Area Forecast Discussion FXUS66 KMTR [Monterey CA] 291138 AFDMTR ∨ FXUS66 KMTR 291138 AFDMTR [HEAD] National Weather Service San Francisco California 4:38am PDT Tue Oct 29 2024 ∨ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO CA 438 AM PDT TUE OCT 29 2024 [HEAD] New aviation, marine. ∨ ...NEW AVIATION, MARINE... [DISC] Synopsis. Issued at 3:06am PDT Tuesday October 29 2024 ∨ .SYNOPSIS... ISSUED AT 306 AM PDT TUE OCT 29 2024 [DISC] Cooler morning temperatures and dry conditions expected today before rain chances return again Wednesday through the end of the week. ∨ COOLER MORNING TEMPERATURES AND DRY CONDITIONS EXPECTED TODAY BEFORE RAIN CHANCES RETURN AGAIN WEDNESDAY THROUGH THE END OF THE WEEK. [DISC] Short term. (today and tonight) issued at 3:06am PDT Tuesday October 29 2024 ∨ .SHORT TERM... (TODAY AND TONIGHT) ISSUED AT 306 AM PDT TUE OCT 29 2024 [DISC] Showers have largely ended over our CWA [County Warning Area; see the LWP home page (link at bottom of page) for a CWA map] with drier conditions prevailing through the rest of today. So how did we do? Well, over the last 24 hours many sites across the Bay Area and interior Central Coast saw at least a few hundredths of an inch. There were a few outliers in the North Bay which saw slightly higher totals between 0.1"-0.18" of rain. Even San Jose, famously impacted by rain shadowing from the Santa Cruz Mountains, recorded 0.01" at the San Jose International Airport making it the rainiest day since May for the City. ∨ SHOWERS HAVE LARGELY ENDED OVER OUR CWA WITH DRIER CONDITIONS PREVAILING THROUGH THE REST OF TODAY. SO HOW DID WE DO? WELL, OVER THE LAST 24 HOURS MANY SITES ACROSS THE BAY AREA AND INTERIOR CENTRAL COAST SAW AT LEAST A FEW HUNDREDTHS OF AN INCH. THERE WERE A FEW OUTLIERS IN THE NORTH BAY WHICH SAW SLIGHTLY HIGHER TOTALS BETWEEN 0.1"-0.18" OF RAIN. EVEN SAN JOSE, FAMOUSLY IMPACTED BY RAIN SHADOWING FROM THE SANTA CRUZ MOUNTAINS, RECORDED 0.01" AT THE SAN JOSE INTERNATIONAL AIRPORT MAKING IT THE RAINIEST DAY SINCE MAY FOR THE CITY. [DISC] Tuesday will be the driest day of the week as short wave ridging moves into the West Coast and brings with it a much drier airmass. The advection of drier air inland will reduce the development of cloud cover across the region and contribute to both a steep cooling of our morning lows and a slight warming of our afternoon highs. At night, cloud cover can act as a form of "insulation" trapping heat at the surface. If no cloud cover is present heat will be able to rise (ie escape) and temperatures will be able to cool at a much faster rate. This effect will be particularly important across the North Bay tonight where satellite imagery confirms that no cloud cover is present. While temperatures are currently in the upper 40s to low 50s, this lack of cloud cover will contribute to increased radiational cooling and allow temperatures to drop into the upper 30s to low 40s this morning. During the day, we expect to see high temperatures about 1–3° warmer than they were yesterday. However, this will not result in any major changes to the overall highs with inland areas still seeing temperatures in the mid to upper 60s and coastal areas in the upper 50s to low 60s. The one thing to keep in mind is that gusty northwest winds are expected to continue through late this