Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 070650
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
250 AM EDT TUE JUL 7 2015

.SYNOPSIS...
A WEAKENING UPPER LOW WILL TRACK EAST ACROSS THE REGION TONIGHT.
A WEAK RIDGE WILL BRING VERY WARM AND HUMID CONDITIONS TO THE
REGION TODAY. A COLD FRONT WILL APPROACH TONIGHT...THEN STALL
OUT ALONG...OR JUST SOUTH OF THE MASON DIXON LINE FOR MIDWEEK. A
FEW WAVES OF LOW PRESSURE WILL RIPPLE EAST ALONG THIS BOUNDARY
BRINGING THE LIKELIHOOD FOR SHOWERS AND THUNDERSTORMS WEDNESDAY
AFTERNOON AND EVENING...AND AGAIN ON THURSDAY. HIGH PRESSURE WILL
BUILD IN FOR FRIDAY AND BRING SLIGHTLY COOLER AND NOTABLY LESS
HUMID WEATHER WITH LITTLE CHANCE FOR RAIN.

&&

.NEAR TERM /THROUGH TODAY/...
LAST VESTIGES OF THE GREATLY WEAKENED UPPER TROUGH ARE SEEN AS
JUST A FEW HIGHLY ISOLATED /BUT BRIEFLY HVY/ RAIN SHOWERS
DRIFTING NORTH ACROSS THE REGION EARLY THIS MORNING.

PLENTY OF CLOUDS AND PATCHY FOG WILL BE AROUND EARLY TODAY AS
THIS FEATURES DEPARTS TO OUR EAST. FOR THE LATE MORNING AND
AFTERNOON HOURS. DEEP SWRLY FLOW...SLIGHTLY DECREASING SFC
DEWPOINTS...AND MID- LEVEL WARMING WILL COMBINE TO BRING US A VERY
WARM DAY WITH TEMPERATURES A FEW- SVRL DEG F ABOVE NORMAL...AND
LITTLE CHANCE FOR RAIN IN MOST PLACES.

A WEAK LEE TROUGH OVER AND TO THE EAST OF THE SUSQ VALLEY...AND A
COLD FRONT WELL OFF TO THE NW WILL BRING LOW CHCS FOR PULSE
SHOWERS/TSRA TO OUR EASTERN ZONES DURING THE MID TO LATE
AFTERNOON HOURS...AND PERHAPS SOME MORE ORGANIZED/STRONGER
MULTI-CELL TSRA CLUSTERS ACROSS THE FAR NW LATE IN THE DAY INTO
TONIGHT.

HIGH TODAY WILL LIKELY BE THE WARMEST THIS WEEK...AND ABOUT 3-4
DEG ABOVE NORMAL. 8H TEMPS TEMPS NR 17C SHOULD TRANSLATE TO MAX
TEMPS WELL INTO THE 80S OVER MOST OF CENTRAL PA.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/...
SFC COLD FRONT SLIDES SLOWLY TO THE SOUTHEAST ACROSS THE
COMMONWEALTH TONIGHT THROUGH WED MORNING...BEFORE STALLING OUT
NEAR...OR JUST TO THE SOUTH OF THE MASON-DIXON LINE.

MAIN FCST PROBLEM/CHALLENGE FOR THE UPCOMING SHIFTS WILL BE TO
TRY TO PIN DOWN /VIA SOME SEMBLANCE OF MODEL CONSENSUS/ THE
LOCATION AND TIMING OF CONVECTIVE FEATURES/AREAS OF LOW PRESSURE
THAT WILL FORM AND RIDE EAST ALONG THIS BOUNDARY WEDNESDAY INTO
THURSDAY.

CURRENTLY...A GEFS/NAM/SREF BLEND POINT TWD THE BEST CHC FOR RAIN
WITH EMBEDDED TSRA FOCUSED ACROSS THE SOUTHERN THIRD TO HALF OF
PENN WEDNESDAY...WHERE PWAT WILL STAY AOA 2.0 INCHES. THE SHARP
GRADIENT TO MUCH LOWER PWAT /AOB 0.75 OF AN INCH/ WILL STAY NEAR
OR JUST TO THE NORTH OF THE PENN/NEW YORK BORDER WHERE CHCS FOR
RAIN WILL BE QUITE LOW WEDNESDAY AND MOST OF WED NIGHT.

