078
FXUS61 KPBZ 210638
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
238 AM EDT SUN JUN 21 2026
WHAT HAS CHANGED
RAINFALL TOTALS FROM SUNDAY NIGHT THROUGH MONDAY NIGHT HAVE
TRENDED A BIT LOWER, AND UNCERTAINTY REMAINS ON WHERE THE AXIS
OF HEAVIEST RAINFALL MAY SET UP. ISOLATED INSTANCES OF FLOODING
AND/OR SEVERE THUNDERSTORMS REMAIN MOST LIKELY TO THE SOUTHEAST
OF PITTSBURGH. MORNING FOG COVERAGE WAS ALSO EXPANDED A BIT FROM
THE PREVIOUS FORECAST.
KEY MESSAGES
1) DRY WEATHER INTO THIS EVENING. AREAS OF VALLEY FOG THIS
MORNING.
2) MORE WIDESPREAD RAIN CHANCES RETURN SUNDAY NIGHT AND MONDAY.
THERE IS HIGH CONFIDENCE IN A SOAKING RAINFALL, BUT LOW
CONFIDENCE IN THE THREAT OF FLOODING.
DISCUSSION
KEY MESSAGE 1...
ONCE REMAINING SHOWERS EXIT TUCKER COUNTY BY 08Z OR SO, MOSTLY
DRY WEATHER IS FORECAST INTO THE EVENING HOURS AS SURFACE HIGH
PRESSURE AND FLAT MID-LEVEL RIDGING CROSS OUR REGION. CLOUD
COVER WILL BE ON THE INCREASE THROUGH THE AFTERNOON AND EVENING
AS UPPER- LEVEL MOISTURE INCREASES AHEAD OF SURFACE LOW
PRESSURE, WHICH WILL ENTER THE LOWER OHIO VALLEY BY 00Z.
AREAS OF FOG, MAINLY IN VALLEYS, HAVE FORMED MAINLY IN
LOCATIONS THAT RECEIVED RAIN DURING THE AFTERNOON AND EVENING
HOURS OF SATURDAY. FOG IS NOT EXPECTED TO BECOME DENSE ON A
WIDESPREAD BASIS, BUT WILL BE MONITORED FOR POTENTIAL SPS
ISSUANCE IF AREAL COVERAGE INCREASES. THE FOG SHOULD QUICKLY
LIFT BY MID-MORNING.
KEY MESSAGE 2...
THE SURFACE LOW SLOWLY RIDES UP THE OHIO VALLEY TONIGHT AND
THROUGH MONDAY, LIKELY CROSSING INTO CENTRAL PENNSYLVANIA AFTER
00Z TUESDAY. THIS IN TURN KEEPS THE ASSOCIATED WARM FRONT FROM
PUSHING AS FAR NORTH AS MODEL RUNS A COUPLE OF DAYS AGO
SUGGESTED, PERHAPS NOT MUCH FARTHER NORTH THAN THE MASON-DIXON
LINE. THIS COULD HAVE IMPLICATIONS FOR WHERE THE HEAVIEST BAND
OF RAINFALL SETS UP INTO MONDAY EVENING. DESPITE THIS,
PRECIPITABLE WATER STILL SURGES INTO THE 1.6 TO 1.8 INCH RANGE
PER HREF/REFS. THE COMPONENT MODELS OF THESE ENSEMBLES ARE A BIT
INCONSISTENT AS TO WHERE THE HEAVIEST BAND OF PRECIPITATION IS
LIKELY TO OCCUR. INTERESTINGLY, AS MOST OF THE EVENT NOW LIES
WITHIN THE ENSEMBLE WINDOWS, HEAVIER PRECIPITATION TOTALS SEEM
MORE LIKELY TO BE CONFINED MOSTLY TO AREAS SOUTH OF I-70, WHERE
90TH PERCENTILE RAINFALL TOTALS EXCEEDING 1.5 INCHES ARE MOST
PREVALENT IN BOTH ENSEMBLES. THESE TOTALS ARE LOWER THAN NBM
PROGS WERE SUGGESTING A COUPLE OF DAYS AGO AND SEEMS TIED TO
THE MORE SOUTHERLY WARM FRONT POSITION. GIVEN THE UNCERTAINTIES
AND APPARENT LOWERING POTENTIAL OF HIGHER-END RAINFALL TOTALS,
WILL BE HOLDING OFF ON A FLOOD WATCH ISSUANCE FOR NOW. ANY
FLOODING THREAT MAY BE TIED TO SMALLER-SCALE STORM TRAINING NEAR
THE BOUNDARY. MODEL SOUNDINGS DO SUGGEST POTENTIAL FOR EFFICIENT
RAIN PRODUCTION GIVEN THE HIGHER PWAT, PROFILE SATURATION, AND
DEEP WARM CLOUD DEPTHS. WPC MAINTAINS A SLIGHT (LEVEL 2 OF 4)
RISK FOR EXCESSIVE RAINFALL SOUTHEAST OF A HLG/AGC/IDI LINE.
