Flash Flood Warning 18, NWS State College, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1241 PM EDT TUE JUN 19 2007

.SYNOPSIS...
WARM AND HUMID AIR WILL CONTINUE FOR ONE MORE DAY AS A COLD FRONT
APPROACHES THE REGION. SHOWERS AND A FEW STRONG THUNDERSTORMS WILL
CROSS THE ARE LATER THIS AFTERNOON AND OVERNIGHT. LESS HUMID AIR
RETURNS WEDNESDAY INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 9 PM THIS EVENING/...

SEVERE THUNDERSTORM WATCH IN EFFECT UNTIL 9 PM THIS EVENING.

UPDATE TO ZONES AND HWO TO INCLUDE SEVERE THUNDERSTORM WATCH OVER
THE NORTHERN HALF OF CWA. WATCH IN EFFECT UNTIL 9 PM. TEMPS
CONTINUE TO RISE WITH SUN OVER MOST OF STATE...EVEN AREAS OVER
EASTERN PA WITH CLOUDS HAVE BREAKS ON VISIBLE SATELLITE.
ADDITIONAL HEATING WITH CURRENT DEW POINTS AND DYNAMICS ENTERING
FROM THE WEST WILL ALLOW THUNDERSTORMS TO DEVELOP TO SEVERE LEVELS
OVER THE NORTHERN HALF OF PA. THESE STORMS HAVE THE POTENTIAL TO
PRODUCE LARGE HAIL AND DAMAGING WINDS...IN ADDITION TO HEAVY
RAIN.

FRONT STILL HOVERING OVER CENTRAL PA LATE THIS MORNING WITH A FEW
SHOWERS AND THUNDERSTORMS IN EASTERN PA. CURRENT (15Z) OBS SHOW
TEMPS WARMING INTO THE LOWER 80S IN THE SOUTH AND UPPER 70S IN THE
NORTH. DEW POINTS ARE IN THE 60S STATE WIDE WITH THE HIGHEST
VALUES IN THE SOUTH-EAST QUADRANT WHERE MID TO UPPER 60S DEW
POINTS ARE BEING REPORTED. ARE EXPECTING MORE SHOWERS AND
THUNDERSTORMS TO DEVELOP IN THE AFTERNOON WITH HOT AND SOMEWHAT
UNSTABLE ATMOSPHERE.

&&

.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... RAIN
FOR THE CRISPY LAWNS ARRIVES THIS AFTERNOON AS A FRONTAL BOUNDARY
APPROACHES FROM THE GREAT LAKES. MOIST AIR IN PLACE WITH DEWPOINTS
IN THE 60S ACROSS THE CWA. SUNSHINE WILL DESTABILIZE THE
ATMOSPHERE TODAY AND ALLOW FOR SCATTERED CONVECTION TO DEVELOP
DURING THE AFTERNOON ACROSS THE ENTIRE AREA. 32KM WRF INDICATES AN
AREA OF CONVECTION MOVING QUICKLY NORTH INTO WARREN COUNTY BEFORE
NOON. OTHERWISE ACTIVITY SHOULD DEVELOP AFTER NOON THROUGH FRONTAL
PASSAGE.

SLIGHT RISK FOR TODAY ACROSS THE CWA. EXTRAPOLATION OF CURRENT
FRONTAL LOCATION AND MOVEMENT...AS WELL AS MODEL
AGREEMENT...PLACES IT OVER WESTERN PA AROUND 22Z. BY 06Z/WED THE
FRONT WILL HAVE MOVED EAST OF THE AREA. BOTH THE NAM AND GFS
INDICATES A WEAK SHORT WAVE MOVING INTO SOUTHEAST PA OR RIGHT
ALONG THE BORDER. THIS MAY HELP FIRE CONVECTION ACROSS THAT AREA
EARLY THIS AFTERNOON.

THE 500 MB TROUGH LAGS THE FRONT UNTIL IT REACHES THE ATLANTIC
COAST TOMORROW MORNING SO THE BEST PARAMETERS FOR SEVERE WILL
REMAIN WELL TO THE NORTH. HOWEVER...WOULD NOT BE SURPRISED AS
STORMS OVER WESTERN PA LAST EVENING WERE ABLE TO DROP A FEW TREES
AND HAIL.

