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[Printable]
901
FXUS61 KCTP 240308
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1108 PM EDT TUE SEP 23 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER WESTERN PENNSYLVANIA WILL DRIFT TO
THE MAINE COAST BY WEDNESDAY AFTERNOON. A LOW PRESSURE SYSTEM WILL
TRACK UP THE MID ATLANTIC COAST WEDNESDAY AND THURSDAY. DEEP AND
MODERATELY STRONG EASTERLY FLOW BETWEEN THESE TWO WEATHER
FEATURES WILL TRANSPORT ABUNDANT MOISTURE IN FROM THE
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 THIS WEEKEND AND
BRING A STRING OF SUNNY...WARM DAYS.

&&

.NEAR TERM /UNTIL 9 AM WEDNESDAY MORNING/...
CIRRUS SHOULD INCREASE A LITTLE IN THE SE...BUT MUCH OF THE AREA
WILL REMAIN CLEAR OVERNIGHT. LOWS TEMPS TONIGHT WILL BE MAINLY IN
THE LOWER TO MID 40S. A FEW SPOTS ACROSS THE NORTH WILL LIKELY DIP
INTO THE U30S. THUS...THE USUAL VALLEY LOCATIONS WILL HAVE FOG
AROUND SUNRISE...WHICH SHOULD BURN AWAY BY 9 OR 10 AM. VERY PATCHY
FROST IS POSSIBLE IN A FEW SPOTS...BUT NOT ENOUGH TO WARRANT A
FROST ADVY ANYWHERE SPECIFIC.

&&

.SHORT TERM /9 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 /03Z WEDNESDAY THROUGH SUNDAY/...
NO CHANGES MADE TO 03Z TAFS.

EARLIER DISCUSSION BELOW.

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...DANGELO/LAMBERT
NEAR TERM...DANGELO
SHORT TERM...LAMBERT
LONG TERM...FITZGERALD/CERU
AVIATION...LAMBERT/MARTIN




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