Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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387 FXUS66 KMTR 010006 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 506 PM PDT Sun Jun 30 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 1235 PM PDT Sun Jun 30 2024 Significant warm up still on the way for next week after near normal temperatures this weekend. Increased fire danger next week as well with temperatures well above normal and dry conditions through next weekend. && .SHORT TERM... (This evening through Monday) Issued at 1235 PM PDT Sun Jun 30 2024 A gorgeously warm day across the region today, and a great day to be outside. Temps warm up a few degrees going into Monday as a weak upper level trough degrades and moves inland. Highs Monday look to be in the 90s across the interior, 80s for much of the Bay shoreline, and 70s along coastal areas. If you live in the interior, now is the time for any outdoor chores you may need to get done before the warm up begins on Monday. && .LONG TERM... (Tuesday through next Saturday) Issued at 1235 PM PDT Sun Jun 30 2024 Significant warmup really begins Tuesday as the very strong ridge settles in across the West Coast. Not much change in the forecast through the middle part of the week. Excessive Heat Warning goes into effect Tuesday morning for interior areas, while lower elevation locations that were once in the Watch have been converted to a Heat Advisory given that they will cool off a little more efficiently at night. Inland and high elevation areas in the Warning will not see as much overnight relief through the end of the week. Compressional heating under the ridge will warm the airmass to near daily record territory above what little will be left (if anything at all) of the marine layer. Guidance continues to advertise 850 mb temps around 28 C, peaking Wednesday. The daily max moving average this time of year is about 26.7 C, and we will be well above the 90th percentile, which is about 23 C. Did nudge high and low temperatures up by a couple of degrees Wednesday into the weekend as of this afternoon forecast package. Far inland areas may actually end up with triple digits into the weekend and the start of the next week. Left the timing of the heat hazards as is for now (expiring Friday night), but will definitely need to look into extending the Excessive Heat Warning through the weekend. Cluster analysis still shows rather high uncertainty regarding the breakdown of the ridge into next week, hence the decision to wait on extending the hazards until we become more confident over the next couple of days. HEAT SAFETY AND IMPACTS: By now youre well aware that it is going to be extremely hot next week with well-above normal temperatures; now lets talk about the impacts of excessive heat and actions we can take to minimize those impacts: With extreme heat, and especially prolonged heat events, it is a marathon, and not a sprint. Our bodies, infrastructure, pets, and livestock will be under duress from heat over the span of days as opposed to just a day or two. Given that there is little overnight relief expected throughout this event, this is where it really becomes a marathon, and precautionary measures are necessitated in order to prevent adverse results such as heat exhaustion and stroke. This is not just for individuals sensitive to heat, but rather, the entire population. Heat for this duration and at these temperatures can be dangerous for everyone. Do your body a favor and if you can, suspend outdoors activities between the hours of 10am and 7pm on days where Excessive Heat Watches or Warnings are in effect. Remain in air conditioning if you have that available to you in your residence, or seek out air conditioned environments such as stores, movie theaters, restaurants, libraries, and cooling shelters. If you cannot access air conditioned environments, must be outside, work outdoors, or otherwise, there are other precautionary measures you can take to keep yourself and your loved ones safe (including pets!) during excessive heat. Take frequent breaks in the shade and ensure that you are drinking plenty of cool water, or other hydrating beverages such as sports drinks with electrolytes. Avoid DEHYDRATING drinks such as alcohol or caffeinated beverages. That aside, visiting your city public pool or a lake, river, or ocean can also help keep you cool, but dont forget the life jacket! If planning on swimming, stick to where there is a lifeguard, and know the ocean or river conditions before you get in. Although outside of our area, its worth repeating: rivers can run fast and cold with snowmelt in the Sierra Nevada mountains, and cold water shock can set in quickly, which can lead to loss of muscle control, and ultimately, drowning. Cold water shock can also set in for ocean- goers. Have fun at the water, but be smart, be safe, and Know Before You Go! Finally, if you do not have air conditioning or cannot access it, and also cannot access a body of