587  
FXUS61 KPBZ 212336  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
636 PM EST WED FEB 21 2018  
   
SYNOPSIS
 
 
PERIODIC RAIN CHANCES WILL CONTINUE THROUGH SUNDAY.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
A SURFACE COLD FRONT IS SHIFTING SOUTHEAST OF THE LAST VESTIGES  
OF THE CWA AT THE MOMENT WITH COLD ADVECTION WELL UNDERWAY  
WALL-TO-WALL. THIS HAS RESULTED IN TEMPERATURES RAPIDLY FALLING  
TOWARD THE 30S, HOWEVER A QUICK LOOK AT REGIONAL OBSERVATIONS  
REVEALS THAT THE FREEZING LINE IS STILL QUITE A DISTANCE  
UPSTREAM. THAT SAID, SOUTHWEST FLOW OFF THE DECK CONTINUES AND  
THUS MOISTURE WILL AGAIN RETURN INTO THE COLDER BOUNDARY LAYER  
AS IT GETS ESTABLISHED OVERNIGHT.  
 
WITH SOUTHWESTERLY FLOW OFF THE DECK AND A MODESTLY-CURVED UPPER  
JET STREAK ENTRANCE REGION SET TO TRAVERSE THE AREA TOWARD  
MORNING, PRECIPITATION SHOULD AGAIN BLOSSOM. PROBLEMS CONTINUE  
TO BE REVEALED, HOWEVER, IN TERMS OF PRECIPITATION TYPE. THE NAM  
CONTINUES TO BE FAR MORE AGGRESSIVE WITH COLD ADVECTION THAN  
THE GFS, WHICH YIELDS A MORE FROZEN/FREEZING PROFILE FOR  
PRECIPITATION ALONG THE I-80 CORRIDOR FROM THE NAM THAN THE GFS.  
FURTHER LOOKING AT THE HREF AND A HANDFUL OF OTHER ENSEMBLE  
GUIDANCE, IT DOES SUGGEST THAT A WINDOW OF FREEZING  
PRECIPITATION IS PLAUSIBLE IN THE CORRIDOR WHERE THE WINTER  
WEATHER ADVISORY WAS PREVIOUSLY ISSUED. WHILE ALL THE CAVEATS OF  
WARM GROUND (FROM RECENT RECORD WARMTH) REMAIN, A FEW AREAS IN  
THE FAR NORTH MAY END UP WITH SOME ICE ON POWER LINES OR TREES  
(PROBABLY NOT MUCH IN THE WAY OF TRANSPORTATION IMPACTS,  
HOWEVER), SO THE ADVISORY WILL REMAIN IN PLACE.  
 
EVERYWHERE WARMS UP EFFICIENTLY ABOVE FREEZING ON THURSDAY AS  
RAINFALL CONTINUES WITH THE WAVE MOVING EAST. THUS, ALL  
FREEZING RAIN/SNOW POTENTIAL SHOULD BE OVER EARLY IN THE DAY.  
FRIES  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/
 
 
AFTER A BRIEF DRY SPELL THURSDAY EVENING, RAIN WILL MOVE BACK IN  
FROM THE WEST WITH A WARM FRONT APPROACHING THE REGION. THIS  
WILL KEEP RAIN IN THE FORECAST THROUGH THE WEEKEND. THERE COULD  
BE HYDROLOGIC CONCERNS THROUGH THE WEEKEND WITH THE AMOUNT OF  
RAIN IN THE FORECAST, BUT WITH THE HEAVIER RAINFALL NOT EXPECTED  
TO MOVE INTO THE REGION UNTIL AT LEAST FRIDAY, FELT IT WAS  
STILL A TOUCH EARLY TO NAIL DOWN A PARTICULAR LOCATION TO PUT IN  
AN AREAL FLOOD WATCH. HIGHS WILL BE IN THE 50S AND 60S, WELL  
ABOVE NORMAL.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
LOW PRESSURE WILL MOVE ACROSS THE WESTERN GREAT LAKES SATURDAY  
NIGHT INTO SUNDAY AND SWEEP A COLD FRONT ACROSS THE OHIO VALLEY,  
PROVIDING SOME DEFINITIVE CLEARING FOR THE LOCAL AREA. THIS  
SHOULD ALLOW FOR A DRY FORECAST FROM SUNDAY NIGHT THROUGH  
WEDNESDAY. ONE MORE DAY OF TEMPERATURES IN THE 60S CAN BE  
EXPECTED ON SUNDAY, BEFORE TEMPERATURES FALL TO SLIGHTLY ABOVE  
NORMAL VALUES FOR THE START OF THE NEXT WORK WEEK.  
 

 
   
AVIATION /00Z THURSDAY THROUGH MONDAY/
 
 
A BRIEF IMPROVEMENT TO VFR IS EXPECTED FOR MOST PORTS THIS  
EVENING BEFORE LOW PRESSURE TRACKS ACROSS THE TN AND OH VALLEY  
REGIONS OVERNIGHT AND THU. RAIN AND DETERIORATION TO MVFR AND  
EVENTUAL IFR IS EXPECTED. SFC TEMPERATURES ARE EXPECTED TO DROP  
BELOW FREEZING N OF I 80, WHERE FREEZING RAIN IS EXPECTED. FZRA  
SHOULD CHANGE BACK TO RAIN WITH WARMING TEMPERATURES BY THU  
AFTN.  
 
THE RAIN SHOULD TAPER OFF FROM W-E DURING THE AFTN, WITH SOME  
LIMITED IMPROVEMENT TO LOW MVFR POSSIBLE LATE.  
 
OUTLOOK...  
PERIODIC RESTRICTIONS ARE EXPECTED THROUGH SUNDAY WITH A SERIES  
OF CROSSING LOW PRESSURE AREAS.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
MD...NONE.  
OH...NONE.  
PA...WINTER WEATHER ADVISORY FROM 1 AM TO 1 PM EST THURSDAY FOR  
PAZ007>009-013>016.  
WV...NONE.  
 

 
 

 
 
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