955
FXUS66 KMTR 031106
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
306 AM PST MON FEB 3 2025
..NEW SYNOPSIS, SHORT TERM, LONG TERM, MARINE
SYNOPSIS
ISSUED AT 304 AM PST MON FEB 3 2025
A SECOND, STRONGER AR ARRIVES LATER TODAY AND CONTINUES INTO
TUESDAY. THIS SYSTEM IS EXPECTED TO BRING MUCH HIGHER RAIN TOTALS
AND A RETURN TO ELEVATED FLOOD RISK ACROSS THE BAY AREA AND
CENTRAL COAST. A FLOOD WATCH WILL GO INTO EFFECT AT 4 PM PST THIS
AFTERNOON AND WILL REMAIN IN EFFECT THROUGH 4 AM PST WEDNESDAY.
WET WEATHER WILL CONTINUE THROUGH THE REMAINDER OF THE WEEK.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 304 AM PST MON FEB 3 2025
KEY POINTS:
* FLOOD ADVISORY CONTINUES FOR PORTIONS OF SONOMA COUNTY INTO MONDAY
* FLOOD WATCH GOES INTO EFFECT 4 PM MONDAY THROUGH 4 AM WEDNESDAY
ACROSS THE BAY AREA AND CENTRAL COAST
* SECOND AR ARRIVES LATE MONDAY BRINGING MODERATE TO AT TIMES HEAVY
RAIN
* THIRD AR ARRIVES THURSDAY-FRIDAY BUT IS EXPECTED TO BE WEAKER AND
AIMED FARTHER SOUTH
* COLD MORNING TEMPERATURES RETURN MID-WEEK BUT TEMPERATURES
WILL DROP MORE SIGNIFICANTLY OVER THE WEEKEND
LIGHT SHOWERS CONTINUE TO THE NORTH OF OUR CWA BUT ARE EXPECTED TO
SHIFT SOUTHWARDS AGAIN AS A SECOND, STRONGER, AR ARRIVES LATER
TODAY. FORECAST IVT VALUES ARE IN EXCESS OF 600 TO 700 KG/MS WHICH
IS SUPPORTIVE OF A MORE MODERATE INTENSITY AR ARRIVING MID TO LATE
MONDAY AND CONTINUING INTO TUESDAY. THE FIRST ROUND OF MODERATE TO
HEAVY RAIN WILL TAKE PLACE LATER IN THE DAY ON MONDAY AND A SECOND
ROUND OF HEAVIER RAIN WILL TAKE PLACE ON TUESDAY. WHILE THE BULK OF
THE MOISTURE IS STILL LOCATED TO OUR NORTH, THERE WILL BE ENOUGH
LINGERING MOISTURE FOR LIGHT SHOWERS ACROSS THE REGION MONDAY
MORNING. BY THE LATE MORNING/EARLY AFTERNOON, SHOWERS WILL START TO
PICK UP IN INTENSITY ACROSS THE NORTH BAY AS TROUGHING DEEPENS OVER
THE PACIFIC AND A SHORTWAVE APPROACHES THE WEST COAST. THIS
SHORTWAVE, IN COMBINATION WITH THE SUB-TROPICAL JET LIFTING
NORTHWARD, WILL PUSH THE MAIN MOISTURE PLUME SOUTHWARDS WITH SHOWER
ACTIVITY SUBSEQUENTLY INCREASING THROUGHOUT THE DAY ACROSS THE BAY
AREA AND CENTRAL COAST. AT THE SAME TIME, A STATIONARY COLD FRONT
OVER NORTHERN CA WILL GRADUALLY GIVE WAY TO A MORE PROGRESSIVE COLD
FRONT AS A SURFACE LOW ASSOCIATED WITH THIS SHORTWAVE MOVES INLAND.
