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Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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658 FXUS66 KMTR 010524 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1024 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. && .UPDATE... Issued at 901 PM PDT Sun Jun 30 2024 Low marine stratus has begun to encroach on our coastal locations and is expected to persist through mid/late morning tomorrow. No significant change in the forecast for the impending heat wave that will begin to ramp up on Tuesday. However, a Red Flag Warning is now in effect for portions of the North Bay Interior Mountains, East Bay Hills, Marin and Sonoma Coastal Ranges beginning tomorrow night. Any activity that could cause an ignition should be avoided, for example dragging trailer chains, unsecured campfires and of course fireworks, the most obvious concern as we move through the Fourth of July holiday and subsequent long weekend. Another hazard more coincident with the timing of the heat wave than the actual heat itself, is the potential for flooding near the coast as we enter a New Moon phase. People flocking to the water to try and escape the heat may encounter more dangerous surf conditions than normal and potential road closures where water spills over on to roadways. && .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... (06Z TAFS) Issued at 1023 PM PDT Sun Jun 30 2024 IFR-LIFR ceilings will persist at the immediate coast and into the Monterey bay region through the night, with stratus retreating to the coast Monday morning. Model output continues to insist on a chance for stratus to flow over the San Mateo Peninsula and impact SFO and OAK, but confidence remains low to moderate. Will monitor the evolution of stratus in the region overnight. Breezy onshore winds will develop Monday afternoon, continuing into the evening. Marginal LLWS concerns continue during the overnight periods, especially at the coast and in the North Bay. Vicinity of SFO...Model output continues to insist on a chance for stratus to flow over the San Mateo Peninsula and impact the terminal tonight. The TAF remains VFR but confidence in that forecast is decreasing as the marine layer is deepening. Will monitor through the night. Breezy west-northwest winds will continue overnight, building again Monday afternoon as gusts reach 20-25 knots. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...IFR-LIFR ceilings continue to impact the terminals through the night, clearing late Monday morning. Breezy northwest flow develops Monday afternoon, with stratus building back into the coastal regions, including MRY, on Monday evening. && .MARINE... (Tonight through next Saturday) Issued at 1023 PM PDT Sun Jun 30 2024 Strong northwesterly breezes with occasional gale force gusts continue over the northern waters. Fresh northwesterly breezes continue over the central and southern waters. By Monday afternoon, winds become northerly and gale force to near gale force gusts become more widespread over the coastal waters as high pressure builds. By mid to late week, winds will gradually weaken and become moderate to fresh. Significant wave heights generally build to 10-12 feet through mid-week before abating by the late week. Portions of the northern outer coastal waters may see peak wave heights between 12-16 feet through mid-week. && .FIRE WEATHER... Issued at 901 PM PDT Sun Jun 30 2024 ...A Red Flag Warning is in effect from Monday evening through Tuesday evening for the East Bay Hills, Marin and Sonoma Coastal Ranges, and the North Bay interior mountains Monday evening through late Wednesday afternoon. A Red Flag Warning has been added to the list of hazards along with the Excessive Heat Warning which remains in place for most of our interior locations, and 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...Red Flag Warning from 11 PM Monday to 11 PM PDT Tuesday for CAZ502-503-515. Excessive Heat Warning from 11 AM Tuesday to 11 PM PDT Friday for CAZ502>504-506-510-512>518. Red Flag Warning from 11 PM Monday to 5 PM PDT Wednesday for CAZ504. Heat Advisory from 11 AM Tuesday to 11 PM PDT Friday for CAZ508- 528-529. PZ...Gale Warning until 3 AM PDT Monday 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 Warning from 3 PM Monday to 3 PM PDT Tuesday 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...DialH 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