370
FXUS66 KMTR 030002
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
402 PM PST SUN FEB 2 2025
..NEW AVIATION, MARINE
SYNOPSIS
ISSUED AT 248 AM PST SUN FEB 2 2025
LIGHTER RAIN IS EXPECTED TODAY BEFORE MORE WIDESPREAD MODERATE TO
HEAVY RAIN RETURNS MONDAY INTO TUESDAY AND WET WEATHER CONTINUES
THROUGH THE END OF THE WEEK. ADDITIONAL FLOOD PRODUCTS ARE LIKELY
TO BE ISSUED THIS WEEK AS INCREASED RUNOFF WILL RESULT IN
ADDITIONAL NUISANCE FLOODING AND SEVERAL RIVERS HAVE THE POTENTIAL
TO RISE ABOVE FLOOD STAGE (SEE HYDROLOGY SECTION).
SHORT TERM
ISSUED AT 150 PM PST SUN FEB 2 2025
(THIS EVENING THROUGH MONDAY)
KEY POINTS:
*FLOOD ADVISORIES CONTINUE FOR NORTH BAY SUNDAY EVENING
*SECOND ATMOSPHERIC RIVER WILL BRING MODERATE TO HEAVY RAIN
MONDAY INTO TUESDAY WITH GUSTY WINDS.
*THIRD ATMOSPHERIC RIVER WILL BRING ONE FINAL ROUND OF RAIN LATE
WEEK
*MUCH COLDER TEMPERATURES BY NEXT WEEKEND
NEAR TERM IMPACTS - RAINS FROM SATURDAY/SATURDAY NIGHT CAUSED
STREAMS/CREEKS TO RISE IN SONOMA PROMPTING FLOOD ADVISORIES. LIGHT
RAIN TODAY ADDED TO ALREADY FULL STREAMS SO FLOOD ADVISORIES
REMAIN IN EFFECT THROUGH AT LEAST TONIGHT. SOME ADVISORIES MAY
NEED TO BE CANCELLED EARLY AS WATER LEVEL LOWER. OTHERWISE, TODAY
IS DEFINITELY FEAST OR FAMINE WITH CLOUDS AND RAIN. KMUX RADAR
CONTINUES TO SHOW SHOWERS STREAMING ACROSS THE BAY AREA AND SANTA
CRUZ MTS. ALSO NOTEWORTHY - RAIN SHADOWING IS IN FULL EFFECT WITH
LITTLE TO NO RAIN IN THE SANTA CLARA.
TONIGHT THROUGH MONDAY: HERE'S THE 20K FOOT VIEW ACROSS THE REGION
AND EASTERN PACIFIC. A ROBUST MOISTURE PLUME (UP TO 1.85" PWAT)
EXTENDS FROM NEAR HI TO THE NORCAL COAST. AT THE SURFACE A NEARLY
STATIONARY FRONT REMAINS DRAPED ACROSS FAR NORTHERN CALIFORNIA (N
OF BAY AREA), WHICH EXTENDS WESTWARD TO A LOW PRESSURE SYSTEM
NEAR 33N 148W. OVER THE NEXT 12 HOURS, MOISTURE WILL CONTINUA TO
STREAM NORTHEAST AND ALONG THE STATIONARY BOUNDARY. AS A RESULT,
PERSISTENT RAIN IS EXPECTED NORTH OF THE BAY AREA. HOWEVER, THERE
IS ENOUGH LINGERING MOISTURE OVER THE BAY AREA AND CENTRAL COAST
THAT NON-IMPACTFUL SHOWERS WILL CONTINUE TONIGHT. BY EARLY MONDAY
A 100+KT SUB-TROPICAL JET WILL HELP NUDGE THE SURFACE LOW
EASTWARD OVER THE EPAC. THIS WILL DO TWO THINGS: CAUSE THE
BOUNDARY TO THE NORTH TO BEGIN TO DRIFT SOUTHWARD AND BRING EVEN
MORE MOISTURE RICH PWAT AIR TOWARD BAY AREA WITH A COLD FRONT.
THE FIRST PART OF MONDAY WILL BE THE PROVERBIAL CALM BEFORE THE
NEXT STORM WITH A FEW SCATTERED SHOWERS AND INCREASING WINDS. BY
MONDAY AFTERNOON, A COLD FRONT BEGINS TO KNOCK ON THE NORTH BAY'S
DOORSTEP WITH HIGHER PWAT AIR INTERACTING WITH THE SFC BOUNDARY.
