FXUS66 KMTR 190124 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 624 PM PDT Thu Jul 18 2024 ...New UPDATE... .SYNOPSIS... Issued at 1252 PM PDT Thu Jul 18 2024 Warmer temperatures begin today and will last through next week. && .UPDATE... Issued at 623 PM PDT Thu Jul 18 2024 Some low clouds are starting to move into Monterey Bay but otherwise, clear skies remain for the rest of the region. Temperatures continue to rise with some higher terrains and interior areas reaching triple digits today! Most inland areas saw max temperatures in the high 80s to 90s, while coastline remained relatively cool with temperatures in the 60s and low 70s. High pressure continues to compress the marine layer as it currently sits below 1,000 feet. The Heat advisory continues to remain in affect until Friday night, and conditions remain on track. Therefore, no changes were made to the forecast. && .SHORT TERM... (This evening through Friday) Issued at 1252 PM PDT Thu Jul 18 2024 A short wave trough off the coast of British Colombia will move inland and weaken over the next 36 hours. At the same time, a 500 mb ridge will develop across the bay area, anchored by strong high pressure centered over Arizona. This building ridge will cause surface temperatures to increase through Friday, with triple digit heat expected at several inland locations. Onshore winds will remain at the surface, and the shallow marine layer will continue to keep coastal areas in the 70s. I continued to use a blend of NBM that comes out to the 62.5 percentile for daily maxT. I'm lured above the deterministic and ensemble mean by the very warm ECMWF ensemble and deterministic runs, which are now being supported by high resolution models and confirmed by some temps already in the 90s today. A Heat Advisory is in effect for interior portions of the North Bay, East Bay, South Bay, and interior portions of Monterey and San Benito Counties through 11 PM Friday night. && .LONG TERM... (Friday night through next Wednesday) Issued at 1252 PM PDT Thu Jul 18 2024 Another weak mid-level disturbance will slide along the western periphery of the SW US high, disrupting the ridge and allowing surface temps to drop a bit over the weekend. While still above normal, there wont be many triple digit thermometers over the weekend and the Heat Advisory is not currently in effect on Saturday or Sunday. At the surface, the gradient between subtropical high pressure and the California trough will tighten, and onshore winds will be stronger than they have been. Winds will be strongest at higher elevations in the East Bay. If you're climbing Mt. Diablo on Saturday afternoon, winds may gust to gale force near the summit. By Monday, the pattern gets more complicated. The weekend disturbance will be out of the picture, allowing the ridge to rebuild over central California. At the same time, a new upper level trough will approach the PNW from stage left. This will bring the temperature back to normal in Seattle for the first time in 3 weeks, but doesn't look to have much effect in the Bay Area, as the stubborn high pressure remains entrenched. While there is still a fair bit of uncertainty, it's safe to assume next week will be well above normal for inland areas. Looking way ahead, there may be a cold front that finally rids us of this high pressure and brings much cooler weather in time for next weekend. We'll be glad to see it go, as it's been influencing our weather since the 4th of July. && .AVIATION... (00Z TAFS) Issued at 430 PM PDT Thu Jul 18 2024 Generally clear through the region with IFR-LIFR stratus limited to the immediate coast. Breezy onshore winds continue this afternoon and evening before diminishing overnight. Moderate confidence that stratus and patchy fog will expand tonight to cover the Monterey Bay region, with low confidence of stratus impacts elsewhere in the inland regions. Any inland stratus that does develop will mix out through Friday morning, with breezy onshore flow resuming in the afternoon. Vicinity of SFO... Low confidence for stratus tonight, but if any stratus expands inland outside of MRY and SNS, SFO and OAK are the likeliest to see IFR ceilings. Probabilities are low, so the TAF remains VFR throughout. West-northwest winds will gust up to 30 knots this afternoon and evening, diminishing overnight before building back in again Friday afternoon. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals... VFR with breezy onshore winds through the evening, when winds diminish LIFR stratus returns. Patchy fog is possible in the early morning on Friday, with stratus mixing out later in the morning while breezy onshore winds resume Friday afternoon. && .MARINE... (Tonight through next Tuesday) Issued at 430 PM PDT Thu Jul 18 2024 The gradient between subtropical high pressure over the eastern Pacific and lower pressure over California will tighten over the next couple days. This will cause strong to near gale force NW winds across the northern and outer waters. In the unprotected waters, short period seas will build to rough Friday and further deteriorate to very rough by Sunday. Conditions will remain hazardous to small craft throughout the forecast period. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory until 11 PM PDT Friday for CAZ503-504-506-510- 513>515-517-518. PZ...Small Craft Advisory until 3 PM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM. Gale Watch from Friday afternoon through Saturday morning for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm- Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM Friday to 9 AM PDT Saturday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM Friday to 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 9 AM PDT Saturday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...JM LONG TERM....JM AVIATION...DialH MARINE...Flynn 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