SPC MESOSCALE DISCUSSION #0035 FOR NRN CA COAST..FAR SWRN ORE COAST
CONCERNING...SEVERE THUNDERSTORM POTENTIAL...

VALID 251511Z - 251700Z

NARROW SQUALL LINE WITH EMBEDDED BOW ECHOES WILL MOVE INLAND OVER
NRN CA OVER THE NEXT COUPLE OF HOURS...AND WILL REACH THE EUREKA
AREA BY 1630Z.  CONVECTIVE SYSTEM WILL LIKELY WEAKEN QUICKLY ONCE
IT MOVES ASHORE.

VWP FROM KBHX INDICATED SUBSTANTIAL SHEAR OVER THIS REGION...WITH
SR-HELICITIES OVER 400 M2/S2 AND 0-6 KM SHEAR IN EXCESS OF 50 KT. 
THIS SHEAR IS SUSTAINING EMBEDDED BOW ECHOES AND LEWPS WITHIN
SQUALL LINE INVOF COLD FRONT NOW SHIFTING NEWD AT 40 KT.  WATER
VAPOR IMAGERY SUGGESTS VERY STRONG AND DEEP LIFTING OCCURING AHEAD
OF IMPRESSIVE UPPER LOW CIRCULATION NOW MOVING TOWARDS THE NRN
CA/SRN ORE COAST.  

MODEL SOUNDINGS NEAR THE COAST YIELD VERY LITTLE INSTABILITY OVER
LAND DUE TO SURFACE TEMPERATURES IN THE 40S.  HOWEVER WHEN THESE
SOUNDINGS ARE MODIFIED USING CURRENT WATER TEMPERATURES IN THE
LOWER 50S...CAPES INCREASE INTO THE 100-200 J/KG RANGE.  THIS IS
MORE THAN SUFFICIENT FOR ORGANIZED CONVECTION AND THE THREAT OF
DAMAGING WINDS AND/OR AN ISOLATED TORNADO AS THE LINE MOVES INLAND
WITHIN THE NEXT 1-2 HOURS.  GIVEN THE WEAK INSTABILITY INLAND AND
MOUNTAINOUS TERRAIN...ACTIVITY SHOULD WEAKEN CONSIDERABLY AFTER
LANDFALL.

..EVANS.. 01/25/01