375
FXUS66 KMTR 171718
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1018 AM PDT MON MAR 17 2025
..NEW AVIATION, MARINE
SYNOPSIS
ISSUED AT 200 AM PDT MON MAR 17 2025
RAIN WILL CONTINUE ACROSS THE BAY AREA AND CENTRAL COAST THROUGH THE
MORNING WITH POST-FRONTAL SHOWERS AND THUNDERSTORMS POSSIBLE THROUGH
THE DAY. LIGHT RAIN IS EXPECTED IN THE BAY AREA ON WEDNESDAY.
TEMPERATURES REMAIN COOL TO AVERAGE THROUGH THE WEEK WITH A GRADUAL
WARMING TREND TOWARDS THE LATTER PART OF THE WEEK.
UPDATE
ISSUED AT 844 AM PDT MON MAR 17 2025
LIGHT RAIN CONTINUES OVER THE CENTRAL COAST THIS MORNING WITH
CONVECTION STARTING TO DEVELOP OVER THE NORTH BAY. THE GREATEST
INSTABILITY WILL BE OVER THE NORTH BAY AND EAST BAY LATE THIS
MORNING AND AFTERNOON WITH MUCAPE VALUES EXCEEDING 250 J/KG. RAINFALL
AMOUNTS GENERALLY REMAIN LESS THAN 0.05" PER HOUR, BUT ANY SHOWERS
AND/OR THUNDERSTORMS WILL BE CAPABLE OF PRODUCING SMALL HAIL,
LOCALLY HEAVY DOWNPOURS, AND STRONG GUSTY WINDS. THE ONGOING
FORECAST REMAINS ON TRACK THIS MORNING WITH NO UPDATES ANTICIPATED
AT THIS TIME.
RGASS
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 200 AM PDT MON MAR 17 2025
RADAR IMAGERY IS SHOWING TWO SUBSTANTIAL RAIN BANDS MOVING THROUGH
THE FORECAST REGION, ONE THAT IS MOVING THROUGH THE SOUTH BAY AND
THE MONTEREY BAY REGION, AND THE OTHER COMING THROUGH THE NORTH
BAY INTO THE SAN MATEO PENINSULA. BETWEEN THE TWO BANDS,
SCATTERED SHOWERS PREVAIL, AND THERE'S EVEN BEEN SIGNS OF AN NCFR,
FEEBLE THAT THEY MAY BE, BUT ONE WHICH HAS BEEN ASSOCIATED WITH
THE CHANGE IN WIND DIRECTION FROM SOUTHERLY FLOW TO A WESTERLY
REGIME. THESE RAIN BANDS WILL CONTINUE MOVING THROUGH THE REGION
INTO THE EARLY MORNING HOURS. SCATTERED SHOWERS WILL THEN LINGER
THROUGH THE EVENING.
IN THE POST-FRONTAL ENVIRONMENT, THE COLDER AIR ALOFT WILL HELP
INCREASE LAPSE RATES, ALLOWING FOR A CHANCE OF CONVECTIVE ACTIVITY
IN THE BAY AREA AND CENTRAL COAST. THE STORM PREDICTION CENTER HAS
PLACED THE BAY AREA AND MUCH OF THE CENTRAL COAST, INCLUDING THE
MONTEREY BAY REGION, INTO A GENERAL RISK FOR NON-SEVERE
THUNDERSTORMS. ALTHOUGH THE HIGHEST CONVECTIVE RISK REMAINS CENTERED
ACROSS THE CENTRAL VALLEY, THE PROBABILITY OF THUNDERSTORMS REMAINS
AT 10-20% FOR TODAY, AND THE POTENTIAL FOR SMALL HAIL, LOCALLY HEAVY
DOWNPOURS, AND LOCALIZED STRONG GUSTS CONTINUES THROUGH THE DAY. THE
CONVECTIVE RISK SHOULD DIMINISH THIS EVENING, AS THE LACK OF SOLAR
HEATING WILL HELP STABILIZE THE ATMOSPHERE.
BREEZY AND GUSTY WINDS WILL DEVELOP ACROSS THE REGION THIS
AFTERNOON, ALTHOUGH THE WIND SPEEDS WILL NOT BE AS STRONG AS THEY
WERE YESTERDAY. GUSTS OF AROUND 25 TO 35 MILES PER HOUR ARE EXPECTED
ACROSS THE REGION. WE ARE NOT EXPECTING WIDESPREAD WIND ADVISORY-
LEVEL GUSTS TO DEVELOP IN THE REGION, BUT THERE IS A POTENTIAL FOR
GUSTS UP TO 45 MILES PER HOUR ALONG THE COASTS AND AT THE RIDGELINES.
