Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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023 FXUS66 KMTR 250950 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 250 AM PDT Wed Sep 25 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 249 AM PDT Wed Sep 25 2024 An upper level trough off of the West Coast will bring cooler temperatures on Wednesday with a gradual warming trend into Friday has high pressure builds over the Desert Southwest. Temperatures return to near seasonal averages for the upcoming weekend. && .SHORT TERM... (Today and tonight) Issued at 249 AM PDT Wed Sep 25 2024 Widespread cloud cover with bases at between 300-1,300 feet continue to spread inland at this hour into the coastal adjacent valleys. As such, temperatures are expected to bottom out in the 50`s for most locations with lower 60`s in the East Bay Valleys and Santa Clara Valley. Cannot rule out mist or drizzle in the favored locations across the region as an upper level low off of the coast deepens the marine layer. Today will mark the much anticipated cool down with temperatures across the interior cooling between 10-20 degrees from yesterday`s maximum temperatures and 1-10 degrees closer to the coast. This is in response to the aforementioned upper level low which has developed over the eastern Pacific. Breezy onshore winds are expected this afternoon and will continue into the evening. Tonight, expecting a 1-5 degree cool-down as temperatures cool aloft. Look for a return of low clouds once again tonight into the coastal adjacent valleys and much better humidity recoveries as well. Winds diminish becoming light and variable overnight. && .LONG TERM... (Thursday through Tuesday) Issued at 249 AM PDT Wed Sep 25 2024 More of a zonal pattern develops to our north on Thursday, while an upper level high develops over the Desert Southwest. This will bring temperatures back up to near seasonal averages on Thursday and above average by Friday. Temperatures trend back to near seasonal norms for the weekend as an upper level low to the to our southwest approaches and an upper level trough impacts the Pacific Northwest. From the previous forecaster: "Model output is beginning to show the potential for light offshore flow during the night and morning hours this weekend. However, confidence in any specific impacts are too low to note in fire weather products at this time. CPC outlooks continue to show a lean towards temperatures above, and precipitation below, seasonal averages through the first week of October." && .AVIATION... (06Z TAFS) Issued at 1047 PM PDT Tue Sep 24 2024 Coastal stratus and fog /LIFR-IFR/ continues to move inland tonight and Wednesday morning. Conditions improving to MVFR-VFR back to the coastline by late Wednesday morning and afternoon. Vicinity of SFO...VFR, then IFR ceiling in stratus 09z-19z Wednesday. Onshore wind 5 to 15 knots. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Stratus and fog /LIFR-IFR/ conditions tonight and Wednesday morning. MVFR-VFR by late Wednesday morning and afternoon. IFR in stratus returning early Wednesday evening. Onshore winds 5 to 12 knots. && .MARINE... (Tonight through next Monday) Issued at 1042 PM PDT Tue Sep 24 2024 Light to gentle northwesterly breezes will continue through Wednesday. Northwesterly breezes increase to become moderate to fresh and seas rebuild to become rough in the outer waters by Thursday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...RGass LONG TERM....RGass/DialH AVIATION...Canepa 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