692
FXUS61 KPBZ 211400 AAA
AFDPBZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
900 AM EST SAT FEB 21 2026
WHAT HAS CHANGED
- FLOOD WATCH EXPIRED
- 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) FLOOD WATCH EXPIRED
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 HAS BEEN ALLOWED TO EXPIRE. WHILE A LOCALIZED
ICE JAM ISSUE IS POSSIBLE, OVERALL FLOWS AND GAUGE LEVELS
INDICATE THE MAIN THREAT FOR ICE JAM FLOODING HAS ENDED. RIVER
LEVELS REMAIN ELEVATION ON THE ALLEGHENY AND OHIO DUE TO RECENT
RAIN AND SNOW MELT, WITH SOME ICE STILL ON THE ALLEGHENY. THE
FLOOD ADVISORY AT THE POINT IN PITTSBURGH REMAINS IN EFFECT
UNTIL SUNDAY MORNING.
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 /14Z SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES...
- MVFR SCATTERS FROM S TO N TODAY, FKL/DUJ UNLIKELY TO CLEAR
- DETERIORATION TO IFR TONIGHT AND SUNDAY IN SNOW
------------------------------------------------------------
MVFR CIGS CONTINUE THIS MORNING NORTH OF A ZZV TO VVS LINE, WITH
LOW LEVEL MOISTURE BELOW A TEMPERATURE INVERSION. EXPECT GRADUAL
CLEARING OF THE LOWER CLOUDS FROM S-N THIS AFTERNOON, AS SURFACE
HIGH PRESSURE RIDGE BUILDS IN ACROSS THE UPPER OHIO VALLEY
REGION. THE CLEARING WILL LIKELY NOT REACH FKL AND DUJ, WITH
MVFR PERSISTING THERE.
MID AND HIGH CLOUDS SHOULD QUICKLY FILL IN BEHIND ANY CLEARING
OF THE LOWER LEVEL CLOUDS LATE TODAY AND TONIGHT, AHEAD OF THE
NEXT APPROACHING SHORTWAVE TROUGH. THIS TROUGH SHOULD RESULT IN
SNOW OVERSPREADING THE REGION OVERNIGHT AND SUNDAY, WITH A
DETERIORATION TO IFR. THE HEAVIER SNOW SHOULD BE FOCUSED ACROSS
THE RIDGES, WHERE UPSLOPE FLOW AND AN INVERTED SURFACE TROUGH
(FROM A MAIN SURFACE LOW ACROSS THE CAROLINAS/MID ATLANTIC) IS
PROGGED TO SET UP. GENERALLY EXPECT A 1-3 INCH SNOWFALL ACROSS
MOST OF THE AREA, WITH HIGHER AMOUNTS EAST OF THE TAF SITES
ACROSS THE HIGHER TERRAIN.
OUTLOOK...
RESTRICTIONS IN SNOW ARE EXPECTED THROUGH MONDAY WITH A
CROSSING UPPER LOW, AND SUBSEQUENT COLD NW FLOW OFF OF THE GREAT
LAKES. VFR SHOULD GRADUALLY RETURN TUESDAY AS HIGH PRESSURE
BUILDS IN. RESTRICTIONS IN SNOW RETURN TUESDAY NIGHT INTO
WEDNESDAY WITH ANOTHER CROSSING SHORTWAVE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...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...WM/CL
AVIATION...WM
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