944  
FXUS61 KPBZ 222323 AAA  
AFDPBZ  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
623 PM EST WED JAN 22 2025  
   
SYNOPSIS
 
 
WIND CHILLS ON EITHER SIDE OF ZERO CONTINUE TONIGHT BUT ARE  
EXPECTED TO REMAIN ABOVE HEADLINE CRITERIA OUTSIDE OF EASTERN  
TUCKER COUNTY. DRY WEATHER OTHERWISE TODAY WITH LIGHT SNOW  
RETURNING THURSDAY NIGHT AND SOME MODIFICATION TO TEMPERATURES  
FOR THE WEEKEND AHEAD.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
KEY MESSAGES:  
 
- DRY WITH INCREASING MID/UPPER CLOUD COVERAGE.  
- COLD OVERNIGHT LOWS, BUT NOT AS COLD AS RECENT NIGHTS.  
-----------------------------------------------------------------  
 
ONLY MINOR CHANGES TO THE OVERNIGHT PERIOD...CLOUD COVER WAS  
ADJUSTED FOR A LITTLE MORE OF AN INCREASE THIS EVENING WITH AN  
AREA OF MID CLOUDS PASSING THROUGH WITH THE WARM AIR ADVECTION.  
THIS AREA SHOULD SHIFT NORTHWARD LATER TONIGHT ALLOWING SKIES TO  
CLEAR BEFORE SUNRISE. OVERNIGHT LOWS WERE UPDATED WITH THE  
LATEST BLENDED GUIDANCE.  
 
PREVIOUS DISCUSSION...  
 
HEADED INTO TONIGHT, LOW TEMPERATURES WILL BE SOME 15-20 DEGREES  
WARMER THAN WEDNESDAY NIGHT THANKS TO MODEST WARM ADVECTION AND  
INCREASED CLOUD COVER, THOUGH THAT STILL ONLY PUTS THE AREA  
INTO THE LOW TO MID SINGLE DIGITS WITH A <20% CHANCE OF  
REMAINING ABOVE 10 DEGREES. LIGHT SOUTHERLY WIND WILL DROP  
APPARENT TEMPERATURES INTO THE NEGATIVE SINGLE DIGITS AND ARE  
LIKELY TO REMAIN ABOVE HEADLINE CRITERIA, BUT IT WILL STILL BE  
QUITE COLD. THE EXCEPTION WILL BE EASTERN TUCKER COUNTY WHERE  
COLDER OVERNIGHT LOWS, MORE ELEVATED WIND, AND THE POTENTIAL FOR  
SOME PERIODS OF BREAKS IN THE CLOUDS WILL RESULT IN WIND CHILLS  
DIPPING BELOW -10F. THE BEST CHANCE FOR THIS WILL BE THE  
HIGHEST ELEVATIONS, AND FOR THAT REASON, HAVE ISSUED A NEW COLD  
WEATHER ADVISORY COVERING 7PM TONIGHT - 10AM THURSDAY.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/
 
 
KEY MESSAGES:  
 
- TEMPERATURES WILL BEGIN TO MODERATE THURSDAY.  
- LIGHT SNOW RETURNS THURSDAY EVENING WITH MINIMAL ACCUMULATION.  
- MOSTLY DRY FRIDAY WITH TEMPERATURES SLIGHTLY COLDER.  
--------------------------------------------------------------------  
 
THE AFOREMENTIONED SHORTWAVE WILL STRUGGLE TO BRING MUCH SNOW TO THE  
GROUND EARLY IN THE MORNING THURSDAY WITH DRY AIR TO OVERCOME.  
ENSEMBLE SOUNDINGS SHOW SOME MID-LEVEL MOISTURE ADVECTION, BUT STILL  
DRY LOW LEVELS FROM ~800 MB DOWN. FOR MOST, THE DAY WILL BE DRY AS  
ESTABLISHING SOUTHERLY FLOW MODIFIES THE AIRMASS WITH A 60+% CHANCE  
OF >25F FOR HIGHS EXTENDING UP TO PITTSBURGH. THE BEST CHANCE  
FOR SOME SNOW SHOWERS WILL COME LATER THURSDAY INTO THE  
OVERNIGHT HOURS WHEN BETTER MOISTURE WORKS IN AND A DECAYING  
BOUNDARY PASSES THROUGH. DISPLACEMENT OF UPPER SUPPORT MOVING  
THROUGH JUST AHEAD OF THE BOUNDARY WON'T HELP OUR SNOW CHANCES.  
THE NAM IS A BIT MORE AGGRESSIVE WITH SATURATION OCCURRING  
QUICKER AND SUGGESTS A COUPLE TENTHS OF AN INCH POSSIBLE, THOUGH  
THIS IS LIKELY MORE REPRESENTATIVE OF THE WORST CASE SCENARIO.  
AS A WHOLE, HREF PROBABILITY FOR A HALF AN INCH OF SNOW THROUGH  
THURSDAY NIGHT IS UP TO ~40% IN THE RIDGES WHERE OROGRAPHIC  
ASCENT MAY AID IN ENHANCED FORCING, THOUGH THE MOISTURE ISSUE  
STILL REMAINS. ELSEWHERE, CHANCES ARE LOW AND THE NATURE LIKELY  
REMAINS LIGHT AND SCATTERED.  
 
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.  
--------------------------------------------------------------------  
 
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 /00Z THURSDAY THROUGH MONDAY/
 
 
VFR CONTINUES THROUGH 12Z WITH HIGH CONFIDENCE. SOME INCREASES  
AND MID-TO-LOW CLOUD COVERAGE IS FORECAST INTO THE MORNING WITH  
WARM ADVECTION. OVERNIGHT, WINDS ARE EXPECTED TO REMAIN  
PREDOMINANTLY SOUTHERLY, VEERING SOUTHWESTERLY WITH DECOUPLING  
IN THE MORNING WITH SOME GUSTS POSSIBLE IN THE AFTERNOON.  
 
CEILINGS CONTINUE TO DROP IN A PASSING AFTERNOON WAVE, THOUGH  
PROBABILITIES OF MVFR DECLINE FROM WEST TO EAST: 70% FOR ZZV  
DOWN TO 40% FOR DUJ/LBE/MGW. ISOLATED SNOW SHOWERS ARE POSSIBLE,  
THOUGH WITH PROBABILITIES LESS THAN 20% FOR NOW, OPTED TO LEAVE  
OUT OF THE TAFS.  
 
OUTLOOK...  
PROBABILITIES OF MVFR ARE AT LEAST 30% OR GREATER THROUGH  
SATURDAY AFTERNOON.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
OH...NONE.  
WV...COLD WEATHER ADVISORY UNTIL 10 AM EST THURSDAY FOR WVZ514.  
 

 
 

 
 
SYNOPSIS...MLB  
NEAR TERM...22/MLB  
SHORT TERM...MLB  
LONG TERM...MLB  
AVIATION...MILCAREK  
 
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