morning which may result in temperatures outside feeling cooler than they actually are. As this will be one of the chilliest mornings we've had all fall, consider taking a sturdier Jacket out with you on any morning errands. For those unenthused by dry weather, read on to the long term to learn more about our next chances for rain. ∨ TUESDAY WILL BE THE DRIEST DAY OF THE WEEK AS SHORT WAVE RIDGING MOVES INTO THE WEST COAST AND BRINGS WITH IT A MUCH DRIER AIRMASS. THE ADVECTION OF DRIER AIR INLAND WILL REDUCE THE DEVELOPMENT OF CLOUD COVER ACROSS THE REGION AND CONTRIBUTE TO BOTH A STEEP COOLING OF OUR MORNING LOWS AND A SLIGHT WARMING OF OUR AFTERNOON HIGHS. AT NIGHT, CLOUD COVER CAN ACT AS A FORM OF "INSULATION" TRAPPING HEAT AT THE SURFACE. IF NO CLOUD COVER IS PRESENT HEAT WILL BE ABLE TO RISE (I.E. ESCAPE) AND TEMPERATURES WILL BE ABLE TO COOL AT A MUCH FASTER RATE. THIS EFFECT WILL BE PARTICULARLY IMPORTANT ACROSS THE NORTH BAY TONIGHT WHERE SATELLITE IMAGERY CONFIRMS THAT NO CLOUD COVER IS PRESENT. WHILE TEMPERATURES ARE CURRENTLY IN THE UPPER 40S TO LOW 50S, THIS LACK OF CLOUD COVER WILL CONTRIBUTE TO INCREASED RADIATIONAL COOLING AND ALLOW TEMPERATURES TO DROP INTO THE UPPER 30S TO LOW 40S THIS MORNING. DURING THE DAY, WE EXPECT TO SEE HIGH TEMPERATURES ABOUT 1 TO 3 DEGREES WARMER THAN THEY WERE YESTERDAY. HOWEVER, THIS WILL NOT RESULT IN ANY MAJOR CHANGES TO THE OVERALL HIGHS WITH INLAND AREAS STILL SEEING TEMPERATURES IN THE MID TO UPPER 60S AND COASTAL AREAS IN THE UPPER 50S TO LOW 60S. THE ONE THING TO KEEP IN MIND IS THAT GUSTY NORTHWEST WINDS ARE EXPECTED TO CONTINUE THROUGH LATE THIS MORNING WHICH MAY RESULT IN TEMPERATURES OUTSIDE FEELING COOLER THAN THEY ACTUALLY ARE. AS THIS WILL BE ONE OF THE CHILLIEST MORNINGS WE`VE HAD ALL FALL, CONSIDER TAKING A STURDIER JACKET OUT WITH YOU ON ANY MORNING ERRANDS. FOR THOSE UNENTHUSED BY DRY WEATHER, READ ON TO THE LONG TERM TO LEARN MORE ABOUT OUR NEXT CHANCES FOR RAIN. [DISC] Long term. (Wednesday through Monday) issued at 3:06am PDT Tuesday October 29 2024 ∨ .LONG TERM... (WEDNESDAY THROUGH MONDAY) ISSUED AT 306 AM PDT TUE OCT 29 2024 [DISC] Temperatures will remain cool through the week with highs generally in the 60s across the interior and in the upper 50s to low 60s along the coast. Morning low temperatures will gradually start to warm up by late week but highs will generally stay in the 40s to low 50s while the coldest sites will remain in the upper 30s to low 40s. Despite shortwave ridging Tuesday, the storm door remains open with a series of progressive upper level troughs expected to move through the West Coast this week. Wednesday, the next upper level trough and surface low pressure system will move into the Pacific Northwest and bring with it widespread light rain to the Bay Area and to coastal portions of the Central Coast. Rain chances increase Wednesday afternoon across the North Bay and gradually increase across the rest of the Bay Area and the Central Coast Wednesday evening into Thursday morning as the surface based cold front progresses southward. The highest totals continue to be in the North Bay (0.2"- 0.3") but coastal areas along the San Francisco Peninsula may see accumulations of up to 0.15" of rain. Across the East Bay, South Bay, and Central Coast totals will generally be