Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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932 FXUS66 KMTR 280953 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 253 AM PDT Fri Jun 28 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM, MARINE... .SYNOPSIS... Issued at 251 AM PDT Fri Jun 28 2024 A well established marine layer and onshore flow will keep temperatures cool near the coast while inland areas warm to into the 90`s throughout the weekend. Pattern change causes a warm up early next week, with monitoring potential excessive heat for the second half of next week. && .SHORT TERM... (Today and tonight) Issued at 251 AM PDT Fri Jun 28 2024 Low clouds are redeveloping near the coast early this morning, especially around the San Fransico Peninsula and the Monterey Bay region. These clouds will retreat to the coast by this afternoon with maximum temperatures expected to warm into the upper 80`s to mid 90`s across the interior with 60`s and 70`s near the coast. Tonight, expecting low clouds to return to the coast with minimum temperatures dropping into the upper 40`s in the North Bay and along the San Francisco Peninsula to low-to-mid 50`s elsewhere. Similar day-to-day trends will continue throughout the weekend with a slight warming trend. && .LONG TERM... (Saturday through Thursday) Issued at 1007 PM PDT Thu Jun 27 2024 There`s good global model agreement that a high pressure system will strengthen approx 1000 miles to the west of the Bay Area by late in the weekend and Monday. Thereafter, the high is forecast to advance eastward toward northern California, large scale downward vertical motion (compressional warming) sending 850 mb temperatures upwards, EPS/GEFS (27 Celsius) 850 mb temp means are near the max moving average in comparison to Oakland upper air soundings long term early July climatology. While recent deterministic output are forecasting 850 mb temps higher, nearing 30C to 31C by July 5th-6th. With large scale compression, expect the marine layer to do the same, to be compressed to near sea level, while winds at this time do not appear to become breezy to gusty offshore; a good idea however to closely monitor because the global/mesoscale models sometimes will under-forecast the ACV-SFO gradient (northerly wind) for example. 850 mb level (~5000 feet) temperatures are a usual reference point for predicting forecast high temperatures at the surface since sinking air parcels under a high pressure system will typically warm dry adiabatically to the surface, daily solar input connecting with these warmed air parcels, post sunrise temperatures quickly warming up as a result. Forecast highs expected to warm up to the 90s/lower 100s, hottest temps Tue-Thu, with likely carryover of hot temps July 5th-6th. With respect to long term Bay Area stations record high temperatures for the 4th of July, many still remain from a 1905 heatwave, including another heatwave early July 1931. Stay tuned to the latest forecast updates, it`s a good idea to plan on above normal to well above normal hot temperatures next week. If the high is slow to move then hot weather will linger to late next week. && .AVIATION... (06Z TAFS) Issued at 1031 PM PDT Thu Jun 27 2024 MVFR-IFR ceilings currently present at the western San Mateo Peninsula and are expected to develop along the immediate coast and Monterey Bay region tonight. Some stratus is also expected to pass through the Golden Gate with low to moderate confidence of ceilings at OAK early Friday morning; otherwise VFR through the TAF period away from the coast. Stratus will retreat towards the immediate coast through the morning with breezy onshore winds in the afternoon and evening. Vicinity of SFO...Currently a moderate to high confidence of VFR through the TAF period. Model guidance has the terminal on the southern edge of stratus decks flowing through the Golden Gate. Will monitor in case stratus flowing east impacts the terminal. West- northwest winds will develop Friday afternoon and evening with gusts up to 25 knots. Some model guidance indicates a similar return of stratus Friday evening with the terminal again on the edge of the stratus deck. SFO Bridge Approach...Less confidence in stratus impacts south of the terminal. Otherwise similar to SFO. Monterey Bay Terminals...IFR ceilings developing tonight with some LIFR ceilings possible. Stratus clears out later Friday morning with breezy onshore winds developing in the afternoon. Stratus returns early Friday evening. && .MARINE... (Today through Wednesday) Issued at 251 AM PDT Fri Jun 28 2024 Fresh to strong northwest winds continue into next week before easing to become moderate across much of the waters. Significant wave heights begin to build to 10-12 feet towards the beginning of the next work week. Light southerly swell continues to move through the waters alongside moderate northwesterly swell. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory from 9 AM Saturday to 9 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory until 3 AM PDT early this morning for Pigeon Pt to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM Saturday to 9 AM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 9 AM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...RGass LONG TERM....Canepa AVIATION...DialH MARINE...DialH 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