575
FXUS61 KPBZ 181741
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1241 PM EST TUE FEB 18 2025
SYNOPSIS
DRY AND SEASONABLY COOL CONDITIONS ARE EXPECTED THROUGH THE
MAJORITY OF WEDNESDAY, SAVE FOR LIGHT SNOW IN THE WEST VIRGINIA
HIGHER TERRAIN. WIDESPREAD SNOW SHOWERS RETURN THURSDAY MORNING
WITH LAKE ENHANCED BANDS POSSIBLE THROUGH FRIDAY MORNING.
MODERATING TEMPERATURE WITH LOW PROBABILITY PRECIPITATION
CHANCES ARE CURRENTLY FAVORED HEADING INTO NEXT WEEKEND.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- A COLD WEATHER ADVISORY MAY BE NEEDED TONIGHT FOR LOW WIND
CHILL VALUES.
- SEASONABLY COOL TEMPERATURE REMAINS DESPITE INCREASING
AFTERNOON SUNSHINE.
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WITH MAINLY MOSTLY SUNNY SKIES IN PLACE NOW, TEMPERATURES AND
APPARENT TEMPERATURES HAVE INCREASED TO ABOVE CRITERIA AND THUS
THE COLD WEATHER ADVISORY HAS BEEN EXPIRED. WITH THE EXCEPTIONS
OF A FEW FLURRIES FLYING IN THE NORTHWEST POTION OF THE AREA,
THE FORECAST REMAINS DRY AND ON TRACK.
DRY CONDITIONS ARE EXPECTED THE REST OF THE DAY UNDER THE
INFLUENCE OF HIGH PRESSURE TO THE WEST AND ZONAL FLOW ALOFT. THE
BIGGEST UNCERTAINTY IS THE DEGREE OF CLOUDINESS THROUGH THE
MORNING HOURS DUE TO UPPER LEVEL JET POSITIONING; EITHER WAY IT
LANDS, AFTERNOON READINGS WILL UPWARDS OF 20 DEGREES BELOW THE
DAILY AVERAGE WITH WIND CHILL VALUES STRUGGLE TO REACH THE
TEENS. 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. A COLD ADVISORY MAY BE NEEDED TONIGHT BUT FINED
TUNING THE CLOUD COVER ARRIVAL WILL BE NEEDED. LIGHTER WIND IS
EXPECTED TO KEEP WIND CHILL CONCERNS LOW.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
KEY MESSAGES:
- LOW PROBABILITY SNOW CHANCES WITH LIMITED 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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ENSEMBLE MODEL TRENDS REMAIN STEADFAST IN KEEPING A LOW PRESSURE
SYSTEM MAINLY SOUTH OF THE REGION WEDNESDAY AS IT SHIFTS FROM
THE CENTRAL PLAINS THROUGH THE TENNESSEE RIVER VALLEY. THOUGH
THE NORTHERN EDGE OF THE SYSTEM MAY BE ABLE TO SQUEEZE SOME
LIGHT SNOW/FLURRIES ALONG AND SOUTH OF THE MASON-DIXON LINE AND
OVER THE WV HIGHER TERRAIN DURING DAYLIGHT HOURS, THE
PROBABILITY OF SEEING MORE THAN 1" OF SNOW ACCUMULATION REMAINS
LESS THAN 30%. THE MAIN IMPACT FROM THIS SYSTEM WILL BE
INCREASED CLOUDINESS THAT LIMITS DIURNAL HEATING THAT KEEPS AREA
TEMPERATURE AROUND 20 DEGREES BELOW THE DAILY AVERAGE.
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, CURRENT FORECAST TRENDED
TOWARD 95TH PERCENTILE EVENT TOTALS (WEDNESDAY NIGHT THROUGH
EARLY FRIDAY MORNING) TO ACCOUNT FOR STRUGGLES GLOBAL MODELS
HAVE WITH LAKE EFFECT PATTERNS. THESE STILL FALL SHORT OF
ADVISORY CRITERIA, BUT FURTHER ANALYSIS WILL NEED TO BE DONE FOR
POTENTIAL IMPACTS OF SNOW BANDS AND THEIR RATES OVER THE NEXT
24-48 HOURS.
LONG TERM /FRIDAY THROUGH TUESDAY/
KEY MESSAGES:
- HIGH PROBABILITY IN 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. 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 SUNDAY INTO 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 /18Z 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...FRAZIER
NEAR TERM...FRAZIER/SHALLENBERGER
SHORT TERM...FRAZIER
LONG TERM...FRAZIER
AVIATION...MLB
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