High Wind in California, November 24, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
300 AM PST SAT NOV 24 2001

LATE FRI NIGHT WE WERE MOMENTARILY CONCERNED AS THE INCOMING STORM
WAS ACTUALLY LOSING ENHANCEMENT AS IT MOVED EWD.  THE TRAILING
SYSTEM N OF HI APPEARED TO BE TAKING ENERGY FROM OUR STORM.
HOWEVER...SINCE THEN OUR STORM HAS ENHANCED RAPIDLY AND RAIN BEGAN
ALMOST SIMULTANEOUSLY OVER OUR ENTIRE DISTRICT IN THE MIDNIGHT-1AM
TIME FRAME.  THE WATER VAPOR PIX INDICATE SOME COMPLEX JET ACTION.  A
WLY JETMAX MOVING INTO THE BACK OF THE FRONTAL BAND NEAR 35/135 HAS
HELPED ENHANCE THE BAND OVER THE PAST COUPLE OF HOURS. ANOTHER JETMAX
IS SWEEPING ONTO THE CNTRL COAST AND APPEARS TO BE PROVIDING LIFT
THAT STARTED THE RAIN OVER MONTEREY COUNTY AS EARLY AS ANYWHERE ELSE
IN THE DISTRICT.  A THIRD JETMAX IS VISIBLE DROPPING SEWD INTO THE
BACK OF THE UPPER LEVEL TROF ASSOCIATED WITH THE STORM.  THIS IS
ADDING A LITTLE EXTRA ENERGY AND COLD AIR TO THE SYSTEM.

THESE FEATURES APPEAR TO ALL BE COMBINING TO RAPIDLY INTENSIFY THE
STORM...JUST AS THE MODELS PREDICTED.  THE HEAVIEST WEATHER FOR OUR
REGION WILL PROBABLY BE BETWEEN ABOUT 4 AM AND NOON AS STRONG UPPER
DIFFLUENCE DEVELOPS AND THE FRONTAL BAND MOVES ONSHORE.
EXTRAPOLATION FROM THE SAT LOOPS CONFIRMS THE MODEL FORECASTS OF
MOVING THE FRONT THRU THE N BAY BY ABOUT 18Z AND THRU MRY COUNTY BY
EARLY AFTN.  THE AVN IS FASTER THAN THE ETA BUT THEY BOTH MOVE THE
SYSTEM THRU RAPIDLY.  ALL AREAS WILL GET A GOOD SHOT OF HEAVY RAIN
BUT DUE TO THE SPEED OF THE SYSTEM ANY ONE PLACE WILL PROBABLY ONLY
EXPERIENCE A DOWNPOUR FOR ABOUT 2-5 HOURS.  CURRENT QPF VALUES OF UP
TO 3 INCHES IN THE WETTEST AREAS LOOK OK...MOST CITIES WILL PROBABLY
GET ONLY 3/4 TO 1 1/2 INCHES.

WINDS ARE RISING RAPIDLY AND THE CURRENT WIND ADVISORY SHOULD VERIFY
NICELY THIS MRNG.  ITS UP FOR THE WHOLE DAY AND WE MAY WIND UP
CANCELING IT SOMETIME THIS AFTN...ESPECIALLY IN THE N BAY NEAR THE
PROJECTED TRACK OF THE SURFACE LOW CENTER.  ALTHOUGH THE MODELS KEEP
A STEEP PRESSURE GRADIENT AFTER FROPA AND MAINTAIN STRONG BOUNDARY
LAYER WINDS...IN FACT THE SURFACE WINDS USUALLY DECREASE RAPIDLY
AFTER FROPA.  DUE TO TIMING DIFFERENCES IN THE MODELS WILL NOT TWEAK
THE ADVISORY RIGHT NOW...BUT EXPECT THE STRONGEST WINDS BEFORE NOON.

WITH THE EARLY FRONTAL PASSAGE...WILL CUT POPS A LITTLE TNGT/SUN AS
WE SHOULD SEE RAPID DRYING.  WOULD CUT THE POSTFRONTAL POPS EVEN
MORE EXCEPT THE AVN FORECASTS OUR DISTRICT TO BE IN THE LEFT FRONT
QUAD OF A DIFFLUENT NWLY JET THIS EVE...AND THIS MAY ENHANCE
SHOWERS AS THE COLD AIR IN THE UPPER TROF REALLY DIGS INTO OUR
DISTRICT.  HOWEVER...SHOWERS SHOULD END BY MIDMRNG SUN EXCEPT
POSSIBLY IN MRY COUNTY WHERE THEY USUALLY PERSIST THE LONGEST IN A
COLD NWLY FLOW WITH LINGERING LOW LEVEL MOISTURE.

THE MODELS NOW BRING ANOTHER BATCH OF MOISTURE THRU THE DISTRICT ON
MON...ASSOCIATED WITH THE TRAILING SYSTEM N OF HAWAII.  THE AVN/ETA
PROJECT RAIN INTO THE N BAY MON AFTN...WHILE THE CANADIAN HOLDS MOST
MOISTURE OFF TIL MON EVE.  WILL HIT THOSE PERIODS WITH SOME RAIN...
THEN DRY TUE/WED UNDER RIDGING BEFORE ANOTHER SYSTEM BREAKS DOWN THE
RIDGE AND BRINGS MORE RAIN THU.  THE NEW MRF IS MUCH WEAKER WITH THE
THU STORM THAN THE PREVIOUS RUN.
STS +63  SFO/SJC/LVK +74  MRY +87.  MARKKANEN

.SFO...TDA...WIND ADVY...ALL ZONES.
             GALE WRNG...PT ARENA TO PT PIEDRAS BLANCAS AND
                         SFO/MRY BAYS.