764
FXUS61 KPBZ 202000
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
300 PM EST THU FEB 20 2025
SYNOPSIS
SNOW SHOWERS WILL TAPER OFF TONIGHT AS HIGH PRESSURE BUILDS
ACROSS THE UPPER OHIO VALLEY REGION. THE HIGH WILL THEN MAINTAIN
DRY WEATHER THROUGH THE WEEKEND. RAIN AND SNOW CHANCES RETURN
WITH A MONDAY WARM FRONT.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- WINTER WEATHER ADVISORY CONTINUES THROUGH 7AM FOR THE RIDGES
- HEAVIER SNOW SHOWERS AND POSSIBLE SQUALLS THROUGH EVENING
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RECENT WATER VAPOR IMAGERY SHOWS AN UPPER LOW CENTERED ACROSS SW
PA. STEEPENING LOW LEVEL LAPSE RATES THROUGH THE DENDRITIC LAYER
WILL ENHANCE LIFT THROUGH EARLY THIS EVENING. THIS COULD RESULT
IN BRIEFLY HEAVY SNOW SHOWERS/POSSIBLE SQUALLS WITH SOME LAKE
AND TERRAIN ENHANCEMENT. CONTINUED THE WINTER WEATHER ADVISORY
FOR THE RIDGES WITH 2-4 INCHES OF SNOW EXPECTED.
THE LAPSE RATES DECREASE BY EARLY EVENING AS WARM ADVECTION
ALOFT BEGINS, AND AS THE UPPER LOW MOVES EAST OF THE REGION. A
WEAK TROUGH ROTATING AROUND THE LOW COULD MAINTAIN A FEW MORE
SNOW SHOWERS INTO THE OVERNIGHT HOURS, THOUGH ACCUMULATIONS
SHOULD BE LIGHT. THE SNOW SHOULD END TOWARD MORNING AS THE
TROUGH EXITS. TEMPERATURES ARE EXPECTED TO AVERAGE 5 TO 10
DEGREES BELOW SEASONABLE LEVELS.
SHORT TERM /FRIDAY THROUGH SUNDAY/
KEY MESSAGES:
- DRY WEATHER THROUGH THE WEEKEND UNDER HIGH PRESSURE
- GRADUAL WARMING TREND
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SURFACE HIGH PRESSURE IS EXPECTED TO BUILD ACROSS THE OHIO
VALLEY REGION, AND IS PROGGED TO BE CENTERED OVER WV ON
SATURDAY. GENERALLY DRY WEATHER IS EXPECTED, WITH STRATOCU
ERODING THROUGH THE DAY FRIDAY. A FEW MORE CLOUDS ARE POSSIBLE
SATURDAY AS A WEAK UPPER TROUGH CROSSES THE REGION, THOUGH
PRECIP IS NOT EXPECTED WITH SUBSIDENCE UNDER THE HIGH.
THE HIGH IS EXPECTED TO MOVE OFF THE EAST COAST ON SUNDAY, WITH
DRY WEATHER CONTINUING. A GRADUAL WARMING TREND IS EXPECTED
THROUGH THE PERIOD, WITH TEMPERATURES NEAR SEASONABLE LEVELS BY
SUNDAY.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
KEY MESSAGES:
- PERIODIC PRECIPITATION CHANCES THROUGH THE PERIOD
- NEAR SEASONABLE TEMPERATURES
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MODEL ENSEMBLES INDICATE AN AMPLIFIED PATTERN WILL SET UP ACROSS
THE CONUS THROUGH NEXT WEEK. TROUGHS EMBEDDED IN THIS PATTERN
WILL RESULT IN PERIODIC PRECIPITATION CHANCES IN THE FORECAST
THROUGH THE WEEK. THE STRONGEST OF THESE TROUGHS IS PROGGED FOR
THURSDAY, WHERE THE HIGHEST POPS ARE INCLUDED IN THE FORECAST.
MAINLY RAIN IS EXPECTED, THOUGH A MIX OR CHANGE TO SNOW IS
POSSIBLE AT TIMES IN COLD ADVECTION AFTER THE PASSAGE OF THESE
TROUGHS.
