Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000 FXUS66 KMTR 191740 AFDMTR Area Forecast Discussion National Weather Service San Francisco Bay Area 1023 AM PDT Thu Apr 19 2018 .SYNOPSIS...A warming trend and dry weather conditions are by Friday and through the upcoming weekend. A weak cutoff low approaches the region mid to late next week. && .DISCUSSION...as of 09:00 AM PDT Thursday... Another cool morning in the wake of a cold frontal passage with temperatures observed around 5 to 10 degrees lower versus 24 hours ago. The upper low responsible for these cooler temperatures is exiting into the Great Basin this morning. Only a handful of sites reported any precipitation from this storm system after it juked southward into Big Sur country just as it approached the Monterey Bay region. Fort Hunter Liggett in southern Monterey county picked up .10" to lead the way while most locations didn`t get a drop. For today, breezy to locally gusty northwest winds will prevail, especially along the coast, with slightly to somewhat warmer temperatures compared to yesterday. Mostly clear skies are expected with some weak cumulus development possible in the afternoon. Fair weather conditions are expected through the weekend and into early next week. A slight warming trend is forecast now through the weekend where temperatures will rise to a few degrees above normal at the coast (mid to upper 60s) and up to 10 degrees warmer than normal farther inland (upper 70s to low 80s). A weak upper trough passes to the north later in the weekend that stems the warming trend over the San Francisco Bay area, but should not mitigate the warming trend for the Monterey Bay area. Temperatures will increase slightly again on Monday. GFS and Euro show a cutoff low approaching the region midweek next week, however, the GFS has it much closer to the CONUS while the EURO keeps it well offshore. Both models agree that the upper low eventually approaches California by late next week, skirting along the NorCal coast before pushing inland over SoCal. Can not rule out light rainfall from this storm at this point but given current data, it will be fairly light and mainly focused over the southern counties. Stay tuned as the story of this storm system comes into view. Finally, the 384 hr GFS shows mainly benign weather for the region, so we may be at the end of the rainy season. Now, who`s ready for stratus season? .PREVIOUS DISCUSSION...as of 3:17 AM PDT Thursday...The system moving south along the coast is rapidly weakening as it moves south. So far the only bucket tips have been in Big Sur with a few stations reporting 0.04 of an inch over the past several hours. Temperatures are also cold in the Santa Lucias...28 degrees at Chews Ridge...so there could be a few snow flurries at higher elevations in Big Sur for the next couple of hours. Precipitation will end this morning as the system moves south. Dry conditions with slightly warmer temperatures are expected today. High pressure building over the eastern Pacific by Friday will bring warmer temperatures through the weekend. Highs over the weekend are forecast to reach into the mid 80s across inland areas by Sunday. Mild conditions to persist into next week. Medium range models are still indicating a closed low moving into California by the middle of next week. The location and track of this low vary by model, so confidence is very low concerning one solution over another. There could possibly be one more shot of rain for the area, but right now it is not looking highly likely. && .AVIATION...As of 10:22 AM PDT Thursday...For 18z tafs. Visible satellite shows patchy low cigs affecting the Monterey Peninsula/Northern Salinas Valley region. Difficult to say if these low clouds will persist and/or lift through the afternoon. Amendments to the KMRY & KSNS TAFs may be necessary as the day progresses. Elsewhere, VFR is expected through the afternoon, with breezy and occasionally gusty onshore winds by early afternoon. There remains some questions whether cigs return this evening. Kept cigs out of the TAF for SF Bay Area terminals for now, but did include cigs tonight for Monterey Bay terminals, with low confidence on coverage and timing. Overall forecast confidence: Moderate Vicinity of KSFO...VFR will prevail through the afternoon and early evening. Afternoon west winds to around 20 kt, with gusts over 25 knots possible. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...Low level clouds affecting KMRY, but should lift above 3000 feet by noon or so. Will amend TAF if necessary. Light to moderate westerly winds this afternoon, 10-15 kt. && .MARINE...as of 9:01 AM PDT Thursday...Breezy NW winds will prevail today into Friday and will produce steep wind waves, making for rough seas. Winds will remain moderate to strong through the weekend as high pressure builds and surface gradients tighten near Cape Mendocino. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pigeon Pt to Pt Pinos 0-10 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA...Mry Bay && $$ PUBLIC FORECAST: DRP AVIATION: BAM MARINE: BAM 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

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