Issued at 124 AM PDT Fri Apr 25 2025
Cloudy and cool conditions prevail with chances for rain and isolated thunder later today into Saturday, with the risk concentrated across the Central Coast and adjacent offshore waters. Dry conditions and a warming trend resume after the rain moves out early on Sunday.
, (Today and tonight) Issued at 124 AM PDT Fri Apr 25 2025
Short Term Key Messages: -Cool and cloudy through the day -Rain chances arrive later today through Saturday -Isolated thunderstorms possible in southern Monterey and San Benito counties -Snow possible on the peaks of the Santa Lucias and Diablo ranges
Cool and cloudy conditions are the story of the day with an upper level low continuing to deepen and approach the state. Satellite imagery and surface observations both support extensive and widespread cloudiness across the region and well into the interior. Some patches of clearing might be possible during the afternoon, but these will be generally short-lived and will dissipate with the approach of the low pressure system. High temperatures today and Saturday will range from the middle 50s to the lower 60s across the lower elevations, and the middle 40s to the lower 50s in the higher elevations, with breezy onshore winds developing this afternoon before a lull tonight into Saturday.
The forecast track of the low has continued to shift southwards into San Luis Obispo and Santa Barbara Counties, with the main axis of rainfall shifting ever so slightly southwards as a result. The main thrust of rain is anticipated to arrive Friday evening and last into Saturday evening. Generally beneficial rainfall is still anticipated for the Central Coast, particularly as the region has missed out on most of the big rainstorms during the winter storm season, with rain totals of a tenth to a quarter of an inch in the Monterey Bay region and the Salinas Valley, and up to half an inch in the Santa Lucias. In Santa Cruz County and the Bay Area, rain totals are very light, up to a tenth of an inch at most, with the region around San Francisco and Oakland seeing a few hundredths of an inch of rain, if any at all, from the system.
The chance for isolated convection remains across the southern halves of Monterey and San Benito counties late on Friday into Saturday, with the primary risk being isolated lightning strikes and brief accumulating hail. 700-500 mb lapse rates in the core of the upper level low will rise to around 7 to 7.5 C/km, allowing for CAPE values of around a few hundred J/kg, although the highest CAPE values remain displaced to SLO and Santa Barbara counties. As noted by the previous forecaster, a more northward track to the low would increase the risk, especially towards the northern halves of Monterey and San Benito Counties, while a more southward track moves the thunderstorm risk even further south.
In addition to all that, the highest peaks of the Santa Lucia and Diablo ranges continue to see a chance for some accumulating snow, with the blended guidance suggesting around a 50% chance of at least 2 inches of snow on the mountaintops. We do not anticipate needing any winter weather products, as the snow accumulation remains confined to the highest peaks.
..(Saturday through Thursday) Issued at 124 AM PDT Fri Apr 25 2025
Long Term Key Messages -Lingering showers through Sunday morning -Dry and warm conditions return after the showers clear.
A few lingering showers could remain across the Central Coast through Sunday morning, with any additional accumulations limited to a few hundredths of an inch generally, and up to a tenth of an inch in favored mountain locations. Sunday remains rather cool, but a drying and warming trend returns to the region as upper level ridging returns to the western United States. The upcoming work week should see high temperatures reach the upper 70s to the lower 80s in the inland valleys, the upper 60s to middle 70s along the San Francisco Bay, and the upper 50s to the middle 60s near the Pacific coast. Longer term predictions support a lean towards temperatures above seasonal averages into the first week of May.
(12z TAFS) Issued at 445 AM PDT Fri Apr 25 2025
A cold core 500 mb low was located 500 miles west-northwest of the Bay Area, with a 500 mb trough extending southeastward from the low center toward the Bay Area and north Central Coast this morning. Mountain top temps are in the 30s. Mt Hamilton is 32F, Chews Ridge is 30F for example. Cold air advection with the aforementioned trough is showing up on the Point Sur profiler. Conditions will be generally VFR-MVFR with a few showers, with improving chances of showers later today, tonight and Saturday with the 500 mb cold core low nearing our coastline. Freezing levels and wet bulb zero heights will lower during the period.
Vicinity of SFO, VFR-MVFR. A few passing light showers today and tonight, better chances of showers Saturday. West wind near 10 knots, southwest during the afternoon and light westerly tonight and Saturday morning.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR-MVFR. A few passing light showers today, better chances of showers tonight and Saturday. West to southwest winds 5 to 10 knots becoming light east to southeast tonight and Saturday.
(today through Wednesday) Issued at 421 AM PDT Fri Apr 25 2025
A chilly upper level low arriving from the northwest will result in scattered showers across the coastal waters and bays today through Sunday morning. Gusty northwest winds and rough seas return across the northern outer coastal waters late Saturday. Dry weather returns early next week due to an eastward moving high pressure system over the Pacific.
Ca, None. PZ, Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM.