RAIN WILL INCREASE IN COVERAGE AND INTENSITY BY LATER
AFTERNOON/EVENING RUSH FOR THE NORTH BAY. THE SURFACE COLD FRONT
IS THEN FORECAST TO MOVE S AND E BRINGING MODERATE TO HEAVY RAIN
WITH IT. IMPACTS TO THE BAY AREA EVENING COMMUTE ARE LIKELY.
IN ADDITION TO RAIN CONCERNS WINDS WILL INCREASE AS THE COLD FRONT
APPROACHES FROM THE NORTH DURING THE DAY ON MONDAY. WINDS WILL BE
STRONGEST OVER THE COASTAL WATERS, IMMEDIATE COASTLINE, AND
HIGHER TERRAIN. THERE IS A 3-6 HOUR WINDS WITH THE FROPA MONDAY
EVENING/MONDAY NIGHT THAT AREA WILL FLIRT WITH WIND ADVISORY
CRITERIA, BUT COVERAGE WILL LIMITED AND THE TIME FRAME SHORT SO
WILL HOLD OFF ON WIND ADVISORY FOR NOW. GUSTS 35 TO 50 MPH
POSSIBLE.
LONG TERM
ISSUED AT 150 PM PST SUN FEB 2 2025
(MONDAY NIGHT THROUGH NEXT SATURDAY)
THE DYNAMICS AND HIGHER PWAT AIR ARE PRETTY SOLID MONDAY NIGHT
AND TUESDAY AS THE COLD FRONT MOVES S AND E. ADDITIONAL SUPPORT
WILL BE FELT ALOFT AS WELL WITH THE ARRIVAL OF A LEFT EXIT JET
REGION (AREA OF DIFFLUENCE ALOFT/ASCENT). HI-RES MODELS ARE ALSO
KEYING IN ON ENHANCED OROGRAPHIC LIFTING WITH HIGHER RAINFALL
ALONG THE COASTAL MOUNTAINS. FINALLY, AR GUIDANCE INDICATES IVT
AND IWV VALUES IN THE REALM OF MODERATE TO NEAR STRONG INTENSITY.
AS SUCH, HAVE BUMPED UP RAINFALL AMOUNTS ACROSS MOST OF THE
FORECAST AREA, ESPECIALLY THE SANTA CRUZ AND SANTA LUCIA MT RANGES
MONDAY THROUGH TUESDAY. RAINFALL TOTALS WITH AR #2 ARE NOW: 4-6"
NORTH BAY MTS, SANTA CRUZ MTS, SANTA LUCIA MTS (6-9" JACKPOTS
ABOVE BIG SUR), 1.5-3.0" ELSEWHERE, LESSER AMOUNTS INTERIOR
CENTRAL COAST AND RAIN SHADOWED SANTA CLARA. WPC HAS THE FORECAST
ARE MAINLY IN A SLIGHT RISK (15%) FOR EXCESSIVE RAINFALL DURING
THIS TIMEFRAME. NEEDLESS TO SAY, WET SOILS, HIGHER STREAM LEVELS,
AND EXPECTED RAINFALL AMOUNTS/INTENSITY WILL LEAD TO ADDITIONAL
FLOODING CONCERNS. CURRENT THINKING IS TO LET CURRENT FLOOD
ADVISORIES/WATCHES END BEFORE ADDITIONAL FLOOD WATCHES GET ISSUED
FOR MONDAY/TUESDAY. FORTUNATELY, MAINSTEM RIVERS APPEAR TO REMAIN
BELOW FLOODING CONCERNS. RAINFALL WILL TRANSITION TO SHOWERS FROM
N TO S ON TUESDAY AS THE FRONT EXITS SOUTHWARD. GUSTY WINDS WILL
LINGER INTO TUESDAY.
A LULL IN ACTIVITY IS EXPECTED ON WEDNESDAY AS ONE SYSTEM EXITS
AND ANOTHER APPROACHES. CURRENT FORECAST WILL KEEP SCATTERED
SHOWERS IN THE FORECAST. HOWEVER, COULD STILL BE DEALING HYDRO
CONCERNS AS CREEKS/STREAMS REMAIN ELEVATED FROM TUESDAY'S RAIN.