less than 0.1" inches. Showers will gradually tapper off by late Thursday morning but drizzly conditions are expected to persist into Thursday evening, adding to the spooky ambiance of the day. While some uncertainty remains, confidence has continued to increase that upper level troughing will deepen over the West Coast Friday into Saturday and provide more widespread rainfall to the region. NBM QPF [Quantitative Precipitation Forecast] guidance has continued to trend upwards with between 0.25" to 0.3" expected across the majority of the area. Areas where upslope flow is favored (coastal North Bay mountains, Santa Cruz Mountains, Santa Lucia Mountains) may see locally higher amounts closer to half an inch. ∨ TEMPERATURES WILL REMAIN COOL THROUGH THE WEEK WITH HIGHS GENERALLY IN THE 60S ACROSS THE INTERIOR AND IN THE UPPER 50S TO LOW 60S ALONG THE COAST. MORNING LOW TEMPERATURES WILL GRADUALLY START TO WARM UP BY LATE WEEK BUT HIGHS WILL GENERALLY STAY IN THE 40S TO LOW 50S WHILE THE COLDEST SITES WILL REMAIN IN THE UPPER 30S TO LOW 40S. DESPITE SHORTWAVE RIDGING TUESDAY, THE STORM DOOR REMAINS OPEN WITH A SERIES OF PROGRESSIVE UPPER LEVEL TROUGHS EXPECTED TO MOVE THROUGH THE WEST COAST THIS WEEK. WEDNESDAY, THE NEXT UPPER LEVEL TROUGH AND SURFACE LOW PRESSURE SYSTEM WILL MOVE INTO THE PACIFIC NORTHWEST AND BRING WITH IT WIDESPREAD LIGHT RAIN TO THE BAY AREA AND TO COASTAL PORTIONS OF THE CENTRAL COAST. RAIN CHANCES INCREASE WEDNESDAY AFTERNOON ACROSS THE NORTH BAY AND GRADUALLY INCREASE ACROSS THE REST OF THE BAY AREA AND THE CENTRAL COAST WEDNESDAY EVENING INTO THURSDAY MORNING AS THE SURFACE BASED COLD FRONT PROGRESSES SOUTHWARD. THE HIGHEST TOTALS CONTINUE TO BE IN THE NORTH BAY (0.2"- 0.3") BUT COASTAL AREAS ALONG THE SAN FRANCISCO PENINSULA MAY SEE ACCUMULATIONS OF UP TO 0.15" OF RAIN. ACROSS THE EAST BAY, SOUTH BAY, AND CENTRAL COAST TOTALS WILL GENERALLY BE LESS THAN 0.1" INCHES. SHOWERS WILL GRADUALLY TAPPER OFF BY LATE THURSDAY MORNING BUT DRIZZLY CONDITIONS ARE EXPECTED TO PERSIST INTO THURSDAY EVENING, ADDING TO THE SPOOKY AMBIANCE OF THE DAY. WHILE SOME UNCERTAINTY REMAINS, CONFIDENCE HAS CONTINUED TO INCREASE THAT UPPER LEVEL TROUGHING WILL DEEPEN OVER THE WEST COAST FRIDAY INTO SATURDAY AND PROVIDE MORE WIDESPREAD RAINFALL TO THE REGION. NBM QPF GUIDANCE HAS CONTINUED TO TREND UPWARDS WITH BETWEEN 0.25" TO 0.3" EXPECTED ACROSS THE MAJORITY OF THE AREA. AREAS WHERE UPSLOPE FLOW IS FAVORED (COASTAL NORTH BAY MOUNTAINS, SANTA CRUZ MOUNTAINS, SANTA LUCIA MOUNTAINS) MAY SEE LOCALLY HIGHER AMOUNTS CLOSER TO HALF AN INCH. [DISC] By late weekend, drier conditions are expected to return with cluster guidance suggesting another "inside slider" type pattern may develop. By Sunday, upper level troughing will have deepened and moved farther souther into California. The European and Canadian models both show a cut off low developing over the California-Arizona border while ridging starts to build back in along the coast. This would result in a prime setup for offshore (northeasterly) winds to develop across our region. While it remains uncertain as to how long this setup will persist, both ensemble and CPC [Climate Prediction Center] guidance indicates that we will see a return to warmer and drier conditions during early November. While we are still a week