553
FXUS61 KPBZ 300548
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
148 AM EDT MON MAR 30 2026
WHAT HAS CHANGED
SLIGHTLY HIGHER SHOWER CHANCES FOR TODAY ARE INDICATED. CONFIDENCE
IN A LATE TUESDAY NIGHT/WEDNESDAY MORNING FRONTAL PASSAGE HAS
INCREASED SLIGHTLY, BUT THERE REMAINS A FAIR AMOUNT OF
UNCERTAINTY.
KEY MESSAGES
1) RAIN AND THUNDERSTORM CHANCES RETURN THIS WEEK, WITH AT LEAST
MODEST SEVERE WEATHER CONCERNS TUESDAY NIGHT INTO WEDNESDAY.
2) A SLOW-MOVING FRONT AND DEEP MOISTURE COULD LEAD TO HEAVY
RAINFALL TOTALS AND POTENTIAL HYDROLOGIC CONCERNS BY LATE WEEK
AND INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1...
LOW-LEVEL CONVERGENCE ALONG A WEAK WARM FRONT/SURFACE TROUGH MAY AID
THE FORMATION OF LIGHT RAIN SHOWERS THIS MORNING, ALTHOUGH THEY WILL
BE HINDERED AT LEAST INITIALLY BY A CONTINUED DRY SUB-CLOUD LAYER.
BETTER RAIN CHANCES ARRIVE FOR TONIGHT INTO TUESDAY. LOW-LEVEL
MOISTURE ISSUES FADE AS OVERALL COLUMN MOISTURE IMPROVES IN LOW-
LEVEL WSW FLOW, WITH PRECIPITABLE WATER VALUES CLIMBING ABOVE AN
INCH. BEST COVERAGE STILL APPEARS TO BE FROM PITTSBURGH ON NORTH,
WHERE A 40-50 KNOT 850MB JET AND ASSOCIATED CONVERGENCE
PROVIDES THE BEST SUPPORT FOR LIFT. HREF MEANS PEAKING AROUND
400-600 J/KG OF MUCAPE NORTH OF I-80 SHOULD SUPPORT SOME
ELEVATED CONVECTION, AND WHILE SOUNDINGS APPEAR TO HAVE ENOUGH
SATURATION TO SUPPORT LOCALIZED DOWNPOURS, MID-LEVEL LAPSE RATES
ARE LIKELY TO REMAIN LESS THAN 7C/KM, SUGGESTING SUB-SEVERE
HAIL DIAMETERS DESPITE 35-40 KNOTS OF 0-6KM SHEAR.
THE FORECAST AREA SHOULD BE FIRMLY IN THE WARM SECTOR BY LATER
TUESDAY MORNING, WITH THE MAIN BOUNDARY WELL TO THE NORTH IN NEW
YORK STATE AND WESTWARD INTO MICHIGAN. HIGH TEMPERATURES SHOULD
CLIMB WELL INTO THE 70S AREAWIDE, REACHING LEVELS ROUGHLY 20 DEGREES
ABOVE CLIMATOLOGY. MOST DAILY RECORDS FOR MARCH 31ST APPEAR SAFE,
UNLESS TEMPERATURES TREND TOWARD THE NBM 90TH PERCENTILE OR A BIT
HIGHER.
THE MAIN QUESTION STILL REMAINS THE TIMING OF THE FOLLOW-UP COLD
FRONTAL PASSAGE, BRINGING THE NEXT WIDESPREAD CHANCE OF SHOWERS AND
THUNDERSTORMS. WITH SUFFICIENT (35-40 KNOTS AT LEAST) DEEP LAYER
SHEAR EXPECTED, FRONTAL TIMING REMAINS KEY IN DETERMINING
INSTABILITY POTENTIAL. THE EURO ENSEMBLE REMAINS THE MOST AGGRESSIVE
WITH A FRONTAL PASSAGE DURING THE PREDAWN/EARLY MORNING HOURS OF
WEDNESDAY, WHILE THE GEFS CONTINUES TO LEAN TOWARDS A MORE MID-TO-
LATE MORNING TIMING. THIS LATTER SCENARIO WOULD REPRESENT A HIGHER
SEVERE RISK FOR PORTIONS OF THE AREA THAT CAN BUILD UP SURFACE-BASED
CAPE AHEAD OF THE BOUNDARY. WHAT IS ALSO INTERESTING IS THAT LONGER-
RANGE CAMS LIKE THE RRFS AND NAMNEST APPEAR TO BE FAIRLY PROGRESSIVE
WITH THE BOUNDARY, DEVELOPING CONVECTION ACROSS THE UPPER
MIDWEST/WESTERN GREAT LAKES TUESDAY AFTERNOON AND DROPPING IT SOUTH
AND EAST WITH TIME, IMPACTING PORTIONS OF THE UPPER OHIO VALLEY LATE
TUESDAY NIGHT, PERHAPS WITH A SEVERE THREAT NORTH OF I-80 BEFORE
AVAILABLE INSTABILITY WANES AS THE LINE DROPS SOUTH. THIS THINKING
MATCHES THE GOING SPC DAY 3 MARGINAL SEVERE RISK. OVERALL,
THERE REMAINS TOO MUCH UNCERTAINTY TO PEG TIMING, LOCATION, AND
LEVEL OF THE SEVERE THREAT WITH MUCH CONFIDENCE. AVAILABLE
MACHINE-LEARNING GUIDANCE REMAINS BROAD WITH ITS FOOTPRINT OF
THE OVERALL SEVERE POTENTIAL, ALTHOUGH THE BEST CHANCES REMAIN
PEGGED TO OUR NORTH AND WEST.
