574  
FXUS61 KPBZ 140533  
AFDPBZ  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PITTSBURGH PA  
133 AM EDT TUE AUG 14 2018  
   
SYNOPSIS
 
 
SCATTERED SHOWERS AND THUNDERSTORMS SHOULD PERSIST THROUGH  
TUESDAY UNDER UPPER LEVEL LOW PRESSURE. DRY WEATHER SHOULD  
BRIEFLY RETURN WEDNESDAY UNDER HIGH PRESSURE.  
 

 
   
NEAR TERM /UNTIL 6 AM THIS MORNING/
 
 
AREAS OF CLOUDS AND ISOLATED SHOWERS ARE EXPECTED TO CONTINUE TO  
ROTATE AROUND AN UPPER LOW CENTERED OVER CENTRAL PA. PATCHY FOG  
IS ALSO EXPECTED, ESPECIALLY WHERE TEMPORARY CLEARING OCCURS.  
LOWS ARE EXPECTED TO BE NEAR AVERAGE.  
 

 
   
SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/
 
 
TUESDAY WILL BE MORE OF THE SAME SCATTERED SHOWERS AND STORMS  
DURING THE PEAK HEATING HOURS. COLUMN MOISTENS UP WITH PWATS  
PUSHING 1.6" AND STORM MOTION REMAINING LESS THAN 10 KNOTS.  
HARD TO PINPOINT ANY PARTICULAR AREA, BUT HIGH WATER REMAINS A  
THREAT AND CONFIDENCE IN COVERAGE PRECLUDES A FLASH FLOOD WATCH.  
THE GOOD THING REGARDING TUESDAY IS JET DYNAMICS WON'T BE AS  
FAVORABLE BEING ON THE ANTICYCLONIC SHEAR SIDE SO COVERAGE WON'T  
BE NUMEROUS. UNDER MORNING SUNSHINE TEMPERATURES WILL CLIMB  
EARLY AND TOP OUR IN THE LOWER 80S MUCH LIKE TODAY.  
 
ONCE THE DIURNAL TREND SETS IN TUESDAY EVENING SHOWERS WILL  
DISSIPATE. H5 HEIGHTS BUILD TO 588DM WEDNESDAY, SO ONCE ANY  
VALLEY FOG ERODES LOOK FOR A VERY WARM AFTERNOON. H8 TEMPS  
APPROACH 16C WHICH CORRESPONDS TO VALUES IN THE UPPER 80S SAVE  
FOR THE MOUNTAINS AND NORTH OF INTERSTATE 80. WEDNESDAY WILL BE  
THE ONLY DRY DAY OF THE WEEK.  
 
A DIGGING MID LEVEL TROUGH RETURNS MOISTURE /MID AND HIGH  
CLOUDS/ WEDNESDAY NIGHT. THIS SHOULD OFFSET FOG FORMATION SAVE  
FOR THE MOUNTAINS AND DEEPER RIVER VALLEYS. THURSDAY IS A TRICKY  
FORECAST AS A BAROCLINIC ZONE SETS UP NORTH OF LAKE ERIE WITH  
IMPULSES RIDGING SOUTH OF IT. THERE WILL BE PLENTY OF MOISTURE  
TO TAP FOR SHOWER AND THUNDERSTORM DEVELOPMENT. DOWNBURSTS ARE  
POSSIBLE GIVEN DELTA THETE-E VALUES OF 20K BETWEEN 10-20KFT. FOR  
NOW WILL KEEP CHANCE POPS, LARGELY BECAUSE ATMOSPHERE WILL BE  
MESSY WITH RESIDUAL OUTFLOW BOUNDARIES AND THEY ARE PEGGING A  
LOT OF DCVA POCKETS. COULD SEE POP NUMBERS INCREASE AS WE HEAD  
THROUGH THE WEEK, BUT FOR NOW, WILL KEEP CONTINUITY GOING  
PERHAPS A TWEAK UPWARD OVER EASTERN OHIO.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
 
