Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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484 FXUS66 KMTR 231752 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1052 AM PDT Mon Sep 23 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 300 AM PDT Mon Sep 23 2024 Temperatures peak today and tomorrow with a Heat Advisory in effect for the interior East Bay, South Bay, and the Santa Cruz Mountains beginning at 11 AM PDT. Temperatures return to near seasonal averages on Wednesday for the remainder of the extended forecast. && .UPDATE... Issued at 1005 AM PDT Mon Sep 23 2024 Satellite imagery shows that the stratus and fog deck has retreated back to the immediate coast. In addition, cirrus clouds flowing southwestward over the state of Nevada and into eastern California hint at the offshore flow aloft, contributing to the warm temperatures expected today. The RTMA analysis shows that temperatures are warmer than this time yesterday across the higher elevations, and colder than this time yesterday in the valleys. Those cold trends are expected to disappear through the day as solar heating kicks in. With a compressed marine layer (around 800 feet via the Fort Ord profiler), not expecting a lot of stratus development inland, although areas that do see stratus could see mist or fog develop. Monitoring the marine layer evolution through the day, as its inland extent tonight could determine how much relief comes overnight, especially in the coastal ranges and near San Francisco Bay. The Heat Advisory for the interior East Bay, South Bay, and Santa Cruz mountains goes into effect at 11 AM today, due to a risk for heat-related illnesses for sensitive populations and people without adequate hydration and/or cooling. Here`s a reminder about heat safety: * Stay hydrated and drink plenty of fluids. * Wear lightweight, light-colored clothing. * Reduce time spent outdoors or stay in the shade. * Never leave people or pets unattended in vehicles. * Use sunscreen if going to the coast or the pool. && .SHORT TERM... (Today and tonight) Issued at 300 AM PDT Mon Sep 23 2024 A Heat Advisory will go into effect later this morning for the interior East Bay, South Bay and Santa Cruz mountains as temperatures climb into the 90s to near 100 for many inland locations. A warm airmass over our area defined by low/mid level temperatures in the 90th percentile (H50 at -6.5C, H85 at 22C) or slightly higher will peak today, though linger through tomorrow, especially over the interior North Bay where a Heat Advisory will remain in effect for Tuesday afternoon as well. With light winds from the surface up to around H50, a lack of ventilation will lead to some haze as well the next couple of days. && .LONG TERM... (Tuesday through Sunday) Issued at 300 AM PDT Mon Sep 23 2024 By late Tuesday night into Wednesday, upper level flow, though still relatively light will regain a westerly component as we begin to feel the influence of a developing trough over the central California coast. Cooler temperatures aloft will translate to near normal surface temperatures for the remainder of the week into next weekend as the upper low currently in our vicinity, is absorbed by a broad, deepening trough out of the Gulf of Alaska that will persist through the remainder of the extended forecast. && .AVIATION... (18Z TAFS) Issued at 1044 AM PDT Mon Sep 23 2024 After a pesky start to the day with VLIFR and IFR impacting terminals all terminals as of the 18Z taf package are VFR. Expecting VFR at all terminals outside of Monterey Bay through the period. High pressure overhead, compressed marine layer, and weak offshore flow will lead to less level moisture/stratus/fog Tuesday morning. While some model guidance suggest some patchy fog around the Bay Area current thinking is the drier offshore flow will win out. Monterey Bay is different where enough of a low level onshore flow will bring some fog/clouds back in again tonight. Vicinity of SFO...VFR. Breezy onshore flow after 23Z this afternoon. Winds easing overnight. SFO Bridge Approach...similar to SFO. Monterey Bay Terminals...VFR through 03-05Z. Will slowly introduce fog there after with peak vis reduction late tonight/early Tuesday. Dissipation likely before end of taf period at 18Z Tuesday. Confidence for fog impacting MRY/SNS is about 50-60%. && .MARINE... (Today through Saturday) Issued at 1044 AM PDT Mon Sep 23 2024 High pressure remains over the Eastern Pacific keeping northwesterly flow over the coastal waters through at least midweek. Northwest winds will strengthen later in the week. Seas rebuild to become rough in the outer waters by Thursday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory until 8 PM PDT Tuesday for CAZ510-515. Heat Advisory until 8 PM PDT this evening for CAZ512>514. PZ...None. && $$ SHORT TERM...JM LONG TERM....JM AVIATION...MM MARINE...MM 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