784
FXUS61 KPBZ 210814
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
314 AM EST SAT FEB 21 2026
WHAT HAS CHANGED
- FLOOD WATCH CANCELLED FOR VENANGO AND JEFFERSON COUNTIES, BUT
REMAINS FOR CLARION, BUSTER, AND ARMSTRONG COUNTIES.
- SLIGHT ADJUSTMENTS TO SNOW TOTALS FOR THE SUNDAY-MONDAY
SYSTEM, BUT OVERALL EXPECTATIONS REMAIN THE SAME, AS DOES THE
WINTER STORM WATCH.
KEY MESSAGES
1) ICE JAM FLOOD WATCH CONTINUES FOR NOW, WILL LIKELY BE
CANCELLED/EXPIRE LATER THIS MORNING.
2) WINTER STORM LIKELY FOR HIGH TERRAIN - THE WATCH WAS
MAINTAINED. STILL HAVE LOWER CONFIDENCE IN SNOW TOTALS
ELSEWHERE.
3) MORE SEASONABLE MIDWEEK TEMPERATURES ALLOW FOR SOME MELTING,
WITH A MIDWEEK SNOW-TO-RAIN POSSIBILITY.
DISCUSSION
KEY MESSAGE 1...
THE FLOOD WATCH WAS CANCELLED FOR VENANGO AND JEFFERSON
COUNTIES, AS THERE IS RELATIVELY HIGH CONFIDENCE THAT THE ICE
JAM THREAT HAS ENDED FOR THESE LOCATIONS. THE EARLIER ICE JAM AT
EMLENTON ON THE ALLEGHENY BROKE DURING THE EVENING, AND THE
STAGE AT PARKER FELL BELOW FLOOD STAGE, ALLOWING FOR EXPIRATION
OF THE FLOOD WARNING NEAR THAT LOCATION.
THE WATCH REMAINS IN BUTLER, CLARION, AND ARMSTRONG, AS
ADDITIONAL ICE JAMS CANNOT BE RULED OUT AS SURGES OF WATER
CONTINUE DOWN THE ALLEGHENY. MONITORING WILL CONTINUE TO BE
NEEDED FOR NOW AT LOCATIONS LIKE EAST BRADY, TEMPLETON, AND
REEDSDALE. THE THREAT LIKELY LESSENS LATER TODAY AS WATER LEVELS
SLOWLY RECEDE.
KEY MESSAGE 2...
NO MAJOR CHANGES WERE MADE TO THE FORECAST FOR THE EXPECTED
WINTER WEATHER SUNDAY THROUGH MONDAY AT THIS TIME. A 500MB
TROUGH IS STILL PROJECTED TO DIG ACROSS THE MIDDLE OHIO VALLEY
LATE TONIGHT AND ACROSS MUCH OF THE EASTERN CONUS SUNDAY. AS
THIS OCCURS, CYCLOGENESIS GETS GOING OFF OF THE NORTH CAROLINA
COAST LATE TONIGHT, WITH THE LOW CENTER DEEPENING AS IT MOVES
ALONG OR JUST OFF OF THE COAST AS A DEVELOPING NOR'EASTER. THE
MAIN UNCERTAINTY LIES IN HOW FAR WEST THE TRACK OF THIS LOW ENDS
UP. PEAK PRECIPITATION COVERAGE STILL APPEARS TO BE MAINLY
DURING THE DAY SUNDAY INTO SUNDAY NIGHT, WITH MORE OF AN UPSLOPE
(AND PERHAPS MODEST LAKE-ENHANCED) INFLUENCE BY MONDAY.
WE STILL HAVE HIGH CONFIDENCE IN IMPACTFUL SNOW ACCUMULATION FOR
THE LAURELS OF PA AND THE HIGHER TERRAIN OF WV, WHERE THE WINTER
STORM WATCH CONTINUES. IT IS HERE WHERE THE BEST CONVERGENCE OF
DECENT LAPSE RATES/MOISTURE IN THE DENDRITIC GROWTH ZONE,
FORCING FROM THE UPPER TROUGH, AND SURFACE TEMPERATURES NEAR
OR BELOW FREEZING WILL OCCUR THROUGH SUNDAY INTO MONDAY.
