Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 232312
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
712 PM EDT TUE SEP 23 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER WESTERN PENNSYLVANIA WILL DRIFT
NORTHEAST TO THE MAINE COAST BY WEDNESDAY AFTERNOON. A LOW
PRESSURE SYSTEM WILL TRACK UP THE MID ATLANTIC COAST WEDNESDAY AND
THURSDAY...THEN OUT TO SEA BY FRIDAY. DEEP AND MODERATELY STRONG
EASTERLY FLOW WILL BETWEEN THESE TWO WEATHER FEATURES WILL TRANSPORT
DEEP...ABUNDANT MOISTURE FROM THE WESTERN ATLANTIC...LEADING TO
PERIODS OF RAIN WEDNESDAY NIGHT INTO THURSDAY ACROSS THE EASTERN
HALF OF THE STATE. AN ANOMALOUS UPPER RIDGE WILL MIGRATE EASTWARD
FROM THE GREAT LAKES TO PENNSYLVANIA THIS WEEKEND BRINGING A
STRING OF SUNNY...WARM DAYS.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
VISIBLE SATL IMAGERY CONTINUES TO DISPLAY NEARLY CLOUD-FREE SKIES
OVER ALL OF PENNSYLVANIA THANKS TO A SPRAWLING 1031 MB SFC HIGH
CENTERED JUST NORTH TO THE GREATER PITTSBURGH AREA.

A SPLENDID AFTERNOON /AND FIRST FULL DAY OF FALL/ WILL CONTINUE
WITH LIGHT WIND AND TEMPS IN THE 60S...TO NEAR 70F IN THE LARGER
METRO AREAS THROUGHOUT THE LOWER SUSQ VALLEY.

TRANQUIL CONDS EXPECTED TONIGHT AS SFC HIGH PRESSURE DRIFTS SLOWLY
NE ACROSS THE COMMONWEALTH. WEAKEST LLVL P-GRADIENT WILL BE OVR
THE N MTNS...WHERE A CALM WIND AND CLEAR SKIES SHOULD PROMOTE
AREAS OF LATE NIGHT VALLEY FOG. FURTHER SOUTH...A DEVELOPING
EASTERLY BREEZE SHOULD LESSEN THE FOG POTENTIAL...BUT PATCHY
1/2-1SM VALLEY FOG STILL APPEARS LIKELY. WAA ALOFT AHEAD OF UPPER
LOW OVR THE SE CONUS MAY SPREAD INCREASING /ALBEIT MAINLY THIN/
CIRRUS INTO SOUTHERN PA VERY LATE TONIGHT.

LOWS TEMPS TONIGHT WILL BE MAINLY IN THE LOWER TO MID 40S. A FEW
SPOTS ACROSS THE NORTH WILL LIKELY DIP INTO THE U30S.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
A DECENT AMOUNT OF SUNSHINE IS EXPECTED EARLY IN THE DAY. CIRRUS
WILL GRADUALLY SPREAD NORTH-NORTHWEST DURING THE MIDDAY AND
AFTERNOON HOURS...WITH A THICK ALTOSTRATUS DECK EXPECTED ACROSS
THE LOWER SUSQ VALLEY /AND POSSIBLY ACROSS THE SCENT MTNS AS WELL/
BY 22Z WED. LIGHT RAIN WILL BE KNOCKING ON THE DOORSTEP OF THE
LOWER SUSQ VALLEY LATE WEDNESDAY AFTERNOON AS THE NOSE OF A
HIGHLY ANOMALOUS ESE 850 MB JET /-3 TO -4 ST DEVIATIONS/...AND
PWATS IN EXCESS OF 1.5 INCHES BECOMES AIMED RIGHT INTO THAT
REGION.

POPS WILL BE ESSENTIALLY ZERO ACROSS PRACTICALLY ALL OF THE CWA
THROUGH 00Z THURSDAY...BUT INCREASE TO 20-30 PERCENT TO THE SE OF
A KTHV AND KLNS LINE.

TEMPS WED SHOULD BE FAIRLY UNIFORM IN THE U60S TO ARND 70F DUE TO
THE THICKEST CLOUDS ARRIVING OVR THE NORMALLY WARMER SOUTHERN
COUNTIES.