THE INITIAL RAIN (ON MONDAY) WILL PRIMARILY BE CONCENTRATED OVER THE
NORTH BAY THROUGH THE LATE AFTERNOON BEFORE WE START TO SEE MORE
MODERATE INTENSITY RAIN SHIFT SOUTH OF THE BAY BRIDGE OVER THE
EVENING HOURS. RAINFALL TOTALS - FOR MONDAY - WILL BE HIGHEST ACROSS
THE NORTH BAY MOUNTAINS WHICH WILL SEE BETWEEN 1.5"-2". ELSEWHERE,
INITIAL RAIN TOTALS OF UP TO AN 1" ARE POSSIBLE ON MONDAY WITH THE
BULK OF THE RAIN FROM THIS AR TO FALL LATE MONDAY INTO TUESDAY. AS
THIS OCCURS, WE WILL SEE A SOUTHWARDS SHIFT IN WHERE THE HIGHEST
RAINFALL TOTALS ARE LOCATED WITH AN EMPHASIS ON THE SANTA CRUZ
MOUNTAINS AND SANTA LUCIA RANGE (SEE THE LONG TERM DISCUSSION FOR
MORE INFORMATION). GUSTY WINDS RAMP UP ALONG THE COAST AND ACROSS
ELEVATED TERRAIN MONDAY INTO TUESDAY. WHILE WINDS GENERALLY STAY
BELOW WIND ADVISORY CRITERIA, COASTAL AREAS MAY FLIRT WITH WIND
ADVISORY CRITERIA MONDAY AFTERNOON/EVENING AROUND THE TIME OF
FRONTAL PASSAGE. FOR NOW, CONTINUING TO HOLD OFF ON A WIND ADVISORY
DUE TO THE SHORT DURATION AND MORE ISOLATED NATURE OF HIGHER GUSTS
BUT WILL CONTINUE TO MONITOR AND UPDATE IF THINGS CHANGE.
THE WPC HAS ISSUED A DAY ONE (MONDAY) SLIGHT RISK (15%) OF EXCESSIVE
RAINFALL FOR THE NORTH BAY AND A MARGINAL RISK (5%) FOR PORTIONS OF
THE BAY AREA AND CENTRAL COAST. A FLOOD WATCH WILL GO INTO EFFECT AT
4 PM PST ON MONDAY FOR THE BAY AREA AND CENTRAL COAST AS RAIN STARTS
TO RAMP UP IN INTENSITY AND BECOMES MORE WIDESPREAD ACROSS THE
REGION. AS HAS BEEN TALKED ABOUT FOR THE PAST FEW DAYS, RAINFALL
ACROSS THE NORTH BAY AND COASTAL AREAS HAS ACTED TO SATURATE SOILS
AND HAS ESSENTIALLY "PRIMED" THEM FOR FLOODING TO OCCUR. FOR AREAS
THAT HAVE NOT RECEIVED AS MUCH RAIN, MODERATE TO HEAVY RAIN IS
EXPECTED TO SATURATE SOILS FAIRLY QUICKLY MONDAY/TUESDAY WITH
INCREASED POTENTIAL FOR URBAN NUISANCE FLOODING AS HEAVIER RAIN
RATES OCCUR. WHILE THE MOST RECENT CNRFC FORECASTS CONTINUE TO LIMIT
MAINSTREAM RIVER FLOODING TO THE NORTH BAY, SMALLER CREEKS AND
STREAMS ACROSS THE REST OF THE BAY AREA AND CENTRAL COAST MAY SEE
SHARP RISES AS THE BULK OF THE RAIN PASSES THROUGH. IF YOU ENCOUNTER
A FLOODED ROADWAY OR ROAD CLOSURE BARRICADES REMEMBER - TURN AROUND,
DON'T DROWN!
