645
FXUS61 KPBZ 231205
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
705 AM EST THU JAN 23 2025
SYNOPSIS
BELOW NORMAL TEMPERATURES WILL CONTINUE THE REMAINDER OF THE WEEK
WITH A SLIGHT CHANCE OF LIGHT SNOW SHOWERS LATER THIS AFTERNOON
AND INTO THE EVENING. TEMPERATURES WILL MODERATE SOME FOR THE
WEEKEND BUT STILL REMAIN BELOW NORMAL.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:
- TEMPERATURES WILL BEGIN TO MODERATE TODAY.
- SLIGHT CHANCE OF LIGHT SNOW LATER THIS AFTERNOON WITH MINIMAL
ACCUMULATION EXPECTED OVERALL.
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PASSING MID CLOUD COVERAGE HAS HELPED KEEP OVERNIGHT LOWS FROM
DROPPING NEARLY AS MUCH AS OBSERVED LAST NIGHT, WITH CURRENT
OBSERVATIONS LARGELY IN THE TEENS. TEMPERATURES SHOULD DROP
ANOTHER COUPLE DEGREES BEFORE RECOVERY BEGINS AFTER DAYBREAK.
WIND CHILL VALUES IN THE HIGHER ELEVATIONS WILL STILL LIKELY
LIKELY DROP BELOW -10F, SO THE COLD WEATHER ADVISORY FOR EASTERN
TUCKER COUNTY REMAINS IN EFFECT UNTIL 10 AM THIS MORNING. LIGHT
SNOW CHANCES WILL INCREASE FROM WEST TO EAST THIS AFTERNOON
AHEAD OF AN APPROACHING SHORTWAVE, BUT ANY ACCUMULATION WILL BE
RELATIVELY LIGHT.
SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- LIGHT SNOW POSSIBLE DURING THE EVENING WITH MINIMAL
ACCUMULATION.
- MOSTLY DRY FRIDAY WITH SLIGHTLY COLDER TEMPERATURES.
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THE BEST CHANCE FOR SNOW SHOWERS WILL COME THIS EVENING AND
INTO THE OVERNIGHT HOURS WITH INCREASED BL MOISTURE AND TROUGH
PASSAGE, BUT EVEN THEN, HREF HOURLY PROBABILITIES ARE 20% OR
LESS FOR ANYTHING MEASURABLE, LARGELY NORTH OF PGH OR IN THE
HIGHER ELEVATIONS. OROGRAPHIC ASCENT WILL ENHANCE LIFT IN THE
RIDGES, BUT MOISTURE IS MARGINAL AT BEST.
SNOW CHANCES TAPER OFF ON FRIDAY AS SURFACE RIDGING RE-
ESTABLISHES FROM THE SOUTHWEST AND WE'RE SANDWICHED BETWEEN TWO
MID-LEVEL WAVES. HIGHS WILL TAKE A HIT BACK DOWN A FEW DEGREES
AS SOME COLDER AIR WORKS IN IN WEST-NORTHWEST FLOW. A SHALLOW,
NEAR DRY-ADIABATIC LAYER WITH COLD ADVECTION AT THE 850 MB LEVEL
WILL STEEPEN LAPSE RATES AND TAP INTO ELEVATED FLOW ALOFT.
MOMENTUM TRANSFER ISN'T ALL THAT IMPRESSIVE WITH ONLY 15-20 KNOT
FLOW, SO WIND MAY TAKE ON MORE OF A 5-10 MPH SUSTAINED NATURE
WITH SPORADIC GUSTS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- BELOW AVERAGE TEMPS ARE EXPECTED TO LINGER THROUGH EARLY NEXT
WEEK.
- ROUNDS OF WEAK DISTURBANCES WILL PRODUCE SCATTERED SNOW
CHANCES.
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A LEAD SHORTWAVE WILL SLIDE THROUGH ZONAL FLOW LOCALLY ON SATURDAY
WITH RELATIVELY GOOD AGREEMENT AMONG THE ENSEMBLES. SURFACE HIGH
PRESSURE PROGGED ACROSS THE CAROLINAS IS FAVORED TO KEEP US DRY,
THOUGH CAN'T ENTIRELY RULE OUT VERY LOW-END SNOW SHOWER CHANCES
CONFINED NORTH OF I-80 IN THE EVENING AS A WARM FRONT LIFTS THROUGH.
