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
196 FXUS66 KMTR 252109 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 209 PM PDT Wed Sep 25 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 104 PM PDT Wed Sep 25 2024 Mild weather today under a deep marine layer. Warming trend begins tomorrow, much warmer by Friday. High temps near or above average persist into next week. && .SHORT TERM... (This evening through Thursday) Issued at 104 PM PDT Wed Sep 25 2024 Quick check of current temps shows about 15-30 degrees cooler than 24 hours ago, depending on where you are. All thanks to a deep marine layer and robust onshore flow in response to a passing upper level trough in the Pacific Northwest. This pattern evolves rather quickly back to a ridge setup with effects beginning Thursday. High temps start to trend upwards Thursday as the marine layer becomes compressed and cloud cover clears sooner in the day, compared to today. Temperatures Thursday look to be about seasonal normals. Some high clouds may end up in the picture this evening for locations in the North Bay, making for a nice sunset if you`re inland or above the stratus. && .LONG TERM... (Thursday night through next Tuesday) Issued at 104 PM PDT Wed Sep 25 2024 Friday is expected to be the warmest day headed into the weekend with highs ranging 5-15 degrees above normal. There`s a short window of a weak offshore gradient that will likely set up in the morning, eroding most of the marine layer and causing temps to increase rapidly. By the afternoon, the gradient will reverse and breezy onshore flow will ensue. Therefore, there is more uncertainty than normal with the highs on Friday based on the timing of the wind reversal. A progressive Gulf of Alaska trough pattern remains through the weekend with another upper level disturbance heading into the PNW Saturday and Sunday. This will aid in flattening the ridge influence, bringing high temps back down towards normal. However, the roller coaster ride continues with a ridge influence building back in through early next week, resulting in another warming trend. Ensemble guidance shows fairly reasonable agreement in this pattern, so confidence is high that we will see above average temperatures at least through the middle of next week. && .AVIATION... (18Z TAFS) Issued at 1024 AM PDT Wed Sep 25 2024 Thanks to an extensive marine layer already 2000-2500 feet deep and deepening, extensive IFR-MVFR stratus covers the inland valleys, beginning to mix out along the edges. Most terminals should clear to VFR by 18-19Z with ceilings persisting through the TAF period at the immediate coast. Breezy onshore flow will develop this afternoon and evening, with stratus returning to the inland valleys tonight, starting to mix out by the end of the 24-hour TAF period. Vicinity of SFO... Terminal has cleared out and should remain VFR for the rest of the day. West-northwest winds develop this afternoon gusting to 15-20 knots, before winds diminish in the late evening hours. MVFR stratus will return this evening and mix out late Thursday morning, followed by afternoon winds gusting to around the same speed as today. SFO Bridge Approach... Some lingering stratus could impact the approach path for the next hour. Otherwise similar to SFO. Monterey Bay Terminals... IFR-MVFR stratus continues to around 19Z at SNS, closer to 20-21Z at MRY. Breezy onshore flow develops in the afternoon and diminishes in the evening, as MVFR stratus returns to the region. Model output is showing potential for reduced visibilities, but a deep marine layer should keep fog concerns at bay. && .MARINE... (Today through Monday) Issued at 1024 AM PDT Wed Sep 25 2024 Light to gentle northwesterly breezes continue today. Northwesterly breezes strengthen to become moderate to fresh and seas rebuild to become rough in the outer waters by Thursday through the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 AM Thursday to 9 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory from 3 PM Thursday to 9 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...Behringer LONG TERM....Behringer 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