weather.gov     
National Weather Service

Area Forecast Discussion
NWS Homepage
This page is being discontinued on March 12, 2014.
The same data is available at this site. Please update your bookmarks.
Thank you, and we apologize for the inconvenience.
Please send an email to SR-SRH.Webmaster@noaa.gov with any concerns.


Current Version
Previous Version:    01  02  03  04  05  06  07  08  09  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  
   31  32  33  34  35  36  37  38  39  40  41  42  43  44  45  46  47  48  49  50  51  52  53  54  55  56  57  58  59  60  
[Printable]
947
FXUS61 KCTP 012122
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
522 PM EDT FRI AUG 1 2014

.SYNOPSIS...
A PERSISTENT MID-LEVEL TROUGH TO OUR EAST AND A STRONG RIDGE OVER
THE WESTERN ATLANTIC WILL ALLOW MOISTURE TO MOVE UP THE EAST
COAST. UNTIL THE TROUGH SURGES TO THE EAST OUR REGION WILL BE ON
THE EDGE OF THE MOISTURE PLUME. THE GENERAL TREND OVER THE NEXT
SEVERAL DAYS IS FOR THE MOISTURE PLUME TO SLOWLY SLIDE EAST.
CHANCES OF ORGANIZED RAIN WILL BE GREATER IN THE EAST AND SHOULD
SLOWLY DECREASE SUNDAY INTO TUESDAY.

&&

.NEAR TERM /UNTIL 9 PM THIS EVENING/...
SLOW MOVING SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER THE
LOWER SUSQUEHANNA VALLEY THIS AFTERNOON. BROKEN LINE FROM ADAMS
COUNTY INTO PORTIONS OF YORK AND CUMBERLAND COUNTY. CELLS ALONG
THE TWO APPARENT LINES ARE LUMBERING TO THE NORTHEAST. THEY SHOULD
AFFECT DAUPHIN COUNTY WITHIN THE NEXT HOUR. LOCALLY HEAVY RAIN
POSSIBLE FROM THESE STORMS.

RADAR IS QUITE IN CENTRAL AND NORTHERN AREAS. A FEW WEAK SHOWERS
IN SOMERSET COUNTY ARE TRYING TO DEVELOP BUT SEEM TO WEAKEN AS
THEY MOVE TOWARD CAMBRIA COUNTY. AN AREA TO WATCH.

POPS WILL BE HIGHER CLEARLY OVER SOUTHEAST SLIGHT LOWER IN
SOUTHWEST AND TAPER OFF AS WE MOVE NORTH TODAY. THE NARRE SHOWS
GOOD AREA OF SHOWERS AND IMPLIED CONVECTION OVER MUCH OF SE PA
THIS AFTERNOON AND WEAKENING THIS EVENING. IT HAS A WEAKER BAND TO
OUR NW WHICH HAS NOT APPEARED ON RADAR...YET. IT IS MUCH WEAKER.

LINGERING RAIN AND SHOWER ACTIVITY EXPECTED IN LOWER SUSQUEHANNA
VALLEY THIS EVENING.

THE FOG AREAS BURNED OFF AND HAVE LEFT AREAS OF HAZY SUNSHINE.

&&

.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM SATURDAY/...
THE FLOW BETWEEN THE 500 HPA TROUGH TO OUR WEST AND THE 500 HPA
RIDGE TO OUR EAST WILL ALLOW MOISTURE PLUME TO SURGE INTO THE
MID-ATLANTIC REGION SATURDAY. THIS WILL INCREASE POPS OVERNIGHT
FRIDAY INTO SATURDAY IN THE EAST. THE NARRE IMPLIES THIS SHOWING
HIGH PROBABILITY OF RAIN/RADAR RETURNS SURGING NORTHWARD FROM
VA/MD/DE IMPLYING IT COULD REACH SE PA OVERNIGHT. IT ALSO HAS SOME
MODEST RETURNS OVER SE PA AT 03Z.

THE NARRE 3HR QPF SHOWS 60-70 POPS IN SE BY AFTER 0000 UTC AND
SURGING AREA HAS 100 PERCENT. THIS IS OF COURSE AND ENSEMBLE
PROBABILITY DISTRIBUTION FUNCTION NOT A MOS-LIKE PROBABILITY. THE
4KM NAM...USED IN THE NARRE...IMPLIES THAT THE RAIN AND SHOWERS
ZIP THROUGH SE PA BEFORE 12Z SATURDAY.

MESSAGE...COULD BE SURGE OF RAIN/THUNDER OVERNIGHT INTO SATURDAY
MORNING IN SE PA.

NAM-GFS-SREF SUGGEST HIGHER POPS IN EAST SATURDAY AM AND MORE
LINGER CLOUDS. LOWER POPS TO WEST THOUGH IMPLIED QPF SHIELDS SHOW
A SQUEEZE PLAY WITH A ZONE OF VERY LOW POPS EXTENDING FROM NY INTO
PA. BUT THIS DRY ZONES POSITION VARIES MODEL TO MODEL. THE NAM IS
MUCH DRIER IN SW MOUNTAINS THAN GFS.

DUE TO DEEP MOISTURE BOUNDARY KEPT POPS RELATIVELY HIGH IN
EAST/SOUTHEAST AND SW MOUNTAINS AND LOWER TO NORTH AND WEST. THE
4KM NAM IMPLIES PRETTY QUIET OVER THE REGION AROUND 8 AM AND
NOTHING OF NOTE CONVECTIVELY UNTIL AFTERNOON. THEN IT SHOWS
LITTLE ORGANIZATION AND MOSTLY SCATTERED SHOWERS...MOST IN WEST-
CENTRAL.

