069
FXUS61 KPBZ 172351 AAA
AFDPBZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
751 PM EDT MON AUG 17 2026
WHAT HAS CHANGED
UPDATED 00Z AVIATION DISCUSSION. ALSO REDUCED AND REMOVED POPS
FOR SOME AREAS THIS EVENING AFTER THE PASSAGE OF A COLD FRONT
WITH DIMINISHING SHOWER/THUNDERSTORM CHANCES.
KEY MESSAGES
1) SCATTERED SHOWERS END THIS EVENING, WITH AREAS OF FOG
DEVELOPING OVERNIGHT. DRY WEATHER RETURNS ON TUESDAY.
2) RAIN CHANCES RAMP BACK UP ON WEDNESDAY WITH A PASSING COLD
FRONT AND COULD LINGER AT LEAST THROUGH WEEK'S END.
DISCUSSION
KEY MESSAGE 1...
THE LATEST SURFACE ANALYSIS SHOWS A COLD FRONT EXTENDING ACROSS
SOUTHERN PA THROUGH CENTRAL/SOUTHERN OHIO. THIS FRONT WILL
CONTINUE TO TRACK SOUTHEASTWARD THIS EVENING BEFORE EXITING THE
AREA. A BAND OF SHOWERS IN THE VICINITY OF THE FRONT WILL
CONTINUE UNTIL FROPA LATER THIS EVENING. THE HEAVY RAINFALL AND
SEVERE WEATHER POTENTIAL HAVE ENDED, WITH DIMINISHING
INSTABILITY AND WARMING CLOUD TOPS.
PARTIAL CLEARING IS EXPECTED OVERNIGHT AS HIGH PRESSURE BEGINS
TO BUILD IN. THIS CLEARING, AND DIMINISHING WIND, SHOULD RESULT
IN RADIATIONAL COOLING AND AREAS OF FOG OVERNIGHT, ESPECIALLY
WITH THE SATURATED GROUND IN PLACE. THE FOG SHOULD DISSIPATE
WITH MIXING AND HEATING TUESDAY MORNING.
TUESDAY WILL BE DRY AREAWIDE WITH QUASI-ZONAL MID-LEVEL FLOW AND
WEAK SURFACE HIGH PRESSURE PROVIDING A COMFORTABLE MID-AUGUST DAY
WITH HIGHS IN THE UPPER 70S AND LOW 60S DEW POINTS.
KEY MESSAGE 2...
OUR ONE DAY OF RELIEF FROM SHOWERS AND STORMS QUICKLY FADES
INTO THE PAST AS YET ANOTHER COLD FRONT MOVES THROUGH ON
WEDNESDAY. RETURN FLOW WILL PULL BETTER GULF MOISTURE BACK INTO
THE LOCAL AREA AGAIN, THOUGH NOT TO THE EXTENT WE SAW OVER THE
PAST WEEKEND, WITH ENSEMBLE MEAN PWAT VALUES CLIMBING BACK UP TO
~1.5" AND DEW POINTS TO THE UPPER 60S. RIGHT ENTRANCE REGION
JET DYNAMICS AND WEAK PVA WILL AID IN SYNOPTIC ASCENT, AND A 40+
KNOT MID-LEVEL JET INCREASE DEEP LAYER SHEAR. THAT SAID,
SURFACE CAPE APPEARS TO BE A PRIMARY LIMITING FACTOR WITH NBM
MEAN AROUND 300-600 J/KG AND ONLY GETTING TO 1000 J/KG WITH THE
90TH PERCENTILE VALUES CONTINGENT LOW PROBABILITY CLEARING IN
THE MORNING AND PUSH OF HIGHER DEW POINTS. CIPS ANALOGS IS NOT
EXCITED ABOUT ANY SEVERE OR FLOODING WITH THE FRONT, SO WE
SHOULDN'T BE LOOKING AT ANY SIGNIFICANT THREAT EITHER WAY ON
WEDNESDAY.
