Severe Thunderstorm Warning 239, NWS State College, PA

CENTRAL PENNSYLVANIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
155 AM EST THU NOV 8 1996

...ZONE SUGGESTIONS/COORDINATION...
...PIT/PHL...NO SIG CHANGES TO SUGGEST. AGREE BEST RAIN THREAT ERN
ZONES WHERE HIGHEST PWATS AND BEST DYNAMICS SET TO CLASH. ONCE
AGAIN CONCERN IS FOR STRONG ENVIRONMENTAL WINDS TO MIX DOWN WITH
ISOLATED CONVECTION AND CAUSE THINGS TO FALL DOWN HERE AND THERE.
WUDN'T GO HIGHER THAN WIND ADV FOR GENERAL CONDITIONS AND EVEN THAT
IS "IFFY" AS CONDITIONS ARE FAIRLY TRANQUIL THUS FAR. DO THINK SE
SXNS WILL BE UNDER MORE CONVENTIONAL SVR THREAT LATER TODAY AS
PARAMETERS COME TOGETHER A BIT BETTER. WUD MENTION POSSIBLE STRONG
THUNDER IN SE ZONES.

...DISCUSSION...
INGREDIENTS SEEM TO BE FALLING INTO PLACE FOR BIG PRECIP MAKER.
STRONG ANAFRONT MOVING EAST INTO APPALACHIANS ACCOMPANIED BY 10-15
DEG TEMP DROPS AND HEAVY PRECIP. ALMOST 5 INCHES OF RAIN IN KY FROM
STORM AND DYNAMICS ARE STRENGTHENING.

SATELLITE SHOWS CONNECTION TO DEEP TROPICS ON WATER VAPOR WITH
PRECIP WATER ANALS IN EXCESS OF 1.5" POISED TO SURGE INTO CENTRAL
AND ERN SXNS DURING DAY. ALSO EVIDENT ON SATELLITE IS DEVELOPING
ANTICYCLONIC BULGE ON BACKSIDE OF MASSIVE BAROCLINIC ZONE WHICH
EXTENDS FROM WRN FL TO JUST EAST OF JAMES BAY. THIS SUPPORTS MODEL
IDEAS OF MULTIPLE WAVES SURGING NORTH ALONG FRONT AS DAY WEARS ON.

WAVY FRONT AT 05Z WAS JUST WEST OF YTR-PIT-HTS-CHA LINE. CONTINUITY
AND PROGS PUTS IT FROM ABOUT COUDERSPORT TO JOHNSTOWN BY 12Z AND
JUST EAST OF ERN CTP CWA BY AROUND 00Z. SYSTEM BEARS A PASSING
RESEMBLANCE TO OCT 20-22 SYSTEM WHICH BROUGHT WIDESPREAD R+ TO
REGION. DEEPENING UPPER TROF IS PROGGED TO DROP INTO ERN GR LAKES
AREA STEEPENING UPPER HGHTS AND CAUSING SFC FRONT TO SLOW
CONSIDERABLY UNDER INCREASINGLY PARALLEL UPPER FLOW WHILE WAVES
FORM AND MOVE UP ALONG IT. AS UPPER LOW DEEPENS AND CUTS OFF...
UPSTREAM RIDGE PUMPS UP BIG TIME ALLOWING JET STREAK ON ERN SIDE OF
TROF TO STRENGTHEN CONSIDERABLY. RESULT IS STRONG NEG TILT TROF AND
POTENT RIGHT ENTRANCE REGION JET CIRCULATION SETTING UP AND MOVING
INTO NERN US. THIS IS A RELIABLE BIG RAIN PRODUCER AS SFC FRONT
RESPONDS TO STRONG FRONTOGENETIC FORCING ON LOWER BRANCH OF
THERMALLY DIRECT JET CELL. MAIN DIFFERENCE BETWEEN OCT 20-22 CASE
AND THIS ONE...IF MEMORY SERVES ME RIGHT...OCT CASE DEVELOPED SFC
LOW ON COAST AND MOVED IT MORE SLOWLY UP TWD NEW ENG WHERE MORE
THAN A FOOT AND A HALF OF RAIN RESULTED. PROGS HANGING MORE ENERGY
BACK WEST WITH THIS SYSTEM WHICH SHUD PRECLUDE SLOW MOVING COASTAL
LOW...BUT STILL MAKE FOR A BIG RAIN.

AS IS THE CASE WITH MANY OF THESE TYPE SYSTEMS...CONCERN BECOMES
POSSIBILITY OF ISOLATED WIND DAMAGE AS FRONT NEARS AND CONVECTION
STARTS TO MIX ENVIRONMENTAL WINDS DOWN TO SFC. GRIDDED DATA SHOW
50-60KT AT 850 ENTRENCHED THRU PM HOURS. SE PA IS PROGGED TO GET
MODERATELY UNSTABLE AS DAYTIME HEATING AND ALMOST SUMMER LIKE
HUMIDITY COMBINE IN WARM AIR. WUD THINK THAT AREA VULNERABLE TO
MORE TRADITIONAL TYPE OF SEVERE OUTBREAK. TIME OF YEAR AND CLOUDS
IN WARM SECTOR WILL LIMIT INSTABILITY...BUT SUPERIOR DYNAMICS CAN
OVERCOME THIS. MODELS PAINT FAIR AMOUNT OF SHEAR IN LOWER ATMOS.
NEED TO BE AWARE OF TORNADO THREAT AS MESO SCALE FORCING EXERTS
ITSELF IN THE FORM OF SFC WAVES RIDING ALONG FRONT AND POSSIBLY
ENHANCING LOW LEVEL VORTICITY FIELDS.

...LAKE SNOW OUTLOOK...
THU 7AM - 7PM...N
THU 7PM - 7AM...N
FRI 7AM - 7PM...N

LA CORTE