SHOULD CLOUDS THICKEN UP FASTER THAN ANTICIPATED ACROSS THE
SOUTH...DAYTIME TEMPS MAY HAVE TO BE TRIMMED BY A FEW TO SEVERAL
DEG F.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE MODELS CONTINUE TO SHOW INCONSISTENCY IN A RUN BY RUN BASIS AS
THE NAM/EC/GEFS/SREF AND GFS NOW BACK PRECIP EASTWARD...THOUGH
STILL WESTWARD ENOUGH TO AFFECT CENTRAL PA. GFS REMAINS THE MOST
CONSISTENT OF THEM AS IT CONTINUES THE HEAVIEST PRECIP IN THE
DELMARVA REGION. MADE CHANGES TO THE WED NITE/THURSDAY FCST...DUE
TO THE CHANGE IN TRACK OF THE COASTAL LOW ACROSS THE DELMARVA.
THIS SYSTEM SHOULD BRING MOIST EAST TO SOUTHEASTERLY FLOW AND
ACCOMPANYING RAINSHOWERS TO AT LEAST THE SE COUNTIES ON THURSDAY.
THE EC BRINGS THE PRECIP NORTHWARD THROUGH CENTRAL PA BEFORE IT
SHIFTS NORTHEASTWARD AND HEADS UP THE COAST. A TIGHT PRESSURE
GRADIENT BETWEEN THE HIGH EAST OF NEW ENG AND SFC LOW RIDING UP
THE EAST COAST SHOULD AMPLIFY THE ANOMALOUS EASTERLY WINDS/PWATS
IN THE 12Z GEFS...THOUGH THE HIGHEST PWATS SHOULD ONLY AFFECT SE
PA WED NIGHT THROUGH THURSDAY MORNING.
SOME ENSEMBLE AND OPERATIONAL RUNS INDICATE A SUBSTANTIAL
RAINFALL OF OVER AN INCH IS POSSIBLE ACROSS PARTS OF SE PA. GIVEN
THE VARIABILITY BETWEEN THE OUTPUTS HAVE QPFS IN THE 0.75 TO ONE
INCH RANGE. HAVE INCREASED MIN TEMPS WED NIGHT AND LOWERED MAX
TEMPS WED SIGNIFICANTLY DUE TO THE EXPECTED CLOUD COVER/RAIN.

GENERAL AGREEMENT AMONG MED RANGE GUIDANCE THAT COASTAL LOW WILL
EXIT THE MID ATLANTIC COAST THURSDAY NIGHT INTO FRIDAY...BRINGING
A RETURN TO FAIR AND MILD WX. ANOMALOUS UPPER LVL RIDGE OVR THE
GRT LKS IS THEN PROGGED TO SLIDE EAST INTO PA OVR THE
WEEKEND...BRINGING THE AREA A PERIOD OF FAIR AND WARM WX THAT
SHOULD LAST INTO EARLY NEXT WEEK. LG SCALE SUBSIDENCE BENEATH THIS
SYSTEM SHOULD RESULT IN MCLEAR SKIES THRU THE WEEKEND. MID LEVEL
TEMPERATURES IN THE GEFS AND ECMWF SHOULD SUPPORT HIGH TEMPS ARND
10F ABOVE NORMAL...WITH AFTN READINGS BTWN 75-80F OVR MUCH OF THE
AREA THROUGH THE WEEKEND. ANOTHER LOW LOOKS TO BE APPROACHING THE
REGION BY THE MIDDLE OF NEXT WEEK. DUE TO THE LARGE VARIATION IN
TIMING HAVE ONLY CHANCE POPS TUESDAY INTO WEDNESDAY.

&&

.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
NICE EARLY FALL EVENING WITH OUTSIDE WITH VFR CONDITIONS.

INTERESTING RETURNS ON RADAR...COULD BE BIRDS.

NOT EXPECTING A LOT OF FOG LATE TONIGHT. PERHAPS A LITTLE
AT UNV AND AOO. LOW CIGS AND SOME FOG WILL BE POSSIBLE AT
IPT. BASED ON GUIDANCE AND HOW THINGS WENT LAST NIGHT...ALONG
WITH HAVING A FAIRLY DRY AIRMASS IN PLACE.

FOR WED...A DEVELOPING...DEEP AND MDTLY STRONG EASTERLY FLOW
/BETWEEN HIGH PRESSURE OVER THE NEW ENGLAND STATES...AND UPPER
LEVEL LOW PRESSURE SYSTEM/SFC TROUGH OVER THE SE U.S./ WILL BRING
CLOUDY SKIES AND A CHANCE FOR RAIN WED NIGHT AND THU...ESP ACROSS
THE EASTERN HALF OF PENN. WIDESPREAD IFR TO MVFR CIGS /AND VSBYS
IN THE SAME CATEGORY/ APPEAR LIKELY WED NIGHT THROUGH THURSDAY.

OUTLOOK...
WED...PATCHY FOG IN THE MORNING...OTHERWISE VFR.
WED NIGHT AND THU...LOW CIGS AND AREAS OF -RA/DZ LIKELY.
FRI-SUN...PATCHY 1/2SM FOG IN THE MORNING...OTHERWISE VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...FITZGERALD/CERU
AVIATION...LAMBERT/MARTIN



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