AREA FORECAST DISCUSSION

FXUS66 KMTR 251139
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
400 AM PDT MON OCT 25 2004

.DISCUSSION...A WEAK SHORTWAVE BROUGHT LIGHT RAINS TO A GOOD PORTION
OF THE DISTRICT ON SUNDAY...WITH AMOUNTS GENERALLY UNDER A TENTH OF
AN INCH. TODAY IS EXPECTED TO BE DRY...AWAITING THE ARRIVAL OF A
STRONGER STORM SYSTEM THAT WILL BE DRIVING RAIN INTO THE REGION FROM
THE NORTH TONIGHT AND TUESDAY. THE MAIN UPPER LOW WITH THE UPCOMING
STORM IS CURRENTLY ALONG THE CENTRAL BC COAST AND IS PROGGED TO DROP
DOWN TO THE OR COAST ON TUE. THE HEAVIEST RAIN SWATH WILL BE SOUTH OF
THIS LOW ALONG A COLD FRONT WRAPPING AROUND THE LOW. CURRENT TIMING
FROM THE GFS AND ETA IS PRETTY CLOSE...WITH THE ETA ONLY ABOUT 3
HOURS SLOWER THAN THE GFS. LOOK FOR RAIN TO ARRIVE IN THE N BAY
DURING THIS EVENING...ACROSS THE BAY AREA BY MIDNIGHT...AND INTO THE
MRY BAY REGION BEFORE DAWN TUESDAY.

INCREASING SOUTHERLY WINDS ARE EXPECTED AHEAD OF THE FRONT BEGINNING
ACROSS THE NORTH BAY THIS EVENING AND SPREADING ACROSS THE REST OF
THE CWA LATER TONIGHT INTO TUESDAY MORNING. WHILE SOME GUSTY WINDS
ARE LIKELY...THIS STORM SHOULD NOT BE NEARLY AS WINDY AS THE ONE
LAST WEEK AS THE SURFACE LOW WILL GENERALLY BE WEAKER AND FURTHER
N. THE 850 MB JET IS PROGGED AT 35-45 KT THIS TIME COMPARED TO THE
45-55 KT JET LAST WEEK. ONCE AGAIN WITH THIS STORM...WE WILL BE IN
THE LEFT FRONT QUAD OF A 140 KT 250 MB JET DIVING S AND SE AROUND THE
BACK OF THE LOW TONIGHT INTO TUE
...ALONG WITH A STRONG VORT MAX AND
OMEGA FIELD MOVING OVER THE CENTRAL COAST. THESE DYNAMICS WILL
HELP SUPPORT LOCALLY HEAVY RAINS...AND EVEN AN ISOLATED THUNDERSTORM
OR TWO
..
.ESPECIALLY WHEN CONDITIONS TURN MORE SHOWERY BEHIND THE
FRONT TUESDAY AFTERNOON AND EVENING. THE FRONT WILL MOVE THROUGH ON
TUESDAY...PERHAPS NOT QUITE AS QUICKLY AS EARLIER FORECASTED...AND
QPF PROJECTIONS FROM CNRFC/HPC HAVE TICKED UP SOMEWHAT...NOW RANGING
FROM 3/4 OF AN INCH TO 1 1/2 INCHES AT LOWER ELEVATIONS TO 1 1/2 TO 2
1/2 INCHES OVER HIGH TERRAIN WITH THE SANTA LUCIA MOUNTAINS FORECAST
TO RECEIVE THE HIGHEST AMOUNTS.

SHOWERS WILL CONTINUE BEHIND THE FRONT INTO WED AS THE UPPER LOW WILL
BE CENTERED OVER NERN CA/NWRN NV WHILE A SECONDARY LOW FORMS OVER OUR
SRN DISTRICT. THE UPPER LOW WILL MOVE EAST WED NIGHT AND THU AND
MEDIUM RANGE MODELS DEVELOP A CUTOFF LOW IN THE TROF WEST OF NRN
BAJA. RIDGING NORTH OF THE CUTOFF SHOULD KEEP THE DISTRICT DRY
THROUGH THE END OF THE WEEK AND INTO THE WEEKEND. COOL TEMPS MOST OF
THE WEEK WILL WARM SLIGHTLY BY THE WEEKEND AS 850 TEMPS RISE FROM
2C DURING THE STORM TUE-WED TO 8-10C FRI-SAT. COOLING ALOFT WILL
RETURN LATE IN THE WEEKEND AND EARLY NEXT WEEK AS HEIGHTS DROP IN
RESPONSE TO A LONG WAVE TROF DROPPING DOWN THRU THE WRN HALF OF THE
CONUS. AT THIS POINT...MOST OF THE RAIN WITH THAT TROF SUN-MON IS DUE
TO REMAIN TO OUR N AND E...BUT WE COULD BE IN LINE FOR MORE RAIN
RIGHT AFTER THAT BY ELECTION DAY...AS A SHORT WAVE DROPS INTO THE
TROF...ALTHO THE HEAVIEST WILL STILL BE UP IN FAR NOCAL THEN.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...NONE.




NEWMAN