568
FXUS61 KPBZ 191751
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
151 PM EDT TUE MAY 19 2026
WHAT HAS CHANGED
THE FORECAST REMAINS LARGELY UNCHANGED, WITH CONTINUED
CONFIDENCE IN STORM ARRIVAL IN EASTERN OHIO AND NORTHWEST
PENNSYLVANIA AFTER 8 PM TONIGHT.
KEY MESSAGES
1) HIGHEST RISK FOR SEVERE STORMS/DAMAGING WIND GUSTS WILL BE IN
AREAS OF NORTHWEST PA/EASTERN OH, WITH DIMINISHING RISK NEAR
PITTSBURGH. CONDITIONAL SEVERE THREATS REMAIN ON WEDNESDAY
SOUTHEAST OF PITTSBURGH WITH A DEPARTING FRONT.
2) STRENGTHENING SIGNAL FOR A WET MEMORIAL DAY WEEKEND.
DISCUSSION
KEY MESSAGE 1...
MID-LEVEL CAPPING (FOCUSED AROUND 500MB PER THIS MORNING'S 12Z
SOUNDING) IS MAINTAINED THROUGH THIS AFTERNOON AND WILL KEEP
ONGOING ISOLATED TO SCATTERED CONVECTIVE ACTIVITY LIMITED TO
SHOWERS AND POSSIBLY A THUNDERSTORM OR TWO WITH A LOW SEVERE
THREAT. THE UPPER RIDGE SUPPORTING THAT CAP BEGINS TO BREAK
DOWN IN RESPONSE TO AN ENCROACHING UPPER MIDWEST/GREAT LAKES
SHORTWAVE, WITH 1500-2000 J/KG OF MUCAPE FORECAST TO DEVELOP BY
THIS EVENING. A MORE ORGANIZED SEVERE THUNDERSTORM THREAT
REMAINS POSSIBLE IN CLOSER PROXIMITY TO AN ADVANCING COLD FRONT
THAT ENTERS THE AREA AFTER 8PM.
THE MOST LIKELY SCENARIO PRESENTED BY CAMS REMAINS THE
DEVELOPMENT OF STRONG TO SEVERE THUNDERSTORMS IN WESTERN OHIO IN
THE 6PM-8PM WINDOW ALONG AND AHEAD OF THE FRONT, PERHAPS
ASSOCIATED WITH A PREFRONTAL TROUGH. THESE STORMS SHOULD BE
WEAKENING AS THEY APPROACH NORTHWEST PA/EASTERN OH AFTER 9PM OR
SO DUE TO DIURNAL BUOYANCY LOSS AS WELL AS 20-25 KNOTS OF 0-6KM
SHEAR FOSTERING ONLY LOOSE ORGANIZATION/LIMITED COLD POOL
CONSOLIDATION. STILL, WITH UP TO 900 J/KG OF DCAPE AVAILABLE
NORTH AND WEST OF PITTSBURGH, STRONG TO SEVERE DOWNDRAFT WINDS
REMAIN A DECENT POSSIBILITY IN THE TALLER STORMS; THIS IS THE
AREA HIGHLIGHTED IN SPC'S DAY 1 SLIGHT (LEVEL 2 OF 5) RISK. HAIL
IS A LESSER CONCERN DUE TO THE LOWER SHEAR AND POOR MID-LEVEL
LAPSE RATES LESS THAN 6C/KM. ALSO, WITH AROUND 100 M2/S2 OF
0-1KM STORM- RELATIVE HELICITY AVAILABLE NORTH OF I-80, A
TORNADO CANNOT BE TOTALLY RULED OUT IN THIS AREA AS LCLS LOWER,
ALTHOUGH 0-3KM CAPE MAY BE A BIT LOW. CONVECTIVE INTENSITY IS
EXPECTED TO WANE OVERNIGHT AS THE PARENT COLD FRONT MOVES IN,
BUT SOME SHOWERS AND STORMS WILL CONTINUE.
WEDNESDAY STILL PRESENTS A LIMITED AND CONDITIONAL SEVERE
THREAT IN THE LAURELS AND IN THE WV RIDGES. THIS WILL DEPEND ON
FRONTAL TIMING AND THE AMOUNT OF RAIN/CLOUD COVER IN THE REGION
DURING THE MORNING INTO THE AFTERNOON. A SLOWER FRONT, WITH LESS
PRECIPITATION AND SOME CLOUD BREAKS OUT AHEAD, COULD ALLOW
SUFFICIENT DESTABILIZATION FOR AN ISOLATED DAMAGING WIND THREAT.
