Skip Navigation Linkswww.nws.noaa.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service Forecast Office   NWS logo - Click to go to the NWS homepage
Pittsburgh, PA banner image
 
 

Area Forecast Discussion
Latest Versions  [Current][-1][-2][-3][-4][-5][-6][-7][-8][-9]



000
FXUS61 KPBZ 301345
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
945 AM EDT TUE SEP 30 2014

.SYNOPSIS...
WEAK LOW PRESSURE WILL CROSS THE REGION TODAY. WARM AND DRY
CONDITIONS WILL FOLLOW UNTIL THE PASSAGE OF A FRIDAY COLD FRONT.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WITH 945AM UPDATE...HAVE CONTINUED TO EXPAND COVERAGE OF LIKELY
AND CATEGORICAL POPS. REGARDLESS OF WHAT THE HRRR AND RAP ARE
CURRENTLY DEPICTING...LINE OF SHOWERS AND ISOLATED THUNDERSTORMS
CONTINUES TO HOLD TOGETHER. HOWEVER...12Z PIT SOUNDING SHOWS A LOT
OF DRY AIR...WHICH IS LIKELY THE REASON THAT MODELS SHOW A
WEAKENING TREND IN SHOWERS LATER TODAY AS THE AIR MASS MOVES
FARTHER EAST. IN ADDITION...THE STORM PREDICTION CENTER HAS
EXPANDED ITS AREA FOR A MARGINAL HAIL THREAT...AND HAVE LIKEWISE
EXPANDED THE AREA IN THE FORECAST THAT MENTIONS A SMALL HAIL
THREAT. 4AM DISCUSSION FOLLOWS.

WEAK BOUNDARY WITH STRONG UPPER LEVEL SUPPORT WILL SLOWLY CROSS
THE AREA TODAY. STILL HAVING A TOUGH TIME GETTING A HANDLE ON HOW
MUCH PRECIPITATION THIS SYSTEM WILL PRODUCE. THE BEST UPPER LEVEL
SUPPORT WILL BE WITH THE MAIN 50H LOW WHICH WILL TRAIL BEHIND THE
FRONT AND MOVE INTO NE OHIO LATE THIS AFTERNOON. THE ATMOSPHERIC
MOISTURE NEVER REALLY GETS LINED UP AS THE MID AND UPPER LEVEL
MOISTURE MOVES IN AHEAD OF THE 50H LOW...BUT THE LOW LEVEL
MOISTURE HANGS BACK WITH THE MAIN SHORTWAVE ROTATING AROUND THE
UPPER LEVEL SYSTEM. FORECAST SOUNDINGS ARE SHOWING A DRY LAYER UP
TO AROUND 5000 FT THROUGH THE ENTIRE DAY...MAKING IT DIFFICULT FOR
SHOWERS TO REACH THE GROUND. WILL LEAVE IN CHANCE POPS FOR TODAY
WITH THE HIGHEST PROBABILITY FOR MEASURABLE RAIN ACROSS THE NORTH
CLOSER TO THE UPPER LEVEL LOW. IF THE LOW LEVELS ARE ABLE TO
SATURATE TODAY THEN MORE WIDESPREAD SHOWER ACTIVITY IS POSSIBLE.

IN ADDITION...COLD POOL ALOFT...WITH PASSING 50H...LOW MAY
PROVIDE ENOUGH ELEVATED INSTABILITY THAT AN ISOLATED STORM COULD
DEVELOP THIS AFTERNOON.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
THE ENTIRE SYSTEM WEAKENS THIS EVENING. THE 50H LOW OPENS UP AND
WHATS LEFT OF THE SURFACE BOUNDARY DRIFTS INTO EASTERN PA. 

UPPER LEVEL WAVES OF ENERGY WILL SWING AROUND THE BACKSIDE OF THE
EXITING 50H LOW SO WILL LEAVE IN SLIGHT CHANCE/LOW CHANCE POPS IN
THE FAR EAST FOR A PORTION OF THE EVENING HOURS. 

UPPER LEVEL RIDGE WILL MOVE IN BEHIND THE LOW ON THURSDAY...
PROVIDING SUNSHINE AND WARM TEMPERATURES.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
STILL SEEING SOME MINOR TIMING ISSUES WITH FRONTAL PASSAGE ON
FRIDAY. LATEST NAM IS SLOWING EVERYTHING DOWN...GFS IS THE MOST
PROGRESSIVE AND THE 12Z ECMWF IS SOMEWHERE IN BETWEEN. FRIDAY DOES
APPEAR LIKE A GOOD CHANCE FOR SOME MUCH NEEDED WIDESPREAD RAIN.
MUCH COLDER AIR WILL SETTLE IN FOR THE WEEKEND.

OVERALL THE PATTERN WILL SHIFT FROM THE QUIET WE HAVE EXPERIENCED
OVER THE LAST TWO OR SO WEEKS...TO A MORE ACTIVE AND COOLER
PATTERN.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
CLOSED LOW ALOFT WILL ROTATE SOUTHEAST TOWARD LAKE ERIE THIS
AFTERNOON WITH A WEAK COLD FRONT TO FOLLOW. BAND OF SHOWERS ACROSS
OHIO THIS MORNING CLOSER TO UPPER LEVEL SUPPORT. MODELS SHOWING
RATHER WIDESPREAD COVERAGE FOR SHOWERS THIS AFTERNOON BUT NOT
WHOLLY CONVINCED OF THIS BASED ON MODEL SOUNDINGS WITH AVAILABLE
MOISTURE. VCSH REMAINS MOST PORTS THIS AFTERNOON WITH RESTRICTIONS
POSSIBLE MAINLY AT KFKL AND KDUJ.

OUTLOOK.../WEDNESDAY THROUGH SATURDAY/...
THE NXT CHC FOR WIDESPREAD RESTRICTIONS WL COME WITH A FRIDAY CDFNT.

&&

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

&&

$$






National Weather Service
Disclaimer Privacy Policy