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
105 FXUS66 KMTR 081716 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 916 AM PST Fri Nov 8 2024 ...New AVIATION... .SYNOPSIS... Issued at 245 AM PST Fri Nov 8 2024 Dry weather lingers today. Expect chilly to cold morning low temperatures and patchy frost in the lower elevations and valleys, possibly nearing a record low or two, otherwise it`ll be milder at elevation in the hills and mountains this morning. Rain returns to the Bay Area early next week. A chance of rain also extends southward to the north Central Coast early next week. && .UPDATE... Issued at 841 AM PST Fri Nov 8 2024 Another mostly clear morning followed by a sunny afternoon with some improvements in humidities expected for today. The overnight temperatures trended cooler than most model and ensemble guidance so one of the focuses in the afternoon forecast package will be to add some extra adjustments to the national blend of models. Other areas of look to be with the time of arrival with the next rain system, which continues to show some delays. -Murdock && .SHORT TERM... (Today and tonight) Issued at 357 AM PST Fri Nov 8 2024 Under a clear sky, light wind and low surface dewpoint temperatures (lingering desert dry air mass, a low amount of water vapor) air temperatures are cooling to near or below Nov 8th normal lows across the lower elevations and valley floors. Expect additional cooling across lower elevations and valley floors until about 7 am. Lows may near a couple Nov 8th record lows like Oakland downtown and Half Moon Bay, records at the long term sites are noted below. At elevation in the hills and mountains it`s a different story, a lower level temperature inversion under 500 mb ridging is resulting in milder temperatures mainly in the 50s however there are a few lower 60s noted at elevation in Big Sur. After sunrise, temperatures will warm up under a clear sky similar to Thursday`s high temps. Chilly temperatures redeveloping in the lower elevations and valleys tonight and Saturday morning, however high clouds possibly becomes a factor slowing cooling overnight. HREF output shows coastal low clouds and fog approaching from the northwest late tonight and Saturday morning too. && .LONG TERM... (Saturday through Thursday) Issued at 357 AM PST Fri Nov 8 2024 A progressive synoptic pattern across the Pacific and CONUS will continue to nudge eastward the 500 mb ridge across our forecast area today. 500 mb heights lower during the weekend with a 500 mb trough along our coast by early Sunday morning. The GFS and ECMWF show surface low pressure development accompanying the 500 mb level trough, but also show dissipation of the low upon reaching the coast. Most models are dry Sunday, except the ECMWF does show light rain reaching Sonoma County to San Mateo County. Official forecast is currently dry Sunday, however stay tuned to updates. The arrival of Monday`s low pressure system brings widespread light to perhaps moderate rain to the Bay Area with a chance of rain extending to southern Monterey and San Benito Counties. The next upstream low pressure system arrives mid to late week with more wet weather at least reaching as far south as the Bay Area. Wind modulated Pacific Decadal Oscillation (PDO) is deep in a cool phase, October 2024 -3.81. The western Pacific warm sea surface temperature anomalies are a source for water vapor for eastward moving lows and fronts. The PNA teleconnection is forecast to trend negative through mid November. It does look like a winter season signature going forward with an expansion in the number of north hemispheric long wave troughs, the potential is there for more actively wet weather ahead. && .AVIATION... (18Z TAFS) Issued at 914 AM PST Fri Nov 8 2024 VFR conditions expected through the TAF period, with the exception of KHAF and KSTS which potentially (30-40% chance) will see lowering ceilings/visibilities early Saturday morning. Vicinity of SFO...VFR. Light winds this morning then stronger onshore winds later today. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR. Increased onshore winds this afternoon diminishing late. && .MARINE... (Today through Wednesday) Issued at 841 AM PST Fri Nov 8 2024 Light to occasionally moderate winds will prevail over the coastal waters and bays today and Saturday. Winds will gradually increase late this weekend and early next week as a storm system swings through. The passing storm system will bring rain to the region over the weekend as well. && .CLIMATE... Issued at 138 AM PST Fri Nov 8 2024 Record lows at the long term climate stations for November 8th. Station Record Low Santa Rosa 26 in 1914 Kentfield 32 in 1938, 1936, 1918 Napa 32 in 1918 Richmond 41 in 1983 Livermore 32 in 1971 San Francisco 46 in 2011, 1994, 1983, 1982, 1897 SFO Airport 42 in 1953, 1951, 1945 Redwood City 35 in 1971 Half Moon Bay 37 in 2011, 2002, 1961 Oakland downtown 44 in 2011 San Jose 34 in 1895 Salinas Airport 35 in 1938 King City 26 in 1983 && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...Canepa LONG TERM....Canepa AVIATION...RGass MARINE...RGass 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