087
FXUS61 KPBZ 182029
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
329 PM EST TUE FEB 18 2025
SYNOPSIS
EXPECT DRY CONDITIONS TO REMAIN OVER THE FORECAST AREA THROUGH
TONIGHT. A FEW INSTANCES OF LIGHT SNOW ARE POSSIBLE OVER
TUCKER/PRESTON COUNTIES TOMORROW INTO TOMORROW NIGHT. SNOW
SHOWERS ARE EXPECTED ON THURSDAY.
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
KEY MESSAGES:
- WIND CHILLS TONIGHT DROPPING TO -0 TO -10 DEGREES TONIGHT.
- INCREASING CLOUD COVER TONIGHT.
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DRY CONDITIONS ARE EXPECTED THROUGH THIS EVENING AS WINDS BEGIN
TO DECOUPLE. THE OVERNIGHT PERIOD WILL REMAIN DRY AND
SEASONABLY COOL WITH INCREASING CLOUDINESS LIKELY TO LIMIT SOME
COOLING AS A LOW PRESSURE SYSTEM DEVELOPS SW OF THE REGION. THIS
INCREASING CLOUDINESS WILL MAKE IT DIFFICULT TO GET -10 DEGREES
OR LESS WIND CHILL OR TEMPERATURE AND THUS DECIDED TO KEEP THE
MENTION OF THE THREAT IN THE HWO.
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- LOW PROBABILITY SNOW CHANCES WITH LITTLE TO NO ACCUMULATIONS
SOUTH OF THE MASON-DIXON LINE WEDNESDAY.
- UPPER TROUGH PASSAGE THURSDAY OFFERS WIDESPREAD SNOW SHOWERS,
WITH POTENTIAL FOR LAKE BANDS DURING THE AFTERNOON/EVENING
HOURS.
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THE CURRENT TREND IN THE ENSEMBLES SUGGEST THE TRACK OF THE
850MB LOW BRINGS THE SYNOPTIC SYSTEM STRAIGHT ACROSS THE CENTRAL
APPALACHIANS AND RIGHT OUT TO SEA. THIS TREND HAS BEEN THE CASE
IN SEVERAL RUNS LEADING UP TO THIS SOLUTION. THUS WILL KEEP THE
MENTION OF SNOW IN THE HWO FOR TUCKER AND PRESTON COUNTIES. THE
REST OF THE FORECAST AREA SHOULD REMAIN FREE FROM ACCUMULATING
SNOWFALL FOR WEDNESDAY AND WEDNESDAY EVENING. IN FACT, THERE IS
ONLY A 10% TO 20% PROBABILITY OF 1 INCH OF SNOW IN TUCKER
COUNTY.
NOW ONTO THE POST FRONTAL UPPER TROUGH ON THURSDAY. WHILE THE
SURFACE LOW SHIFTS TOWARD THE ATLANTIC COAST, THE UPPER TROUGH
AXIS AND ITS CLOSED LOW CENTER WILL CROSS THE OHIO RIVER VALLEY
LATE WEDNESDAY NIGHT INTO THURSDAY. WEAK MID- LEVEL MOISTENING
COMBINED WITH JET ENHANCED LIFT IS EXPECTED TO PROMOTE MORE
WIDESPREAD SNOW MAINLY DURING THE MORNING TO EARLY AFTERNOON
THURSDAY. WEAKER FORCING AND MOISTURE PROFILES ARE LIKELY TO
KEEP SNOWFALL RATES BELOW 0.5"/HR DURING THIS PERIOD WITH THE
HIGHEST ACCUMULATION TOTALS LIKELY FOCUSED OVER THE HIGHER
TERRAIN DUE TO SOME UPSLOPE WIND COMPONENT.
NORTHWEST FLOW AND SOME COOLING AT 850MB AS THE UPPER LOW EXITS
EAST THURSDAY NIGHT SHOULD TRANSITION THE AREA FROM WIDESPREAD
LIGHT SNOW TO LOCALIZED LAKE ENHANCED SNOW BANDS. IT REMAINS
TOO EARLY TO IDENTIFY FAVORED CORRIDORS FOR THESE BANDS AND THE
POTENTIAL SNOWFALL ACCUMULATION RATES AS HI-RES MODELING DOESN'T
EXTRAPOLATE THAT FAR OUT. THAT SAID, THE NBM PROBABILITIES
SUGGEST THAT 20% TO 30% POTENTIAL FOR 1 INCH OR MORE AND THUS
THE ENSEMBLES ARE NOT HANDLING THE UPSLOPE/LAKE ENHANCEMENT OF
THE TROUGH VERY WELL. WILL NEED TO MONITOR AND ADDRESS THE
POTENTIAL WHEN THE HI-RES MODELS COVER THE CONCERNING PERIOD.
LONG TERM /FRIDAY THROUGH TUESDAY/
KEY MESSAGES:
- HIGH PROBABILITY IN RIDGING AND TEMPERATURE MODERATION
THROUGH THE WEEKEND.
- PRECIPITATION CHANCES TETHERED TO SHORTWAVE MOVEMENT WITHIN
THE BROADER NW FLOW PATTERN.