THE BETTER CHANCE, ALBEIT WITH LOW ACCUMULATION POTENTIAL, WILL COME
ON SUNDAY. ENSEMBLES BRING A SECOND WAVE WITH MINOR DISAGREEMENT ON
ITS DEPTH, AS SURFACE LOW PRESSURE DRAGS A COLD FRONT THROUGH. ONE
ENSEMBLE CLUSTER WITH A DEEPER SHORTWAVE SUGGESTS SLIGHTLY HIGHER
PROBABILITY OF >0.5" EXTENDING DOWN OFF OF THE LAKE, BUT EVEN IN
THIS SCENARIO, THE CHANCE OF REACHING 1" IS LESS THAN 20%. THE
PRIMARY ISSUE LOOKS TO BE AVAILABLE MOISTURE AS THE LACK OF
AMPLIFICATION WITH WESTERLY MID-LEVEL FLOW ISN'T PULLING FROM A
GREAT MOISTURE SOURCE REGION.
WEEKEND TEMPERATURES WILL MODERATE IN COMPARISON TO THE PAST
WEEK, BUT CONTINUE TO REMAIN BELOW AVERAGE WITH AFTERNOON HIGHS
IN THE UPPER 20S/LOW 30S AND OVERNIGHT LOWS IN THE LOW 20S
THROUGH SUNDAY. PROBABILITIES TO ECLIPSE THE FREEZING MARK FOR
HIGHS ARE BETTER ON SUNDAY EXTENDING A 50-70% CHANCE AS FAR
NORTH AS PITTSBURGH.
ENSEMBLES EJECT YET ANOTHER SHORTWAVE ON MONDAY THROUGH THE STILL
ESTABLISHED WESTERLY ZONAL FLOW. NOTED DISAGREEMENT COMES INTO PLAY
AT THIS POINT WITH THE PROGRESSION OF THE UPPER LEVELS AS SOME
CLUSTERS EXHIBIT A POTENTIALLY PHASED SOLUTION WITH A SOUTHERN
STREAM AND NORTHERN STREAM SHORTWAVE. OTHERS KEEP THEM UNPHASED AND
WEAKER WITH QUICK PROGRESSION THROUGH THE AREA. MOST OF THE GUIDANCE
IS NOT BULLISH ON MUCH WITH THIS DISTURBANCE EITHER AS WE AGAIN LACK
SUFFICIENT DEEP LAYER MOISTURE. THE MEAN QPF FROM 3/4 CLUSTERS
THROUGH MONDAY NIGHT IS GENERALLY <0.10" AREAWIDE, WITH THE 90TH
PERCENTILE AS HIGH AS 0.15", WHICH WOULD SUGGEST LOW-END SNOW
ACCUMULATION POTENTIAL. THE OUTLIER AT THIS POINT IS ONE CLUSTER
THAT SUGGESTS A MUCH DEEPER, PHASED, AND SLOWER TROUGH. THIS
SOLUTION POINTS TOWARD MORE QPF AND MORE REPRESENTATIVE OF THE
CURRENT NBM 90TH PERCENTILE SUGGESTING 1-2 INCHES OR SO IN THE
RIDGES. OVERALL CONFIDENCE IS LOW, BUT THE TREND POINTS TOWARD
A LESSER IMPACT EVENT.
AVIATION /12Z THURSDAY THROUGH MONDAY/
VFR IS EXPECTED THROUGH THIS AFTERNOON/EVENING, THOUGH STRATOCU
CIGS WILL OVERSPREAD THE AREA AHEAD OF AN APPROACHING COLD
FRONT. WIND WILL ALSO INCREASE THROUGH THE DAY WITH A TIGHTENING
PRESSURE GRADIENT AHEAD OF THE FRONT, WITH GUSTS AROUND 20KT
FROM THE SW BY THIS AFTERNOON.
THE FRONT WILL CROSS THE REGION LATE THIS AFTERNOON AND
EVENING, WITH MVFR CIGS. MOISTURE IS LIMITED WITH THE FRONT,
THOUGH ENOUGH SATURATION IN THE DENDRITIC ZONE COULD RESULT IN
SCATTERED SNOW SHOWERS. INCLUDED A PROB30 MENTION OF SNOW
SHOWERS IN THE TAFS AS THE FRONT CROSSES. MVFR CIGS ARE EXPECTED
TO CONTINUE TONIGHT AFTER FROPA.
OUTLOOK...
MVFR CIGS ARE LIKELY TO CONTINUE THROUGH FRIDAY UNDER COLD NW
FLOW AND A CROSSING UPPER TROUGH. VFR RETURNS LATE FRIDAY
THROUGH EARLY SATURDAY UNDER HIGH PRESSURE. RESTRICTIONS AND
SNOW SHOWERS ARE THEN POSSIBLE THROUGH SUNDAY WITH A CROSSING
COLD FRONT. VFR RETURNS MONDAY UNDER HIGH PRESSURE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ514.
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...MLB/88
AVIATION...WM/SHALLENBERGER
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