Severe Thunderstorm Warning 89, NWS State College, PA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
925 AM EDT WED JUN 14 1995

WATER VAPOR SHOWS UPPER LOW LIFTING NE ALONG ERN SEA BOARD WITH
LAST OF DEFORMATION ZONE CLOUDS OVER PA BREAKING UP AS LOW LIFTS.
88D SHOWS WEAK RETURNS AVP-YORK ALSO SHOWING SIGNS OF DRYING UP.

MAIN CONCERN TODAY IS NGM PROG OF T-TOTALS >56 AND LI'S -5 OVER PA
BY 00Z (UNABLE TO LAND ETA). SFC BOUNDARY IS DROPPING ALMOST DUE
SOUTH WITH WATER VAPOR SHOWING AN UPPER LEVEL TROF IN TOW.
SATELLITE AND MODELS HINT AT BEST UPPER SUPPORT SHEARING OFF TO OUR
NORTHEAST BUT WITH SFC FEATURE PLOWING DOWN INTO INSTABILITY
...AFTERNOON COULD PROVE TO BE SOMETHING OTHER THAN QUIET.

INTERESTING CONFLICTS IN THE MODELS...AT LEAST THE AVN AND NGM. NGM
MAKES IT VERY UNSTABLE WHILE MAKING SFC DEWPOINTS ONLY NUDGE ABOVE
50. AVN PROGS SFC DEWPOINTS TO 60 OR HIGHER. HARD TO RESOLVE GIVEN
NRLY FLOW AND NO TD'S UPSTREAM NEAR 60. DIFFERENCES LIKELY ARISE
FROM AVN MAKING ATMOS MUCH COOLER IN LOW LEVELS (EVAP COOLING FROM
HIGHER QPF?) AND AS MUCH AS 3 DEG WARMER IN MID TO UPPER LEVELS.
ANOTHER PARADOX IS AVN CRANKING OUT MORE PRECIP THAN NGM DESPITE
ABOVE PARAMETERS POINTING TO MORE STABLE LATE DAY AIRMASS. NEED TO
LOOK AT 12Z AND SEE WHICH MODEL INITIALIZES BETTER TO DECIDE WHICH
IS LYING. WHAT THEY AGREE ON IS UPPER LEVEL WIND FIELD PRODUCING
WEAK CONVERGENCE OVER AREA BY 00Z. HAVE SEEN THIS THWARTED MANY
TIMES WHEN CONVECTION PUNCHES THRU THO. IF NGM PANS OUT...WUD NOT
BE SURPRISED TO SEE SELS OUTLOOK FOR SLGT SVR. BUF SOUNDING DRY IN
MID LEVELS AND ONLY NEEDS TO BE TWEAKED A LITTLE TO COME UP WITH LI
OF -7 AND A CAPE OF 2300. GUSTY TRW WILL BE THE MAIN THREAT SHUD
ANY DEVELOP.

THINK LOW POPS STILL RSNBL GIVEN SOME DEGREE OF INSTABILITY AND A
LOW LEVEL TRIGGER TO APPROACH DURING THE PM.

    HI TEMPS      POPS
BFD   75           3
UNV   76           3
AOO   79           3
JST   75           3
IPT   82           3
MDT   78           3

LA CORTE