LOW TEMPERATURES THIS MORNING RANGE FROM THE MIDDLE 40S TO NEAR 50
ACROSS THE LOWER ELEVATIONS, INTO THE UPPER 30S TO LOWER 40S IN THE
HIGHER ELEVATIONS. TODAY'S HIGHS RANGE FROM THE MIDDLE TO UPPER 50S
IN THE LOWER ELEVATIONS, DOWN TO THE MIDDLE 40S TO LOWER 50S IN THE
HIGHER ELEVATIONS.
LONG TERM
(TUESDAY THROUGH SUNDAY)
ISSUED AT 222 AM PDT MON MAR 17 2025
CLEAR NIGHTS AND CALM WINDS ACROSS THE REGION WILL LEAD TO SOME
CHILLY MORNING TEMPERATURES TUESDAY AND WEDNESDAY MORNING. A FROST
ADVISORY HAS BEEN ISSUED FOR THE NORTH BAY VALLEYS, THE SOUTHERN
SALINAS VALLEY, THE SANTA LUCIAS, AND THE MOUNTAINS OF SAN BENITO
AND INTERIOR MONTEREY COUNTIES, FOR TUESDAY MORNING FROM 2 AM TO 9
AM, AS LOW TEMPERATURES REACH THE MIDDLE TO UPPER 30S, LEADING TO
THE RISK OF HYPOTHERMIA FOR VULNERABLE POPULATIONS, INCLUDING
CHILDREN, THE ELDERLY, AND PEOPLE WITHOUT ADEQUATE HEATING.
ELSEWHERE, LOWS IN THE INLAND VALLEYS REACH THE UPPER 30S TO LOWER
40S, WITH THE COASTAL REGIONS SEEING LOWS IN THE LOWER TO MIDDLE
40S. SIMILAR TEMPERATURES ARE EXPECTED WEDNESDAY MORNING.
A NEW RAINMAKER ARRIVES ON WEDNESDAY WITH GENERALLY BENEFICIAL
IMPACTS ACROSS THE BAY AREA, WITH UP TO 0.5" IN THE SONOMA COASTAL
RANGES AND THE MAYACAMAS, 0.1-0.25" IN THE NORTH BAY VALLEYS, RAIN
TOTALS RANGE FROM A FEW HUNDREDTHS OF AN INCH TO AROUND A TENTH OF
AN INCH IN THE BAY AREA, UP TO 0.25" IN THE SANTA CRUZ MOUNTAINS,
AND LESS THAN 0.1" IN MONTEREY AND SAN BENITO COUNTIES. A SYSTEM
THAT WAS EXPECTED TO BRUSH PAST THE NORTH BAY LATER IN THE WEEK HAS
CONTINUED TO DRIFT TOWARDS THE NORTH, AND THE CURRENT FORECAST SHOWS
NO APPRECIABLE RAINFALL ACROSS THE FORECAST REGION AFTER THURSDAY.
THROUGHOUT THE REST OF THE WEEK, TEMPERATURES REMAIN COOL TO NEAR
THE SEASONAL AVERAGE ACROSS THE REGION. A GRADUAL WARMING TREND
BEGINS ON TUESDAY, WITH TEMPERATURES IN THE INLAND VALLEYS REACHING
NEAR THE SEASONAL AVERAGE, OR THE MIDDLE TO UPPER 60S, BY MIDWEEK.
BY THE WEEKEND, AS A SHORTWAVE RIDGE BUILDS OVER THE WESTERN UNITED
STATES, MOST OF THE FORECAST REGION WILL SEE TEMPERATURES NEAR OR
SLIGHTLY ABOVE THE SEASONAL AVERAGE, WITH TEMPERATURES REACHING THE
LOWER TO MIDDLE 70S IN THE INLAND VALLEYS AND THE LOWER TO MIDDLE
60S ALONG THE COAST.
