Severe Thunderstorm Warning 154, NWS State College, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
750 PM EDT TUE JUL 11 1995

RAMSDIS VSBL IMAGERY SHOWS RW/TRW IN NERN PA FIRING OFF A BNDRY
THAT APPEARS TO HV FORMED OFF LAKE ERIE AND WORKED E ACRS NRN PA.
DARKENING APPARENT ON 4 KM WV IMAGERY THIS EVE ACRS ERN PA
INDICATING THAT S/W TROF WAS ALSO HELPING THE CNVTN ALONG IN NW FLO
SET-UP. SET-UP IN NOT ALL THAT DIFFERENT FROM YSTA EXCEPT S/W IS
WEAKER AND AMS IS A BIT MORE STBL. MOST OF THE ACTION IS E OF FA
AND APPEARS TO BE ON THE WANE ALSO. WV IMAGERY SHOWS ANTI-CYLONIC
TWIST OVR NRN PLAINS INDICATING SIGNIFICANT HGHT RISES AS UPR RDG
BUILDS E. APPEARS THAT SOME SPILL OVER CI FROM CONVECTIVE COMPLEXES
TO OUR NW MAY AFFECT OUR FA OVERNIGHT AFTER DIURNAL CU FALLS APART.
THIS CI LOOKS TO BE THINNING OUT... SO MO CLR WILL WORK ALL ZONES.
DRYER AIR ON N-NW SFC FLO WILL CONTINUE ACRS FA TONIGHT. GRIDDED
DATA SHOWS SIGNIFICANT MOISTURE DVRGE... NEG THETA-E ADVECTION...
AND SUBSDC TONIGHT ACRS REGION SUPPORTING A MAINLY CLR FCST. SUS
VLLY AND OTHER VLLYS IN NRN PA WILL LIKELY BE DECOUPLED OVERNIGHT
INCREASING CHC/S FOR VALLEY FOG. WILL MENTION VLLY FOG MAINLY FOR
PHL CTP ZONES TONIGHT.

A RATHER DRY STBL AIR MASS WILL BE OVER THE REGION ON WED AS SFC
DWPTS ARE MAINLY IN THE 50S. WAA DOES BEGIN DURG THE DAY AND A S/W
IS PROGGED TO APPRCH THE REGION BUT APPEARS TO BE STAYING FAR ENUF
TO THE W. ALSO WITH STBL AIR IN PLACE DON/T THINK THIS S/W WILL DO
MUCH WED NGT. APPEARS ONLY SPILL-OVER CI AND SOME SCT CU FOR WED.
WILL GO PC ALL ZONES.

THE MAIN ACTION WED/WED NGT APPEARS TO BE OVER THE WESTERN LAKES.
MODELS INDICATE A STRG LLJ FEEDING MOISTURE AND INSTABILITY INTO AN
UPR LVL JET SEGMENT N OF MN-MI. WITH SIGNIFICANT ANTI-CYCLONIC
CURVATURE ALOFT ARND UPR RDG... AN MCC IS PSBL OVR GREAT LAKES BY
F36 WHICH WILL INCREASE CHC/S FOR CI WED NGT. SOME SPILL OVER RW
MAY BE A PSSBLY FOR NRN PA LATE WED NGT. WILL NOT PUT IN ZONES
NOW... BUT WILL HV TO KEEP AN EYE ON THIS LATER SHIFTS. NGM FAVORS
THIS SCENARIO MORE HVG CONVECTION FURTHER S THAN ETA WHICH KEEPS
SIG CNTVN WED NGT IN CANADA TO FAR N TO BOTHER US. WILL HV FAIR ALL
ZONES WED NGT FOR NOW.

60 HR AVN REVEALS THAT UPR LVL HI WORKS CLOSE TO REGION AS SRLY SFC
FLO CONTS TO FEED HIGHER DWPTS INTO THE REGION. DWPTS WILL MAINLY
BE IN THE MID-UPPER 60S. NO AVN GRIDS TODAY... BUT TEMPS AT 500 MB
AND 700 MB FROM NGM/ETA GRIDS APPEAR THEY WILL BE PRETTY WARM IN
THIS UPR AIR RDG TO GET HI CAPES. AVN GRIDS ALSO SHOWS SUBSDC AT
700 MB E OF RDG AXIS AS ONE WUD EXPECT. SO THINK AFTRN TRW WILL BE
LIMITED TO OROGRAPHICALLY FRCD AREAS ON THU ONLY. WILL CARRY A 30
POPS ONLY MTN AREAS. NO POPS ELSEWHERE.

CTP ZONES WILL BE SENT AS PHLADMCTPX BY ARND 8 PM.

NICOSIA