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Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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473 FXUS66 KMTR 281730 AAA AFDMTR Area Forecast Discussion...UPDATED National Weather Service San Francisco CA 930 AM PST Fri Feb 28 2025 ...New UPDATE... .SYNOPSIS... Issued at 259 AM PST Fri Feb 28 2025 Warm again today. Cool and wet weather returns for the weekend and lasts through much of the next work week. && .UPDATE... Issued at 929 AM PST Fri Feb 28 2025 Overall, the short term forecast remains in good shape, with just a couple of aesthetic changes. An upper low continues to churn off the Southern California Bight. This feature continues to send largely mid and upper level cloud cover northward, especially across the Interior Central Coast. 12 UTC soundings from Oakland and Vandenberg shows a dearth of dry air (a little less dry farther south) which should translate to a mostly rain-free day today (Friday). The satellite presentation does indicate a more cumuliform type look to the clouds, suggesting the presence of mid/upper level instability. With some spotty reports of virga, I`ve elected to throw in a mention of sprinkles across southern Monterey and San Benito counties. This shouldn`t translate to much fan fare, but I wouldn`t be surprised if a few drops of rain are observed later this morning and into the afternoon. Outside of adjusting sky cover and Wx grids, the rest of the forecast remains unchanged. Updated products have been shipped. && .SHORT TERM... (Today and tonight) Issued at 259 AM PST Fri Feb 28 2025 It has been a quiet night. We`ve been seeing mostly high-level clouds rotating around a cut-off low to the southwest, but otherwise quiet. The increasing cloud cover and the pattern change offering more onshore flow will prevent temperatures from seeing the 80s like yesterday. Highs will still be above average with widespread 60s and into the 70s for the more interior areas. Things will steadily cool into the night with the potential for fog building in the early night. The stronger chances for fog look to fall in the North Bay valleys, with the best chances being around Santa Rosa. && .LONG TERM... (Saturday through Thursday) Issued at 259 AM PST Fri Feb 28 2025 Fog dissipates in late Saturday morning with the next cold front approaching that evening, bringing widespread light rain. The parent low pressure system of this front builds in quickly in the post frontal environment, keeping the rain chances pretty persistent through the weekend and into Monday. Potential for shattered thunderstorms increases as the low moves through the area, with the best chances hitting around 15% near the Monterey Bay and along the Big Sur Coast Monday morning. Rainfall totals from the Saturday through Monday rain event look to range between 0.10" to 0.50" with higher elevations in the Santa Cruz Mtns and in the Santa Lucias getting closer to 0.75" After a brief pause, another rain-maker arrives mid Tuesday. Overall model and ensemble confidence is good that light to moderate rain will push through along another cold front and low pressure combo. There also looks to be a fair consensus for rain chances lasting through Friday. The main point of forecasting concerns for this one is the orientation of the low as it builds in, which could make the focus of the highest rainfall amounts to shift in the next few forecast updates. As of the current forecast, the low pressure moves inland at the Big Sur Coast, offering the higher rain amounts in the Santa Lucias (1.50"-2"). However, if the low turns inland sooner, the North Bay Coast would be the rainfall leader. This is all to say that there is still a fair amount of polishing needed to be done in the longer term portion of the forecast. && .AVIATION... (12Z TAFS) Issued at 419 AM PST Fri Feb 28 2025 This upcoming TAF cycle will be a tale of two pressure systems: broad area of high pressure across the West and a cutoff low off the coast of Southern California. The cutoff low is responsible for the high clouds overhead and the offshore flow. As it progresses eastward, it`ll take the clouds with it and diurnal winds will return. As onshore flow returns, so too does the humidity. With higher relative humidity and a lack of overhead clouds under a broad area of high pressure (subsiding air), the marine layer will likely be compressed/shallow with low ceilings and visibilities with conditions expected to be the worst near the coast. Vicinity of SFO...Currently VFR and calm. The sea breeze will return this afternoon, prevailing through the TAF period. Moderate confidence in a reduction to MVFR by late tonight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Currently VFR with easterly flow at MRY and VFR with drainage flow at SNS. Onshore flow will develop by mid- morning, prevailing through the TAF period. High confidence in a reduction in flight category to IFR by late tonight. && .MARINE... (Today through Wednesday) Issued at 259 AM PST Fri Feb 28 2025 A moderate northwesterly breeze on Friday will increase to a fresh northwesterly breeze on Saturday. Significant wave heights will fluctuate between moderate and rough through Tuesday. Widespread rainfall can be expected Saturday through Monday with a slight chance for thunderstorms Sunday and Monday. && .BEACHES... Issued at 419 AM PST Fri Feb 28 2025 Hazardous beach conditions are expected Friday through Monday due to building long period westerly swell supporting breaking waves of 14- 19 feet. This will be both a beachgoer and a mariner threat. Everyone should remain out of the water due to life-threatening surf conditions. Stay off of jetties, piers, and other waterside infrastructure, keep pets on a leash and away from the water, and never turn your back on the ocean! Sarment && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement from 9 PM PST this evening through Saturday morning for CAZ006-505-509-530. High Surf Advisory from 9 AM Saturday to 9 PM PST Monday for CAZ006-505-509-530. Beach Hazards Statement from 9 PM PST this evening through Monday evening for CAZ529. PZ...Small Craft Advisory from 9 AM to 3 PM PST Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 3 PM PST this afternoon for Pigeon Pt to Pt Pinos 10-60 NM. && $$ UPDATE...Bain SHORT TERM...Murdock LONG TERM....Murdock AVIATION...Sarment MARINE...Sarment Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea