805
FXUS61 KPBZ 041145
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
745 AM EDT MON MAY 4 2026
WHAT HAS CHANGED
AVIATION DISCUSSION UPDATED FOR 12Z ISSUANCE. OTHERWISE, NO
MAJOR CHANGES WERE MADE TO THE FORECAST.
KEY MESSAGES
1) SHOWER AND THUNDERSTORM CHANCES INCREASE LATE THIS
AFTERNOON/EVENING.
2) AN ACTIVE PATTERN WILL KEEP SHOWER AND/OR THUNDERSTORM
CHANCES IN THE FORECAST THROUGH THE WEEKEND.
3) POTENTIAL FOR FROST RETURNS THURSDAY NIGHT, MAINLY ACROSS
I-80 CORRIDOR AND IN THE RIDGES.
DISCUSSION
KEY MESSAGE 1...
MAINLY DRY WEATHER IS EXPECTED INTO THIS AFTERNOON, THOUGH A FEW
SPRINKLES OR ISOLATED LIGHT SHOWERS ARE POSSIBLE WITH WARM
ADVECTION. DIURNAL INSTABILITY IS EXPECTED TO BUILD IN THE WARM
SECTOR ON THROUGH THE DAY AS A SHORTWAVE TROUGH APPROACHES. ML
CAPE IS PROGGED TO REACH AROUND 1,000 J/KG ACROSS OHIO DURING
THE AFTERNOON, WITH LESSER AMOUNTS TO THE EAST. SHEAR IS ALSO
EXPECTED TO INCREASE, WITH 30-35KT FROM 0-6KM. A FEW STRONG
STORMS WITH WIND AND HAIL WILL BE POSSIBLE, ESPECIALLY ACROSS
OHIO, BEFORE A GENERAL DECREASING TREND OCCURS THROUGH THE
EVENING AND OVERNIGHT AS INSTABILITY GRADUALLY WANES. LATEST
CAMS HAVE BEEN FAIRLY RELUCTANT TO INITIALIZE SHOWERS/STORMS
OVER EASTERN OHIO LATE THIS AFTERNOON/EVENING, SO IT IS POSSIBLE
WE SEE ONLY A FEW ISOLATED NON-SEVERE THUNDERSTORMS.
KEY MESSAGE 2...
SURFACE LOW PRESSURE WILL CROSS NORTH OF THE GREAT LAKES TODAY
AND TUESDAY, SLOWLY DRAGGING A COLD FRONT INTO THE REGION
TUESDAY. BOUNDARY-PARELLEL FLOW WILL SLOW PROGRESSION OF THE
FRONT AS IT SINKS ACROSS OUR AREA LATE TUESDAY AND WEDNESDAY.
TUESDAY SHOULD BE THE WARMEST DAY OF THE WEEK, WITH GUSTY SOUTH
WIND AHEAD OF THE FRONT. INSTABILITY IS EXPECTED TO BE LIMITED
AS THE FRONT CROSSES THE REGION, THOUGH A FEW THUNDERSTORMS ARE
POSSIBLE. AT THIS TIME THERE IS AN 80-90 PERCENT PROBABILITY OF
SEEING AT LEAST A HALF INCH OF RAIN WITH THIS SYSTEM, WITH
PROBABILITIES AROUND 70 PERCENT FOR AN INCH OF RAIN NORTH OF
PIT.
SHOWER CHANCES WILL CONTINUE ON THURSDAY AS THE FRONT BECOMES
QUASI-STATIONARY ACROSS THE LOWER OHIO VALLEY AND MID-ATLANTIC
REGION AND AS A WAVE OF LOW PRESSURE TRACKS ALONG IT. A
SHORTWAVE TROUGH SHOULD FINALLY DRIVE THE FRONT OUT THE AREA
THURSDAY NIGHT INTO FRIDAY, BUT LINGERING UPPER TROUGHING WILL
MAINTAIN SHOWER CHANCES THROUGH THE WEEKEND. AFTER A WARM START
TO THE WEEK, COOLER THAN AVERAGE TEMPERATURES ARE EXPECTED
BEHIND THE MID WEEK COLD FRONT.
