Sunrise 6:07 AM   Sunset 8:02 PM Moonrise 3:12 AM   Moonset 3:21 PM

  Print   HELP   Reset   Save   Recall

PZZ531 San Francisco Bay South Of The Bay Bridge- 837 Am Pdt Sat May 4 2024
.small craft advisory in effect through this evening - ..small craft advisory in effect from Sunday afternoon through late Sunday night - .
Today - SW winds 10 to 20 knots with gusts up to 30 knots. Rain.Tonight - W winds 15 to 25 knots with gusts up to 30 knots. Sun - W winds 10 to 15 knots. Sun night - W winds 15 to 20 knots with gusts up to 25 knots. Mon - W winds 10 to 15 knots. Mon night - W winds 10 to 20 knots with gusts up to 25 knots. Tue - NW winds 10 to 15 knots. Wed - NW winds 10 to 15 knots.

PZZ500 837 Am Pdt Sat May 4 2024
Synopsis for the central california coast and bays including the Monterey bay - Greater farallones - .and cordell bank national marine sanctuaries - .
widespread rain and fresh southwesterly breezes are affecting the waters. Fresh northwesterly breezes will prevail behind main rain band with scattered rain showers possible into the evening. Dry conditions return and winds reduce into Sunday. Gusty winds build into the middle of the next work week and last into the late week.

FXUS66 KMTR 041543 AFDMTR

Area Forecast Discussion National Weather Service San Francisco CA 843 AM PDT Sat May 4 2024

New UPDATE, MARINE

SYNOPSIS
Issued at 1201 AM PDT Sat May 4 2024

A cold front will bring rain, strong winds, and much colder temperatures to the area today. A gradual warming trend will start Monday with dry weather and plenty of sunshine next week.

UPDATE
Issued at 838 AM PDT Sat May 4 2024

Forecast on track with no changes needed this morning as rain has spread well into the Bay Area. Some evidence of a narrow cold frontal rain band evident on radar, currently exiting the North Bay as of writing. Expect gusty winds and brief heavy rain as this feature passes through, with lingering light to moderate rain behind it into late morning. Rain totals appear largely on track with between 0.50-0.80" in the North Bay so far. As far as we can tell, no major impacts so far, outside of some very minor water on roadway reports. See previously issued SHORT TERM for more info.

SHORT TERM
(Today and tonight)
Issued at 1201 AM PDT Sat May 4 2024

KMUX is starting to pick up on the main frontal rain band as it approaches the North Bay early this morning. To add timing precision, I used a blend of high-resolution short term models to create 1 hourly PoP grids. Based on the new official forecast, rain is expected to reach Santa Rosa by 4 AM, San Francisco by 6 AM, San Jose by 8 AM, and Salinas by 10 AM. The main band of rain should last 6-8 hours before tapering off. The expected total rainfall is continuing to tick up slightly, with 0.5-1.0" in most lowlands and 1.0-1.5" in the coastal mountains. Prefrontal SW winds are moderate this morning, but will increase to a strong breeze as the front approaches and switch to a NW direction after it passes.

The confidence in the prefrontal stratiform rain described above is quite high, with very little ensemble spread. The bigger question today is if thunderstorms will develop in the cold, post frontal environment. The expected 700 mb temperature is near the daily minimum, which would suggest some instability, but there's a few complications. First, the coldest mid-level air doesn't settle in until Saturday night, after the surface temperature is on the down swing. Second, the 500 mb temperature is not as impressive as the 700 mb temperature with a more stable 3.5 C/km lapse rate between those two levels. This indicates any convection that initiates tomorrow will have a vertical limit of about 10,000 ft.
With the top end of the hail growth zone (-30C) at over 22,000 ft, this limits the amount of ice that will be generated. The most likely scenario is that after the front moves through some isolated, low-topped convective showers will pop up through the evening. There is a scenario, however, where the skies clear after the front passes and the surface temperature increases more than expected. This could lead to some evening thunderstorms, particularly in the North Bay where the front will clear first and the potential surface heating is higher. To demonstrate this, I adjusted the NAM model sounding at Santa Rosa, increasing the surface temperature a few degrees to line up with our forecast of 13C/55.4F. This alone increased the CAPE from 130 J/kg to over 500 J/kg. If the surface temperature exceeds our expectations, the instability will be even higher. In other words, if the sun comes out in the afternoon, the chance for evening thunderstorms increases significantly.