WITH THE 500 MB TROUGH LAGGING THE SURFACE FRONT...SHOWERS MAY
LINGER WEDNESDAY MORNING OVER THE CENTRAL AND EAST. ALL AREAS WILL
CLEAR OUT DURING THE DAY WEDNESDAY AS HIGH PRESSURE BUILDS IN.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
NO SIGNIFICANT CHANGES TO THE LONG TERM THINKING AGAIN TODAY. AT
THE BEGINNING OF THE PERIOD A STRONG NORTHERN STREAM TROF WILL BE
TEMPORALLY SQUASHING THE UPPER RIDGE THAT HAD BUILD OVER THE
EASTERN THIRD OF THE COUNTRY. SHOWERS AND THUNDERSTORMS SHOULD BE
ENDING QUICKLY BY WEDNESDAY MORNING AS SURFACE HIGH PRESSURE
MOVES OVER THE STATE.

FROM WEDNESDAY ON...SURFACE HIGH PRESSURE UNDER FLAT TO SLOWLY
BUILDING UPPER HEIGHTS WILL DOMINATE THE REMAINDER OF THE PERIOD.
THIS SHOULD SUPPORT MAINLY DRY CONDITIONS WITH ONLY ISOLATED
SHWR/TSTM ACTIVITY...AND TEMPERATURES WITHIN A FEW DEGREES OF
SEASONAL AVERAGES. SEVERAL SHORTWAVES LOOK TO BE PRESENT IN THE
UPPER FLOW AND MAY SERVE TO STIMULATE MORE THAN ISOLATED CONVECTIVE
ACTIVITY. AT THIS POINT...GUIDANCE SUGGESTS THAT A SIGNIFICANT
TROF WILL MOVE THROUGH THE FLOW ON SATURDAY. HAVE THUS INCREASED
POPS SATURDAY AND SATURDAY NIGHT TO CHANCE RANGE. MUCH OF THE
REST OF THE TIME KEPT POPS TO SLIGHT CHANCE OR LESS.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
WDSPRD 3-5SM BR/HZ WITH SOME LCL IFR /2SM/ THIS MORNING SHOULD
SLOWLY MIX OUT ACROSS THE WESTERN AND CENTRAL TERMINALS AS SFC
DEWPOINTS REMAIN IN THE 60S. DEEP/STRONG LLVL INVERSION WILL KEEP
MVFR HZ LOCKED IN ACROSS THE LWR SUSQ VLY THROUGH AT LEAST NOON.
SCT-BKN MID LVL CLOUDS WILL BE ON THE INCREASE FROM WEST TO EAST
AHEAD OF COLD FRONT MOVG THROUGH THE OH VLY AND LWR GRT LKS.

LATEST MOS GUID BACKING OFF OF THE PROLONGED LOWERED /MVFR/ CONDS
THIS AFTN AND EVENING...FOCUSING MUCH OF THE CONVECTION WITH A
PRE-FRONTAL OR LEE-SIDE TROF THAT SETS UP JUST EAST OF THE SPINE
OF THE APPALACHIANS. GIVEN LACK OF A DISCERNIBLE KICKER SHORT WAVE
OR UPPER LEVEL DISTURBANCE...CONVECTIVE ACTIVITY MAY BE SLIGHTLY
MORE SCT IN NATURE WITH THE BULK OF THE PCPN AND LOWERED CIGS/VIS
ALONG OR BEHIND THE ACTUAL COLD FRONT...WHICH WILL NOT ARRIVE UNTL
LATE THIS EVENING. WILL TRIM BACK THE MVFR A TAD AND DECREASE
CONVECTIVE COVERAGE A BIT IN THE TAFS THIS PACKAGE...WHICH SEEMS
TO GO ALONG WITH THE LATEST MOS TRENDS.

CANNOT TOTALLY RULE OUT AN ISOLD TSRA BY THE EARLY AFTN INVOF
REMNANT QUASI-WARM FRONT. OTHERWISE...TIMING OF BEST TSRA
COVERAGE STILL LOOKS TO BE 19-01Z FROM BFD-MDT. A FEW STORMS MAY
BE SEVERE.

