Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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395 FXUS66 KMTR 181842 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1142 AM PDT Tue Jun 18 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 850 AM PDT Tue Jun 18 2024 Upper level trough will remain over the region through the next several days, with breezy onshore winds and temperatures near seasonal averages prevailing through Thursday. The trough will weaken for Friday and the weekend, with warmer conditions developing once again across the inland areas. && .UPDATE... Issued at 850 AM PDT Tue Jun 18 2024 Water vapor imagery shows a broad trough of low pressure over the West this morning, with another disturbance poised off the Northern California Coast. Meanwhile, visible imagery is showing quite a bit of smoke filtering into the area from the Site Fire in Colusa County. For the most part, it appears this smoke is aloft, as all of our surface observing sites are reporting 10 SM and the majority of the air quality sites are satisfactory to acceptable this morning. Visible imagery is also showing quite a bit of high cloud cover associated with this next disturbance, so expect increasing clouds as we go through the day today and tonight. Also expect onshore flow to increase once again this afternoon, but not anticipating the onshore flow to be quite as strong today, as we have seen the past couple of days. Daytime temperatures will be similar to what we saw yesterday, maybe a degree or two warmer inland and a degree or two cooler along the coast. Current forecast seems to be handling these trends will, so no update is planned at this time. Palmer && .SHORT TERM... (Today and tonight) Issued at 123 AM PDT Tue Jun 18 2024 Winds are generally light this morning with the upper level trough that drove the intense daytime winds progressing eastward across the Intermountain West. Mid to high level clouds will flow over the region today. Breezy onshore winds will develop this afternoon, but they won`t be as intense as what we`ve seen this last weekend. Low temperatures this morning will generally be in the low to mid 50s in the lower elevations, to the upper 50s and around 60 in the higher elevations. High temperatures today will range from the upper 50s to mid 60s along the coast, to the mid to upper 70s along the Bayshore, and the mid 80s to lower 90s in the inland valleys. Smoke from the Point Fire in northwestern Sonoma County and the Sites Fire in Colusa County is expected to travel towards the south and southeast, impacting the Bay Area and Central Coast with haze and moments of smoke. Although the Red Flag Warning for the North Bay interior mountains was allowed to expire last night, elevated fire danger remains across the interior regions. The air remains very dry with daytime relative humidities in the 10-30 percent range across the inland areas and the coastal ranges, with breezy onshore winds gusting up to 20-30 miles per hour in the afternoon. Humidity recoveries overnight are expected to progressively improve through the week, but remain poor across the interior mountains and the Santa Lucias. && .LONG TERM... (Wednesday through Monday) Issued at 123 AM PDT Tue Jun 18 2024 A weak upper level trough develops over the state, continuing to hover over the area for the next few days and promoting the redevelopment of the marine layer and its associated stratus clouds. Temperatures dip on Wednesday with highs in the upper 70s to mid 80s in the inland valleys to the mid 50s to lower 60s along the coast, before Thursday sees a few degrees of warming. By Friday, the trough will erode as a ridge builds into the western United States. The warmest temperatures are expected on Saturday, where highs will range from the 90s to lower 100s for the inland regions, the mid 70s to low 80s for the Bayshore, and the low to mid 60s for the coast. && .AVIATION... (18Z TAFS) Issued at 1141 AM PDT Tue Jun 18 2024 VFR through the TAF period for the majority of terminals, with the exception of Monterey Bay. Smoke continues to linger throughout the region this morning bringing hazy skies but is expected to clear towards the afternoon as onshore flow helps push smoke eastward. That being said, winds expected to be onshore and breezy today, though not as gusty as in previous days. A few gusts nearing 20 kt are not out of the question for coastal terminals, higher at SFO. In the late night, winds ease to become light for the majority of terminals. Stratus will begin to creep up the coastline, and will begin to advect inland where it is expected to bring MVFR CIGs to KOAK and KMRY. Terminals elsewhere are likely only to see FEW low clouds develop in the overnight. Vicinity of SFO...Winds W/NW and moderate this afternoon, gusting nearly to 30 kt at the highest. Winds ease into the late night, but are not expected to become light until the early morning of Wednesday. That aside, VFR expected through the TAF period, though stratus pushing inland in the overnight hours is likely to bring SCT low clouds. At this time, confidence is low in MVFR CIG development for SFO in the night tonight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR through the evening tonight with breezy NW winds. By the late evening, winds decrease and stratus is expected to form MVFR CIGs. However, there is some question as to whether CIGs this evening will develop at IFR altitudes rather than MVFR initially, as the Ft. Ord Profiler currently shows a marine layer very near to the surface. Confidence on CIGs initially developing at MVFR levels is only moderate. && .MARINE... (Today through Sunday) Issued at 1141 AM PDT Tue Jun 18 2024 Fresh and gusty northwesterly winds continue. Gusty winds will diminish overall towards late Wednesday with strong breezes persisting over the northern outer waters through the weekend. Significant wave heights will build to 9-11 feet today, abate through Friday, and build back up to 10-12 feet towards the end of the the weekend as larger northwesterly swell enters the waters. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Mry Bay-SF Bay N of Bay Bridge. Small Craft Advisory from 9 AM to 3 PM PDT Wednesday for SF Bay N of Bay Bridge. Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Mry Bay. Small Craft Advisory until 9 PM PDT Wednesday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory until 9 AM PDT Wednesday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 3 AM PDT Wednesday for Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory from 9 PM Wednesday to 9 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...Palmer LONG TERM....DialH AVIATION...AC MARINE...AC 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