out, this setup is something to keep an eye on as it may bring elevated fire weather concerns back to our CWA [County Warning Area; see the LWP home page (link at bottom of page) for a CWA map]. ∨ BY LATE WEEKEND, DRIER CONDITIONS ARE EXPECTED TO RETURN WITH CLUSTER GUIDANCE SUGGESTING ANOTHER "INSIDE SLIDER" TYPE PATTERN MAY DEVELOP. BY SUNDAY, UPPER LEVEL TROUGHING WILL HAVE DEEPENED AND MOVED FARTHER SOUTHER INTO CALIFORNIA. THE EUROPEAN AND CANADIAN MODELS BOTH SHOW A CUT OFF LOW DEVELOPING OVER THE CALIFORNIA- ARIZONA BORDER WHILE RIDGING STARTS TO BUILD BACK IN ALONG THE COAST. THIS WOULD RESULT IN A PRIME SETUP FOR OFFSHORE (NORTHEASTERLY) WINDS TO DEVELOP ACROSS OUR REGION. WHILE IT REMAINS UNCERTAIN AS TO HOW LONG THIS SETUP WILL PERSIST, BOTH ENSEMBLE AND CPC GUIDANCE INDICATES THAT WE WILL SEE A RETURN TO WARMER AND DRIER CONDITIONS DURING EARLY NOVEMBER. WHILE WE ARE STILL A WEEK OUT, THIS SETUP IS SOMETHING TO KEEP AN EYE ON AS IT MAY BRING ELEVATED FIRE WEATHER CONCERNS BACK TO OUR CWA. [DISC] Aviation. (12Z [5am PDT] TAFs [Terminal Aerodrome Forecasts]) issued at 4:37am PDT Tuesday October 29 2024 ∨ .AVIATION... (12Z TAFS) ISSUED AT 437 AM PDT TUE OCT 29 2024 [AVIA] High confidence that VFR [Visual Flight Rules] will persist over the region throughout Tuesday. Onshore winds increase by late Tuesday morning and will remain gusty at times throughout the afternoon. Winds ease overnight with a medium to high confidence for continued VFR [Visual Flight Rules] conditions. High clouds will begin to spread over the region late in the TAF [Terminal Aerodrome Forecast] period ahead of an approaching frontal boundary. ∨ HIGH CONFIDENCE THAT VFR WILL PERSIST OVER THE REGION THROUGHOUT TUESDAY. ONSHORE WINDS INCREASE BY LATE TUESDAY MORNING AND WILL REMAIN GUSTY AT TIMES THROUGHOUT THE AFTERNOON. WINDS EASE OVERNIGHT WITH A MEDIUM TO HIGH CONFIDENCE FOR CONTINUED VFR CONDITIONS. HIGH CLOUDS WILL BEGIN TO SPREAD OVER THE REGION LATE IN THE TAF PERIOD AHEAD OF AN APPROACHING FRONTAL BOUNDARY. [AVI2] Vicinity of SFO [San Francisco CA]… VFR [Visual Flight Rules], high confidence. Onshore winds increase this afternoon before diminishing during the overnight hours. ∨ VICINITY OF SFO...VFR, HIGH CONFIDENCE. ONSHORE WINDS INCREASE THIS AFTERNOON BEFORE DIMINISHING DURING THE OVERNIGHT HOURS. [AVI2] SFO [San Francisco CA] bridge approach… similar to SFO [San Francisco CA]. ∨ SFO BRIDGE APPROACH...SIMILAR TO SFO. [AVI2] Monterey Bay terminals… VFR [Visual Flight Rules], medium to high confidence. Onshore winds increase slightly this afternoon and diminish by late evening. ∨ MONTEREY BAY TERMINALS...VFR, MEDIUM TO HIGH CONFIDENCE. ONSHORE WINDS INCREASE SLIGHTLY THIS AFTERNOON AND DIMINISH BY LATE EVENING. [AVI2] Marine. (today through Sunday) issued at 4:37am PDT Tuesday October 29 2024 ∨ .MARINE... (TODAY THROUGH SUNDAY) ISSUED AT 437 AM PDT TUE OCT 29 2024 [AVIA] Winds will continue to diminish and seas will subside throughout Tuesday. Another cold front will move through Wednesday night, increasing winds back to a fresh northwest breeze and rebuilding rough seas through the day Thursday and into Friday. ∨ WINDS WILL CONTINUE TO DIMINISH AND SEAS WILL SUBSIDE THROUGHOUT TUESDAY. ANOTHER COLD FRONT WILL MOVE THROUGH WEDNESDAY NIGHT, INCREASING WINDS BACK TO A FRESH NORTHWEST BREEZE AND REBUILDING ROUGH SEAS THROUGH THE DAY THURSDAY AND INTO FRIDAY. [AVI2] MTR Watches/Warnings/Advisories
