Area Forecast Discussion
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000
FXUS61 KPBZ 290019
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
719 PM EST FRI NOV 28 2014

.SYNOPSIS...
A WARM FRONT CROSSES TONIGHT BRINGING SNOW SHOWERS ALONG AND NORTH
OF INTERSTATE 80. A WARM UP IS IN STORE THIS WEEKEND AS WINDS
ORIGINATE FROM THE SOUTH ALLOWING DAYTIME HIGHS TO CLIMB INTO THE
40S SATURDAY AND 50S SUNDAY. THERE WILL BE AN ABUNDANCE OF CLOUDS
AND POSSIBILITY OF LIGHT RAIN SATURDAY NIGHT INTO SUNDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
WITH 715PM UPDATE...HAVE REDUCED POPS FOR LINE OF SNOW PREVIOUSLY
ACROSS CENTRAL OHIO THAT HAS FALLEN APART. HOWEVER...ADDITIONAL
SNOW SHOWERS HAVE DEVELOPED ACROSS NORTHERN OHIO...AND WILL
MAINTAIN AT LEAST SLIGHT CHANCE POPS FOR THESE SHOWERS AS THEY
MAKE THEIR WAY TO THE EAST. PREVIOUS DISCUSSION FOLLOWS.

THERE WILL BE LITTLE BREAK IN THE ACTIVE WEATHER REGIME WITH FAST
MID LEVEL WINDS STEERING SYSTEMS THROUGH AT LESS THAN 12 HOUR
INTERVALS. WARM FRONT RACES SE CLIPPING NORTHERN REACHES OF CWA
OVERNIGHT. INCREASED CONSENSUS AMONGST 12Z NCEP CHAIN HAS YIELDED
AN INCREASED IN POPS TO LKLY FOR I-80 REGION AFTER MIDNIGHT. THERE
WILL BE A SHARP CUTOFF AS LOCATIONS ALONG AND SOUTH OF I-76 SHOULD
REMAIN PRECIP FREE AFTER MIDNIGHT. ATMOSPHERE THERMAL PROFILE
ILLUSTRATES ALL SNOW WITH THE ENTIRE COLUMN BELOW 0C. BEST CHANCE
FOR MEASURABLE QPF WILL BE AROUND MIDNIGHT. ANY SNOW ACCUMULATION
SHOULD BE AROUND AN INCH OR LESS. AS AREA GETS IN WARM SECTOR
DURING THE PREDAWN HOURS...FORECAST A NON DIURNAL TEMPERATURE
TREND...AS WINDS WILL PICK UP WHILE ANY INVERSION IS SCOURED OUT
EVEN IN THE DEEPEST VALLEYS DUE TO BL FLOW OF 15KTS.

BROAD SOUTHERLY FLOW IN THE LOWER LEVELS OF THE ATMOSPHERE PUMP
MOISTURE FROM THE SOUTH...THUS DESPITE BEING IN THE WARM SECTOR
OVERCAST OR NEAR OVERCAST SKY COVER IS PREDICTED FOR
SATURDAY...ESPECIALLY IN THE AFTERNOON.  ANY PCPN ARRIVES FIRST
IN EASTERN OHIO BY AFTERNOON.  BUFKIT SOUNDINGS DO NOT SHOW ANY
THREAT OF MIXED PRECIPITATION FROM WAA ALOFT...SO LIGHT RAIN IS
FORECAST.

TEMPERATURES WERE CONSTRUCTED INITIALLY FROM THE GRIDDED LAMP
TONIGHT THEN A BLEND OF THE EXISTING FORECAST AND ADJ MET BIAS
CORRECTED GRIDS SATURDAY.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
WEATHER DOES NOT CHANGE MUCH SATURDAY NIGHT COMPARED TO DURING
THE DAY AS BROAD LOW LEVEL SOUTHERLY FLOW CONTINUES TO BACK BUILD
ALL THE WAY TO THE LOWER MISSISSIPPI RIVER VALLEY. CROSS SECTIONS
OF POTENTIAL TEMPERATURE INDICATES UPGLIDE / POSITIVE PRESSURE
ADVECTION FROM THE SURFACE TO 775MB. SPECIFIC HUMIDITY ARE
SURPRISINGLY MODEST FOR THIS EVENT WITH VALUES REACHING 6GKG-1
SATURDAY NIGHT AT 290K. QPF VALUES WILL NOT BE THAT GREAT GIVEN
LACK OF ANY SYNOPTIC SCALE WEATHER FEATURE. AMOUNTS WILL RUN ON
THE ORDER OF FIVE HUNDREDTHS OR LESS...WHICH WARRANTS LIGHT RAIN
ATTRIBUTE IN WEATHER GRIDS. INCREASED POPS TO LKLY FOR EASTERN
OHIO AND NORTHWEST PA WHILE MAINTAINING CHANCE POPS ELSEWHERE.

THE WEAK COLD FRONT WILL GRADUALLY MAKE IT`S APPROACH BY LATE
SUNDAY. WHILE THE GREATEST CHANCE FOR MEASURABLE PRECIPITATION
WILL NOT COME UNTIL THE FRONTS PASSAGE SUNDAY NIGHT...A STRONG MID-
LEVEL JET SHOULD SUPPORT THE DEVELOPMENT OF SOME SHOWERS IN ADVANCE
OF THE FRONT. THUS...LIKELY POPS WERE CARRIED OVER OHIO DURING THE
DAY SUNDAY...WITH HIGH CHANCE ELSEWHERE. OUT AHEAD OF THE
FRONT...STRONG W-SW FLOW SHOULD ALLOW FOR TEMPERATURES TO WARM
ABOVE SEASONAL AVERAGES.

THE MODELS GENERALLY AGREE THAT THE FRONT WILL BE THROUGH THE
REGION BY MONDAY AFTERNOON...SO THE HIGH TEMPERATURES FOR THE DAY
WILL BE REALIZED EARLY.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
COOL TEMPERATURES WILL ONLY LINGER FOR A DAY BEFORE SOUTHWESTERLY
FLOW RETURNS ON TUESDAY. NEARLY ZONAL PATTERN WILL SUPPORT FOR
WEAK...FAST MOVING STORM SYSTEMS AND SHOWER CHANCES THROUGH THE
END OF THE LONG TERM.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
PREVAILING VFR ARE EXPECTED TO BE INTERRUPTED BY A PD OF
RESTRICTIONS...MAINLY MVFR...TNGT AS A FAST SHRTWV INTERACTS WITH
AN ADVNG WARM FRONT. THOSE RESTRICTIONS MAY LINGER UNTIL ABOUT
DAYBREAK AT FKL AND DUJ WITH THE WARM FRONT IN VCNTY. OTHERWISE
EXPECT A LGT SFC WIND BACKING FM SW TO S AS THESE FEATURES
PROGRESS.

OUTLOOK.../SATURDAY THROUGH WEDNESDAY/...
THE NEXT CHANCE FOR WIDESPREAD RESTRICTIONS IS WITH THE ADVN AND
PASSAGE OF A CDFNT DURING THE LATE SATURDAY THROUGH MONDAY PD.

&&

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

&&

$$





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