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 304 AM PST MON FEB 3 2025
HEADING INTO TUESDAY, HEAVIER SHOWERS WILL SPREAD INTO THE REST OF
THE BAY AREA AND CENTRAL COAST OVERNIGHT WITH THE HIGHEST
ACCUMULATIONS ANTICIPATED IN THE SANTA CRUZ MOUNTAINS AND SANTA
LUCIA RANGE. RAIN MAY BRIEFLY LIGHTEN MID TO LATE MORNING BUT
WIDESPREAD HEAVY RAIN WILL RETURN TUESDAY AFTERNOON AS A SECOND
PULSE OF MOISTURE (HIGHER IVT VALUES IN EXCEEDANCE OF 700 KG/MS)
ARRIVES. THIS SECOND PULSE WILL BE ASSOCIATED WITH WITH THE GREATEST
FLOOD RISK AS ANY AREAS NOT PREVIOUSLY SATURATED BY THE FRIDAY TO
SUNDAY RAINS WILL BE AT LEAST PARTIALLY SATURATED FROM THE MONDAY TO
EARLY TUESDAY MORNING RAINS. MODERATE TO HEAVY RAINS WILL THEN
PERSIST THROUGH THE EVENING HOURS BEFORE RAINS DECREASE IN INTENSITY
OVERNIGHT TUESDAY INTO WEDNESDAY. WHEN ALL IS SAID AND DONE FROM
MONDAY TO TUESDAY, THE NORTH BAY WILL (IN TOTAL) SEE AN ADDITIONAL
2"-4", AN ADDITIONAL 1"-3" SOUTH OF THE BAY BRIDGE, 3"-5" IN THE
SANTA CRUZ MOUNTAINS, 1"-2" ACROSS THE CENTRAL COAST, AND 5"-8"+ IN
THE SANTA LUCIA RANGE. GIVEN THAT THE MOISTURE PLUME IS ORIENTED
ALMOST PERPENDICULAR TO THE COASTLINE, AREAS WHERE OROGRAPHIC UPLIFT
IS FAVORED MAY SEE LOCALLY HIGHER TOTALS THAN PREVIOUSLY MENTIONED.
AN ADDITIONAL FACTOR IS THAT OVER THE LAST FEW GRID UPDATES THE
FORECASTED QPF TOTALS HAVE CONTINUED TO INCREASE FOR THIS EVENT WITH
PARTICULAR EMPHASIS ON THE SOUTHERN PORTIONS OF OUR CWA (SANTA CRUZ,
MONTEREY, AND SAN BENITO COUNTIES). AS SUCH, IT IS IMPORTANT TO STAY
UP TO DATE ON THE MOST RECENT FORECAST AND BE AWARE THAT THERE IS
ELEVATED POTENTIAL FOR FLOODING TO OCCUR. THE WPC HAS ISSUED A
WIDESPREAD DAY TWO (TUESDAY) SLIGHT RISK (15%) OF EXCESSIVE RAINFALL
EXCEEDING FLASH FLOOD GUIDANCE ACROSS THE BAY AREA AND COASTAL
CENTRAL COAST AND A MARGINAL RISK (5%) OF EXCEEDING FLASH FLOOD
GUIDANCE ACROSS INTERIOR MONTEREY/SAN BENITO COUNTIES. GUSTY WINDS
WILL CONTINUE THROUGH THE DAY ON TUESDAY BEFORE WEAKENING TUESDAY
NIGHT INTO WEDNESDAY. WINDS CONTINUE TO LOOK BELOW WIND ADVISORY
CRITERIA ON TUESDAY BUT WE WILL CONTINUE TO MONITOR IN CASE FRONTAL
PASSAGE SLOWS DOWN AND THE TIME PERIOD OF STRONGER WINDS BECOMES
MORE PROLONGED.
WEDNESDAY WILL BE THE LULL BETWEEN OUR MONDAY-TUESDAY AR AND OUR
THURSDAY-FRIDAY AR. LINGERING MOISTURE MAY BE ENOUGH TO SUPPORT
SCATTERED, LIGHT SHOWERS BUT ANY TOTALS FROM THIS WILL GENERALLY BE
BELOW A TENTH OF AN INCH. NOTABLY, MORNING TEMPERATURES WILL BEGIN
TO DROP WEDNESDAY AFTER COLD FRONTAL PASSAGE OCCURS MONDAY/TUESDAY.
THIS MAY NECESSITATE THE ISSUANCE OF FROST/FREEZE PRODUCTS FOR
PORTIONS OF THE BAY AREA AND CENTRAL COAST.
THURSDAY TO FRIDAY WILL SEE A THIRD, ALBEIT WEAKER, AR IMPACTING OUR
CWA WITH ADDITIONAL TOTALS BETWEEN 1"-2" LIKELY ACROSS THE REGION.