THE 3RD AR (WEAK ONE) WILL BEAR DOWN ON THE REGION LATE WEDNESDAY
INTO THURSDAY. THIS SYSTEM WILL NOT BE AS ROBUST. ADDITIONALLY,
THIS SYSTEM IS MUCH COLDER WITH LOWER SNOW LEVELS ACROSS THE
REGION. SOME WET SNOW WILL BE POSSIBLE OVER THE HIGHER ELEVATIONS.
REGARDLESS OF SNOW, STILL LOOKS WET FROM WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT. LASTLY, THE FOCUS OF HEAVIER RAINFALL KEEPS
SHIFTING TOWARD THE CENTRAL COAST. RAINFALL AMOUNTS GENERALLY
0.5-1.5" WITH HIGHEST AMOUNTS ALONG THE COASTAL MOUNTAINS.
AS PRECIP BEGINS TO END ON FRIDAY THE FOCUS QUICKLY SHIFTS FROM
PRECIP TO TEMPERATURES. LATEST FORECAST CONTINUES TO ADVERTISE
SOME VERY COLD TEMPERATURES ACROSS THE INTERIOR (UPPER 20S/LOW
30S). WILL LIKELY NEED A MIX OF FROST/FREEZE PRODUCTS. GIVEN THE
DAMP CONDITIONS FROM RECENT RAINS IT WILL ALSO FEEL COLDER WITH
IMPACTS FOR PEOPLE WITHOUT ACCESS TO ADEQUATE HEAT
OR SHELTER.
AVIATION
(00Z TAFS)
ISSUED AT 401 PM PST SUN FEB 2 2025
A BIT OF A MIXED BAG WITH VFR CONDITIONS NEAR SOUTH BAY AND MONTEREY
BAY, AND A MIX OF MVFR/IFR/LIFR CONDITIONS NEAR SF BAY, EAST BAY,
AND NORTH BAY. SOME TERMINALS WILL IMPROVE BUT MOST TERMINALS WILL
REMAIN MVFR/IFR THROUGH THE TAF PERIOD. MODERATE CONFIDENCE ON
TIMING BUT VFR SHOULD RETURN FOR KLVK NEAR 03Z AND KMRY, KSNS, AND
KSFO BY 18Z. CHANCES FOR RAIN WILL CONTINUE THROUGH THE TAF PERIOD
FOR NORTH BAY BUT MOST TERMINALS WILL START SEEING RAIN RETURNING BY
LATE MONDAY AFTERNOON/EARLY EVENING. SOUTHERLY WINDS WILL START TO
BUILD TO BREEZY AND GUSTY BY MONDAY MORNING.
VICINITY OF SFO...IFR WITH SOME LIGHT RAIN OVER THE TERMINAL. LOW TO
MODERATE CONFIDENCE WHETHER CONDITIONS IMPROVE TO VFR BUT MODELS
HINT AT 06Z. THERE IS A CHANCE THAT MVFR CONDITIONS MAY CONTINUE
THROUGH THE TAF PERIOD, BUT CONFIDENCE IS LOW TO INCLUDE IN TAFS.
EXPECT MVFR CONDITIONS TO RETURN BY MONDAY AFTERNOON AS RAIN
REBUILDS. MODERATE TO BREEZY SOUTHERLY WINDS WILL BUILD TO STRONG
AND GUSTY BY MONDAY MORNING.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...VFR BUT THERE IS A CHANCE FOR MVFR
CONDITIONS OVERNIGHT, BUT THERE IS SOME UNCERTAINTY AS MODELS SHOW
SOME DISAGREEMENTS. IF CEILINGS LOWER, EXPECT NEAR 10-11Z.
MARINE
(TONIGHT THROUGH NEXT SATURDAY)
ISSUED AT 401 PM PST SUN FEB 2 2025
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 840 PM PST SUN FEB 2 2025
SUNDAY AM UPDATE - FLOOD WATCH WAS UPDATED TO CANCEL THE WATCH FOR
AREAS SOUTH OF THE GOLDEN GATE. THE FLOOD WATCH REMAINS IN EFFECT
FOR THE NORTH BAY THROUGH SUNDAY EVENING.
