366
FXUS61 KPBZ 262351
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
751 PM EDT SUN JUL 26 2026
WHAT HAS CHANGED
UPDATED TO REFLECT THE END OF THE MARGINAL SEVERE THREAT, AS
WELL AS FOR THE POSSIBILITY OF PATCHY OVERNIGHT FOG. THE AVIATION
DISCUSSION WAS ALSO UPDATED.
KEY MESSAGES
1) QUIET WEATHER TONIGHT ASIDE FROM ISOLATED EVENING SHOWERS.
2) THUNDERSTORMS POSSIBLE MONDAY AND MONDAY NIGHT WITH
HEIGHTENED SEVERE WEATHER POTENTIAL.
DISCUSSION
KEY MESSAGE 1...
STRONG CAPPING IN PLACE THIS EVENING HAS LARGELY SUPPRESSED
CONVECTION, ASIDE FROM A FEW MAINLY LIGHT SHOWERS SUPPORTED BY A
WEAK MID-LEVEL SHORTWAVE. LITTLE IMPACT IS EXPECTED FROM THESE,
AND THEY ARE FORECAST TO DISSIPATE LATER THIS EVENING AS WE
DIURNALLY STABILIZE.
A QUIET NIGHT IS FORESEEN UNDER WEAK SURFACE HIGH PRESSURE.
SCATTERED CLOUD COVER, NEARLY CALM WIND, AND DEWPOINTS IN THE
LOWER AND MID 60S ARE EXPECTED TO SUPPORT AT LEAST PATCHY FOG
DEVELOPMENT LATE TONIGHT.
KEY MESSAGE 2...
AS AN EASTERN TROUGH SHIFTS EAST, AND A MIDWEST RIDGE FILLS IN
BEHIND, THE POTENTIAL FOR UPSTREAM MCS DEVELOPMENT INCREASES
INTO MONDAY AND TUESDAY, ALONG WITH THE CHANCE OF RUN-OF-THE-
MILL AFTERNOON CONVECTION.
THE CHANCES OF AN ACTUAL MCS MONDAY AFTERNOON APPEAR LOW FOR
NOW, BUT AFTERNOON STORM CHANCES ARE CERTAINLY PREVALENT.
DIURNAL HEATING AND DESTABILIZATION ALOFT PUSHED NBM 25TH-75TH
SBCAPE TO 1000-2000 J/KG, AND SFC-6KM SHEAR INCREASES TO 30KTS
TO 35KTS, WITH THE LARGEST PROPORTIONAL INCREASE TO WINDS IN
THE SFC-3KM LAYER FROM THE DAY PRIOR. 25TH TO 75TH HREF DCAPE
SHOWS 800 TO 1000, CERTAINLY CAPABLE OF DOWNBURST WIND THREATS
WITH HIGH ENOUGH VERTICAL DEVELOPMENT. THAT BEING SAID, THERE IS
STILL A SPLIT IN CAMS FOR CONVECTION PRESENCE/INTENSITY MONDAY.
MODELS LIKE THE FV3/HRRR/ARW SHOW MORE ROBUST MID-LEVEL ASCENT
AND LESS CAPPING WITH MORE WIDESPREAD CONVECTION, WHILE CAMS
LIKE THE NAM/RGEM HAVE WEAKER FORCING AND SLIGHTLY MORE CAPPING.
SO, THERE IS AGAIN A CONDITIONAL PROBABILITY FOR SEVERE MONDAY,
PERHAPS MORE LIKELY THAN SUNDAY. DOWNBURST WINDS AND TORRENTIAL
DOWNPOURS ARE MOST LIKELY, THOUGH HAIL AND ISOLATED TORNADOES
COULD NOT BE RULED OUT.