THIS SYSTEM WILL BE SPURRED BY THE ARRIVAL OF ANOTHER UPPER LEVEL
SHORTWAVE AND A SURFACE LOW PRESSURE SYSTEM WITH IVT GUIDANCE
SHOWING A SUBTROPICAL MOISTURE TAP. THE MAIN THING TO NOTE ABOUT
THIS SYSTEM IS THAT, SO FAR, IT LOOKS FAIRLY PROGRESSIVE AND HAS
STARTED TO TREND MORE SOUTHWARDS (CENTRAL COAST INTO SOUTHERN CA) ON
RECENT MODEL RUNS. THIS MAY RESULT IN ADDITIONAL FLUCTUATIONS IN
FORECASTED QPF AMOUNTS THURSDAY AND FRIDAY AS WE GET CLOSER TO THIS
AR. ANOTHER COLD FRONT IS EXPECTED TO PASS THROUGH THE REGION ON
FRIDAY BRINGING WITH IT LOCALLY GUSTY WINDS AND A MORE SIGNIFICANT
DROP IN MORNING TEMPERATURES ON SATURDAY/SUNDAY. CURRENT GUIDANCE
SUGGESTS TEMPERATURES MAY DROP INTO THE 30S TO UPPER 20S. THE
COMBINATION OF PROLONGED WET CONDITIONS, GUSTY WINDS, AND COOLER
TEMPERATURES WILL CREATE HAZARDOUS CONDITIONS FOR ANYONE WITHOUT
ACCESS TO ADEQUATE HEATING OR SHELTER. THE ISSUANCE OF ADDITIONAL
FROST AND FREEZE PRODUCTS ARE LIKELY SATURDAY AND SUNDAY.
AVIATION
(06Z TAFS)
ISSUED AT 949 PM PST SUN FEB 2 2025
CONDITIONS ARE STARTING TO IMPROVE, BUT TERMINALS ARE STILL
EXPERIENCING A MIX OF VFR, MVFR, IFR, AND LIFR CONDITIONS (WITH
IFR/LIFR MOSTLY IN THE NORTH BAY). LOW CONFIDENCE ON CLEARING TO
VFR, AS MOST MODELS SHOW TERMINALS REMAINING MVFR/IFR THROUGH THE
TAF PERIOD. CHANCES FOR RAIN WILL CONTINUE THROUGH THE TAF PERIOD
FOR NORTH BAY BUT MOST TERMINALS WILL START SEEING HEAVIER RAIN
RETURNING BY LATE MONDAY AFTERNOON/EARLY EVENING. MODERATE TO
BREEZY SOUTHERLY WINDS OVERNIGHT, WITH WINDS BUILDING TO BREEZY
AND GUSTY BY MONDAY MORNING.
VICINITY OF SFO...VFR BUT THERE IS A HIGH CHANCE THAT MVFR WILL
RETURN SHORTLY AFTER 06Z, AS CONFIDENCE IS LOW THAT CEILINGS WILL
REMAIN LIFTED. RAIN HAS HALTED FOR A MOMENT BUT EXPECT POSSIBLE
VICINITY SHOWERS THROUGH THE NIGHT. MODELS DO SHOW THAT HERE IS A
CHANCE THAT MVFR/IFR CONDITION PREVAILING THROUGH THE TAF PERIOD,
BUT CONFIDENCE IS LOW TO INCLUDE IN TAFS AT THE MOMENT. EXPECT
MVFR CONDITIONS TO RETURN BY LATE MONDAY AFTERNOON AS RAIN
REBUILDS. MODERATE TO BREEZY SOUTHERLY WINDS WILL BUILD TO STRONG
WITH GUST UP TO 32 KNOTS BY MONDAY AFTERNOON.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR BUT MODELS INDICATE MVFR CEILINGS
BUILDING NEAR 09Z. THERE IS A CHANCE THAT MVFR DEVELOPS A BIT
SOONER, BUT CONFIDENCE IS LOW. ONCE CEILINGS DEVELOP, EXPECT
CONDITIONS TO LINGER INTO MONDAY MORNING, WITH VFR RETURNING BY 17-
18Z.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 304 AM PST MON FEB 3 2025
LIGHT ISOLATED SHOWERS CONTINUES OVERNIGHT BEFORE HEAVIER RAIN
MOVED OVER THE WATER EARLY MONDAY MORNING, ESPECIALLY FOR THE
NORTHERN WATERS. GUSTY SOUTH WINDS WILL PERSIST ACROSS OUR
COASTAL WATERS OUT AHEAD OF A COLD FRONT THAT PASSES THROUGH OUR
AREA BEGINNING TUESDAY MORNING, WHEN GUSTY NORTHERLY WINDS DEVELOP
BEHIND THE COLD FRONT FOR THE REMAINDER OF THE FORECAST PERIOD.
