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
545 FXUS66 KMTR 011131 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 431 AM PDT Sat Jun 1 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 255 AM PDT Sat Jun 1 2024 Cooler conditions today with temperatures near seasonal averages across most of the region. Warmer to hotter temperatures return Tuesday with moderate HeatRisk through the interior. && .SHORT TERM... (Today and tonight) Issued at 431 AM PDT Sat Jun 1 2024 Coastal stratus and mist continue to develop due to a combination of surface to near surface cool air advection and nocturnal radiative cooling. The marine layer depth varies from 1200 feet at Bodega Bay to 2000 feet at Fort Ord. Northwest and southeast winds are juxtaposed along the coastline and inland, the northerly ACV-SFO pressure gradient is 4.9 mb, the SMX-SFO and SNS-SJC southerly pressure gradients are 1.6 mb and 2.1 mb respectively. Stratus and mist will continue developing through about sunrise then begin to mix out under diurnal surface warming as well as due to a strengthening and gusty northerly wind overlapping the immediate coastline later on today. Daytime highs today will be cooler most locations except the North Bay where downsloping winds will offset cooling. Highs today 60s/70s coastside and bayside, inland highs in the 80s. Coastal stratus redeveloping tonight and Sunday morning, lows cooling back to the upper 40s and 50s. && .LONG TERM... (Sunday through Friday) Issued at 431 AM PDT Sat Jun 1 2024 Night and morning stratus likely mixing out back to near the coastline Sunday afternoon and possibly again Monday afternoon. By late Sunday and Monday increasing amounts of water vapor will move across our forecast area, per comparison with Oakland upper air early June climatology precipitable water will reach the max moving average and may briefly exceed the early June daily maximum. Water vapor in contact with chilly sea surface temperatures favors stratus and we may also see light coastal drizzle. Beginning Tuesday the weather will then become quickly influenced by the strengthening of the subtropical high pressure system over the Pacific. The high will strengthen while sandwiched between a strong late season mid-latitude storm track reaching southwestern Canada and the Pacific NW (with a soaking rain) and the seasonally northward nudged Intertropical Convergence Zone well to our south. Global models are in better agreement with the overall motion of next week`s high pressure system, though there is some difference in the strength of the high. 850 mb temps (helpful for forecasting surface temperatures via dry adiabatic compressional warming of air parcels to the surface) vary by a couple degrees Celsius, these values are forecast to near the early June max moving average, possibly exceeding the daily maximum if the ECMWF verifies. Expect warm to hot daytime temperatures at least during Tuesday through Thursday, it`ll be hottest inland with 90s to lower 100s. At the coast there may be lingering sea-breezes though the marine layer will likely get compressed to 1000 feet or even lower, still tough to say with certainty since this is still a few days out, and the warm season maritime vs land temperature contrasts naturally keeps a thermally direct circulation potential in place. Another item to watch for, the meso to synoptic pattern may favor a southerly wind reversal either late Wednesday or Thursday. The PDO is still in a negative (cool phase). Hottest daytime temperatures this week look to be Tuesday-Wednesday with carryover into Thursday, and if the high pressure system becomes stationary then hot temperatures will carry into late week before sea breeze relief reaches inland. Though again, the global models do show potential for a southerly wind reversal i.e. sea breeze before late week. Lots of factors in the forecast next week, please stay tuned to updates. For the time being it`s a good idea to plan on at least moderate heat risk inland in our forecast area beginning Tuesday next week. && .AVIATION... (06Z TAFS) Issued at 1119 PM PDT Fri May 31 2024 VFR persists through the TAF period for the majority of terminals with the exception of Monterey Bay, KSFO, and KOAK where IFR conditions are expected overnight. KSFO may see SCT low clouds develop over the terminal this morning, later forming a CIG to usher in IFR conditions. In the daytime, VFR will return and winds will increase to become moderate and gusty with many coastal terminals seeing winds reach up to 15-20 knots. Winds will be largely out of the W, later turning to develop a slight SW component. It is not until early Sunday that winds are expected to fully diminish. Vicinity of SFO...Currently VFR, though low clouds will begin to push over the terminal vicinity as stratus continues to travel north along the CA coastline. Models do not have good agreement, but seem to suggest intermittent CIGs forming at KSFO early Saturday morning. Therefore, have included a TEMPO in the TAF to reflect this, though confidence on CIG formation is low. Come the later morning, VFR is expected to return, with winds strengthening rapidly to become strong and gusty. Gusty winds will reach into the 30 kt range in the afternoon, and will remain gusty through the late night. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...IFR conditions last through the first portion of the TAF period with clearing not expected until the late morning of Saturday as stratus begins to mix out. CIGs lowering to become LIFR this morning is not out of the question, though confidence is currently low, therefore have kept IFR conditions in the TAF. Winds increase in the daytime out of the W to become moderate in the afternoon around 15 knots. && .MARINE... (Today through Wednesday) Issued at 849 AM PDT Fri May 31 2024 Breezy to gusty northwest winds will continue over the outer waters into the weekend with gale force winds expected late Friday and into Saturday. This will cause a hazardous marine environment. Significant wave heights will reach up to about 11-12 feet Friday afternoon, but will begin to reduce today through the remainder of the weekend. && .CLIMATE... Issued at 127 AM PDT Sat Jun 1 2024 Record high temperatures at the long term climate stations for June 4th and 5th: Station June 4th June 5th Santa Rosa 98 in 1949 102 in 1926 Kentfield 101 in 1981 102 in 1926 Napa 102 in 1981 105 in 1903 Richmond 90 in 1955 86 in 1983 Livermore 105 in 1960 104 in 1926 San Francisco 92 in 1949 95 in 1883 SFO Airport 92 in 1955, 1949 89 in 1972 Redwood City 100 in 1981 97 in 2002, 1972 Half Moon Bay 71 in 1955 74 in 1958 Oakland downtown 96 in 1981 87 in 2002 San Jose 98 in 1904 100 in 1926 Salinas Airport 92 in 1949 87 in 1949 King City 102 in 1981, 1957 105 in 1926 && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for SF Bay N of Bay Bridge. Small Craft Advisory from 9 AM this morning to 3 AM PDT Sunday for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 9 AM PDT this morning for Pt Arena to Pt Reyes 0-10 nm. Gale Warning from 9 AM this morning to 3 AM PDT Sunday for Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. Gale Warning from 3 PM this afternoon to 3 AM PDT Sunday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory from 9 AM this morning to 9 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm. Gale Warning from 9 PM this evening to 3 AM PDT Sunday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Gale Warning until 3 PM PDT this afternoon for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...Canepa LONG TERM....Canepa AVIATION...AC MARINE...Murdock 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