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THOUGH LINGERING LIGHT LAKE ENHANCED SNOW SHOWERS ARE POSSIBLE
TO START THE DAY FRIDAY, THERE IS HIGH CONFIDENCE THAT HEIGHT
RISES ALOFT AND HIGH PRESSURE DEVELOPMENT OF THE OHIO RIVER
VALLEY WILL LEAD TO DRY CONDITIONS FRIDAY INTO SATURDAY AND MOST
OF SUNDAY. THOUGH FLOW ALOFT IS LIKELY TO REMAIN NW, SOUTHWEST
RETURN FLOW AT THE SURFACE WILL RESULT IN RISING TEMPERATURE
EACH DAY WHERE SATURDAY'S HIGHS WILL ONLY FALL AROUND 5 DEGREES
BELOW THE DAILY AVERAGE.
THE LONG TERM WEATHER PATTERN SUGGESTS PERIODIC SHORTWAVE
MOVEMENT WITHIN THE BROADER NORTHWEST FLOW ACROSS THE EASTERN
CONUS MONDAY INTO TUESDAY NEXT WEEK. DEPTH AND POSITIONING OF
THE WAVE WILL DICTATE FAVORED (AND DRY) REGIONS, BUT THE
CONTINENTAL CANADA ORIGINS WOULD SUGGEST ANY SYSTEM WILL BE
FAIRLY LIGHT ON TOTAL MOISTURE CONTENT. AND EARLY MODEL MEANS
SUGGESTS SURFACE FLOW WILL MAINTAIN SOME SOUTHERLY COMPONENT TO
KEEP AREA TEMPERATURE NEAR TO SLIGHTLY BELOW AVERAGE. ANY
PRECIPITATION THAT DEVELOPS WOULD THEN BE EITHER RAIN OR SNOW
(DEPENDING ON TIME OF DAY/LOCATION) WITH ANY SNOWFALL
ACCUMULATIONS BEING LIGHT DUE TO REDUCED EFFICIENCY AND LESS
THAN IDEAL THERMAL PROFILES.
AVIATION /20Z TUESDAY THROUGH SUNDAY/
A SCT TO BKN STRATOCU FIELD HAS DEVELOPED THIS AFTERNOON WITH
BOUNDARY LAYER MIXING UP TO THE BASE OF AN INVERSION SITTING
AROUND 3.5KFT. FORECAST SOUNDINGS DON'T WIGGLE THE INVERSION
MUCH, SO EXPECT THAT THE LOW-END MVFR DECK WILL CONTINUE INTO
THIS EVENING, WITH PERHAPS A BRIEF DIP TO 3KFT CIGS, UNTIL
MIXING CEASES. IN THE WAKE OF THE STRATOCU DECK, INCREASING
MID-LEVEL CLOUD COVERAGE WILL STREAM IN AND GRADUALLY LOWER FROM
THE WEST AS MOISTURE WORKS IN AHEAD OF APPROACHING LOW
PRESSURE.
PERIODIC GUSTS TO 20-25 KNOTS HAVE BEEN OBSERVED THUS FAR TODAY
AND WILL LIKELY CONTINUE THROUGH THE DAYTIME HOURS WITH MIXING,
THOUGH IT MAY MANIFEST AS MORE OF A 10-13 KT SUSTAINED WIND AS
OPPOSED TO A GUSTY WIND. EITHER WAY, CALMER CONDITIONS ARE
EXPECTED OVERNIGHT SETTLING TO 5-8 KNOTS WITH DIRECTION
GRADUALLY VEERING TO THE NORTH-NORTHWEST.
AFOREMENTIONED LOW PRESSURE WILL PASS TO OUR SOUTH ON WEDNESDAY
AND PROVIDE A <20% CHANCE OF MEASURABLE PRECIP THROUGH 00Z
THURSDAY; UNFAVORABLE UPPER JET STREAK DYNAMICS, DISPLACED
FORCING, AND LACK OF LOW-LEVEL MOISTURE POINTS TOWARD A PRECIP
FREE DAY, THOUGH IF ANY WAS TO OCCUR, IT WOULD BE AT MGW IN
CLOSEST PROXIMITY TO THE LOW AND PRECIP SHIELD. OTHERWISE, MVFR
PROBS INCREASE TOWARD THE END OF THE CURRENT TAF PERIOD AS
WRAPAROUND MOISTURE ON THE BACKSIDE OF THE DEPARTING LOW
PRESSURE SYSTEM INTRODUCES WIDESPREAD LIGHT SNOW LATE WEDNESDAY
NIGHT INTO THURSDAY.
OUTLOOK...
DRIER WEATHER WITH GENERALLY LIGHT WIND IS FAVORED TO RETURN TO
CLOSE OUT THE WEEK AND HEADED INTO THE WEEKEND UNDER BUILDING
HIGH PRESSURE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...SHALLENBERGER
NEAR TERM...SHALLENBERGER
SHORT TERM...FRAZIER/SHALLENBERGER
LONG TERM...FRAZIER
AVIATION...MLB
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