THE QUESTION BEYOND THAT POINT IS THE PROGRESSION, OR LACKTHEREOF,
OF THE FRONT. MID-LEVEL FLOW TURNS MORE ZONAL AND SUBSEQUENTLY MORE
PARALLEL TO THE FRONT SUGGESTING IT SLOWS/STALLS ABSENT ANY
MECHANISM TO GIVE IT A KICK TO KEEP MOVING. NBM DEW POINT SPREAD AS
A PROXY FOR BOUNDARY PLACEMENT BASICALLY SUGGESTS IT COULD STALL
ANYWHERE FROM I-80 TO I-70, THOUGH ENSEMBLE CLUSTERS LEAN TOWARD
SLOW PROGRESSION SOUTH THURSDAY AND FRIDAY FOCUSING THE BEST RAIN
CHANCES ALONG AND SOUTH PITTSBURGH BY THE SECOND HALF OF THE DAY ON
THURSDAY. OBVIOUSLY WILL HAVE TO WATCH FOR REPEATED ROUNDS OF
RAIN OVER THE SAME AREAS, BUT GENERALLY WEAK FORCING MIGHT LEND
MORE TOWARD SCATTERED, DIURNALLY DRIVEN SHOWERS AND STORMS WITH
THE HIGHEST COVERAGE ON THURSDAY AFTERNOON AS A SHORTWAVE TRACKS
ACROSS THE BOUNDARY. NBM 90TH PERCENTILE 24 HOUR TOTALS SIT
ABOUT AS HIGH AS 1.75", SO THE RAINFALL TOTALS CEILING SHOULD
BE A BIT LOWER THAN WE'VE SEEN IN THE PAST WEEK. MACHINE
LEARNING PEGS A LOWER END FLOOD RISK.
SAID SHORTWAVE LIKELY GIVES THE STALLED BOUNDARY THE PUNCH IT
NEEDS TO EXIT OUR AREA BY THE WEEKEND, THOUGH A TROUGHY PATTERN
LIKELY KEEPS US ACTIVE WITH LONGER RANGE AI & ML GUIDANCE
SUGGESTING OUR NEXT SEVERE WEATHER RISK POPPING UP ON SATURDAY.
AVIATION /00Z TUESDAY THROUGH SATURDAY/
A COLD FRONT CONTINUES TO DROP SOUTHEASTWARD ACROSS SOUTHERN
PA-SOUTHER/CENTRAL OHIO. A BAND OF SHOWERS NEAR THE FRONT WILL
AFFECT MGW EARLY THIS EVENING, OTHERWISE VFR IS EXPECTED.
PARTIAL CLEARING, ALONG WITH RADIATIONAL COOLING AND A MOIST
GROUND IN PLACE, SHOULD RESULT IN AREAS OF IFR TO LIFR FOG
DEVELOPING FOR MOST AIRPORTS OVERNIGHT. THIS FOG SHOULD
DISSIPATE TUESDAY MORNING AS MIXING BEGINS WITH SURFACE HEATING.
THE CU RULE AND MODEL SOUNDINGS INDICATE A SCATTERED CUMULUS
FIELD IS LIKELY ON TUESDAY, WITH NW WIND AT 5-10KT.
OUTLOOK...
OTHER THAN EARLY MORNING FOG, VFR IS THEN EXPECTED THROUGH
EARLY WED UNDER HIGH PRESSURE. RESTRICTION AND SHOWER/THUNDERSTORM
CHANCES EXPECTED LATER WED AND WED NIGHT WITH THE APPROACH AND
PASSAGE OF A COLD FRONT. VFR RETURNS LATER THU AND FRI UNDER
HIGH PRESSURE. SHOWER AND THUNDERSTORM POTENTIAL RETURNS
SATURDAY WITH THE APPROACH OF A COLD FRONT.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...WM/MLB
AVIATION...WM
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