715  
FXUS61 KPBZ 190109  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
909 PM EDT THU SEP 18 2025  
   
SYNOPSIS  
 
HIGH PRESSURE WILL MAINTAIN WARM AND MOSTLY-DRY WEATHER INTO  
THE WEEKEND. RAIN CHANCES RETURN TO THE FORECAST NEXT WEEK,  
THOUGH THE CHANCE FOR WIDESPREAD WETTING RAIN REMAINS LOW.  
 
 
   
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/  
 
KEY MESSAGES:  
 
- DRY WEATHER CONTINUES  
- VALLEY FOG IS POSSIBLE TONIGHT  
---------------------------------------------------------------  
 
HIGH PRESSURE WILL CONTINUE TO MAINTAIN DRY WEATHER TONIGHT.  
SOME LIMITED INCREASE IN CLOUD COVER IS POSSIBLE TOWARD DAYBREAK  
AHEAD OF AN APPROACHING, WEAKENING COLD FRONT. DRY AIR HAS MIXED  
DOWN THROUGH THE DAY, WITH MOST LOCATIONS REPORTING DEW POINTS  
IN THE 40S TO NEAR 50. THIS SHOULD PRECLUDE FOG FOR MOST  
LOCATIONS, THOUGH AS TEMPERATURES COOL, RIVER VALLEY STEAM FOG  
WILL BE POSSIBLE. OVERNIGHT LOWS ARE EXPECTED TO BE NEAR  
SEASONABLE LEVELS.  
 
 
   
SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/  
 
KEY MESSAGES:  
 
- DRY WEATHER CONTINUES TO END THE WORK WEEK  
- A WEAK FRONT BRINGS SLIGHTLY COOLER TEMPERATURES  
--------------------------------------------------------------  
 
THE SET UP ON FRIDAY WILL FEATURE HIGH PRESSURE STILL IN CONTROL  
WITHIN DEVELOPING NORTHWEST FLOW ACROSS THE AREA. FRIDAY NIGHT  
WILL FEATURE NORMAL OR JUST ABOVE NORMAL TEMPERATURES AGAIN WITH  
THE POTENTIAL OF FOG DEVELOPMENT, MAINLY IN THE RIVER VALLEYS.  
ENSEMBLES CONTINUE TO SHOW THE HIGH CENTER POSITIONED TO THE  
NORTH INTO THE GREAT LAKES SHIFTING SOUTHEAST INTO THE ENGLAND  
AREA. AS THIS HAPPENS, A WEAK SHORTWAVE WILL DROP INTO THE UPPER  
OH VALLEY. THIS WILL BRING SOME MOISTURE TO THE REGION ALONG  
WITH A WEAK CHANCE OF PRECIP OVER THE NORTHERN WV COUNTIES. THE  
NBM IS ADVERTISING A 20% TO 40% PROBABILITY OF 0.01 OR MORE WITH  
THIS WEAK TROUGH ON SATURDAY.  
 
 
   
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/  
 
KEY MESSAGES:  
 
- STILL MOSTLY DRY AND WARMER THAN NORMAL THROUGH THE WEEKEND  
- SLIGHT UPTICK IN RAIN CHANCES NEXT WEEK  
- TEMPERATURES REMAIN ABOVE NORMAL MONDAY THROUGH WEDNESDAY,  
ALBEIT WITH A SLIGHT DOWNWARD TREND  
------------------------------------------------------------------  
 
THE MENTIONED TROUGH FURTHER INFILTRATES THE REGION BY SATURDAY  
NIGHT INTO SUNDAY AS ADDITIONAL MOISTURE ARRIVES INTO THE  
REGION. WITH A WEAK BOUNDARY IN PLACE, THE WINDS BEGIN TO SHIFT  
TO A MORE SOUTHERN FLOW. THIS WILL ENSURE A BETTER CHANCE OF  
MEASURABLE PRECIPITATION. THUS, THE NBM COMES UP WITH 40% TO 60%  
PROBS OF 0.01 OR MORE FOR SATURDAY NIGHT INTO SUNDAY. SUNDAY  
MORNING WILL ALSO STAND THE CHANCE FOR SOME VALLEY FOG  
DEVELOPING, ESPECIALLY IN RIVER VALLEYS.  
 
