249
FXUS61 KPBZ 081127
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
727 AM EDT THU OCT 8 2026
WHAT HAS CHANGED
ISAIAS HAS BECOME A HURRICANE AND ENSEMBLES SHOW MORE CONFIDENCE
IN RAINFALL FOR SUNDAY AND MONDAY.
KEY MESSAGES
1) DRY WEATHER CONTINUES INTO THE WEEKEND WITH A WARMING TREND
BY SATURDAY
2) THE REMNANT LOW OF ISAIAS MAY PROVIDE A SOAKING RAIN SUNDAY
INTO SUNDAY NIGHT, ALTHOUGH WIDESPREAD FLOOD RISKS REMAIN LOW
DISCUSSION
KEY MESSAGE 1...
DRY WEATHER IS EXPECTED TO CONTINUE THROUGH FRIDAY AND SATURDAY
AS SURFACE HIGH PRESSURE REMAINS IN CONTROL. TEMPERATURES
REMAIN A A BIT ABOVE CLIMATOLOGY THROUGH FRIDAY. SOUTHERLY FLOW
AND RISING HEIGHTS BEHIND THE DEPARTING HIGH MAY PUSH DAYTIME
HIGHS SOME 10 DEGREES ABOVE CLIMATOLOGY ON SATURDAY.
KEY MESSAGE 2...
THE UPPER LEVEL PATTERN HEADING INTO THE SUNDAY THROUGH MONDAY
NIGHT TIME FRAME CONTINUES TO SUPPORT A BROAD UPPER RIDGE OVER
THE EAST WITH HURRICANE ISAIAS COMING ASHORE AND TRACKING NORTH
INTO THE OHIO VALLEY AND THE LOWER GREAT LAKES. THE TREND IN THE
ENSEMBLES, INCLUDING THE NBM AS WELL AS SOME DETERMINISTIC
MODELS SHOW A SHIFT TO THE WEST OF THE TRACK OF THE LANDFALLING
HURRICANE. PRECIP BEGINS TO MOVE INTO THE FORECAST AREA BY LATE
SATURDAY NIGHT. BY 00Z MONDAY, THE LOW CENTER BEGINS TO TRACK
EAST BUT SURFACE HIGH PRESSURE OFF THE EAST COAST SLOWS THE EXIT
AS BIT. THIS FACTOR WILL NEED TO BE MONITORED AS ADDITIONAL
RESIDENCE TIME WILL MEAN MORE RAINFALL, AND POTENTIAL MINOR
PROBLEMS, ESPECIALLY WITH THE LEAVES BEGINNING TO FALL AND
CLOGGING DRAINS IN THE CITY. FOR NOW, THE SWATH OF MOISTURE
EXITS TO THE EAST.
AT THIS TIME, CONCERNING THE RAINFALL, THE MEAN SOLUTION HAS
ABOUT 1.20" TO 1.40" FOR THE EVENT. A MORE AMPLIFIED PATTERN
COULD KEEP THE TROPICAL SYSTEM IN PLACE A BIT LONGER. THUS, A
90TH PERCENTILE SOLUTION BRINGS 2.00" TO 2.50" TO THE FORECAST
AREA IN A 48 HOUR PERIOD. MOST FFG GUIDANCE ACROSS THE AREA IS
AROUND 1.50" TO 1.75" FOR 1 HOUR AND UP TO 3.00" FOR 6 HOUR
AMOUNTS. THE NBM PROBS FOR EXCEEDING 2.50" IS AROUND 10% SO,
STILL AT THIS POINT, NO MAJOR FLOODING IS EXPECTED BUT
CERTAINLY NEEDS WATCHED GIVEN THE SLOWED TRACK POTENTIAL. THE
PROBS OF EXCEEDING 250 J/KG OF SB CAPE IS STILL AROUND 30% SO
SEVERE IS STILL NOT EXPECTED TO BE A CONCERN.
AVIATION /12Z THURSDAY THROUGH MONDAY/
HIGH PRESSURE WILL KEEP LARGELY VFR CONDITIONS IN CONTROL OVER
THE NEXT 24 HOURS. PATCHES OF CIRRUS ARE POSSIBLE DURING THE
DAY, WITH AFTERNOON CUMULUS EXPECTED TO BE SCANT AT BEST. BY
MIDDAY, MIXING OF NW FLOW AT 850MB SHOULD SUPPORT GUSTS TO
AROUND 20 KNOTS, WHICH WOULD SUBSIDE BY SUNSET. SOME PATCHY
VALLEY FOG MAY BE POSSIBLE LATE TONIGHT, PARTICULARLY AT FKL,
BUT CHANCES ARE TOO LOW FOR INCLUSION AT THIS POINT.
OUTLOOK...
OTHER THAN VARYING CHANCES FOR MORNING RIVER VALLEY STEAM FOG,
VFR IS FAVORED THROUGH SATURDAY. RESTRICTIONS WILL BECOME MORE
LIKELY STARTING SATURDAY NIGHT AS THE REMNANTS OF ISAIAS ARRIVE
DURING THE LATTER HALF OF THE WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
DISCUSSION...SHALLENBERGER
AVIATION...CL
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