MESSAGE...LOTS OF UNCERTAINTY SATURDAY BUT RELATIVELY DRY MORNING
AFTER 7-8AM IN EAST THEN SCATTERED SHOWERS/TSTMS SATURDAY
AFTERNOON.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
THE FORECAST AREA WILL BE NEAR THE NWRN EDGE OF THE EXTENSIVE
DEEP MOISTURE PLUME STREAMING NNE FROM THE ERN GOMEX AND WRN
ATLANTIC THIS WEEKEND. THE SHORT WAVE TROUGH TO OUR WEST...AND
PERIODS OF WEAK-MDT LARGE SCALE UVVEL ASSOCIATED WITH COMPACT
WAVES AT THE SFC AND ALOFT RIDING NEWD...WILL SPARK ISOLATED TO
SCATTERED NOCTURAL SHOWERS...AND A CHANCE OF A FEW AFTERNOON TSRA
BOTH SUNDAY AND MONDAY.

THE MID AND UPPER FLOW VEERS AROUND TO THE WEST TUESDAY AHEAD OF
SIGNIFICANT UPPER WAVE /AND POTENT SFC CFRONT/ DROPPING SE ACROSS
THE GLAKES. A SECONDARY CFRONT WILL MOVE SE THROUGH THE AREA
DURING THE DAY WEDNESDAY. PWATS WILL BE DROPPING BACK TO NEAR OR
SLIGHTLY BELOW NORMAL /EVEN AHEAD OF THE 2 CFRONTS/.
HOWEVER...850-500 MB LAPSE RATES AHEAD OF BOTH FEATURES WILL BE AS
MUCH AS 6.5C/KM...WHICH WILL LEAD TO SCATTERED...MAINLY AFTERNOON
AND EARLY EVENING TSRA. A FEW OF THE TSRA EACH AFTERNOON COULD BE
ON THE STRONG SIDE. 0-3KM BULK SHEAR WILL BE AOB 15 KTS...SO THE
CFROPAS BOTH DAYS DON/T APPEAR TO POSE A SIGNIFICANT...CONVECTIVE
WIND THREAT ATTM.

FOR LATER NEXT WEEK...A LARGE AREA OF HIGH PRESSURE AT THE SFC
/BENEATH BROAD WESTERLY CONFLUENT FLOW ALOFT/ WILL BUILD IN FROM
THE MIDWEST AND SHOULD BRING AT LEAST A FEW DAY PERIOD OF PARTLY
TO MOSTLY SUNNY WEATHER AND LOW HUMIDITY.

A BLEND OF GEFS...GFS...AND EC GUIDANCE INDICATES SLIGHTLY RISING
HEIGHTS AND A WEAK SHORT WAVE OR TWO EMBEDDED IN THE WESTERLY FLOW
ALOFT. THIS WILL BRING AN INCREASE IN PWATS LATE FRIDAY NIGHT AND
SATURDAY WITH SCATTERED SHRA/TSRA DEVELOPING AS WE HEAD INTO NEXT
WEEKEND.

AFTER A NEAR PERFECT MATCH OF MONTHLY AVG HIGH AND LOW TEMPS TO
NORMAL AT KMDT AND KIPT IN JULY...MAX AND MIN TEMPS IN THE LONG
TERM PERIOD DON/T APPEAR TO STRAY SIGNIFICANTLY FROM NORMAL.
THE WARMEST TEMPS APPEAR TO BE TUESDAY AHEAD OF THE INITIAL CFRONT
AS A DECENT WESTERLY DOWNSLOPE LLVL COMPONENT KICKS IN.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS ACROSS THE REGION...EXCEPT SOME AREAS LIKELY SEEING
ISOLATED MVFR/IFR CONDITIONS IN SHOWERS AND THUNDERSTORM OVER THE
MIDDLE/LOWER SUSQUEHANNA REGION.

BASED ON LATEST RADAR...HAVE REMOVED VCTS FROM TAFS FOR THE
REMAINDER OF THIS AFTERNOON AND EVENING. ONLY TAF SITE WHICH LOOKS
IMMINENT TO SEE A SHOWER IN THE NEXT HOUR OR TWO IS KIPT...AND
HAVE INCLUDED VCSH IN THEIR TAF.

FOR THE MOST PART...DIURNAL SHOWERS SHOULD WANE DURING THE
EVENING. HOWEVER...SHORT TERM / HIGH RESOLUTION MODELS HINT AT
REGENERATING PRECIPITATION FOR THE SOUTHEASTERN AIRFIELDS
OVERNIGHT.

OVERALL...LOOK FOR FOG AND HAZE DEVELOPMENT OVERNIGHT...WITH
WIDESPREAD MVFR...AND AREAS OF IFR/LIFR.

CONDITIONS IMPROVE SATURDAY BUT THE CLOUDS AND MOISTURE TO OUR
EAST ARE NOT FORECAST TO MOVE OUT ALL TOO FAST.

OUTLOOK...
SAT-SUN...AM MVFR/IFR...THEN MAINLY VFR BUT WITH SCATTERED AFTERNOON
SHRA/TSRA IMPACTS POSSIBLE.
MON...POSSIBLE AM FOG AREAS MVFR/IFR. OTHERWISE MAINLY VFR.
TUE...SCATTERED SHRA/TSRA WITH APPROACHING COLD FRONT.
WED...SCATTERED SHRA/TSRA.
&&

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

&&

$$
SYNOPSIS...GRUMM
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...ROSS/LAMBERT
AVIATION...GRUMM/JUNG




U.S. Dept. of Commerce
NOAA National Weather Service
1325 East West Highway
Silver Spring, MD 20910
E-mail: w-nws.webmaster@noaa.gov
Page last modified: May 16, 2007
NATIONAL WEATHER SERVICE: for Safety, for Work, for Fun - FOR LIFE