LONG TERM
(Sunday through Friday)
Issued at 1201 AM PDT Sat May 4 2024

The cold front and associated low pressure system will clear the area by Sunday, leaving cold air in place. Sunday morning will be on the chilly side, with many inland areas dropping into the upper 30s or low 40s. There is a slight chance for some lingering showers on Sunday, but they should be isolated and on a decreasing trend through the day (if anything develops in the first place).
Otherwise a gradual warming trend will kick off next week with Sunday highs in the 50s and 60s and Friday highs in the 70s and 80s. Expect lots of sunshine with breezy winds along the coast, especially during the first half of the week.

AVIATION
(12Z TAFS)
Issued at 447 AM PDT Sat May 4 2024

Currently seeing the low pressure system and its associated cold front moving southeast across the region with STS already reporting rain. This cold front will continue to traverse across the region through the morning bringing widespread rain, winds with gusts of up to 25 knots, and MVFR conditions to all terminals. Winds will briefly become southerly/southwesterly ahead and through the cold frontal passage. VFR conditions and westerly winds will prevail at all terminals once the cold front moves out from over a terminal.

Vicinity of SFO...Currently MVFR with breezy southwesterly flow.
Winds will become gusty ahead and through the cold frontal passage.
Behind the cold front, VFR conditions and westerly winds prevail.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently MVFR with breezy southerly flow at MRY and IFR with breezy northerly flow at SNS. Winds will become gusty out of the southwest ahead and through the cold frontal passage. Behind the cold front, VFR conditions and westerly winds prevail.

MARINE
(Today through Thursday)
Issued at 838 AM PDT Sat May 4 2024

Widespread rain and fresh southwesterly breezes are affecting the waters. Fresh northwesterly breezes will prevail behind main rain band with scattered rain showers possible into the evening. Dry conditions return and winds reduce into Sunday. Gusty winds build into the middle of the next work week and last into the late week.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 3 PM PDT this afternoon for SF Bay N of Bay Bridge.

Small Craft Advisory until 9 PM PDT this evening for Mry Bay-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 9 AM Sunday to 3 AM PDT Monday for Mry Bay-Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pt Arena to Pt Reyes 0-10 nm.

Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM.

Small Craft Advisory from 3 PM Sunday to 3 AM PDT Monday for Pigeon Pt to Pt Pinos 0-10 nm.

Gale Warning until 9 AM PDT this morning for Pt Pinos to Pt Piedras Blancas 0-10 nm.

Small Craft Advisory until 9 AM PDT this morning for Pt Arena to Pt Reyes 10-60 NM.

Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM.

toggle option: (graph/table)

Palo Alto Yacht Harbor
Click for Map
Sat -- 04:12 AM PDT     Moonrise
Sat -- 05:03 AM PDT     1.09 feet Low Tide
Sat -- 06:09 AM PDT     Sunrise
Sat -- 10:18 AM PDT     7.03 feet High Tide
Sat -- 04:20 PM PDT     Moonset
Sat -- 05:10 PM PDT     0.34 feet Low Tide
Sat -- 08:01 PM PDT     Sunset
Sat -- 10:58 PM PDT     7.90 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Palo Alto Yacht Harbor, California, Tide feet

Dumbarton Point 2.3 mi NE
Click for Map
Sat -- 02:50 AM PDT     -1.05 knots Max Ebb
Sat -- 04:12 AM PDT     Moonrise
Sat -- 05:15 AM PDT     0.01 knots Slack
Sat -- 06:09 AM PDT     Sunrise
Sat -- 07:49 AM PDT     1.23 knots Max Flood
Sat -- 10:45 AM PDT     -0.01 knots Slack
Sat -- 03:04 PM PDT     -1.13 knots Max Ebb
Sat -- 04:20 PM PDT     Moonset
Sat -- 05:25 PM PDT     0.01 knots Slack
Sat -- 08:01 PM PDT     Sunset
Sat -- 08:08 PM PDT     1.49 knots Max Flood
Sat -- 11:12 PM PDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION

Dumbarton Point 2.3 mi NE, South San Francisco Bay, California Current, knots

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

San Francisco Bay Area, CA,