ENSEMBLES/CLUSTER ANALYSIS CONTINUE TO SHOW A SLOWER TREND WITH  
THE PROGRESS OF THE NEXT UPSTREAM TROUGH, WITH THE AXIS  
PROGRESSING FROM THE UPPER MISSISSIPPI VALLEY TO JUST THE  
WESTERN/CENTRAL GREAT LAKES BY TUESDAY. SOME SOLUTIONS EVEN  
SUGGEST THE DEVELOPMENT OF A CUTOFF UPPER LOW SOMEWHERE OVER THE  
EASTERN PLAINS. THIS TREND, IN TURN, RESULTS IN JUST A SLOW  
INCREASE TO MINIMAL POPS, WITH SLIGHT CHANCE VALUES NORTHWEST OF  
PITTSBURGH SUNDAY NIGHT/MONDAY, BEFORE EVENTUALLY OVERSPREADING  
THE AREA TUESDAY/WEDNESDAY. QPF EXPECTATIONS ARE NOT HIGH. THE  
NBM SHOWS A 40-60 PERCENT CHANCE OF 0.10" OR MORE DURING THE  
72-HOUR PERIOD ENDING AT 12Z THURSDAY. WITH INCREASING RAINFALL  
DEFICITS, WE WILL NEED HEALTHIER PRECIPITATION TOTALS TO PUT A  
BETTER DENT IN THE DEVELOPING DROUGHT.  
 
OVERALL, ABOVE-NORMAL TEMPERATURES CONTINUE TO BE THE  
EXPECTATION THROUGH THE MIDDLE OF NEXT WEEK. STILL, WITH THE  
SLOWLY FALLING HEIGHTS AND INCREASING CLOUD COVER POTENTIAL, A  
MODEST DOWNWARD TREND IS THE MOST LIKELY SCENARIO. THE 25TH-75TH  
PERCENTILE SPREADS DO INCREASE THROUGH THIS PERIOD, INDICATING  
INCREASING UNCERTAINTY IN THE ULTIMATE VALUES. THIS IS  
REASONABLE GIVEN THE RANGE OF POTENTIAL SOLUTIONS REGARDING THE  
SPEED/POSITIONING OF THE UPSTREAM TROUGH.  
 
 
   
AVIATION /01Z FRIDAY THROUGH TUESDAY/  
 
VFR CONTINUES TO BE FAVORED FOR THE MOST PART THROUGH TOMORROW  
MORNING, WITH FEW TO NO CLOUDS AS WELL AS LIGHT AND VARIABLE WIND.  
WARMER OVERNIGHT LOWS WILL LIKELY REDUCE VALLEY FOG DEVELOPMENT  
COMPARED TO THIS MORNING.  
 
A WEAK FRONTAL BOUNDARY SETTLES INTO WESTERN PA BY 12Z FRIDAY. WHILE  
NO NOTABLE PRECIPITATION IS EXPECTED WITH THE BOUNDARY, ENOUGH LOW-  
LEVEL MOISTURE WILL ACCOMPANY IT TO PRODUCE A STRATOCUMULUS LAYER AT  
FKL/DUJ. THERE IS HIGH CONFIDENCE THAT CLOUD HEIGHTS WILL BE AROUND  
2000 FEET, HOWEVER THERE IS ONLY MODERATE CONFIDENCE THAT SKIES WILL  
BE BROKEN AT THESE TWO SITES. THE BOUNDARY WILL ALSO VEER LIGHT WIND  
SLIGHTLY TO THE NORTH.  
   
OUTLOOK.  
 
VFR IS FAVORED THROUGH SATURDAY WITH CONTINUED HIGH PRESSURE.  
THE APPROACH OF AN UPPER-LEVEL TROUGH MAY FOSTER LOW-PROBABILITY  
RAIN/SPRINKLES SUNDAY AND MONDAY, FAVORING LOCATIONS NORTHWEST OF  
PITTSBURGH. THOSE THAT OBSERVE ANY PRECIPITATION COULD SEE MVFR  
CEILINGS, BUT VFR IS LIKELY TO PERSIST ACROSS MOST OF THE AREA.  
 
 
   
PBZ WATCHES/WARNINGS/ADVISORIES  
 
PA...NONE.  
OH...NONE.  
WV...NONE.  
 
 
 
 
 
SYNOPSIS...SHALLENBERGER  
NEAR TERM...WM  
SHORT TERM...SHALLENBERGER  
LONG TERM...CERMAK/SHALLENBERGER  
AVIATION...CL/LUPO  
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