004
FXUS61 KPBZ 211236
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
836 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 /12Z SUNDAY THROUGH THURSDAY/
THE MORNING FOG ACROSS THE REGION HAS DISSIPATED AND MUCH OF THE
AREA HAS RETURNED TO VFR CONDITIONS. DRY CONDITIONS ARE EXPECTED
THROUGH THE DAY WITH VFR CONDITIONS PERSISTING AT LEAST THROUGH
06Z. WINDS ARE EXPECTED TO BE LIGHT AND VARIABLE THROUGH THE
DAY. CLOUD COVER WILL FEATURE SOME MID AND UPPER LEVEL CLOUD
COVER THROUGH THE DAY.
BY 06Z TONIGHT, A LOW PRESSURE SYSTEM WILL APPROACH FROM THE
WEST WITH SHOWERS OVERSPREADING THE AREA DURING THE 06Z TO 12Z
PERIOD OF THE TAF. MOST LOCATIONS WILL SEE A DIP TO MVFR AS THE
SHOWERS BECOME MORE INTENSE. THE TIMING WILL BE LATER IN THE
MORNING FOR THE EASTERN TERMINALS. THERE IS A CHANCE FOR
THUNDERSTORMS, MAINLY IN THE 09Z TO 12Z RANGE. THERE IS SOME
UNCERTAINTY HERE SOME PROB30S WERE USED FOR THE THUNDER
POTENTIAL. THE WINDS ALOFT WILL BE OVER 40 KNOTS IN SOME
INSTANCES SO LLWS WAS USED IN THE 08Z TO 12Z TIMEFRAME. WINDS AT
THE SURFACE WILL MAINLY BE SOUTHWEST WITH SOME GUSTS UP TO 20
KNOTS.
OUTLOOK...
THE DAY ON MONDAY WILL FEATURE CONTINUED SHOWERS AND
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...SHALLENBERGER
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