FXUS66 KMTR 061214 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 514 AM PDT Fri Sep 6 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 133 AM PDT Fri Sep 6 2024 Hot and dry conditions again for Friday, resulting in a moderate to major risk of heat-related illness and near critical fire weather conditions. A pronounced cooling trend starts on Saturday and continues into next week. && .SHORT TERM... (Today and tonight) Issued at 133 AM PDT Fri Sep 6 2024 Today is forecast to be the last hot day across the interior, with slight cooling tomorrow. Expecting temperatures to range from 95- 105 degrees across the the far interior and in the higher elevations, 80's to mid 90's inland just away from the coast, and upper 60's to mid 80's near the coast. As such, moderate HeatRisk persist for inland areas where a Heat Advisory remains in effect until 8 PM this evening. With high pressure aloft, dry conditions will persist above the 500 foot marine layer as minimum humidities this afternoon will lower to 10-30% range. Overnight humidity recoveries will be slightly higher tonight except for the highest peaks. Nevertheless, we are still anticipating elevated to near critical fire weather conditions across the interior on Friday. Tonight, expect minimum temperatures to lower into the low-to-upper 50's near the coast and adjacent coastal valleys, near 60 degrees in the South Bay and Santa Clara Valley, and the upper 60's to upper 70's in the higher elevations. && .LONG TERM... (Saturday through Thursday) Issued at 133 AM PDT Fri Sep 6 2024 A significant pattern change will bring relief to the region on Saturday as the ridge flattens in response to an upper level trough digging out of the Gulf of Alaska and into the eastern Pacific. By Sunday, onshore flow will increase and bring temperatures back to near seasonal averages which will continue into early next week. Onshore winds will increase also with breezy to locally gusty conditions in the gaps and passes. From previous forecaster: "Heading into the later part of next week, model clusters are starting to hint at a low pressure system that could bring some chances for rain to the North Bay. That said, the model clusters continue to diverge on location and timing, so uncertainty towards this part of the period remains high." && .AVIATION... (12Z TAFS) Issued at 514 AM PDT Fri Sep 6 2024 Mix of VFR and LIFR CIGs across the board. Confidence is lower now that stratus will extend inland as the marine layer has stayed compressed below 1000 ft. Night Fog shows stratus has not pushed far into the East Bay as it was initially thought it would. LAMP probability plots indicate some short lived stratus may be possible 13-16Z at APC, OAK, and SFO but confidence remains low. Patchy fog continues to impact STS, MRY, and SNS with visibility and CIG height expected to continue fluctuating through the mid morning. Winds generally remain light and west to northwest through the morning before more moderate northwest flow returns during the afternoon. Locally gustier conditions may be possible for OAK and SFO during the afternoon/evening. Vicinity of SFO...Patchy IFR CIGs may temporarily impact SFO from 13- 16Z but confidence is low. Night Fog shows that stratus has receded away from SFO in the last several hours and not continued its initial strong push through the Golden Gate/into the East Bay. This has decreased confidence in stratus developing for a prolonged period of time at SFO and OAK. However, temporary IFR CIGs remain possible as the main stratus bank is located just offshore of the SF Peninsula/to the west of SFO and another inwards push cannot be ruled out. Additionally, ensemble guidance indicated that IFR CIG development became slightly more likely around 13/14Z. Winds generally stay out of the northwest and strengthen during the afternoon/evening with gusts up to 20 knots currently anticipated with lighter winds expected overnight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...LIFR conditions continue at MRY and SNS with VFR returning mid to late morning. Night Fog shows an eddy developing over the Monterey Bay which is starting to pull cloud cover away from MRY/SNS. LIFR CIGs are still expected to be the prevailing condition but will continue to monitor the eddy as it develops/amend as needed. Patchy fog has been observed at MRY overnight and remains possible through the mid morning. Light, northwest winds continue through the morning before becoming more moderate and west to northwest during the afternoon/evening. && .MARINE... (Today through Wednesday) Issued at 514 AM PDT Fri Sep 6 2024 Fair weather continues as high pressure persists over the region. Moderate seas and moderate winds from the west to northwest continue. Occasional fresh gusts are possible over the southern waters, particularly along the Big Sur coastline, into the weekend. Looking ahead to the middle of next week, unsettled seas and widespread strong northwest winds return. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory until 8 PM PDT this evening for CAZ502>504-506-510- 512>518. PZ...None. && $$ SHORT TERM...RGass LONG TERM....RGass AVIATION...Kennedy MARINE...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