Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 210646
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
246 AM EDT THU AUG 21 2014

.SYNOPSIS...
AN UPPER LOW OVER THE GREAT LAKES WILL DRIFT SLOWLY SOUTHEAST
ACROSS UPSTATE NY AND NEW ENGLAND BY THE WEEKEND. A LARGE AREA OF
HIGH PRESSURE OVER THE CANADIAN MARITIMES WILL RIDGE SOUTHWARD
ALONG THE EAST-SIDE OF THE APPALACHIANS INTO EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
WATER VAPOR LOOP AT 05Z SHOWING SHORTWAVE OVR WESTERN PA ROTATING
THRU BASE OF UPPER LOW. THIS FEATURE IS SUSTAINING LINGERING
CONVECTION ACROSS THE CENTRAL MTNS AT 05Z AND LATEST RAP/HRRR
OUTPUT SUGGEST DWINDLING SHRA AND A FEW TSRA WILL PUSH INTO THE
EASTERN COUNTIES BEFORE EXITING THE AREA ARND DAWN. BASED ON RADAR
TRENDS AND RAP/HRRR DATA...WILL MAINTAIN HIGHEST /CHC/ POPS ACROSS
THE MID SUSQ VALLEY AND MTNS N OF IPT DURING THE PRE-DAWN HOURS.

WET GROUND...LGT WIND AND CLEARING SKIES BEHIND SHORTWAVE SHOULD
PROMOTE AREAS OF FOG EARLY THIS MORNING. DWPTS INDICATE MIN TEMPS
WILL RANGE FROM THE L/M60S ACROSS THE REGION.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM FRIDAY/...
THE HRRR IS PRETTY POSITIVE ON LITTLE OR NO CONVECTION IN THE
EARLY MORNING. THE CONVECTION AND WAVE IT HAS IN THE MIDWEST IS
FORECAST TO DRIVE INTO THE OHIO VALLEY.

LARGER SCALE MODELS SHOW OUR PW VALUES ARE RELATIVELY LOW IN THE
MORNING AND ARE FORECAST TO SLOWLY RISE DURING THE DAY AND INTO
THE EVENING. THE CAPE IN MOST MODELS COMES UP INTO THE 600 TO
1800JKG-1 RANGE SECOND HALF OF THE DAY.

BEST CHANCE OF SHOWERS AND THUNDERSTORMS WOULD BE IN THE
AFTERNOON. MOST GUIDANCE STILL TENDS TO SUPPORT THIS.

OLDER SREF AND OTHER MODELS SEEM TO IMPLY THIS WITH MORE MEMBERS
WITH RAIN LATER IN DAY. IMPLIED LULL IS IN THE 09 TO 18Z
TIMEFRAME.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CURRENT MID RANGE MODEL GUIDANCE PUTS US IN A RING OF FIRE PATTERN
LATE THIS WEEK AND INTO THE WEEKEND...WITH AFTERNOON CONVECTION
POSSIBLE ON FRIDAY AND SATURDAY. STRONG FLOW ALOFT SHOULD ENHANCE
THIS POSSIBILITY THOUGH LACK OF MOISTURE OF FRIDAY COULD INHIBIT
CONVECTION. GEFS IS SHOWING PWAT ANOMALIES ON SATURDAY AS
SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD THE REGION FROM THE
MIDWEST. CURRENT SET UP FOCUSES THREAT ON WESTERN AND CENTRAL
PA...WHERE EASTERN PA IS LIKELY TO REMAIN DRY. DESPITE APPROACH OF
UPPER RIDGE...NO BIG WARMUP EXPECTED...AS LARGE SFC HIGH OVR THE
CANADIAN MARITIMES WILL CIRCULATE AN EASTERLY FLOW INTO CENTRAL
PA. TEMPS THIS WEEKEND LOOK TO BE BELOW NORMAL. THERE MAY BE
ISSUES WITH AM LOW CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY
FLOW OVR THE AREA. DRIER WEATHER LOOKS TO BE IN STORE INTO EARLY
NEXT WEEK AS RIDGE BUILDS OVER THE REGION.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
UPPER LEVEL S/WV CURRENTLY ROTATING ACROSS CENTRAL PA IS HELPING
TO SUSTAIN ISOLD CONVECTION OVER THE AIRSPACE EARLY THIS MORNING.
ONLY TERMINAL IMPACT ATTM APPEARS TO BE IPT WHICH SHOULD GET A
-SHRA WITH A FEW LTG STRIKES NEARBY 07-08Z. HRRR/COSPA DATA SHOWS
LINGERING SHOWERS DISSIPATING OR MOVG E THROUGH DAYBREAK.

FOG AND LOW CLOUDS LKLY TO BE MORE OF A FACTOR EARLY THIS MORNING
GIVEN RECENT RAIN/WET GROUND...LIGHT WINDS AND HIGH BOUNDARY
LAYER MOISTURE/SFC DEWPOINTS IN THE 60S. CUT BACK ON EXTENT OF IFR
CONDS FROM PREVIOUS FCST WITH HIGHEST CONFIDENCE AT TERMINALS THAT
RECEIVED DECENT RAINFALL YESTERDAY. REDUCED CONDITIONS SHOULD
IMPROVE TO VFR BY MID-LATE MORNING. A CONSENSUS OF HIRES MDL
GUIDANCE INDICATES MORE DISORGANIZED/WDLY SCT SHRA AND TSTMS
DEVELOPING THIS AFTN. WILL LKLY ADD SOME MENTION INTO 12Z TAFS BUT
FOR NOW WENT WITH SCT-BKN 040-050. ANTICIPATE DECREASING CVRG OF
SHRA AND TSTMS INTO THE LATE EVE/OVERNIGHT PERIOD WITH AREAS OF
FOG/ST DEVELOPING AGAIN WITH SOME CLEARING/LGT WINDS/MOIST
AIRMASS.

OUTLOOK...
FRI-SAT...AM LOW CIGS/FOG FOLLOWED BY SCT SHOWERS/TSTMS AND BRIEF
MVFR/IFR RESTRICTIONS.
SUN-MON...AM LOW CIGS PSBL. OTHERWISE MAINLY VFR.

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...FITZGERALD
SHORT TERM...GRUMM
LONG TERM...FITZGERALD/CERU
AVIATION...STEINBUGL


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