AVIATION
(18Z TAFS)
ISSUED AT 1017 AM PDT MON MAR 17 2025
A MESSY AND TRANSIENT TAF CYCLE IS AHEAD OF US AS THE COLD FRONT
THAT BROUGHT WIDESPREAD RAINFALL OVERNIGHT HAS LEFT US WITH, YOU
GUESSED IT, COLDER AIR WHICH IS LEADING TO INSTABILITY ACROSS THE
AREA. BECAUSE OF THIS, THERE'S A SLIGHT CHANCE FOR THUNDERSTORMS
THROUGH SUNSET TONIGHT WHICH WOULD POSE THE RISK FOR LOCALLY HEAVY
RAINFALL AND GUSTY WINDS, LIGHTNING, AND PEA SIZED HAIL. WHILE NO
LIGHTNING HAS BEEN REPORTED YET AND EVEN IF THAT REMAINS TRUE THE
REST OF THE DAY, THE OTHER HAZARDS REMAIN IN PLAY AND HAVE ALREADY
BEEN OBSERVED ACROSS THE REGION. RAIN SHOWER ACTIVITY AND WINDS WILL
DIMINISH AFTER SUNSET.
VICINITY OF SFO...CURRENTLY VFR WITH SOUTHWESTERLY FLOW.
SOUTHWESTERLY WINDS WILL EVER SO SLIGHTLY VEER TO BECOME WESTERLY
AND GUSTY THIS AFTERNOON WITH GUSTS UP TO 35 KNOTS TO BE EXPECTED
THIS AFTERNOON AND EVENING. VFR CONDITIONS ARE EXPECTED TO PREVAIL;
HOWEVER, IF A RAIN SHOWER PASSES DIRECTLY OVER THE TERMINAL EXPECT A
REDUCTION IN CEILINGS AND VISIBILITIES.
SFO BRIDGE APPROACH...SIMILAR TO SFO.
MONTEREY BAY TERMINALS...CURRENTLY VFR WITH SOUTHERLY FLOW AT MRY
AND MVFR AND CALM AT SNS. VFR CONDITIONS ARE EXPECTED TO PREVAIL;
HOWEVER, IF A RAIN SHOWER PASSES DIRECTLY OVER THE TERMINAL EXPECT A
REDUCTION IN CEILINGS AND VISIBILITIES.
MARINE
(TODAY THROUGH SATURDAY)
ISSUED AT 1017 AM PDT MON MAR 17 2025
WIDESPREAD HAZARDOUS CONDITIONS CONTINUE TODAY WITH STRONG
NORTHWESTERLY WINDS WITH GALE FORCE GUSTS AND ROUGH TO VERY ROUGH
SEAS. THERE'S ALSO A SLIGHT CHANCE FOR THUNDERSTORMS TODAY WHICH
WOULD POSE THE RISK FOR LOCALLY HEAVY RAINFALL AND GUSTY WINDS,
LIGHTNING, AND PEA SIZED HAIL. ANOTHER SYSTEM WILL BRING RENEWED
CHANCES FOR RAINFALL, ROUGH SEAS, AND A STRONG SOUTHERLY BREEZE
WEDNESDAY INTO THURSDAY.
BEACHES
ISSUED AT 450 AM PDT MON MAR 16 2025
STILL NOT A PLEASANT DAY FOR A BEACH VISIT WITH LINGERING SHOWERS
AND ANOTHER PUSH OF STRONGER WINDS IN THE AFTERNOON. ADDITIONALLY,
FRESH SWELL WILL LEAD TO BIGGER SHORE BREAK LATER THIS AFTERNOON
AND EARLY TONIGHT. ROUGH SURF ZONE IS EXPECTED. IF YOU BRAVE THE
ELEMENTS AND HIT THE BEACH, DON'T TURN YOUR BACK TO THE OCEAN
TODAY.
MM
MTR WATCHES/WARNINGS/ADVISORIES
CA...FROST ADVISORY FROM 2 AM TO 9 AM PDT TUESDAY FOR CAZ506-516>518.
PZ...SMALL CRAFT ADVISORY UNTIL 9 AM PDT TUESDAY FOR MRY BAY-PIGEON
PT TO PT PINOS 0-10 NM-PT ARENA TO PT REYES 0-10 NM-PT
REYES TO PIGEON PT 0-10 NM-SF BAY N OF BAY BRIDGE.
SMALL CRAFT ADVISORY UNTIL 9 PM PDT TUESDAY FOR PT PINOS TO PT
PIEDRAS BLANCAS 0-10 NM.
SMALL CRAFT ADVISORY UNTIL 3 PM PDT TUESDAY FOR PIGEON PT TO PT
PINOS 10-60 NM-PT ARENA TO PT REYES 10-60 NM.
SHORT TERM...DIALH
LONG TERM....DIALH
AVIATION...SARMENT
MARINE...SARMENT
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