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Area Forecast Discussion
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000
FXUS61 KPBZ 250506 AAC
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
106 AM EDT FRI APR 25 2014

.SYNOPSIS...
LOW PRESSURE...AND ITS ASSOCIATED COLD FRONT...WILL BRING RAIN
AND A CHANCE FOR A THUNDERSTORM TODAY. SEASONAL TEMPERATURES ARE
EXPECTED THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
MADE ADJUSTMENTS TO OVERNIGHT POPS AS NEW DATA HAS ARRIVED. MODEL
DEPICTIONS CONTINUE TO SLOW THE EASTWARD MOVEMENT OF TODAY'S
SYSTEM. THIS IS LIKELY DUE TO THE FACT THE STORM HAS BECOME MORE
ENERGETIC...DIGGING A DEEPER TROUGH INTO THE UPPER LEVEL PATTERN.
IN ADDITION TO THE REDUCED SPEED...A VERY DRY ATMOSPHERE IS IN
PLACE OVER THE AREA. THIS SHOWS UP WELL ON CURRENT OBS...WHERE A
25 TO 30 DEGREE SPREAD IN TEMP/TD EXISTS. IT WILL TAKE SOME TIME
FOR THE LOWER LEVELS OF THE ATMOSPHERE TO SATURATE. IT IS LIKELY
THERE WILL BE A PERIOD OF VIRGA WITH THE INITIAL INTRUSION OF THE
RAIN SHIELD AS DAWN APPROACHES. HAVE ADJUSTED OVERNIGHT TEMPS TO
LATEST GUIDANCE.

THE SLOW MOVING AND DEEPENING SYSTEM WILL MOVE ACROSS OHIO THIS
MORNING. SHOWERS WILL OVERSPREAD THE WESTERN HALF OF THE REGION
DURING THOSE HOURS...REACHING WESTERN PA BY LATE MORNING/EARLY
AFTERNOON. THE SYSTEM WILL BEGIN TO OPEN UP A BIT...IN THE UPPER
LEVELS...AS IT APPROACHES PA. THIS WILL ASSIST IN DECREASING THE 
OVERALL RAINFALL AMOUNTS AS IT MOVES THROUGH. STILL HAVE CONCERN
OVER THE POSSIBILITY OF A LINE OF CONVECTION DEVELOPING RIGHT
ALONG THE SURFACE FRONT LATE THIS MORNING AND THROUGH THE
AFTERNOON. THE ATMOSPHERE WILL DESTABILIZE AHEAD OF THE SYSTEM...
CONVECTIVE TEMPS ARE REACHABLE AND THE K INDEX WILL HANG RIGHT
AROUND 30 THROUGHOUT THE DAY. CAPE AND SHEAR VALUES ARE NOT OVERLY
IMPRESSIVE SO DO NOT THINK THAT ANY CONVECTION WILL BE REAL
ORGANIZED. THE OTHER LIMITING FACTOR WILL BE THE CLOUD SHIELD
AHEAD OF THE LOW. HAVE DECIDED TO INCLUDE THE MENTION OF ISO TRW
WITH FRONTAL PASSAGE.

DUE TO THE SLOWER MOVEMENT OF THE SYSTEM...RAIN AND CLOUDS WILL
LAST LONGER INTO THE DAY.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
SYSTEM CLEARS ALL OF MY AREA BY EARLY THIS EVENING...BRINGING AN
END TO THE SHOWERS. A SECONDARY FRONT WILL APPROACH THE AREA FROM
THE NORTH LATE TONIGHT. THIS WILL PROMPT THE REINTRODUCTION OF
POPS LATE TONIGHT AND THROUGH MUCH OF SATURDAY. FOR NOW...WILL GO
WITH SCHC TO CHC AS THE MOISTURE IS LIMITED AND UPPER LEVEL
SUPPORT IS WEAK. THERE WILL BE A PUSH OF COLDER AIR BEHIND
SATURDAY'S FRONT...SO TEMPS WILL BE A BIT COOLER SATURDAY AND THEN
NOTICEABLY COLDER SATURDAY NIGHT.

WARMER AIR WILL RUSH BACK INTO THE REGION ON SUNDAY...AS AN UPPER
LEVEL RIDGE MOVES THROUGH THE MIDWEST. EXPECT HIGH AND MID CLOUDS
TO PASS THROUGH THE AREA AND TEMPS WILL BE SEASONABLE.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
UPPER LEVEL PATTERN WILL BECOME QUITE STAGNANT NEXT WEEK. AN UPPER
LOW OVER NEBRASKA WILL DRIFT TO ILLINOIS DURING THE LONG TERM
PERIOD. THE ASSOCIATED SURFACE LOW WILL SIMILARLY MAKE A LACK OF
EASTWARD PROGRESS. ALTHOUGH THE ENTIRE WEEK SHOULD NOT BE A
WASHOUT WITH CONTINUOUS RAIN FOR FOUR DAYS...THE PATTERN IS
EXPECTED TO BRING INTERMITTENT SHOWERS AND BELOW NORMAL
TEMPERATURES.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
HIGH PRES WL MAINTAIN VFR AND LGT SFC WIND TNGT. SHWR AND MVFR
POTENTIAL WL INCRS ON FRI WITH THE APCH AND PASSAGE OF A CDFNT.
ISOLD TSTMS ARE PSBL FRI AFTN BUT CHCS TOO LOW FOR TAF MENTION
ATTM. GUSTY W WNDS WL BRIEFLY DVLP AFT FROPA.

.OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/...
RSTRNS ARE PSBL INTO FRI NGT TO THE N OF I 70 AS COOL NW FLOW
ENSUES IN THE WAKE OF FRIDAYS FROPA.

&&

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

&&

$$






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