Severe Thunderstorm Warning 94, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
145 PM EDT TUE JUN 16 1998

WORK ZONES WILL BE SENT TO PIT AND PHL VIA PHLADMCTP BY 245 PM.

...DISCUSSION...

15Z SFC ANAL SHOWS A WEAK DIFFUSE SFC PATTERN.  THE PRIMARY COLD
FRONT IS ARCED FROM NEAR ART TO JUST NE OF LGA AND IS FOCUSING +SHRA
AND +TSRA OVER E NEW ENG.  IN ITS WAKE DEWPTS ARE IN THE MID 60S
WITH LOW 70S UP INTO THE MID ATL.  THE AIR IS RATHER MOIST UP
THROUGH 85H WITH VERY WEAK WINDS ALOFT.  WE HAVE ALSO COOLED ABOUT A
DEGREE AT 50H AND WILL COOL ANOTHER BY 0Z WED.  SO AIR MASS BECOMING
MORE UNSTABLE AS AFTN PROGRESSES.

WIND PROFILES REMAIN UNFAVORABLE FOR WIDESPREAD SVR WX THRU THE AFTN
BUT WITH LIGHT WINDS ALOFT THERE IS SOME POTENTIAL FOR BACK
BUILDING. THIS COULD LEAD TO ENOUGH RAIN FOR SOME FLASH FLOODING BUT
THE PICTURE IS SO DIFFUSE IT IS TOUGH TO MAKE A CALL AS TO WHERE TO
PUT UP THE WATCH.

MY INCLINATION IS TO PLACE IT ACROSS THE NORTH AND CENTRAL WHERE A
WARM FRONT APPRS TO BE DEVELOPING ON THE SAT LOOP. BUT THE SHRA
DEVELOPING ALONG THIS BOUNDARY APPRS TO BE MOVG RIGHT ALONG AND WE
NEED TO CONCENTRATE OR SLOW SHRAS TO PRODUCE ENUF RAIN FOR FF.

ANOTHER AREA FOR POTENTIAL FF WOULD BE SOUTHERN TIER COUNTIES WHERE
VORT MAX IS EXPECTED TO CROSS.  INFLOW AT LOW LEVELS IS QUITE STRONG
WHEN COMPARED TO WINDS ALOFT AND THIS COULD SLOW THE NET MOVEMENT OF
STORMS AND DUMP HEAVY RAIN.  PWATS ARE HIGHER OVR S PA MD WV AND VA
AND A SOUTH OR SW INFLOW AT LOWER LEVELS COULD PULL IN SOME GOOD
JUICE FOR HEAVY RAIN PRODUCERS.  I WOULD WAIT AND SEE IF CENTRAL AND
NORTH BECOMES ACTIVE THIS PM AND IF IT DOES NOT...ISSUE FFA FOR
SOUTHERN COUNTIES.

SE PA AND LOWER SUSQ WILL SEE RAIN AFTER SUNSET.  AREA APPRS CAPPED
AFTER CFROPA BUT COOL POOL AT 50H SHUD MOVE OVR TONITE AND
DESTABILIZE THIS REGION.  GUIDANCE NUMBERS ARE LOW IN THIS REGION
AND BACK BUILDING IS POSSIBLE AS WARM MOIST AIR RETURNS ON LLJ
DEVELOPING AHEAD OF VORT MAX THIS EVENING.

WE FINALLY START DRYING OUT WED WITH TROPA AND SUBSIDENCE ON BACK
SIDE...SUN WILL BE MORE PREVALENT.  CANT RULE OUT THE CHANCE OF A
TSHR THOUGH AS THERE WILL BE SOME RESIDUAL MOISTURE.  BUT THESE WILL
BE OF THE POPCORN VARIETY AND WILL NOT PRODUCE ANY HEAVY RAIN.
MODEL SOUNDING TOMORROW IS SLIGHTLY CAPPED BUT THERE WILL BE MORE
SFC HEATING. SO A 30 POP MIGHT NOT BE A BAD IDEA.

HEAD

PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-162100-

SEVERE WEATHER OUTLOOK
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1145 AM EDT TUE JUN 16 1998

...THUNDERSTORMS COULD PRODUCE LOCALLY EXCESSIVE RAINFALL THIS
AFTERNOON AND THIS EVENING...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING...

...DETAILS...

THE RISK AREA INCLUDES ALL OF CENTRAL PENNSYLVANIA.

A VIGOROUS UPPER LEVEL WEATHER SYSTEM IS TRIGGERING AN EXPANDING
AREA OF THUNDERSTORMS OVER OHIO...INDIANA AND KENTUCKY LATE THIS
MORNING.  THESE STORMS ARE MOVING NORTHEAST TOWARD CENTRAL
PENNSYLVANIA.

THE GREATEST THREAT FROM THUNDERSTORMS WILL BE EXCESSIVE RAINFALL
THAT COULD CAUSE FLASH FLOODING. ISOLATED HAIL AND STRONG STRAIGHT
LINE WINDS ARE ALSO A POSSIBILITY.

AT THIS TIME IT IS TOO SOON TO DETERMINE WHAT PART OF CENTRAL
PENNSYLVANIA HAS THE GREATEST RISK OF FLASH FLOODING.  WHEN
CONDITIONS COME INTO FOCUS THIS AFTERNOON...A FLASH FLOOD WATCH MAY
BE REQUIRED.

SKYWARN ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

HEAD

PAZ024>028-033>036-056-057-059-063>066-170200-

SPECIAL WEATHER STATEMENT...SEVERE THUNDERSTORM WATCH
NATIONAL WEATHER SERVICE STATE COLLEGE PA
420 PM EDT TUE JUN 16 1998

...A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR SOUTHERN
PENNSYLVANIA INCLUDING THE FOLLOWING COUNTIES...

CAMBRIA...BLAIR...HUNTINGDON...MIFFLIN...JUNIATA...PERRY...DAUPHIN...
LEBANON...SOMERSET...BEDFORD...FULTON...FRANKLIN...CUMBERLAND...ADAMS
...YORK... AND LANCASTER COUNTIES.

...DETAILS...

AN AREA OF STRONG TO SEVERE THUNDERSTORMS ARE MOVING TOWARD
PENNSYLVANIA.  THE AIR MASS OVER THE SOUTHERN PART OF THE STATE HAS
BECOME INCREASINGLY UNSTABLE AND WILL MAINTAIN THE THUNDERSTORM
COMPLEX WELL INTO THE EVENING.

HAIL TO 2 INCHES IN DIAMETER AND WIND GUSTS TO 80 MPH ARE POSSIBLE
WITH THESE STORMS AS THEY MOVE THROUGH.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD REMAIN ALERT TO THREATENING WEATHER
CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.

HEAD