San Francisco Bay South of the Bay Bridge Marine Forecast
|Tonight...Nw Winds 10 To 15 Kt With Gusts Up To 25 Kt, Diminishing To 5 To 10 Kt After Midnight.|
|Wed...Nw Winds 15 To 20 Kt With Gusts Up To 25 Kt.|
|Wed Night...Nw Winds 10 To 15 Kt With Gusts Up To 25 Kt.|
|Thu...Nw Winds 10 To 15 Kt With Gusts Up To 25 Kt.|
|Thu Night...Nw Winds 5 To 10 Kt.|
|Fri...Nw Winds 10 To 15 Kt With Gusts Up To 25 Kt.|
|Fri Night...Sw Winds 5 To 10 Kt.|
|Sat...W Winds 10 To 15 Kt.|
|Sun...W Winds 10 To 15 Kt.|
|844 AM PDT Tue Jul 27 2021 .Synopsis for the Central California Coast and Bays Including the Monterey Bay...Greater Farallones...and Cordell Bank National Marine Sanctuaries... Lingering storms out over the ocean are producing occasional lightning and locally erratic gusty winds. Chances for thunderstorms diminish into Tuesday afternoon. Winds will remain out of the northwest and fairly weak yet continue to be the influence on the sea state at around 6 to 8 seconds along with a weak southerly swell. Winds and gusts look to increase Tuesday afternoon and into the evening through the Golden Gate gap into the San Francisco Bay. Locally generated steep wind waves may be hazardous for smaller vessels.|
| Area Forecast Discussion|
National Weather Service San Francisco Bay Area
1031am PDT Tuesday July 27 2021
Monsoon moisture continues to move into our region. Slight chance of showers and isolated thunderstorms continues into Tuesday morning before diminishing in the afternoon. Long range trends remain seasonably warm and dry through the end of the month.
as of 02:03am PDT Tuesday...KMUX radar still shows a band of showers moving northward through Monterey County. Observations have largely been dry with a couple hundredths of an inch reported in far SE Monterey County and 0.07" at Fort Hunter Liggett since this evening. However, the bulk of this band of showers has rotated offshore over the southern coastal waters. It appears that most of this will continue to shift westward as it progresses to the north and keep most of the precipitation offshore. Even if this were not the case, lower levels of the atmosphere remain fairly dry so not much precipitation would make it to the surface. Thus far, have not observed any lightning strikes over our area with most activity confined to the Sierra. Water vapor imagery shows a dry swath of air over much of southern California and shifting northward behind the aforementioned showers with that monsoonal moisture to the north through the rest of the state. IR imagery also shows less impressive cloud tops compared to the complex we observed move into soCal last night with the situation currently appearing more disorganized.
The rest of this mid/upper level moisture will move through the Bay Area by early this morning before reaching the North Bay by early afternoon. Models have most of the instability north of the Bay Area and with highest values over the northern coastal waters through the early afternoon. Synoptically, there is an upper low to the SW of southern California that will move northward slowly throughout the day. In order to get any decent lightning over our area we typically need all of these factors to align just right with a robust plume of moisture coinciding with instability and lift. Given that the upper low that would provide such lift is too far south and the moisture plume is not as deep as models had previously suggested, it appears unlikely for any widespread thunderstorm/lightning activity over the area during this event. Latest high res models show only a few isolated cells over land into mid to late morning. A few isolated cells may occur before the afternoon with some small hail, but odds are low. The most likely area for convective development would be over the northern waters where the NAM has MUCAPE at 150-200 J/kg and TT values over 30 into this morning. Though so far, radar is only picking up weak echos out over the northern waters with no lightning strikes detected. Therefore, trimmed back some of the thunderstorm chances in the grids.
By late this afternoon into the early evening the monsoon moisture should be out of our area and drier weather will then return. A very broad upper ridge remains entrenched over much of the CONUS and will exert its influence over our interior locations mid to late week resulting in a warming trend. Most of the region will remain fairly seasonable as a troughing pattern continues in the eastern Pacific. Far inland locations however will be about 5 to 10 degrees above normal through Friday with highs in the mid 90s to around 100 deg F. At this time, heat risk will be limited to low to moderate inland, but will keep an eye on conditions over the next couple days. The coast and Bay Areas will remain more seasonable as onshore flow and marine influence persist. High pressure will weaken into the weekend as an upper low off the coast of British Columbia expands southward off the West Coast of the United States. This will cool things back down a bit to more seasonable temperatures across the interior. The coast and Bay Area will continue to benefit from marine influence.
as of 10:08am PDT Tuesday...Lingering storms out over the ocean are producing occasional lightning and locally erratic gusty winds. Chances for thunderstorms diminish into Tuesday afternoon. Winds will remain out of the northwest and fairly weak yet continue to be the influence on the sea state at around 6 to 8 seconds along with a weak southerly swell. Winds and gusts look to increase Tuesday afternoon and into the evening through the Golden Gate gap into the San Francisco Bay. Locally generated steep wind waves may be hazardous for smaller vessels.
.MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...SF Bay from 3 PM