.MTR WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 9 PM PDT THIS EVENING FOR MRY BAY. [WARN]
SMALL CRAFT ADVISORY UNTIL 9 AM PDT THIS MORNING FOR PT ARENA TO PT REYES 0-10 NM-PT REYES TO PIGEON PT 0-10 NM. [WRN2]
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PIGEON PT TO PT PINOS 0-10 NM-PIGEON PT TO PT PINOS 10-60 NM-PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM. [WRN2]
SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR PT ARENA TO PT REYES 10-60 NM. [WRN2]
SHORT TERM...KENNEDY LONG TERM....KENNEDY AVIATION...RGASS MARINE...RGASS [WRN2] VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO [LINK] Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea ∨ FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSBAYAREA WWW.TWITTER.COM/NWSBAYAREA WWW.YOUTUBE.COM/NWSBAYAREA [DISC] |
Point Forecast Half Moon Bay CA 29 Oct 06:35am PDT Today Sunny, with a high near 58°. WNW wind 7 to 10 mph. Tonight Increasing clouds, with a low around 47°. WNW wind 3 to 8 mph. Wednesday Cloudy through mid morning, then gradual clearing, with a high near 58°. Calm wind becoming SW 5 to 7 mph in the afternoon. Wednesday Night Rain, mainly after 11pm. Low around 50°. South wind 6 to 9 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible. Thursday A 50% chance of rain. Partly sunny, with a high near 58°. West wind 6 to 8 mph. New precipitation amounts of less than a tenth of an inch possible. Thursday Night A 40% chance of rain. Mostly cloudy, with a low around 49°. New precipitation amounts of less than a tenth of an inch possible. Friday A 40% chance of rain. Partly sunny, with a high near 56°. Friday Night Rain likely, mainly after 11pm. Mostly cloudy, with a low around 49°. Saturday A chance of rain. Partly sunny, with a high near 57°. Saturday Night A slight chance of rain before 11pm. Partly cloudy, with a low around 48°. Sunday Sunny, with a high near 59°. Sunday Night Mostly clear, with a low around 48°. Monday Sunny, with a high near 66°. Today Sunny, with a high near 58. West northwest wind 7 to 10 mph. Tonight Increasing clouds, with a low around 47. West northwest wind 3 to 8 mph. Wednesday Cloudy through mid morning, then gradual clearing, with a high near 58. Calm wind becoming southwest 5 to 7 mph in the afternoon. Wednesday Night Rain, mainly after 11pm. Low around 50. South wind 6 to 9 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible. Thursday A 50 percent chance of rain. Partly sunny, with a high near 58. West wind 6 to 8 mph. New precipitation amounts of less than a tenth of an inch possible. Thursday Night A 40 percent chance of rain. Mostly cloudy, with a low around 49. New precipitation amounts of less than a tenth of an inch possible. Friday A 40 percent chance of rain. Partly sunny, with a high near 56. Friday Night Rain likely, mainly after 11pm. Mostly cloudy, with a low around 49. Saturday A chance of rain. Partly sunny, with a high near 57. Saturday Night A slight chance of rain before 11pm. Partly cloudy, with a low around 48. Sunday Sunny, with a high near 59. Sunday Night Mostly clear, with a low around 48. Monday Sunny, with a high near 66. |
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