ACCUMULATION IS ALSO LIKELY TO LINGER HERE LONGER INTO MONDAY
THAN THE LOWLANDS DUE TO UPSLOPE FLOW. ACCUMULATIONS OF 6
INCHES OR MORE HAVE A 50-80 PERCENT PROBABILITY IN THE WATCH
AREA, WITH THE HIGHER WEST VIRGINIA RIDGES HAVING ROUGHLY A
50-50 SHOT AT DOUBLE DIGIT ACCUMULATIONS.
LOWLAND ACCUMULATIONS ARE MORE UNCERTAIN. FIRST OF ALL, THE MOST
LIKELY SCENARIO REMAINS A GENERAL 1-3 INCH ACCUMULATION FOR THE
MAJORITY OF THE NON-TERRAIN FORECAST AREA, ASSUMING A MORE
OFFSHORE TRACK OF THE SURFACE LOW. HOWEVER, A LOW PERCENTAGE OF
ENSEMBLE (MAINLY GEFS) MEMBERS SHOW A TRACK ALONG OR EVEN
SLIGHTLY INLAND THAT COULD PUSH HIGHER ACCUMULATIONS A BIT
WESTWARD. THE WORST CASE (15-20 PERCENT CHANCE) OF MORE SURFACE
LOW INFLUENCE AND POTENTIAL FRONTOGENETIC BANDING STILL SUGGEST
6-10 INCHES IN THE LOWLANDS EAST OF PITTSBURGH AND 15-20 INCHES
FOR THE HIGHER RIDGES. THIS SCENARIO STILL EXISTS IN THE LONG
TAIL OF THE OVERALL DISTRIBUTION, BUT HAS NOT BECOME ANY MORE
LIKELY IN THE LATEST RUNS.
ALSO OF NOTE: THE SUGGESTED NBM MEAN SNOW-TO-LIQUID RATIOS FOR
THE EVENT STILL SEEM TOO HIGH FOR NON-RIDGE LOCATIONS, GIVEN AT
LEAST SOME DEGREE OF ABOVE-FREEZING TEMPERATURES ESPECIALLY
DURING THE DAY ON SUNDAY, WHEN SNOW RATES MAY BE HIGHEST.
SOMETHING MORE LIKE 10:1 OR 12:1 SEEMS MORE LIKELY THAN 15:1.
THE GROUND SURFACE HAS ALSO WARMED RECENTLY WITH THE
DISAPPEARANCE OF SNOW COVER AND RECENT WARMER TEMPERATURES.
SNOW WOULD BE MORE LIKELY TO ACCUMULATE AFTER SUNSET SUNDAY ON
UNTREATED ROADS, BUT COULD BE MORE OF A GRASSY ACCUMULATION IN
SPOTS DURING THE DAY. A MIX WITH RAIN IS ALSO NOT TOTALLY OUT OF
THE QUESTION IN SOME METRO VALLEY AREAS.
THUS, BOTTOM LINE: MOST-LIKELY SYSTEM TOTALS REMAIN 1-3" FOR
MOST LOWLAND AREAS, PERHAPS 3-5" IN THE FOOTHILLS, AND 6-10" IN
THE HIGHER TERRAIN, PERHAPS UP TO A FOOT ON THE HIGHEST PEAKS.
SOME REFINEMENT TO THIS REMAINS POSSIBLE WITH MODEL RUNS LATER
TODAY.
KEY MESSAGE 3...