WOULD ANTICIPATE SOME POST-FRONTAL LOWER CIGS AND FOG AS HIGH
PRESSURE BEGINS TO BUILD IN FROM THE WEST CLOSER TO 12Z...ESP
ACROSS THE ERN TERMINALS WHERE -SHRA WILL LKLY LINGER THE LONGEST.

VFR SHOULD DOMINATE THROUGH THE END OF THE WEEK UNTL A MORE POTENT
UPPER LEVEL DISTURBANCE MOVES IN FOR SAT.

&&

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

&&

SYNOPSIS...MARTIN/STEINBUGL
NEAR TERM...ONDREJIK/TYBURSKI
SHORT TERM...FITZGERALD/TYBURSKI
LONG TERM...GARTNER
AVIATION...STEINBUGL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
315 PM EDT TUE JUN 19 2007

PAZ004>006-010>012-017>019-037-041-042-045-046-201915-
WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD-
NORTHERN CENTRE-SOUTHERN CENTRE-TIOGA-NORTHERN LYCOMING-SULLIVAN-
SOUTHERN CLINTON-SOUTHERN LYCOMING-
315 PM EDT TUE JUN 19 2007

...SEVERE THUNDERSTORM WATCH 418 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO
WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE
INFORMATION ABOUT THE FOLLOWING HAZARDS.

   SEVERE THUNDERSTORM WATCH.

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM
WATCH...IN EFFECT UNTIL 9 PM THIS EVENING. THUNDERSTORMS WILL
INCREASE IN COVERAGE THROUGH THE AFTERNOON AND INTO THE EVENING
HOURS ACROSS THE AREA WITH STORMS REACHING A MAXIMUM INTENSITY
DURING PEAK HEATING OR BETWEEN 2 AND 8 PM. DAMAGING WIND GUSTS AND
LARGE HAIL WILL BE THE MAIN SEVERE WEATHER THREATS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

PAZ024>028-033>036-049>053-056>059-063>066-201915-
CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-SOMERSET-BEDFORD-FULTON-
FRANKLIN-UNION-SNYDER-MONTOUR-NORTHUMBERLAND-COLUMBIA-PERRY-DAUPHIN-
SCHUYLKILL-LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER-
315 PM EDT TUE JUN 19 2007

...SEVERE THUNDERSTORM WATCH 420 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO
WEATHER.GOV/STATECOLLEGE ON THE INTERNET FOR MORE
INFORMATION ABOUT THE FOLLOWING HAZARDS.

   SEVERE THUNDERSTORM WATCH.

THE NATIONAL WEATHER SERVICE HAS ISSUED A SEVERE THUNDERSTORM
WATCH...IN EFFECT UNTIL 9 PM THIS EVENING. THUNDERSTORMS WILL
INCREASE IN COVERAGE THROUGH THE AFTERNOON AND INTO THE EVENING
HOURS ACROSS THE AREA WITH STORMS REACHING A MAXIMUM INTENSITY
DURING PEAK HEATING OR BETWEEN 2 AND 8 PM. DAMAGING WIND GUSTS AND
LARGE HAIL WILL BE THE MAIN SEVERE WEATHER THREATS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

GARTNER/ONDREJIK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
237 PM EDT TUE JUN 19 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0220 PM     TSTM WND DMG     5 NE WILLIAMSPORT       41.29N 76.95W
06/19/2007                   LYCOMING           PA   TRAINED SPOTTER

            NUMEROUS TREES DOWN AND MINOR STREET FLOODING NORTH OF
            WILLIAMSPORT.

&&

BENTLEY/HEAD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE STATE COLLEGE PA
239 PM EDT TUE JUN 19 2007

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0230 PM     HAIL             1 N WILLIAMSPORT        41.25N 77.02W
06/19/2007  E0.75 INCH       LYCOMING           PA   TRAINED SPOTTER

            PENNY SIZE HAIL REPORTED IN GRAMPIAN HILLS 1.6 MILES
            NORTH OF WILLIAMSPORT.

&&

BENTLEY/HEAD