FXUS66 KMTR 121619 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 919 AM PDT Thu Sep 12 2024 ...New UPDATE, MARINE... .SYNOPSIS... Issued at 130 AM PDT Thu Sep 12 2024 An upper level trough to our north continues to shift farther inland with wind speeds diminishing throughout the day, yet will remain breezy to gusty at times. Slightly warmer for Friday, near seasonal averages. Then another trough will begin to impact the region bringing chances of precipitation at times through next week. && .UPDATE... Issued at 905 AM PDT Thu Sep 12 2024 Forecast remains on track with no updates needed as a weak, low- amplitude ridge begins to build into place. As a result, temperatures today will near seasonable averages with gusty winds still expected this afternoon and evening as the upper-level low continues to move out of the region. && .SHORT TERM... (Today and tonight) Issued at 130 AM PDT Thu Sep 12 2024 The mid/upper level trough axis will continue to shift farther inland as higher pressure builds in from the west. This will bring temperatures up to near seasonal averages, especially across the North Bay and East Bay with mid-to-upper 80's expected. Elsewhere, afternoon maximum temperatures are expected to be in the 60's to 70's near the coast and up to the mid 80's across the interior. Today will be less windy than yesterday but afternoon and evening gusts of 20-40mph (locally stronger in the favored windy spots). Tonight, again northwest facing slops will be favored for low clouds as northwest flow continues over the Pacific in response to the exiting trough. Temperatures will cool into the low-to-mid 50's, upper 50's in the Santa Clara Valley, and up to the mid-to-upper 60's in the higher terrain. && .LONG TERM... (Friday through Wednesday) Issued at 130 AM PDT Thu Sep 12 2024 Friday will be the warmest day of the week region-wide as the aforementioned high pressure builds inland. However, it will be short lived as troughing returns to the West Coast and cools temperatures aloft on Sunday. As the trough digs southward, it will bring rain chances to the region Sunday afternoon and into Monday. However, rainfall amounts still remain in question and forecast models diverge on the timing and placement of the through. One thing we have higher confidence on is that a cool down will take place! This unsettled pattern will persist into next week as another upper level through develops on the heels of the upper level low. Stay tuned... && .AVIATION... (12Z TAFS) Issued at 447 AM PDT Thu Sep 12 2024 Patchy stratus continues over much of the Bay Area and Central Coast. CIGs have been fluctuating between IFR and MVFR with CIGs expected to predominantly be MVFR through the remainder of the morning. Stratus coverage may temporarily transition from broken to scattered but, overall, stratus is expected to prevail through 17- 18Z at OAK, MRY, and SNS. Stratus may temporarily impact SFO, SJC, and LVK through 16Z after which stratus is expected to dissipate for good with RH values expected to drop. By late morning, VFR returns to all sites and moderate to gusty winds generally out of the west to northwest return. Low to moderate confidence on timing of stratus return this evening. Current thinking is that a late stratus return around 08-09Z will take place with a slightly earlier return expected along the Central Coast. Vicinity of SFO...Patchy stratus continues through 16Z after which decreasing moisture lowers confidence in stratus persisting. VFR conditions persist through late Thursday/early Friday morning with low to moderate confidence in stratus returning around 09Z. Moderate west to northwest winds will strengthen and become gusty during the afternoon/evening with gusts up to 25 knots expected before weakening again overnight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Stratus and MVFR-IFR CIGs are expected to continue through 17-18Z. Stratus has been patchy with CIGs temporarily improving and becoming few/scattered at MRY and SNS overnight. Moderate confidence that CIGs will persist through 17-18Z with some potential for earlier clearing beginning around 16Z. In particular, SNS may clear before MRY as stratus has been consistently patchier there all night. VFR conditions persist through the afternoon and into the evening with a mix of MVFR-IFR expected by late evening and into the night. Light, variable winds continue through the morning before becoming more moderate during && .MARINE... (Today through Tuesday) Issued at 905 AM PDT Thu Sep 12 2024 The gradient between subtropical high pressure and a trough over California is supporting a fresh to strong NW breeze with gale force gusts in the northern outer waters. Conditions will gradually improve through the next 48 hours and Saturday will be a nice day on the water. A new system will increase winds and rebuild seas on Sunday with unsettled weather possible through the fist half of next week. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory until 3 AM PDT Friday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt to Pt Pinos 0-10 nm. Gale Warning until 3 AM PDT Friday for Pt Arena to Pt Reyes 10- 60 NM. && $$ SHORT TERM...RGass LONG TERM....RGass AVIATION...Kennedy MARINE...Flynn 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