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
463 FXUS66 KMTR 181812 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1112 AM PDT Wed Sep 18 2024 ...New AVIATION... .SYNOPSIS... Issued at 1252 AM PDT Wed Sep 18 2024 Chance of scattered showers today, tapering off from north to south gradually through Thursday morning. A warming trend is on tap for the rest of the week with seasonal normal temps expected by the weekend. && .UPDATE... Issued at 924 AM PDT Wed Sep 18 2024 Precipitation over the region has been mainly across the northern Santa Cruz Mountains and into the East Bay with reports up to 0.06" at Rocky Ridge (RGEC1). However, expecting rain to increase over the North Bay in the next couple of hours as a rain band approaches the region. As the low pressure center remains offshore, rain is expected to be less widespread as once thought with the region picking up around a trace to a few hundredths of an inch through the afternoon and evening. That said, the forecast remains on track with no updates anticipated at this time. && .SHORT TERM... (Today and Thursday) Issued at 1252 AM PDT Wed Sep 18 2024 The next system is currently moving in, made noticeable by the influx of higher cloud cover through the evening. As of about midnight, the surface low was located just off the coast of Oregon. The low will move southward through this morning, bringing light rain chances to the Bay Area by mid-to-late morning. There is a slight chance (~15%) of thunder during this time period, mainly in the North Bay. As the low moves through, moisture wrapping around the back side will affect areas south of the Bay Area, including the Central Coast, by the middle of Thursday morning. There is also a slight chance of thunder here during this time. Though a small chance, there could be some terrain enhancement over the Santa Lucia, resulting in isolated, brief heavier rain than what will be seen elsewhere. Shower activity ends gradually Thursday evening as the low moves inland. && .LONG TERM... (Friday through Tuesday) Issued at 1252 AM PDT Wed Sep 18 2024 A warming trend will kick off Friday into the weekend as the upper low exits and confidence grows in an a broad upper level ridge situated off the west coast. Temperatures through the weekend are expected to be near seasonal normals. Warming continues into early next week where we will begin to see slightly above normal temperatures. && .AVIATION... (18Z TAFS) Issued at 1112 AM PDT Wed Sep 18 2024 Approaching showers have slowed down slightly but are expected to reach the Bay Area by late this morning and continue into the afternoon. Currently a mix of mid-level clouds and MVFR CIGs with VFR conditions to return during the afternoon/evening. Any showers that do directly impact airports may result in temporary decreased visibility and lowered ceilings. Confidence remains low on inclusion of thunderstorms in TAFs. For all sites except STS, there is a less then 8% chance of thunderstorms. For STS, thunderstorm chances reach 10-12% beginning early this afternoon through the evening. Shower chances decrease at all airports except MRY and SNS beginning this evening with MVFR CIGs expected to return overnight. Light to moderate southwesterly winds continue into the afternoon before becoming more northwesterly after cold frontal passage later this afternoon. Vicinity of SFO...Scattered showers will arrive within the next few hours. Any precipitation that reaches the surface will generally be light but if a stronger shower moves directly over the airport visibilities may temporarily decrease. A low chance (~5%) of thunderstorms continues for SFO through this afternoon. Confidence is too low to include in TAFs but will continue to monitor as showers start to approach the SF Peninsula. Moderate west to northwest winds continue with winds weakening slightly overnight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Scattered showers are expected to move through the Central Coast through late this evening. Low chance of thunderstorms (~4-5%) continues through this evening but confidence remains too low to include thunderstorms in TAFs. MVFR to IFR CIGs are expected to return later this evening with an early return around 02-03Z. Low to moderate confidence on timing of transition from MVFR to IFR CIGs overnight. Moderate northwesterly winds are expected during the day with lighter, variable winds overnight. && .MARINE... (Today through Monday) Issued at 924 AM PDT Wed Sep 18 2024 Northwesterly winds will become gusty across the outer waters by late Wednesday. Seas will be moderate, building to become rough in the outer waters by Thursday. Unsettled conditions will continue over the outer waters through the weekend. Showers continue over the coastal waters through this afternoon. There is up to a 12% chance for thunderstorms in the mid morning which could produce lightning, locally heavy rainfall, locally gusty winds. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM Thursday to 3 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...Behringer LONG TERM....Behringer AVIATION...Kennedy MARINE...Kennedy 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