Severe Thunderstorm Warning 129, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
145 PM EDT MON AUG 11 1997

...SUGGESTIONS...

PIT...THINK TUES WILL BE DOMINATED BY COOL AIR DAMMING REGIME WITH
SFC HIGH PASSING NORTH. BEST WX LIKELY TO BE IN PM AFTER SUN HAS
HAD A CHANCE TO SCOUR OUT THE LOW CLOUDS AND FOG. THINK CHC OF RAIN
TMRW WILL BE SMALL AND ONCE AGAIN CONFINED MAINLY TO PM HRS. WUD
USE LOWEST POPS AVAILABLE. WED SHOWERS AND THUNDERSTORMS CUD BE
SEVERE.

PHL...AGREE WITH IDEA THAT RAIN WILL RETURN TMRW NITE AFTER BREAK
TMRW. MODELS STILL MAKE AREA A BIT UNSTABLE TUE PM SO LOW CHC POPS
MAY BE BEST ALL BUT FAR NORTH WHERE DRIEST AIR SETTLES IN AND STAYS
MOST STABLE. THINK IT WILL START OFF CLOUDY ALL AREAS WITH
IMPROVEMENT LATE AM AND PM AS SUN BURNS UP THE STRATUS. ERN ZONES
ARE FURTHEST REMOVED FROM STRONGEST LIFT TUE NITE WITH WARM FRONT
...BUT MODELS COOK UP IMPRESSIVE WARM THETA-E ADVECTION EVEN OVER
CTRL PA SO R/RW LOOKS LIKELY. WED...SAME AS ABOVE.

...DISCUSSION...
FRONT DROPPING INTO NRN MOUNTAINS ACCOMPANIED BY SHOWERS AND
POSSIBLE THUNDER. ACTIVITY FORMS A NICE LINE FROM NEAR SYR BACK TO
SOUTH OF CLE. SOUTH OF THERE RW/TRW ARE MORE SPORADIC AND
DISORGANIZED. DESPITE CONSIDERABLE CLOUDCOVER...REGION IS GROWING
MORE UNSTABLE ACCORDING TO MESO ANALS OFF ADAP AND PSU HOMEPAGE
DATA. DEWPOINTS ARE POOLING INTO THE UPPER 60S LOCALLY WHICH
ACCOUNTS FOR MOST OF THE DECREASE IN STABILITY. WIND FIELDS REMAIN
WEAK SO ORGANIZATION IS UNLIKELY EXCEPT ALONG FRONTAL BOUNDARY.
EVEN THERE DON'T EXPECT SEVERE DUE TO INSTABILITY BEING LIMITED BY
LACK OF SUN.

BIGGER PICTURE HAS FRONT SAGGING SOUTH OVER THE NEXT 12HRS BEFORE
STALLING JUST TO OUR SOUTH. ETA/NGM AND AVN ALL COME IN LINE IN
DEVELOPING SIGNIFICANT SHORTWAVE AND ACCOMPANYING SFC CYCLONE LATER
TUES INTO WED. BY WED AM SYSTEM IS SURGING UP TO OUR WEST WHILE
DEEPENING SIGNIFICANTLY. COLD FRONT AT 12Z IS ENTERING OHIO VALLEY
SUGGESTING A STRONG FROPA DURING MAX HEATING HERE WED.

FOR AUG DYNAMICS ARE IMPRESSIVE WITH STRONG UPPER WIND FILED
DEVELOPING AND MOVING EAST. AT THIS TIME IT APPEARS AS IF BEST
OVERRUNNING TYPE RAINS WILL SURGE UP TO OUR WEST TUE NITE WITH PA
BEING ON ERN FRINGE OF STRONG ISENTROPIC LIFT. WE SHUD STILL SEE A
PERIOD OF LGT-MDT RAINS ACCOMPANYING WARM FRONT TMRW NITE SO
INCREASING POPS LOOKS LIKE THE WAY TO GO. WE THEN SEE WARM FRONT
MOVE THRU ALLOWING DESTABILIZATION DURING THE DAY WAITING FOR COLD
FRONT TO ARRIVE.

STRONG UPPER JET MOVES EAST WITH ETA AND NGM SHOWING REGION BEING
ON THE NOSE OR JUST ON THE RIGHT SIDE OF THE EXIT REGION DURG WED.
STRONG AGEOSTROPHIC TRANSVERSE CIRCULATION RESULTS WHICH AIDS IN
THE DEVELOPMENT OF AN UNSEASONABLY POTENT JET ON THE LOWER BRANCH
OF THIS CIRCULATION. ALL MODELS COOK UP AN 850 JET ON THE ORDER OF
40-50KT AND SHOOT IT UP INTO THE LOCAL AREA BY ERLY WED. PROGGED
SOUNDINGS SHOW STRONG WIND FIELD AND IMPRESSIVE VEERING STRUCTURE
TO PROFILE. LIMITING FACTOR WILL BE HOW FAST WE CAN GET SUNSHINE
OUT AD COOKING IN WARM SECTOR...PRESUMING COLD FRONTAL TIMING WILL
HOLD TRUE.

BOTTOM LINE LOOKS LIKE WED COULD BE A SEVERE DAY WITH STRONG COLD
FRONT AND IMPRESSIVE DYNAMICS. WITH A RETREATING WARM FRONT AN$D
PROGGED WIND PROFILES...HAVE TO BE AWARE OF TORNADO POSSIBILITIES
WITH ACCOMPANYING CONVECTION.

LA CORTE