KEY MESSAGE 3...
POTENTIAL FOR LIGHT WIND AND TEMPERATURES BELOW 37F RANGES FROM
50-70% ACROSS THE I-80 CORRIDOR AND IN THE RIDGES THURSDAY
NIGHT/EARLY FRIDAY MORNING. THIS COULD LEAD TO FROST
DEVELOPMENT FOR THOSE AREAS, BUT WILL LARGELY BE DEPENDENT
WHETHER OR NOT SKIES CLEAR OVERNIGHT.
AVIATION /12Z MONDAY THROUGH FRIDAY/
VFR IS LIKELY TO PREVAIL THROUGH THE ENTIRE PERIOD. WIND WILL
PICK UP NOTABLY THIS MORNING AND AFTERNOON OUT OF THE SOUTHWEST
WITH A TIGHTENING GRADIENT AND MOMENTUM TRANSFER IN MODEL
SOUNDINGS SUGGESTING AT LEAST 20 KNOT GUSTS. THE STRONGEST LOW
LEVEL FLOW LIKELY DOESN'T ARRIVE UNTIL THE EVENING HOURS. CAN'T
RULE OUT A BRIEF PERIOD OF ENHANCED GUSTS IF THE ARRIVAL OF THE
STRONGER WINDS ALOFT ENDS UP BEING EARLIER, BUT WITH NOCTURNAL
DECOUPLING BEGINNING TO OCCUR AROUND THAT TIME ANY WINDOW FOR
HIGHER GUSTS WOULD BE BRIEF.
OVERNIGHT, 925 MB FLOW RAMPS UP TO AROUND 40 KNOTS AND 850 MB
FLOW TO 45-50 KNOTS. ENSEMBLE GUIDANCE CONTINUES TO SUGGEST
DECOUPLING DOES NOT OCCUR AND GUSTS CONTINUE INTO OVERNIGHT
HOURS, DESPITE WARM AIR ADVECTION REINFORCING A NOCTURNAL
INVERSION JUST OFF THE SURFACE. THE ALTERNATIVE SCENARIO IS THAT
WE DECOUPLE AND SURFACE GUSTS SUBSIDE, WHICH WOULD THEN LEAD TO
AN INCREASING LLWS THREAT AS SFC-2KFT SHEAR STRENGTHENS TO NEAR
OR JUST ABOVE 30 KNOTS. THERE IS STILL A BIT TOO MUCH
UNCERTAINTY WHICH SCENARIO WILL PLAY OUT, WHICH PRECLUDES THE
MENTION OF LLWS IN TAFS AT THIS TIME, BUT IT'S SOMETHING THAT
WILL WARRANT KEEPING AN EYE ON.
WITH INCREASING WARM ADVECTION, SOME SHOWERS MAY DEVELOP IN THE
EVENING AND EVEN POTENTIALLY LINGERING INTO OVERNIGHT HOURS
(THE LATTER MOST LIKELY OCCURRING NORTH OF PIT). THE SCATTERED
NATURE AND RUN TO RUN MODEL INCONSISTENCY WITH TIMING/OCCURRENCE
CONTINUES TO WARRANT -SHRA MENTION IN PROB30S RATHER THAN
PREVAILING GROUPS. IF CONFIDENCE IN OCCURRING/TIMING INCREASES
THROUGH THE DAY, A MORE TARGETED WINDOW FOR PREVAILING -SHRA MAY
BE INCLUDED. THUNDER IS POSSIBLE AS WELL, THOUGH WITH LIMITED
AVAILABLE INSTABILITY AND UNCERTAINTY REGARDING WHETHER UPDRAFTS
ARE ABLE TO GET TALL ENOUGH TO EXCEED -10C IN DRIER MID-LEVEL
AIR, THE PROBABILITIES FOR LIGHTNING ARE TOO LOW TO WARRANT
INCLUDING IN THE TAFS AT THIS TIME.
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/RACKLEY
AVIATION...CERMAK/MLB
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