OVERNIGHT, UNCERTAINTIES COMPOUND. THE FIRST WILL BE THE AFFECT
OF WHAT HAPPENS MONDAY. IF WIDESPREAD SEVERE OCCURS MONDAY,
THAT WOULD PERHAPS MUDDLE THE ENVIRONMENT FOR OVERNIGHT
CONVECTION MONDAY NIGHT WHETHER AN MCS OCCURS OR NOT. SECOND
WILL BE THE EXACT POSITION AND TIMING OF AN MCS. WHILE CERTAINTY
HAS INCREASED IN THE LAST 24 HOURS, THE WINDOWS ARE STILL FAIRLY
WIDE FOR POSITION AND TIMING. AT THE MOMENT, A BEST-GUESS
ENVELOPE FOR AN MCS PASSAGE IS BETWEEN 8PM MONDAY AND 8AM
TUESDAY, WITH A "BEST GUESS" LOCATION BEING ANYWHERE BETWEEN
INDIANA AND EASTERN OHIO. IN ANY EVENT, A BLOW TO EASTERN OHIO
WOULD HAVE THE HIGHEST CHANCE OF IMPACTING OUR AREA. SHOULD
CONVECTION NOT OCCUR MONDAY, THE HIGHEST CONDITIONAL THREAT
SEVERE WINDOW WOULD BE EARLIER IN THE NIGHT. THIS WOULD BRING
THE HIGHEST CHANCE OF DAMAGING WINDS, WITH ISOLATED TORNADOES
AND A FLASH FLOODING THREAT. SHOULD CONVECTION OCCUR DURING THE
DAY MONDAY, THE HIGHEST CONDITIONAL THREAT OF SEVERE WEATHER
WOULD BE A LATER ARRIVAL PERHAPS, WITH SLIGHTLY LOWER THREATS OF
WIND AND TORNADOES WITH DIURNAL COOLING. BE SURE TO MONITOR THE
FORECAST FOR UPDATES AS WE DRAW CLOSER.
TUESDAY WILL AGAIN DEPEND ON WHAT HAPPENS OVERNIGHT MONDAY. IF
AN MCS OCCURS, SEVERE THREAT WOULD BE CONDITIONALLY LOWER AND
VISE VERSA. ENSEMBLES SHOW SOME STEEPENING LAPSE RATES BEHIND A
COLD FRONT, BUT BY THEN THE MID-LEVEL JET HAS PUSHED EAST.
NONETHELESS, SCATTERED STORMS REMAIN POSSIBLE WITH A MARGINAL
DOWNBURST THREAT, FAVORING SOUTH OF I-70. NCAR ML, CSU ML, AND
CIPS AGREE WITH A MORE "MID-ATLANTIC" THREAT TUESDAY.
AVIATION /00Z MONDAY THROUGH FRIDAY/
MAINLY VFR CONDITIONS ARE IN PLACE THIS EVENING, WITH BROKEN
HIGH-BASED CUMULUS AND ALTOCUMULUS IN PLACE. A FEW ISOLATED
SHOWERS MAY FLOAT ACROSS THE REGION THROUGH 02Z OR SO BEFORE
DIURNAL STABILIZATION, BUT CHANCES OF DIRECT IMPACT ON ANY ONE
TERMINAL ARE SLIM.
OVERNIGHT, CHANCES FOR AT LEAST PATCHY FOG INCREASE. AT LEAST
PARTIAL CLEARING, NEARLY CALM SURFACE WIND, AND DEWPOINTS IN
THE LOWER TO MID 60S SHOULD FOSTER DEVELOPMENT. NEAR-TERM
SOUNDINGS SUPPORT A NEAR-SURFACE INVERSION DEVELOPING AS
CROSSOVER TEMPERATURES ARE APPROACHED, AND HREF IFR VISIBILITY
PROBABILITIES ARE GENERALLY IN THE 40 TO 70 PERCENT RANGE AT
SEVERAL AREA TERMINALS. HLG, ZZV, AND MGW HAVE THE BEST CHANCE
OF SEEING NOTABLE IMPACTS.
FOG SHOULD LARGELY LIFT BY 14Z, WITH A RETURN OF VFR CONDITIONS
WITH AT LEAST SCATTERED CUMULUS. SHOWER AND THUNDERSTORM
POTENTIAL BEGINS TO INCREASE DURING THE AFTERNOON, BUT
UNCERTAINTY IN TIMING AND AREAL EXTENT REMAINS FAIRLY HIGH. HAVE
USED PROB30 GROUPS AT MOST TERMINALS NORTH OF I-70 FOR NOW AFTER
18Z TO REFLECT THIS LACK OF CONFIDENCE. A FEW OF THE STRONGER
STORMS MAY BE CAPABLE OF STRONG WIND GUSTS, BUT BETTER CHANCES
OF THIS LIKELY LIE AFTER 00Z TUESDAY.
OUTLOOK...
THUNDERSTORM CHANCES CONTINUE INTO TUESDAY WITH THE APPROACH
AND PASSAGE OF A COLD FRONT. A FEW STORMS COULD BE SEVERE. LOW
SHOWER/STORM CHANCES CONTINUE WEDNESDAY WITH ANOTHER PASSING
WAVE, BEFORE VFR RETURNS THURSDAY UNDER BUILDING HIGH PRESSURE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...MILCAREK
AVIATION...CL
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