TEMPERATURES ARE EXPECTED TO AVERAGE NEAR SEASONABLE LEVELS
THROUGH THE PERIOD.
AVIATION /19Z THURSDAY THROUGH TUESDAY/
MVFR CIGS AND MVFR/IFR VSBYS WITH SNOWFALL RATES LESS THAN
0.5"/HR (AROUND 90% PROBABILITY) CAN BE EXPECTED THROUGH THE TAF
PERIOD AS AN UPPER LOW CROSSES THE REGION. THE HIGHEST
PROBABILITY OF IFR VSBYS WILL BE DURING THE AFTERNOON AS STRONG
COLD ADVECTION ON THE BACK SIDE OF THE TROUGH STEEPENS LAPSE
RATES AND SNOW BECOMES MORE CONVECTIVE. LATEST GUIDANCE SHOWS A
60% CHANCE OF IFR CIGS THROUGH THE TAF PERIOD.
THE MENTIONED CONVECTIVE SHOWERS LOOK LIKELY TO BEGIN BY EARLY
AFTERNOON (18Z) AND LASTING THROUGH 00Z. ON AND OFF WIDESPREAD
HEAVIER SNOW SHOWERS THAT CAN QUICKLY DROP VISIBILITY TO LESS
THAN 1 MILE AND HAVE SNOWFALL RATES BETWEEN 0.5"-1"/HR (30-50%
PROBABILITY OF THOSE RATES) WILL BE POSSIBLE. SHORT-DURATION
BURSTS CAN BE EXPECTED BUT TIMING OF IMPACTS AND LOCATION OF
HEAVIEST BANDS IS TOO DIFFICULT BEYOND TEMPO GROUPS TO NOTE THE
THREAT. INCREASED NW WIND WILL DEVELOP DURING THE AFTERNOON WITH
25-30KT PEAK GUSTS.
LOSS OF HEATING AND SLOWLY INCREASING SUBSIDENCE WILL TAPER OFF
SHOWERS BY 00Z, BUT RESIDUAL COLD ADVECTION IN NW FLOW MAKES IT
LIKELY THAT A LAKE-ENHANCED BAND OR TWO PERSISTS THROUGH THE END
OF THE TAF PERIOD. THERE IS HIGH UNCERTAINTY IN THE POSITIONING
OF THESE BANDS (IF THEY DEVELOP) AND THE POTENTIAL RATES WITHIN
THEM. IN GENERAL, THE COLD ADVECTION AND RESIDUAL BOUNDARY
LAYER MOISTURE WILL FOSTER MVFR TO SPOTTY IFR CIGS OVERNIGHT,
WITH VSBY ISSUES TETHERED TO THESE LAKE BANDS.
OUTLOOK...
INCREASING SUBSIDENCE AND DRY ADVECTION IN NW WILL ERODE
REMAINING LIGHT SNOW SHOWERS THROUGH FRIDAY MORNING AND SLOWLY
LIFT/SCATTER MVFR STRATOCU DECK. AREAS SOUTHEAST OF KPIT ARE
FAVORED FOR A RETURN TO VFR BY FRIDAY AFTERNOON (LESS THAN 30%
PROBABILITY OF MVFR PERSISTENCE), BUT MODELS SUGGEST SOME
POTENTIAL FOR LINGERING STRATOCU FOR NORTHERN SITES LIKE FKL/DUJ
INTO SATURDAY MORNING (40-60%).
DRY WEATHER IS EXPECTED SATURDAY INTO SUNDAY BEFORE A SERIES OF
SHORTWAVES DROP OUT OF THE GREAT LAKES EARLY NEXT WEEK, BRINGING
RESTRICTIONS AND PERIODIC PRECIPITATION CHANCES.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...WINTER WEATHER ADVISORY UNTIL 7 AM EST FRIDAY FOR PAZ074-076-
078.
OH...NONE.
WV...WINTER WEATHER ADVISORY UNTIL 7 AM EST FRIDAY FOR WVZ510>514.
COLD WEATHER ADVISORY UNTIL 10 AM EST FRIDAY FOR WVZ514.
SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...88
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