-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPBZ 300529
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1229 AM EST SAT NOV 30 2013

.SYNOPSIS...
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HIGH PRESSURE WILL BRING DRY WEATHER TODAY BEFORE A WEAK COLD
FRONT CROSSES THE REGION SUNDAY.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TODAY/...
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WAA CONTINUING TO BRING MID AND HIGH DECK FROM THE WEST OVERNIGHT
THROUGH TODAY. TRIED TO MAINTAIN PARTLY CLOUDY/PARTLY SUNNY
WORDING IN FORECAST FOR SATURDAY. ONLY MAJOR ADJUSTMENT MADE TO
NEAR TERM FORECAST WAS FOR NORTHERN COUNTY TEMPERATURES OVERNIGHT AS COLDER
AIR WAS ABLE TO FILTER IN WITH WEAK NORTHEAST FLOW EARLIER.
OTHERWISE TEMPERATURES ACROSS THE MAJORITY OF THE REGION SHOULD
NOT FLUCTUATE MUCH DUE TO WAA AND CLOUD COVER OVERNIGHT.
TEMPERATURES TODAY WILL RISE ABOVE FREEZING AS WEAK WAA FLOWS FROM
THE SOUTHWEST.
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&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
HIGH PRESSURE CONTINUES TO RETREAT INTO NEW ENGLAND SAT
NGT...HOWEVER RETURN FLOW ALLOWS FOR A WARMER NIGHT WITH SWRLY
WINDS OUT AHEAD. OVERALL MODELS ARE IN GOOD AGREEMENT WITH THE
NEXT WEATHER SYSTEM SUN - MON NIGHT. BOTH DEPICT A FULL LATITUDE
TROUGH ACROSS THE EASTERN CONUS...BUT LITTLE IN THE WAY OF ANY
BAROCLINICTY AT THE SFC. ALL OF THE ENERGY RESIDES WITH THE
CYCLONE TRACKING OFF THE ERN SEABOARD. UPSTAIRS THERE ARE PASSING
S/W TROUGHS DURING THIS PERIOD THAT WILL YIELD LIGHT QPF. H5
TROUGH BECOMES NEGATIVELY TILED AS IT SWEEPS THROUGH MONDAY
NIGHT...BUT WITH THE LACK OF AGEOSTROPHIC DIVERGENCE AT H2 AND
5-10KTS OF LLVL CONV...ONLY LIGHT PCPN EXPECTED. CONTINUED THEME
OF HIGHLIGHTING AREAS ALONG AND N OF I-80 FOR MEASURABLE QPF
SUNDAY INTO SUNDAY NIGHT. THERMAL PROFILES ILLUSTRATE POTENTIAL
FOR A RA/SN MIX. HIGH PROBABILITY OF ALL SNOW THE CLOSER TO LAKE
ERIE AS COLUMN IS COLDER.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
HIGHLIGHTS:
- SLOW WARMING TREND CONTINUES
- ABOVE NORMAL TEMPS BY THE END OF NEXT WEEK
- STRONG LOW PRESSURE PASSES THUR - FRI

FORECAST CONFIDENCE IS ABOVE AVERAGE FOR THE FIRST TWO DAYS OF
THE LONG RANGE THEN LOWERS. TRANSITORY MID LVL RIDGE CROSSES MID WEEK
ALLOWING TEMPS TO WARM INTO THE 40S MELTING ANY LEFTOVER SNOW
PACK.

LATTER PART OF THE WEEK BOTH OPERATIONAL RUNS OF ECMWF AND GFS
SHOW A GOOD SHOT AT RAIN WITH LOW PRESSURE TRAVELING ALONG THE
MTNS. THIS TRACK WHICH IS FURTHER SUPPORTED BY THEIR RESPECTIVE
ENSEMBLE MEANS PLACE US ON THE WARM SIDE OF THE SYSTEM. THE
CHALLENGE IS TIMING AND IF A SECOND WAVE RIDES ALONG THE BOUNDARY
AS MID LVL FLOW BECOMES PARALLEL TO THE FRONT. STRONG ISENTROPIC
UPGLIDE ON 290-300K WITH WINDS INTERSECTING THETA SFCS AT RIGHT
ANGLES. SPECIFIC HUMIDITY VALUES PUSH 4-5 GKG-1 WHICH IS ABOVE
NORMAL THIS TIME OF YEAR. GEFS PLUME DIAGRAMS SHOW POTENTIAL FOR
0.50 TO 1.25 INCHES OF RAIN WITH VERY LITTLE SNOW ON THE BACK
SIDE.

A LOT OF SPREAD EXISTS AFTER THE COLD FRONT COMES THROUGH.  ECMWF IS
STRONGER WITH UPSTREAM RIDGE AXIS THEREBY HAVING ANOTHER WAVE OF
LOW PRESSURE PASSING FRIDAY W OF THE MTNS. GFS IS WEAKER WITH RIDGE
THUS HAVING LOW PRESSURE PASS TO OUR SE. GIVEN GUIDANCE SPREAD
FROM MOS IS WELL INTO THE 60S ROLLED WITH LKLY POPS NEXT THUR AND
FRI.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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VFR FORECAST FOR THE PERIOD. HIGH AND MID-LEVEL CLOUDS WILL
OVERSPREAD THE AREA AND HOLD THROUGH MUCH OF THE DAY. SFC WINDS
WILL INCREASE TOWARD DAWN...WITH GUSTS TO 20KTS POSSIBLE ACROSS
THE NORTH BY AFTERNOON.

.OUTLOOK.../FRIDAY NIGHT THROUGH WEDNESDAY/...
NO WIDESPREAD AREAS OF IFR WEATHER EXPECTED. BRIEF MVFR
RESTRICTIONS ARE POSSIBLE WITH THE NEXT WEATHER SYSTEM SUNDAY.
-- End Changed Discussion --

&&

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

&&

$$