741
FXUS61 KPBZ 181122
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
722 AM EDT TUE AUG 18 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES WITH THE LATEST FORECAST PACKAGE AS
HAZARDOUS WEATHER RISKS REMAIN LIMITED OVER THE NEXT 7 DAYS.
KEY MESSAGES
1) SHOWERS AND LOWER PROBABILITY THUNDERSTORMS RETURN WEDNESDAY
INTO THURSDAY, FEATURING LIMITED FLOOD CONCERNS.
2) PERIODIC RAIN CHANCES AND A SEASONABLY COOL PATTERN IS
FAVORED FOR THE LATE WEEK TO WEEKEND PERIOD.
DISCUSSION
KEY MESSAGE 1...
SURFACE RIDGING AND DRIER ZONAL FLOW ALOFT TODAY WILL BE SHUNTED
SOUTHEAST AS A WEAK SHORTWAVE TROUGH AND ASSOCIATED SURFACE COLD
FRONT DROP SOUTHEAST WEDNESDAY. DUE TO WEAK FORCING AT
SURFACE/ALOFT, MODELS GENERALLY FAVOR A BROKEN LINE OF
SHOWERS/LOW PROBABILITY THUNDERSTORMS PUSHING SOUTHEAST AHEAD OF
THE FRONT THAT DAY. LIMITED SURFACE MOISTURE RETURNS AHEAD OF
THE FRONT COMBINED WITH THE LACK OF NOTABLY COOLING ALOFT
ENSURES AREA BUOYANCY IS LOW (MEAN VALUES LESS THAN 1000 J/KG
CAPE) TO KEEP SEVERE RISKS AT BAY. PWATS SLOWLY RISE AMID MID-
LEVEL MOIST ADVECTION MAINLY ASSOCIATED WITH THE 700MB JET BUT
EVEN IT ONLY RISES SLIGHTLY ABOVE AVERAGE FOR THE SEASON.
THE ONLY NOTABLE FEATURE ARRIVES OVERNIGHT WEDNESDAY INTO
THURSDAY WHEN A SECONDARY SHORTWAVE ENHANCES 500-700MB MOISTURE
CONTENT AT THE SAME TIME THE SURFACE BOUNDARY POTENTIALLY
STALLS NEAR THE I-70 CORRIDOR. THE INFLUX OF MOISTURE (PUSHING
PWATS JUST UNDER THE 90TH PERCENTILE) COMBINED WITH BETTER JET-
AIDED ASCENT AND MORE PARALLEL FLOW WITH RESPECT TO THE SURFACE
BOUNDARY COULD RESULT IN A NARROW BAND OF HEAVIER RAIN THAT MAY
CAUSE LOCALIZED FLOODING CONCERNS ON SATURATED GROUNDS,
ESPECIALLY IF SOME SEMBLANCE OF TRAINING OCCURS. MORE LIKELY,
THE LACK OF STRONGER BUOYANCY WILL KEEP RAINFALL RATES LOW AND
ENSURE ANY POTENTIAL 2" TOTAL ACCUMULATIONS (AS SUGGESTED COULD
OCCUR BY 24-HR 90TH PERCENTILES) IS OVER A PROLONGED PERIOD.
EVENTUAL PASSAGE OF THE UPPER TROUGH SHORTWAVE AXIS PLUS
BUILDING SURFACE HIGH PRESSURE RETURNS DRY CONDITIONS TO THE
REGION BY FRIDAY.
KEY MESSAGE 2...
LONG RANGE GUIDANCE IS FAIRLY FIRM IN THE PERSISTENCE OF A
WESTERN CONUS RIDGING, EASTERN CONUS TROUGHING PATTERN THIS
WEEKEND AND POTENTIALLY INTO THE START OF NEXT WEEK.
PRECIPITATION CHANCES THEN WILL COINCIDE WITH EMBEDDED
SHORTWAVES MOVING THROUGH THE TROUGH AND IS LIKELY TO BE
PERIODIC (~EVERY 12 HOURS OR SO) UNTIL HEIGHT RISES CAN BEGIN.
TEMPERATURE ALSO RESPONDS TO THE DEEPENING OF THIS TROUGH
PATTERN AND FALLS BELOW SEASONAL AVERAGES FOR SATURDAY/SUNDAY.
UNCERTAINTY RISES AFTER SUNDAY WHEN MODELS DIVERGE IN THE
DEGREE/QUICKNESS OF HEIGHT RISES FOR THE FOLLOWING WEEK.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
IN MONDAY'S POST-FRONTAL ENVIRONMENT, A SIGNIFICANT AREA OF
BROKEN/OVERCAST STRATUS AROUND 5-6 KFT HAS DEVELOPED OVER MUCH
OF EASTERN OH, SOUTHWESTERN PA, AND NORTHERN WV. THIS HAS, AND
WILL CONTINUE TO, PRECLUDE FOG DEVELOPMENT AT THOSE SITES
THROUGH THE REMAINDER OF THE EARLY MORNING HOURS. ELSEWHERE
FARTHER NORTH, WHERE STRATUS DID NOT DEVELOP, FOG HAS SETTLED IN
AND DETERIORATED CONDITIONS AT FKL/DUJ TO PREVAILING IFR AND
BOUNCING DOWN TO LIFR AT TIMES. THIS WILL PERSIST FOR AN HOUR OR
TWO AFTER SUNRISE BEFORE HEATING AND MIXING ERODES THE FOG
RESTRICTIONS AND RETURNS VFR.
VFR IS THEN FAVORED FOR THE REST OF THE TAF PERIOD WHILE
ADDITIONAL SCATTERED TO BROKEN CU DEVELOP BETWEEN 4-6 KFT AFTER
15Z WITH DIURNAL HEATING/MIXING. WIND REMAINS GENERALLY LIGHT
OUT OF THE NW AT 5-10 KNOTS. CU WILL COLLAPSE WITH SUNSET
TONIGHT GIVING WAY TO SCT CIRRUS COVERAGE AND LIGHT AND VARIABLE
WIND.
OUTLOOK...
SHOWER AND LOW PROBABILITY THUNDERSTORM CHANCES RETURN WEDNESDAY
INTO THURSDAY AHEAD OF A SLOWER MOVING COLD FRONT. EXPECT
WIDESPREAD RESTRICTIONS ASSOCIATED WITH THE FRONT BY THURSDAY
MORNING. PERIODIC RESTRICTION/RAIN CHANCES ARE FAVORED INTO THE
WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...FRAZIER
AVIATION...FRAZIER/MLB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page