Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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706 FXUS66 KMTR 242340 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 440 PM PDT Mon Jun 24 2024 ...New UPDATE, AVIATION, FIRE WEATHER... .SYNOPSIS... Issued at 142 PM PDT Mon Jun 24 2024 Temperatures near to slightly above seasonal averages with a slight cooldown midweek. Very low chance of high-based convection and associated dry lightning in the Central Coast today. The threat will shift northward into the Bay Area and North Bay tonight into Tuesday evening. && .UPDATE... Issued at 433 PM PDT Mon Jun 24 2024 Forecast update to add slight chance of thunderstorms into Tuesday for portions of our service area. Radar is showing high based shower this afternoon with one strike so far over the Santa Cruz Mountains. Models are indicating that showers will continue overnight and through much of Tuesday while slowly transiting north and east. && .SHORT TERM... (This evening through Tuesday) Issued at 142 PM PDT Mon Jun 24 2024 We continue to see a small threat (10-15%) for high-based convection across Monterey and San Benito County this afternoon and that threat will shift northward throughout the night and into tomorrow morning, potentially into the afternoon/evening as well. This is as mid-level moisture is being advected in from the south and will move across the entire Bay Area through Tuesday evening with forecast MUCAPE between 100-300 J/kg. Mid-level moisture is the most certain ingredient, with a plume of moisture migrating northwards with PWAT values up to 1-1.25". For context, if those values were reported at our upper air site at Oakland airport, those precipitable water values would be at or above the 90th percentile value for all observed soundings at this time of year. The main impact if convection does develop would be the possibility for dry lightning setting off grass and shrub fires, but this is a "low confidence- high impact" type of event at this stage. Otherwise, temperatures are expected to be near seasonal averages for coastal areas and slightly above for the interior the next several days with most areas away from the coast only getting to Minor HeatRisk. && .LONG TERM... (Tuesday night through Sunday) Issued at 1243 AM PDT Mon Jun 24 2024 Wednesday sees an upper level trough move in which will push the moisture out of our region, and herald a gradual cooling trend in temperatures for the interior regions. By the end of the week, temperatures across the interior will top out at around 90 in the warmest spots, with most of the inland valleys seeing temperatures within the 80s. Towards the beginning of July, model ensemble clusters are indicating a couple of ridges approaching the West Coast, with early indications of a warming trend towards the end of the 7-day forecast. && .AVIATION... (00Z TAFS) Issued at 433 PM PDT Mon Jun 24 2024 Satellite shows mostly clear skies over the region with a band of high-based convection clouds moving north from the south. Therefore, there is a slight chance for dry thunder and lightening. Conditions will remain VFR through the TAF period for all terminals, except Monterey Bay terminals where low stratus will return tonight. Models hint that low ceilings will return for the remainder of the terminals tonight, but due to lack of model agreement and persistence, VFR was kept in the TAFs. Moderate to breezy onshore winds will diminish to light and variable tonight. Winds will rebuild by Tuesday afternoon. Vicinity of SFO...VFR through the TAF period models hint at MVFR developing early Monday morning, but will monitor if any updates are needed to TAFs. NW strong winds will diminish tonight before rebuilding to breezy Tuesday afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR until tonight where IFR conditions are expected to return. Timing of clearing is uncertain as models show disagreement but moderate confidence that clearing will occur near 14-15Z. && .MARINE... (Today through Saturday) Issued at 910 AM PDT Mon Jun 24 2024 Hazardous conditions for small crafts persist across the northern coastal waters through early week. Fresh to strong north to northwest winds continue over the northern coastal waters. Moderate northwest winds continue over the southern coastal waters with the occasional fresh gust possible over the outer waters. Significant wave heights over the northern waters will build to 10-11 feet through today before wave heights abate below 10 feet by Tuesday. Widespread fresh to strong winds are expected to return over the coastal waters by late week with wave heights gradually building to 10 feet across portions of the northern coastal waters. && .FIRE WEATHER... Issued at 433 PM PDT Mon Jun 24 2024 Slight chance of thunderstorms were added to the forecast through Tuesday. While these thunderstorms will be accompanied by showers, it is possible that rain will be limited. So far convection that has occurred in southern areas has shown measurable precipitation. Winds at 4 pm today have been gusting into the 20 mph range in the mountains, but single digits in the low lands. Any strikes that do occur may cause a fire start in the fine fuels. The additional concern is any strikes in the fine fuels that sleep for a few days when the onshore winds kick in. This could cause rapid growth in the grasses even with higher humidity. No strike or spark, no fire. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 AM PDT Tuesday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...BFG/RGass LONG TERM....RGass/DialH AVIATION...SO MARINE...SO/Kennedy 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