Area Forecast Discussion
Issued by NWS State College, PA

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000
FXUS61 KCTP 210245
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1045 PM EDT WED AUG 20 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 THURSDAY MORNING/...
STILL SOME WIDELY SCATTERED SHOWERS AND THUNDERSTORMS ABOUT THE
STATE TONIGHT CENTRAL AREAS. THERE IS ONE PERSISTENT AND SLOW TO
DIE ORGANIZED AREA OF CONVECTION OVER ELK AND NORTHERN CLEARFIELD
COUNTIES TONIGHT. IT IS MOVING SLOWLY TO THE SOUTH AND EAST. IT
HAS HELD TOGETHER ON RADAR FOR HOURS AND COLD CLOUD AREA IMPLIES
IT HAS SOME LIFE LEFT. LOW-LEVEL VELOCITY DATA IMPLIES IT HAS A
COLD POOL WHICH WILL LIKELY ALLOW IT TO PERSIST FOR A FEW MORE
HOURS. SO WE HAD TO KEEP RAIN AND POPS 80 TO 90 PERCENT UP THERE.

THE HRRR SHOWS THIS SYSTEM SPLITTING AND GOING ACROSS CENTRAL PA
THROUGH 0700 UTC. COULD SEE ISOLATED THUNDER AND RAIN AREAS IF THE
23Z HRRR IS CORRECT.

MOST OTHER AREAS UNAFFECTED BY THIS CONVECTION SHOULD SEE FOG
DEVELOP. PERHAPS PATCHY DENSE FOG IN AREAS.

&&

.SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...

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. THE 13KM RAP FROM 0100 UTC
SHOWS LITTLE OR NO RAINFALL OVERNIGHT AND ORGANIZED RAIN WELL TO
OUR WEST IN MORNING HOURS. AN OPTIMISTIC ENSEMBLE OF TWO.

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 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 /03Z THURSDAY THROUGH MONDAY/...
DID NOT CHANGE A LOT ON THE 00Z TAF PACKAGE FROM THE EARLIER
SET.

MAIN CONCERN IS CONVECTION ACROSS THE NW NEAR BFD. OTHER
WIDELY SCATTERED SHOWERS AND STORMS COULD MOVE EAST INTO
THE REST OF THE AREA OVERNIGHT.

MAIN ISSUE FOR AVN CONCERN OVERNIGHT WILL BE FOG AND LOW
CLOUDS WITH LGT/VRB WINDS AND HIGH BLYR MSTR/SFC DEWPOINTS.
FOR THIS...WENT CLOSE TO EARLIER FCST. DID LOWER CIGS IN
SOME CASES. A BLEND OF GUIDANCE AND TIMING FROM LAST NIGHT.

FOR THU...EXPECT LESS SHOWER AND THUNDERSTORM ACTIVITY...AS
THE WIND SHIFT LINE AND DYNAMICS SHIFT EASTWARD.

OUTLOOK...
FRI-SAT...AM LOW CLOUDS/FOG FOLLOWED BY PERIODS
OF SHOWERS/TSTMS AND BRIEF MVFR/IFR RESTRICTIONS.
SUN-MON...MAINLY VFR.

&&

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

&&

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



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