water to stay cool: consider taking cold showers or baths, turn on those sprinklers or garden hose and have a fun time in your own makeshift water park, or lay a damp, cool towel across your head or body. Even just dipping your hands and feet in cool water can help to abate feelings of excessive heat. For pets and livestock, make sure they have access to shade structures or areas, and have clean water freely available to them at all times. They do not have the same resources or ability to notify of feeling heat-stressed as we do, so check in on them! If theyre permanently outdoors, consider giving them a quick rinse- down with the hose or set up misters, as the evaporation will help to keep them cool as well. && .AVIATION... (00Z TAFS) Issued at 504 PM PDT Sun Jun 30 2024 VFR through the TAF period with the exception of MRY and SNS. Incoming high pressure has kept the marine layer fairly compressed which should keep any stratus that does develop close to the shoreline. The NBM leaned towards stratus filtering into portions of the Bay Area but, given how compressed/shallow the marine layer current is, that scenario is incredibly low confidence. Gusty W to NW winds continue through the evening before weakening overnight. Breezy to at times gusty W/NW winds are expected to return tomorrow afternoon. Vicinity of SFO...VFR through the TAF period. Gusty west to slightly west-northwest winds continue into the evening before weakening during the early morning. Gusts greater than 35 knots are expected to continue until 04Z with gusts dropping down to 25 knots after. Winds weaken significantly by the early morning before gusty conditions return by late morning. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR becoming LIFR overnight. A highly compressed marine layer will keep stratus confined to the Monterey Bay with impacts expected at MRY and SNS. Current Fort Ord wind profiler data shows the top of the marine layer around 600 feet with incoming high pressure expected to compress it further. Model consensus increased that CIGs will develop for MRY and SNS tonight but confidence still remains higher for MRY than SNS. Any CIGs that do develop are expected to be fairly close to the surface (given the shallow nature of the marine layer) resulting in IFR to LIFR CIGs and potential visibility impacts tonight. Gusty W/NW winds up to 20 knots continue through the evening before lighter, more variable winds return overnight. Gusty conditions are likely to return again tomorrow at SNS with gusts up to 20 knots currently expected. && .MARINE... (Tonight through next Saturday) Issued at 504 PM PDT Sun Jun 30 2024 Strong northwesterly breezes with occasional gale force gusts continues through the mid-week. As high pressure builds on Monday, winds will become more northerly and widespread near-gale force gusts will develop and spread across the waters. Significant wave heights build to 10-12 feet generally through mid-week before beginning to abate. Some potential for higher wave heights between 12-16 feet remains possible over portions of the northern outer coastal waters. && .FIRE WEATHER... Issued at 344 PM PDT Sun Jun 30 2024 ...Critically low relative humidity expected across the interior and in higher terrain this upcoming week, especially Tuesday and Wednesday... An Excessive Heat Warning is in place for most of our interior locations, with a Heat Advisory for some locations closer to the shoreline that may still see minimal influence of the Marine Boundary Layer. Minimum RH values inland for the upcoming week and beyond will mostly be in the teens, with some single digit values in areas of higher elevation. Overnight RH recover will be poor to non-existent as the heat wave persists through the week, and potentially into next weekend. The hot and dry conditions continue to move ERCs into the 70-80 percent range. With the long holiday weekend, and the many outdoor activities expected, people need to be careful with any campfires, and fireworks should not be used. Any wildfire that ignites will have the potential for rapid spread. Lightning is the only natural ignition for wildfires and there are no thunderstorms in the forecast. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning from 11 AM Tuesday to 11 PM PDT Friday for CAZ502>504-506-510-512>518. Heat Advisory from 11 AM Tuesday to 11 PM PDT Friday for CAZ508- 528-529. PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm. Gale Warning until 9 PM PDT this evening for Pt Arena to Pt Reyes 0-10 nm. Small Craft Advisory until 3 AM PDT Monday for Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 9 PM PDT Monday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory until 3 PM PDT Monday for Pt Arena to Pt Reyes 10-60 NM. Gale Watch from Monday afternoon through Tuesday morning for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 3 AM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...Behringer LONG TERM....Behringer 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