Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
194 FXUS66 KMTR 081952 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1252 PM PDT Sat Jun 8 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 1205 PM PDT Sat Jun 8 2024 Seasonal temperatures with breezy onshore winds will last through Sunday before another warm up begins Monday. && .SHORT TERM... (This evening through Sunday) Issued at 1205 PM PDT Sat Jun 8 2024 The stratus clouds have eroded everywhere except along the immediate coast. Despite the clearing, area profilers and the morning sounding confirm the marine layer is roughly 2,000 ft deep. This is allowing cool air to infiltrate into the valleys and keep the afternoon temperatures mild. A short wave trough at 500 mb is approaching the coast this afternoon. This wave will amplify and become a cut-off low SW of the Channel Islands by Sunday evening. This synoptic change will cause the mid-level winds to shift from southerly to northerly over the next 36 hours. This change won`t be as obvious at the surface. While the surface wind direction should veer a bit, the weather Sunday will continue to be dominated by a deep marine layer, morning stratus, and breezy onshore winds in the afternoon. Broadly speaking, the temperatures Sunday will be similar to Saturday and the seasonal averages. && .LONG TERM... (Sunday night through next Friday) Issued at 1205 PM PDT Sat Jun 8 2024 Abandoned by the jet stream, the Southern California cut-off low will continue to drift south Monday, allowing a ridge of high pressure to build across the Bay Area. This ridge will cause the marine layer to compress from 2,000 ft over the weekend to around 1,000 ft by Tuesday. While the cut-off low is part of the typical offshore wind equation, we are missing the other piece of the puzzle; strong high pressure over the intermountain West. While weak offshore winds are expected at 700 mb Mon-Tue, they likely won`t reach the surface. The combination of offshore winds aloft, and a shallow marine layer will cause inland areas to warm above seasonal averages from Monday through Wednesday. Tuesday currently looks like the warmest day of the week, with inland highs in the 90s. Coastal areas will stay in the 60s and 70s. By Thursday, an approaching trough will kick the cut-off low inland, where it will quickly weaken. This will bring the return of onshore flow and allow temperatures cool back to the seasonal average. && .AVIATION... (18Z TAFS) Issued at 1032 AM PDT Sat Jun 8 2024 Coastal stratus is eroding and VFR conditions will prevail through the remainder of the day. Moderate SW winds will prevail in the North Bay, with NW winds at SJC and westerly winds elsewhere. MVFR-IFR stratus will return to most terminals overnight. Vicinity of SFO...VFR under high clouds. WNW winds will be moderate to strong this afternoon, and will remain fairly consistent once they get started. The big question at SFO is if ceilings will return overnight. The TAF keeps it clear for now, but there is a 20-30% chance of a low MVFR ceiling in the early morning hours Saturday, similar to what was observed this morning. OAK has a better chance, and MVRF ceilings were included in the TAF from 13-17Z Sunday. SFO Bridge Approach...The bridge approach will likely stay clear of low clouds, even if SFO and OAK develop ceilings Sun morning. Monterey Bay Terminals...MVFR ceilings are lingering, but the visible satellite loop shows they will soon break at both MRY and SNS. VFR conditions are likely for about 9-12 hours before the stratus returns this evening. GFSLAMP shows a 15% chance of LIFR ceilings developing around 12Z at MRY, and with subtle compression expected in the marine layer, the ceilings may drop lower than they were this morning (OVC006). Otherwise, moderate onshore winds will persist through the TAF period. && .MARINE... (Today through Thursday) Issued at 1032 AM PDT Sat Jun 8 2024 The gradient between subtropical high pressure and lower pressure over the SW US is supporting a moderate to fresh NW breeze. As the high pressure slowly encroaches towards the coast, the pressure gradient will tighten, causing the wind speed to increase through the weekend. A fresh to strong NW breeze will persist through next week with the potential for gale force winds by next weekend. Significant wave heights will mostly be dominated by wind driven waves, though there is a moderate NW swell and a low SW swell mixed in. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 AM PDT Sunday for SF Bay N of Bay Bridge. Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 3 AM PDT Monday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...Flynn 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