Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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757 FXUS66 KMTR 172053 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 153 PM PDT Mon Jun 17 2024 ...New SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 153 PM PDT Mon Jun 17 2024 Red Flag Warning remains in effect for the North Bay Interior Mountains until 8 PM tonight. Dry and breezy conditions continue into Monday night. Better onshore flow and moisture return by midweek. Another warming trend on the way for the upcoming weekend. && .SHORT TERM... (This evening through Tuesday) Issued at 153 PM PDT Mon Jun 17 2024 Gusty northwest winds continue to mix down toward the surface this afternoon, as high as 30 mph in some of our higher locations over the interior coastal ranges and passes. The gusty winds combined with a dry air mass producing min RH values as low as 10 percent will persist for the remainder of this afternoon into the evening hours. A Red Flag Warning remains in effect until 8pm for the North Bay Interior Mountains in Napa county. A positively tilted upper level trough will keep winds elevated wrt the normal diurnal trend overnight into Tuesday. Embedded weak shortwave ridging will help to ease surface winds Tuesday, especially inland away from the coast, however the Salinas Valley will reamin breezy as onshore northwest surface flow channels inland. Temperatures will remain near seasonal averages through midweek. && .LONG TERM... (Tuesday night through next Sunday) Issued at 145 PM PDT Mon Jun 17 2024 A warm up continues to highlight the extended forecast. Persistent upper level troughing over our region begins to shift east and flatten late Thursday into early Friday, continuing into the weekend. A weak ridge begins to build with the ridge axis just to our east over the Sierra Mountains Friday afternoon. An increase in heights and thickness will allow another round of heat to build, especially the farther you move inland from coastal areas. Elevated areas of southern Monterey and San Benito county may see triple digit heat, along with portions of Contra Costa and Alameda county to the north on Saturday, which should be the peak of this round of heat. && .AVIATION... (18Z TAFS) Issued at 1058 AM PDT Mon Jun 17 2024 Currently VFR at all terminals. VFR through the TAF period for all terminals except MRY. Thanks to wildfires in the area, high pressure trapping the smoke, and northerly/northwesterly winds, smoke will likely be seen across the area, particularly at the terminals of APC, LVK, and STS, although no significant visibility reductions are to be expected. With the exception of STS, winds will become more westerly/onshore through the TAF period. Vicinity of SFO...Currently VFR with northerly flow. VFR through the TAF period. Winds will transition to become westerly this afternoon with gusts up to 30 knots to be expected. Westerly winds diminish overnight before becoming gusty again tomorrow afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Currently VFR with northwesterly flow at both terminals. Winds will be gusty out of the west/northwest through this evening before diminishing overnight. Moderate confidence on MRY getting an IFR ceiling with lower confidence on if it`ll reach SNS. && .MARINE... (Today through Saturday) Issued at 1058 AM PDT Mon Jun 17 2024 Widespread strong northerly/northwesterly breezes with near gale- force gusts will persist through Wednesday. These northerly/northwesterly breezes will diminish overall beginning Thursday with strong breezes remaining exclusive to the outer waters. Significant wave heights will build to 10-12 feet today, abate through Friday, and build back up to 10-12 feet towards the end of the period. && .FIRE WEATHER... Issued at 245 AM PDT Mon Jun 17 2024 ...Red Flag Warning remains in effect interior North Bay Mts Monday... ...Elevated Fire Weather Conditions Through Monday night... *Breezy to gusty northerly winds, especially higher terrain *Lowering relative humidity values day and night Point Wildfire (near Lake Sonoma): Latest heat trends on GOES satellite and webcams show less heat, but that doesn`t mean the fire is "out" or contained. For fire specific updates follow CalFire for the latest. Weather wise, winds near the fire remain NW with gusts in the 10-20 mph range. Despite the breezy conditions, RH values have crept upward to moderate, which is good. Transport flow continues to show smoke impacts SE of Lake Sonoma stretching into the East Bay. This is also being reflected at the surface with AQ sensors showing poor AQ. For more AQ info check BAAQMD. Overall fire weather concerns: No change with ongoing Red Flag for interior North Bay for later today. The northerly shift in winds are still on track with gusts in the 25-40 mph. Winds will be strongest over the higher terrain of the North and East Bay. While winds increase RH values will begin to plummet. Hi-res guidance continues to advertise RH values dropping into the upper single digits to lower teens this afternoon. The greatest impact will be over the North Bay Interior Mts - hence the Red Flag. Elsewhere, conditions will be marginal for Red Flag, but still elevated nonetheless. Winds remain breezy offshore for Monday night into Tuesday keeping elevated fire weather concerns in play. Better relief arrive Tuesday into Wednesday with increased onshore flow. Longer range forecast will need some watching as hot and dry conditions return to the district. MM && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Red Flag Warning until 8 PM PDT this evening for CAZ504. PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-Pt Arena to Pt Reyes 10-60 NM-SF Bay N of Bay Bridge. Small Craft Advisory from 3 PM to 9 PM PDT Tuesday for SF Bay N of Bay Bridge. Small Craft Advisory from 9 AM Tuesday to 3 AM PDT Wednesday for Mry Bay. Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm. Gale Warning from 3 PM Tuesday to 3 AM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Gale Warning from 9 PM this evening to 3 AM PDT Tuesday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...JM LONG TERM....JM AVIATION...Sarment MARINE...Sarment 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