MAX TEMPS WEDNESDAY COULD EASILY TURN OUT TO BE SEVERAL DEG F OR
MORE BELOW CURRENT FCST VALUES DEPENDING ON THE TIMING AND EXTENT
OF CONVECTION ACROSS THE CENTRAL AND SOUTH. CURRENT TEMP FCST
BUSTING ON THE LOW SIDE FOR WEDNESDAY`S HIGH IS A VERY LOW
PROBABILITY. WILL BE ADJUSTING THESE TEMPS WITH 03Z SREF AND 06Z
OP GUIDANCE WHERE NEEDED.
&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE 07/00Z MODEL AND ENSEMBLE GUIDANCE IS PROVIDING A FAIRLY
CONSISTENT SIGNAL THAT THE AREA WILL REMAIN IN A LOW AMPLITUDE
QUASI-ZONAL MID/UPPER FLOW PATTERN WITHIN THE NORTHERN STREAM
WESTERLIES. AS MIGHT BE EXPECTED IN THIS PATTERN...THERE IS LOW
PREDICTABILITY/CONFIDENCE GIVEN DEGREE OF SPREAD AND MEANINGFUL
DIFFERENCES ASSOCIATED WITH SHORTWAVE DETAILS. THIS LARGELY
UNSETTLED AND RECENTLY PERSISTENT WEATHER PATTERN FOR THE LOCAL
AREA WILL BE MODULATED TO SOME EXTENT BY RETROGRESSION OF
UNSEASONABLY STRONG UPPER TROUGH/RIDGE COUPLET OFF THE WEST COAST
AND OVER THE SOUTHEAST AND SCENTRL U.S. THERE IS BROAD SUPPORT FOR
ANOTHER MEAN TROUGH TO DEVELOP OVER THE NORTHEAST/MID ATLANTIC
STATES BY NEXT WEEK/JULY 13TH AS ENERGY EJECTING FROM CA UPPER LOW
EVOLVES DOWNSTREAM IN THE WESTERLIES AND TEAMS WITH VORTEX OVER
HUDSON BAY.

IN TERMS OF SENSIBLE WEATHER...A WELL-DEFINED COLD FRONT ENTERS
CENTRAL PA EARLY WEDNESDAY ACCOMPANIED BY SHOWERS/TSTMS...THEN
BECOMES WAVY AS IT STALLS OUT FROM NEAR THE OH RIVER/MASON DIXON
LINE. EXPECT ONE OR MORE EPISODES OF PCPN THRU LATE WEEK MOST LKLY
DUE TO MCS REMNANTS OR CONVECTIVELY INDUCED LOWS TRACKING EWD FROM
THE MID MS/OH VLY...BUT TOO DIFFICULT TO PIN POINT TIMING/LOCATION
AT THIS POINT. FWIW THE MODEL BIAS IS USUALLY TOO FAR NORTH WITH
MCS ACTIVITY. PCPN RISK SHOULD EVENTUALLY BE ENHANCED TOWARD THE
END OF THE PERIOD INTO EARLY NEXT WEEK AS CA LOW ENERGY AND
ASSOCIATED SFC SYSTEM REACHES THE GREAT LAKES.

WHAT WE CAN SAY WITH RELATIVE CERTAINTY IS THAT WE DO NOT EXPECT
ANY HEAT WAVES OR EXTENDED PERIODS OF DRY WEATHER OVER THE NEXT 7+
DAYS.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
SENT 03Z TAF PACKAGE.

STILL SOME SHOWERS AND STORMS ACROSS THE EAST.

EARLIER DISCUSSION BELOW.

CONDITIONS OVER THE STILL MAINLY RAIN FREE LOWER SUSQ
VALLEY...WITH REDUCED CONDITIONS CONTINUING OVER THE LAUREL
HIGHLANDS WHERE SHOWERS ARE MORE NUMEROUS.

EXPECT SHOWER ACTIVITY TO INCREASE IN COVERAGE AND SPREAD FROM
SOUTH TO NORTH THROUGH THE AFTERNOON. SHOWERS WILL TEND TO BE
SLOW-MOVING AND COULD PRODUCE HEAVY DOWNPOURS AND LOCAL IFR
CONDITIONS. THE UPPER LOW WILL WEAKEN AS IT ENTERS CENTRAL PA
OVERNIGHT...BUT WE SHOULD MAINTAIN A RISK FOR SCT SHOWERS.

EXPECT CIGS/VSBYS TO TREND GRADUALLY LOWER OVERNIGHT GIVEN
DIURNAL COOLING...VERY HUMID AIRMASS AND LIGHT WINDS...WITH AT
LEAST MARGINAL RESTRICTIONS LIKELY AT MANY SITES INTO TUESDAY
MORNING.

LOWER CONDITIONS TUESDAY MORNING WILL IMPROVE BY MID MORNING TO
MID DAY. A COLD FRONT WILL APPROACH THE AIRSPACE FROM THE LOWER
LAKES/OH VALLEY BY LATE IN THE DAY AND SHIFT SLOWLY SEWD INTO THE
AIRSPACE TUE NIGHT/WED BEFORE STALLING OUT NEAR PA/MD BORDER
THURS INTO FRIDAY.

OUTLOOK...

WED-SAT...VFR/MVFR WITH PERIODS OF SHRA/AFTN TSTMS.

&&

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

&&

$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LA CORTE/LAMBERT
LONG TERM...GARTNER/STEINBUGL
AVIATION...LA CORTE/MARTIN


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