ANY SNOW ACCUMULATION WILL NOT LAST NEARLY AS LONG ON THE GROUND
AS FROM THE JANUARY SYSTEM. COOLER TEMPERATURES LINGER INTO
TUESDAY, BUT THEREAFTER, VALUES BECOME MORE SEASONAL IN THE WAKE
OF THE DEPARTING TROUGH. HIGHS IN THE 40S BY WEDNESDAY SHOULD
ALLOW FOR SOME DAYTIME MELTING. A MIDWEEK SHORTWAVE MAY PROVIDE
A SNOW-TO-RAIN SETUP, WITH DRIER WEATHER AND MILDER TEMPERATURES
BY WEEK'S END.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES...
- BREEZY WINDS TO CONTINUE BEFORE SLACKENING SATURDAY MORNING
- MVFR SETTLING IN FROM THE NORTH OVERNIGHT
- MVFR SCATTERS FROM S TO N TOMORROW, FKL/DUJ UNLIKELY TO CLEAR
------------------------------------------------------------
WHAT WERE VERY GUSTY WINDS EARLIER TODAY HAVE SLACKENED SOME AS
EXPECTED OVERNIGHT. BREEZY CONDITIONS ARE EXPECTED TO CONTINUE
INTO SATURDAY MORNING BEFORE SLACKENING FURTHER. WINDS GO LIGHT
AND VARIABLE AT MANY LOCATIONS BY THE END OF THE 24HR TAF
WINDOW.
LOW CLOUDS FILTERING IN ARE SLOWLY LOWERING AND MVFR IS
CREEPING SOUTHWARD ACROSS THE REGION AT THIS TIME. PIT AND AGC
ARE EXPECTED TO FALL SHORTLY, WITH HLG NOT FAR BEHIND. ZZV WILL
BE NEAR THE EXPECTED SOUTHERN EXTENT OF THESE CLOUDS. HREF
PROBABILITIES FOR MVFR AT ZZV PEAK NEAR 40% BUT HAVE ERRED ON
THE SIDE OF CAUTION GIVING A FEW HOURS OF MVFR BEFORE SCATTERING
OUT AGAIN BEFORE SUNRISE. MGW IS FAR ENOUGH SOUTH THAT IT
LIKELY REMAINS VFR THROUGHOUT THE PERIOD. IFR PROBABILITIES ARE
HIGHEST (NEAR 90%)OVERNIGHT FOR FKL/DUJ BUT THE NEAR 80% CHANCE
THEY HAVE OF OCCURRENCE AT THIS TIME CERTAINLY ISN'T PANNING OUT
SO I HAVE INITIALIZED A LITTLE MORE OPTIMISTICALLY FOR THESE
PORTS.
A GENERAL S TO N CLEARING BEGINS BY EARLY MORNING AT ZZV THEN
PROGRESSES THROUGH THE MORNING AND MIDDAY HOURS AS FAR NORTH AS
BVI, RETURNING VFR TO ALL PORTS NOT NAMED FKL OR DUJ. FKL/DUJ
LIKELY REMAIN LOCKED INTO MVFR IF NOT IFR THROUGH MUCH OF THE
DAY.
BKN VFR CIGS AND LIGHT SNOW RETURN TO MOST PORTS BY THE CLOSE
OF THE CURRENT 24HR TAF PERIOD.
OUTLOOK... WIDESPREAD, LIGHT SNOW IS EXPECTED LATE SATURDAY
NIGHT THROUGH MONDAY WITH A CROSSING UPPER LOW. PROBABILITIES
FAVOR A 1-3 INCH SNOWFALL OUTSIDE OF THE RIDGES. VFR SHOULD
GRADUALLY RETURN TUESDAY AS HIGH PRESSURE BEGINS TO BUILD IN.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH UNTIL 9 AM EST THIS MORNING FOR PAZ008-014>016-022.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE MONDAY NIGHT
FOR PAZ074-076.
OH...NONE.
WV...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE MONDAY NIGHT
FOR WVZ510>514.
DISCUSSION...CL
AVIATION...AK
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