679  
FXUS61 KPBZ 240104 AAB  
AFDPBZ  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
904 PM EDT MON APR 23 2018  
   
SYNOPSIS
 
 
SLOW- MOVING LOW PRESSURE WILL RETURN RAIN CHANCES LATE TONIGHT  
THROUGH MID-WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM TUESDAY MORNING/
 
 
SHOWERS SPREADING NORTH AND EAST AHEAD OF A SURFACE LOW ARE  
FINDING IT DIFFICULT TO REACH THE GROUND, AS A VERY DRY  
ATMOSPHERE IS IN PLACE ACROSS THE REGION. 00Z PIT SOUNDING SHOWS  
A VERY DRY ATMOSPHERE BELOW 700MB, WITH ONLY SOME MODEST  
INCREASE IN MOISTURE ABOVE 700MB UP TO 500MB. WOULD THINK THAT  
SHOWERS THAT SWING THROUGH THE AREA TONIGHT WOULD USE MOST OF  
THEIR AVAILABLE MOISTURE TO SLOWLY SATURATE THE LAYERS BELOW  
500MB. HAVE KEPT POPS MAINLY IN THE CHC CATEGORY OVERNIGHT.  
 

 
   
SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/
 
 
BETTER RAIN CHANCES ARE EXPECTED TUE WITH INCREASING DEEP-  
LAYER MOISTURE AND DYNAMIC SUPPORT AS THE CLOSED UPPER LOW  
DRIFTS NEWD, DESPITE DOWNSLOPING, SHALLOW SELY LOW-LEVEL FLOW.  
 
THE SELY WIND IS EXPECTED TO BECOME GUSTY ON THE LEE SIDE OF THE  
RIDGES, THOUGH MODEL SOUNDING PROGS INDICATE THE STRONGEST  
WINDS CAPPED ABOVE AN INVERSION WITH GUSTS OF 20-30 KT EXPECTED.  
 
ALTHOUGH THE CLOSED LOW WILL DECAY INTO AN OPEN WAVE, NEW MODELS  
SUGGEST THAT THE WAVE MAY NOT PHASE AS EFFECTIVELY AS PREVIOUSLY  
THOUGHT WITH AN APPROACHING NRN-STREAM WAVE. AS A RESULT, THERE  
MAY COME A PRECIPITATION GAP IN WRN PA TUE NIGHT BEFORE GREATER  
COVERAGE RETURNS WITH THE ARRIVAL OF THE NRN WAVE ON WED.  
 
BY WED AFTERNOON, MOISTURE WILL BE SHUNTED EWD, WITH ANY RAIN  
SHOWERS QUICKLY SHIFTING TO THE RIDGES AND NRN LAKE-ENHANCEMENT  
ZONES. LOWERING INVERSION HEIGHTS AND ERODING MOISTURE SHOULD  
LEAD TO A RAPID DECREASE IN PRECIPITATION.  
 

 
   
LONG TERM /THURSDAY THROUGH MONDAY/
 
 
THE LAST IN A SERIES OF SHORTWAVE TROUGHS WILL IMPACT THE REGION  
ON FRI AS IT DRIVES A COLD FRONT ACROSS THE GREAT LAKES.  
INCREASING RAIN CHANCES CAN BE EXPECTED TO END THE WORK WEEK,  
BUT THE TRACK OF THE WAVE MAY PRECLUDE A WIDESPREAD WET DAY.  
 
THEREAFTER, AN OVERALL PATTERN SHIFT APPEARS TO BE IN THE  
OFFING, WITH A STRONG WRN-CONUS TROUGH AND AMPLIFYING ERN-CONUS  
RIDGE. THIS PATTERN OF RISING HEIGHTS AND A STRENGTHENING UPPER  
RIDGE SPELLS A GENERAL WARMING TREND FOR THE REGION, WITH DRY  
WX AND A RETURN TO SEASONAL TEMPERATURE OVER THE WEEKEND.  
 

 
   
AVIATION /01Z TUESDAY THROUGH SATURDAY/
 
 
VFR CONDITIONS ARE EXPECTED TO CONTINUE AT MOST PORTS THROUGH  
THE NIGHT. CLOUDS WILL THICKEN AND LOWER FROM THE WEST LATE  
TONIGHT, WITH ZZV EXPECTED TO LOWER TO MVFR AFTER 06Z. NON-  
RESTRICTIVE LIGHT RAIN WILL ARRIVE OVERNIGHT, WITH ITS  
INTENSITY HINDERED AS IT ENCOUNTERS A VERY DRY ATMOSPHERE.  
WIDESPREAD MVFR CIG AND VIS IS EXPECTED AFTER DAWN ON TUESDAY.  
WINDS WILL INCREASE ONCE AGAIN ON TUESDAY, WITH GUSTS OF 20 TO  
30 KNOTS EXPECTED AREAWIDE BY LATE MORNING AND THROUGH THE  
AFTERNOON.  
 
OUTLOOK...  
MVFR/IFR CONDITIONS ARE LIKELY TUESDAY THROUGH WEDNESDAY FOR  
ALL SITES WITH SLOW MOVING LOW PRESSURE.  
 

 
   
PBZ WATCHES/WARNINGS/ADVISORIES
 
 
MD...NONE.  
OH...NONE.  
PA...NONE.  
WV...NONE.  
 

 
 

 
 
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