AN ATMOSPHERIC RIVER WILL BRING PERIODS OF LIGHT TO MODERATE
RAINFALL THROUGH NEXT WEEK. THIS WILL RESULT IN AN INCREASED RISK
FOR RAPID RISES IN NORTH BAY RIVERS AND THE ASSOCIATED CREEKS AND
STREAMS. WHILE UNCERTAINTY EXISTS, THE PROBABILITIES OF EXCEEDING
FLOOD THRESHOLDS HAVE INCREASED ACROSS SEVERAL RIVERS IN THE NORTH
BAY. THE FIRST STORM THAT IS CURRENTLY MOVING INTO THE NORTH BAY IS
EXPECTED TO PRIME THE SOILS OVER THE WEEKEND RESULTING IN QUICKER
AND MORE NOTEWORTHY RISES OF AREA STREAMS AND CREEKS FOR THE SECOND
ROUND OF RAIN THAT IS PROGGED TO IMPACT THE NORTH BAY MONDAY INTO
TUESDAY. THE HIGHER ELEVATIONS OF THE NORTH BAY WILL LIKELY
ACCUMULATE AROUND 8 TO 11 INCHES OF (STORM TOTAL) PRECIPITATION
WHILE NORTH BAY VALLEYS WILL LIKELY ACCUMULATE AROUND 4 TO 6 INCHES
OF (STORM TOTAL) PRECIPITATION. SHALLOW LANDSLIDES WILL BE POSSIBLE
IN COASTAL AREAS OF THE NORTH BAY. THE THREAT WILL EXTEND SOUTHWARD
TO HIGHER ELEVATIONS OF THE BAY AREA, PARTICULARLY THE SANTA CRUZ
MOUNTAINS BY TUESDAY.
DETERMINISTIC FORECASTS KEEP MAINSTEM RIVERS BELOW FLOOD STAGE;
HOWEVER, THE EXCEEDANCE PROBABILITIES (OF RISING ABOVE FLOOD STAGE)
FOR REACHING FLOOD THRESHOLDS ARE INCREASING TUESDAY AND WEDNESDAY
ACROSS THE NORTH BAY. THE RUSSIAN RIVER AT GUERNEVILLE - GUEC1 HAS A
50% PROBABILITY OF EXCEEDING ACTION/MONITOR STAGE AND A 36%
PROBABILITY OF EXCEEDING MINOR FLOOD STAGE. SHEC1 - NAPA NEAR
SAINT HELENA HAS A 34% PROBABILITY OF EXCEEDING ACTION/MONITOR
STAGE AND A 23% PROBABILITY OF EXCEEDING MINOR FLOOD STAGE. APCC1 -
NAPA NEAR NAPA HAS A 34% PROBABILITY OF EXCEEDING ACTION/MONITOR
STAGE AND A 20% PROBABILITY OF EXCEEDING MINOR FLOOD STAGE. OTHER
POINTS THAT SHOW A HIGH PROBABILITY OF REACHING ACTION/MONITOR OR
MINOR FLOOD STAGE ARE: CTIC1 - LAGUNA DE SANTA ROSA AT STONY
POINT ROAD NEAR COTATI HAS A GREATER THAN 97.5% PROBABILITY OF
REACHING MINOR FLOOD STAGE, MWEC1 - MARK WEST CREEK AT MIRABEL
HEIGHTS HAS A GREATER THAN 97.5% PROBABILITY OF REACHING
ACTION/MONITOR STAGE AND A 95% PROBABILITY OF REACHING MINOR
FLOOD STAGE, AND GEYC1 - RUSSIAN RIVER AT GEYSERVILLE HAS A 59%
PROBABILITY OF REACHING ACTION/MONITOR STAGE AND A 43% PROBABILITY
OF REACHING MINOR FLOOD STAGE.
SARMENT
MTR WATCHES/WARNINGS/ADVISORIES
CA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 3 AM PST TUESDAY FOR SF BAY N OF BAY
BRIDGE.
SMALL CRAFT ADVISORY FROM 9 AM MONDAY TO 3 PM PST TUESDAY FOR
MRY BAY-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PST TUESDAY FOR PIGEON PT TO PT
PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-PT ARENA TO PT
REYES 0-10 NM-PT ARENA TO PT REYES 10-60 NM-PT REYES TO
PIGEON PT 0-10 NM.
SHORT TERM...MM
LONG TERM....MM
AVIATION...SO
MARINE...JM
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