 
HIGHLIGHTS:  
 
- WET WEATHER RETURNS THURSDAY NIGHT - SATURDAY  
- DRY SUNDAY AND MONDAY  
- TEMPERATURES ABOVE NORMAL  
 
GEFS/EPS HAVE A GOOD HANDLE ON THE LATE WEEK WEATHER SYSTEM, BUT  
DIVERGE ON ARRIVAL OF THE NEXT SYSTEM JUST BEYOND DAY 7.  
SURFACE COLD FRONT HAS BEEN PUSHED BACK 12 HOURS FROM THE  
FORECAST LATE LAST WEEK. IT WILL BE CROSSING THURSDAY NIGHT INTO  
FRIDAY. WITH THIS TIMING, POTENTIAL FOR SEVERE WEATHER IS VERY  
LOW. THERE WILL BE PLENTY OF CLOUDS NOT TO MENTION BEST UPPER  
LEVEL DYNAMICS CROSS THROUGH THE GREAT LAKES. GEFS HAS OVER A  
60% PROBABILITY OF GREATER THAN 0.01" OF RAIN WHICH IS IN LOCK  
STEP WITH FORECAST, SO MAY TWEAK POPS A SMUDGE HIGHER GIVEN  
INCREASED CONFIDENCE.  
 
AFTER THE FRONT CROSSES FRIDAY MORNING, MID LEVEL TROUGH REMAINS  
OVER THE REGION ALLOWING IMPULSES TO CROSS IN NORTHWEST FLOW.  
WILL KEEP CHANCE POPS GIVEN COOLING ALOFT INTERACTING WITH  
DAYTIME HEATING. A TRANSITORY RIDGE ARRIVES SUNDAY AND MONDAY  
ALLOWING DRY WEATHER. H8 TEMPS DON'T MOVE MUCH OVER THE NEXT  
SEVEN DAYS, SO DAYTIME WILL BE IN THE LOWER TO MID 80S  
 

 
   
AVIATION /06Z TUESDAY THROUGH SATURDAY/
 
 
CHALLENGING FORECAST FOR THE FIRST 6-8 HOURS OF THE TAF PERIOD.  
TRIED TO KEEP THE MOST RESTRICTIVE FLIGHT CONDITIONS DUE TO  
FOG/LOW CLOUDS TO LOCATIONS THAT RECEIVED RAINFALL TODAY, LIKE  
DUJ, MGW, AND AGC, WITH MVFR OR VFR ELSEWHERE. COMPLICATING  
FACTORS INCLUDE THE MID CLOUD DECK ROTATING FROM NORTH TO SOUTH,  
A DECOUPLED BUT STILL LOCALLY STIRRED BOUNDARY LAYER, AND  
DEVELOPING SHOWERS EAST OF PIT. OVERALL, THE FIRST PORTION OF  
THE TAF IS A LOW CONFIDENCE FORECAST THAT WILL LIKELY REQUIRE  
AMENDMENTS.  
 
PAST 14Z, FOG AND LOW CLOUDS SHOULD LIFT BACK TO VFR IN MOST  
CASES. ONE MORE DAY OF DIURNAL SHOWERS AND THUNDERSTORMS IS  
EXPECTED UNDER THE SOON-DEPARTING UPPER LOW. USING VCSH/VCTS  
ONCE AGAIN WITH THE USUAL TIMING/DURATION QUESTIONS.  
 
CLOUDS WILL DECREASE THIS EVENING AS THE UPPER LOW FINALLY LIFTS  
OUT. FOG DEVELOPMENT AFTER 04Z WEDNESDAY WILL DEPEND ON  
RAINFALL PATTERN AND SLACKENING WINDS.  
 
OUTLOOK...  
SUB VFR WEATHER IS POSSIBLE THURSDAY EVENING INTO FRIDAY  
MORNING WITH A COLD FRONT.  
 

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

 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab OH Page
The Nexlab PA Page
The Nexlab WV Page
The Nexlab MD Page Main Text Page