SCENARIOS WITH A FASTER FRONT AND MORE SOLID CLOUD COVER COULD
LARGELY CHOKE OFF THE THREAT FOR STRONG CONVECTION. THIS WILL
NEED TO BE MONITORED, AND THE SPC MARGINAL (LEVEL 1 OF 5) RISK
SOUTHEAST OF PITTSBURGH SHOWS THE POTENTIAL THREAT AREA WELL.
KEY MESSAGE 2...
PROBABILITIES FOR A SOAKING RAIN OVER MEMORIAL DAY WEEKEND
CONTINUE TO INCREASE AS AN ACTIVE PATTERN PERSISTS THROUGH THAT
TIME. LATEST GUIDANCE SUGGESTS A SURFACE LOW LIFTS NORTHEASTWARD
INTO THE LOWER OHIO VALLEY TO OUR WEST FRIDAY INTO SATURDAY,
BRINGING A WARM FRONT AND WIDESPREAD RAIN CHANCES TO THE REGION.
DURING THAT TIME, SURFACE HIGH PRESSURE IS FORECAST TO BE
CENTERED OVER THE UPPER GREAT LAKES AND NEW ENGLAND STATES.
THIS SETUP IS SIMILAR TO PAST EVENTS THAT HAVE GENERATED 2+
INCHES OF RAINFALL ACROSS THE LOCAL AREA, THOUGH IT SHOULD BE
NOTED THAT MINOR DEVIATIONS (E.G., EAST-WEST POSITIONING OF THE
LOW OR STRENGTH OF THE RIDGE) COULD RESULT IN THE AXIS OF
HEAVIEST RAINFALL SHIFTING AROUND (OR AWAY FROM) THE LOCAL
AREA. LATEST NBM PROBABILITIES SHOW A 60-80% CHANCE FOR AT LEAST
AN INCH OF 24-HR RAINFALL ACCUMULATION FRIDAY INTO SATURDAY,
AND A 20-40% CHANCE FOR 2+ INCHES.
A SECOND WAVE OF RAIN IS THEN FORECAST LATER IN THE WEEKEND,
THOUGH THAT ONE APPEARS A BIT MORE PROGRESSIVE IN NATURE AND NBM
PROBABILITIES REFLECT THAT WITH ONLY A ~20% CHANCE OF EXCEEDING
AN INCH OF 24-HR RAINFALL SUNDAY INTO MONDAY. STILL, COMBINED
WITH THE PRECEDING FRIDAY-SATURDAY RAINFALL, IT IS LOOKING MORE
POSSIBLE THAT WEEKEND TOTALS APPROACH OR EXCEED 1-2 INCHES, AND
POTENTIALLY EVEN 3 INCHES (20% CHANCE IN NBM). IT IS STILL TOO
EARLY TO DISCUSS IMPACTS AS A LOT COULD CHANGE OVER COMING DAYS,
BUT THIS SIGNAL WILL WARRANT MONITORING THROUGH THE WEEK.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
A SHOWER/THUNDERSTORM AT LBE/MGW THROUGH MID-AFTERNOON. SW WIND
IS EXPECTED TO GUST TO AROUND 20-25KT DURING THE DAY WITH MIXING.
MORE SHOWERS AND THUNDERSTORMS ARE EXPECTED TO TRACK ACROSS OHIO
LATE THIS EVENING/NIGHT IN ADVANCE OF AN APPROACHING COLD
FRONT. IT APPEARS THAT THE INSTABILITY SHOULD BE DIMINISHING AS
THESE STORMS ADVANCE EASTWARD, WITH AN OVERALL WEAKENING TREND
BY LATE EVENING. INCLUDED PROB30 MENTIONS FOR MOST SITES ACROSS
OHIO AND WESTERN PA, FROM MID TO LATE EVENING AS THESE STORMS
APPROACH.
RESTRICTIONS AND SHOWERS ARE LIKELY TO CONTINUE THROUGH
WEDNESDAY AS THE COLD FRONT SLOWLY CROSSES THE UPPER OHIO VALLEY
REGION. A FEW THUNDERSTORMS ARE ALSO POSSIBLE.
OUTLOOK...
RESTRICTIONS ARE POSSIBLE MAINLY SOUTH OF PIT WEDNESDAY NIGHT
AND THURSDAY AS A WAVE OF LOW PRESSURE TRACKS ALONG THE FRONT.
RESTRICTIONS AND SHOWERS RETURN FROM S-N FRIDAY INTO SATURDAY AS
A WARM FRONT LIFTS NORTH ACROSS THE AREA.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CERMAK/CL
AVIATION...WM/LUPO
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