MODERATE SIGNIFICANT WAVE HEIGHTS WITH FRESH SWELLS AND STEEP WIND
WAVES CAN BE EXPECTED TO RESULT IN HAZARDOUS MARINE CONDITIONS.
HYDROLOGY
ISSUED AT 803 PM PST SUN FEB 2 2025
DETERMINISTIC FORECASTS KEEP MAIN STEM RIVERS BELOW FLOOD STAGE;
HOWEVER, THE EXCEEDANCE PROBABILITIES (OF RISING ABOVE FLOOD STAGE)
FOR REACHING FLOOD THRESHOLDS ARE NON-ZERO FOR THE FOLLOWING
MAIN STEM FORECAST POINTS: GUEC1 - RUSSIAN RIVER AT GUERNEVILLE
HAS A 36% PROBABILITY OF EXCEEDING ACTION/MONITOR STAGE AND A 25%
PROBABILITY OF EXCEEDING MINOR FLOOD STAGE, HEAC1 - RUSSIAN RIVER
NEAR HEALDSBURG HAS A 5% PROBABILITY OF EXCEEDING ACTION/MONITOR
STAGE, APCC1 - NAPA RIVER NEAR NAPA HAS A 27% PROBABILITY OF
EXCEEDING ACTION/MONITOR STAGE AND A 20% PROBABILITY OF EXCEEDING
MINOR FLOOD STAGE, SHEC1 - NAPA RIVER NEAR SAINT HELENA HAS A 32%
PROBABILITY OF EXCEEDING ACTION/MONITOR STAGE AND AN 18%
PROBABILITY OF EXCEEDING MINOR FLOOD STAGE, BTEC1 - SAN LORENZO
RIVER AT BIG TREES HAS AN 11% PROBABILITY OF EXCEEDING
ACTION/MONITOR STAGE AND A LESS THAN 2% PROBABILITY OF EXCEEDING
MINOR FLOOD STAGE. DETERMINISTIC FORECASTS FOR THE NON-MAIN STEM
FORECAST POINTS OF CTIC1 - LAGUNA DE SANTA ROSA AT STONY POINT
ROAD NEAR COTATI AND MWEC1 - MARK WEST CREEK AT MIRABEL HEIGHTS
REACH MINOR FLOOD STAGE BETWEEN NOW AND FRIDAY.
SARMENT
MTR WATCHES/WARNINGS/ADVISORIES
CA...FLOOD WATCH FROM THIS AFTERNOON THROUGH LATE TUESDAY NIGHT FOR
CAZ006-502>506-508>510-512>518-528>530.
PZ...SMALL CRAFT ADVISORY UNTIL 3 PM PST THIS AFTERNOON FOR PIGEON PT
TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-SF BAY N
OF BAY BRIDGE.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 9 PM PST THIS EVENING
FOR MRY BAY-SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 3 PM PST THIS
AFTERNOON FOR MRY BAY-PT PINOS TO PT PIEDRAS BLANCAS 0-10
NM.
SMALL CRAFT ADVISORY UNTIL 9 AM PST THIS MORNING FOR PT ARENA TO
PT REYES 0-10 NM-PT REYES TO PIGEON PT 0-10 NM.
GALE WARNING FROM 9 AM THIS MORNING TO 9 PM PST THIS EVENING FOR
PT ARENA TO PT REYES 0-10 NM.
GALE WARNING FROM 9 AM THIS MORNING TO 3 AM PST TUESDAY FOR PT
REYES TO PIGEON PT 0-10 NM.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 9 AM PST TUESDAY FOR
PIGEON PT TO PT PINOS 0-10 NM.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 3 PM PST TUESDAY FOR PT
PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
GALE WARNING UNTIL 9 PM PST THIS EVENING FOR PT ARENA TO PT
REYES 10-60 NM.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 3 AM PST TUESDAY FOR
PIGEON PT TO PT PINOS 10-60 NM.
SHORT TERM...KENNEDY
LONG TERM....KENNEDY
AVIATION...SO
MARINE...CANEPA
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