KEY MESSAGE 2...
THE FRONT, REGARDLESS OF TIMING, EVENTUALLY ENCOUNTERS NEARLY
PARALLEL MID-LEVEL FLOW, RESULTING IN SLOWING MOVEMENT. THERE ARE
ENSEMBLE INDICATIONS THAT THE BOUNDARY MAY STALL NEAR OR JUST SOUTH
OF THE SOUTHERN PORTIONS OF THE FORECAST AREA BY WEDNESDAY NIGHT.
THE BOUNDARY MAY THEN LIFT BACK NORTH AS A WARM FRONT DURING
THE LATE WEEK PERIOD, BUT ADDITIONAL WAVES ALONG THE BOUNDARY
MAY ALLOW IT TO WAVER IN OUR REGION INTO NEXT WEEKEND. NBM
LONG-RANGE PROGS INDICATE THAT THE HEAVIEST RAIN POTENTIAL
REMAINS TO OUR WEST TOWARDS THE GREAT LAKES AND THE MISSISSIPPI
VALLEY, WITH A DIRECT FEED FROM THE GULF INDICATED. STILL, PRECIPITABLE
WATER REMAINING IN THE 95TH PERCENTILE OR HIGHER THROUGH THE
PERIOD SHOWS THAT LOCAL RAINFALL TOTALS WILL NEED TO BE
MONITORED AS WELL FOR POTENTIAL HYDROLOGIC CONCERNS. MMEFS
LONG-RANGE RIVER LEVEL GUIDANCE STILL SUGGESTS THERE IS SOME
POTENTIAL FOR AT LEAST ACTION STAGES ON LARGER RIVERS LIKE THE
OHIO AND THE ALLEGHENY.
AVIATION /06Z MONDAY THROUGH FRIDAY/
VFR CONDITIONS CONTINUE OVERNIGHT WITH A BKN TO OVC MID-LEVEL
CLOUD DECK. WITH LIGHT SURFACE FLOW BENEATH A 35-40 KNOT LOW
LEVEL JET, A BRIEF PERIOD OF LOW LEVEL WIND SHEAR IS PROBABLE
FOR ALL SITES AFTER 06Z UNTIL ABOUT 10Z WHEN THE CORE OF THE
JET DEPARTS. HI RESOLUTION GUIDANCE CONTINUES TO ALLUDE TO THE
POTENTIAL FOR SHOWERS TO CROSS THE AREA BETWEEN THE 08Z AND 15Z
TIMEFRAME THIS MORNING, BUT ANY PRECIPITATION WILL HAVE TO
OVERCOME PRONOUNCED LOW LEVEL DRY AIR EVIDENT ON OUR 00Z
SOUNDING, WHICH LEADS TO A GOOD BIT OF UNCERTAINTY OF
OCCURRENCE, BUT HAVE INCLUDED PROB30S WITH MINIMAL VIS
RESTRICTION TO ADDRESS THE CHANCE.
WITH MIXING, SOUTHWEST FLOW WILL INCREASE THROUGH THE DAY AS
WILL MOISTURE AND CLOUDS WILL THICKEN WITH LOWERING BASES. NBM
IS AGGRESSIVELY BRINGING IN MVFR CIGS AREAWIDE BY MID-MORNING,
BUT A LOOK AT FORECAST SOUNDINGS AND HREF DATA DOESN'T SUGGEST
THAT WE'LL BE ABLE TO MOISTEN THE ANTECEDENT VERY DRY LOW LEVELS
QUITE AS QUICKLY, SO HAVE OPTED TO HOLD ON THE LESS AGGRESSIVE
SIDE OF GUIDANCE AND KEEP VFR IN PLACE THROUGH MOST OF THE DAY
ON MONDAY. HIGHER PROBABILITY (>60%) FOR MVFR ARRIVES FOR
FKL/DUJ MONDAY EVENING.
COVERAGE OF SHOWERS AND STORMS IS EXPECTED TO INCREASE NORTH OF
PIT AROUND SUNSET MONDAY NIGHT ALONG A WARM FRONT. HAVE HIGHEST
CONFIDENCE IN IMPACTS TO FKL/DUJ AND LESSER AS FAR SOUTH AS PIT,
BUT ENOUGH TO INCLUDE ANOTHER PROB30 GROUP FOR ALL BUT
ZZV/LBE/MGW. FARTHER NORTH, CONFIDENCE IN THUNDER IS HIGHER, SO
HAVE INCLUDED TSRA MENTION ACCOMPANYING SHOWERS. BETTER LOWER
LEVEL SATURATION IS SUGGESTED OVERNIGHT, AND ACCORDINGLY, MVFR
CIG PROBS JUMP TO 60+% AREAWIDE, HIGHER TO THE NORTH.
OUTLOOK...
A RETURN TO VFR IS FAVORED TUESDAY EVENING. BY WEDNESDAY
MORNING, ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO MOVE INTO
THE AREA RETURNING THE POSSIBILITY FOR SHOWERS/THUNDERSTORMS AS
WELL AS CEILING RESTRICTIONS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CL
AVIATION...MLB
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