THE POTENTIAL FOR AT LEAST ISOLATED SEVERE STORMS WILL NEED TO
BE MONITORED AS WELL. SPC MAINTAINS A MARGINAL (LEVEL 1 OF 5)
RISK JUST TO THE SOUTHEAST OF THE SLIGHT RISK OF EXCESSIVE
RAINFALL NOTED ABOVE. WITH THE WARM FRONT IN THE REGION DURING
THE MORNING, BACKED LOW-LEVEL FLOW AND DEEP SHEAR OF 30-40 KNOTS
CREATE SOME IMPRESSIVE-LOOKING HODOGRAPHS, ALTHOUGH WHATEVER
MEAGER CAPE THERE IS AT THAT TIME IS LIKELY TO BE ELEVATED.
STILL, THIS WILL NEED TO BE MONITORED, AS ANY SURFACE-BASED
BUOYANCY DEVELOPING EARLIER THAN ANTICIPATED COULD RESULT IN AN
ISOLATED TORNADO THREAT. WHILE BUOYANCY MAY IMPROVE DURING THE
MIDDAY AND AFTERNOON HOURS, VEERING LOW-LEVEL FLOW LEADS TO
MORE UNIDIRECTIONAL HODOGRAPHS DURING PEAK HEATING, MAKING
DAMAGING WIND GUSTS THE MOST LIKELY ISOLATED SEVERE THREAT BY
THAT TIME. THERE REMAINS SOME QUESTION AS TO HOW MUCH SURFACE
HEATING CAN OCCUR, DEPENDING ON CLOUD BREAKS BETWEEN
SHOWERS/STORMS.
COVERAGE OF SHOWERS/STORMS WILL DECREASE FROM WEST TO EAST
MONDAY NIGHT WITH THE DEPARTURE OF THE SURFACE LOW, SETTING UP A
DRIER PATTERN AND NEAR-TO-BELOW NORMAL TEMPERATURES FOR THE
MIDDLE OF THE WEEK.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
THE MAIN ISSUE EARLY ON WILL BE VALLEY FOG, MAINLY IN AREAS THAT
RECEIVED SHOWERS AND THUNDERSTORMS SATURDAY AFTERNOON AND
EVENING. CONDITIONS MAY VARY BETWEEN MVFR AND LIFR AT ZZV, FKL,
AND DUJ, WITH SOME LIGHTER MVFR FOG POSSIBLE AT LBE AND MGW
CLOSER TO SUNRISE. OTHER SITES ARE NOT EXPECTED TO BE IMPACTED
BY FOG AT THIS TIME. ANY FOG SHOULD LIFT BY 12Z ON THIS LONGEST
DAY OF THE YEAR.
OTHERWISE, VFR CONDITIONS AND DRY WEATHER IS ANTICIPATED FOR
MOST OF THE TAF PERIOD, SAVE FOR PERHAPS THE FIRST SHOWERS
ARRIVING AFTER 04Z MONDAY AT ZZV AHEAD OF AN ADVANCING SURFACE
LOW. BEFORE THEN, CLOUD COVER WILL MAINLY BE LIMITED TO THE
MIDDLE AND UPPER-LEVEL VARIETY AS SLOW WARM ADVECTION ENSUES
LATER TODAY. MODEL CUMULUS RULE DOES SUGGEST SOME SCATTERED
DEVELOPMENT THIS AFTERNOON MAINLY NORTH OF PIT THAT WOULD
COLLAPSE WITH SUNSET. THANKS TO CROSSING SURFACE HIGH PRESSURE,
SURFACE WIND WILL GENERALLY REMAIN UNDER 10 KNOTS OUT OF THE W
AND NW.
OUTLOOK...
PROBABILITIES FAVOR OVERNIGHT SUNDAY INTO MONDAY FOR WIDESPREAD
SHOWERS (LOW PROBABILITY THUNDERSTORMS) RESULTING IN MVFR/IFR
RESTRICTIONS AS A DEEPER TROUGH/SURFACE LOW COMBO TRAVELS
THROUGH THE OHIO RIVER VALLEY REGION. VFR CONDITIONS ARE LIKELY
TO RETURN TUESDAY, SAVE FOR PERHAPS ANOTHER ROUND OF MORNING
FOG.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...CL
AVIATION...CL
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