOUNT OF CLOUD COVER IN PLACE
AND THE RESULTING RADIATIONAL COOLING.
AVIATION /18Z MONDAY THROUGH SATURDAY/
SCATTERED TO BROKEN MID-LEVEL CLOUD DECKS CONTINUE TO MOVE
ACROSS THE REGION THIS AFTERNOON ALONG WITH BREEZY SOUTHWEST
WINDS GUSTING TO 20-25 KNOTS. SCATTERED SHOWERS AND POSSIBLY A
FEW THUNDERSTORMS DEVELOP THIS EVENING ALONG THE NOSE OF A
MODEST LOW- LEVEL JET CHARACTERIZED BY 925MB-850MB FLOW AROUND
40-45 KNOTS. THERE IS STILL UNCERTAINTY REGARDING WHICH
TERMINALS, IF ANY, SEE IMPACTS FROM THE ISOLATED EVENING
CONVECTION. THE MOST CONSISTENT HI-RES MODEL SIGNAL HAS BEEN A
CLUSTER MOVING WEST TO EAST ACROSS NORTHERN WV AND ANOTHER
SOMEWHERE IN THE VICINITY OR NORTH OF PIT/BVI. STILL, DUE TO
THE COVERAGE UNCERTAINTY, OPTED TO MAINTAIN PROB30S IN TAFS.
HOWEVER, INCREASING SIGNALS IN GUIDANCE THAT MUCAPE WILL TREND
NEAR 500 J/KG DURING EVENING HOURS PROVIDED ENOUGH CONFIDENCE
TO INTRODUCE THUNDER IN THIS TAF CYCLE. THE MOST LIKELY TIMING
FOR THE EVENING THUNDERSTORMS WILL BE 22Z-02Z.
AS THE LOW-LEVEL JET OVERSPREADS THE AREA TONIGHT, THERE WILL
BE A LLWS RISK AT ANY TERMINALS THAT ARE ABLE TO DECOUPLE
ENOUGH FOR SURFACE GUSTS TO SUBSIDE. SHOWER ACTIVITY LINGERS
OVERNIGHT AS WELL, BUT LIKELY SHIFTS NORTHWARD AND REMAINS
MOSTLY OVER NORTHEAST OH AND NORTHWEST PA, WITH THE GREATEST
CHANCE FOR IMPACTS AT FKL.
OUTLOOK...
A FEW THUNDERSTORMS ARE POSSIBLE ON TUESDAY. MORE WIDESPREAD
RESTRICTIONS IN SHOWERS AND THUNDERSTORMS ARE LIKELY TUESDAY
NIGHT INTO WEDNESDAY AS A WAVE OF LOW PRESSURE TRACKS ALONG AN
ADVANCING COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM
AVIATION...CERMAK
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