Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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339 FXUS66 KMTR 040411 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 911 PM PDT Wed Jul 3 2024 ...New UPDATE, MARINE... .SYNOPSIS... Issued at 257 PM PDT Wed Jul 3 2024 Extremely hot conditions continue through at least Wednesday of next week. Heat products have been extended, Red Flag Warnings have been extended, Fire Weather Watch has been upgraded to a Red Flag Warning for Monterey and San Benito. && .UPDATE... Issued at 907 PM PDT Wed Jul 3 2024 It was another HOT day across the interior with a couple of records broken at Livermore and San Rafael (see below). However, temperatures were slightly cooler across the board minus far interior portions of the East Bay and interior Monterey and San Bentio counties. Low clouds have worked their way northward up the Big Sur coast and most recently started to impact the Monterey Peninsula. It is unclear how far north they will go and whether or not the will push much inland in the Salinas Valley (or any other coastal adjacent valleys). Tonight, temperatures will lower into the mid 50`s to lower 60`s in coastal areas and cooler interior valleys, lower 70`s in the warmer valleys (such as the southern Santa Clara Valley), and mid 60`s to low 80`s in the higher terrain. This will provide minimal overnight relief from today`s heat. ...RECORD HIGH TEMPERATURES WEDNESDAY, JULY 3, 2024... LOCATION HIGH PREVIOUS RECORD --------------------------------------------------------------- SAN RAFAEL 100 99 IN 2001 LIVERMORE 110 109 IN 2001 These data are preliminary and have not undergone final quality control by the National Centers for Environmental Information. Therefore, these data are subject to revision. Final and certified climate data can be accessed at www.ncei.noaa.gov. && .SHORT TERM... (This evening through Thursday) Issued at 257 PM PDT Wed Jul 3 2024 Guess what? Its another AFD about very hot temperatures! But not just that, Red Flag conditions as well. Let`s list the changes up front and center: -Excessive Heat Warning has been extended through 11pm Wednesday July 10th. -Heat Advisory for northern Monterey Bay, Northern Salinas Valley, and SF Bay shorelines has been extended through 11pm Wednesday July 10th. -Red Flag Warning for Interior North Bay Mountains and East Bay Hills has been extended through 9 PM Saturday July 6th. -Fire Weather Watch has been upgraded to a Red Flag Warning for the mountains of Monterey and San Benito Counties, and the southern Salinas Valley for very low RH values, and critically dry fuels. -Coastal Flood Advisory has been extended through 5am Friday July 5th for high astronomical tides and possible flooding of low lying areas around the SF Bay. Now let`s dig in: While you`re probably sick of hearing it, it can not be emphasized enough how warm things are going to be over the stretch of a week. Not just a few days. A week. As it currently stands, we are officially on Day 2 of this heat wave, if you`re going by the guidance of how long the Excessive Heat Warning persists. As cluster analysis continues to show a general consensus of this ridge sticking around even through day 9, hot temperatures are expected to continue with high temperatures of 100-105 continuing through at least next Wednesday for interior areas. 850 mb temps continue to trend on the very warm side, with this mornings 12Z KOAK sounding showing 850 mb temps at 26.4 degrees Celsius (79.5 degrees Fahrenheit). A glance at models continues to show 850 mb temps exceeding this 26 C mark through at least early next week. Continued and building high pressure may also lead to some hazy skies the next few days as particulate matter including smog, smoke from wildfires and fireworks, and even dust will be trapped near the ground. For questions regarding air quality forecasts, reach out to your local air quality district. Aside from the hot daytime temps, overnight lows will also continue to provide little to no relief, ESPECIALLY in thermal belted areas where overnight lows likely will not dip below the mid 80s. In lower elevations, overnight lows are not likely to dip lower than the mid 70s. This is an ultra-marathon, not just for our bodies, but our pets and livestock, and infrastructure too. Without the overnight relief, our bodies do not experience the normal cooling and respite they normally would, therefore increasing the demand on our respiratory and circulatory systems to help keep up cool. With that being said, it is very likely that we will see a number of heat- related fatalities throughout this event, not just from homeless populations who may not be able to escape the lethal heat, but from housed people too that perhaps lack air conditioning (which many houses in the Bay Area do lack this!), or perhaps simply cannot afford to turn it on, even if they have it. It is imperative to take measures to protect yourself, loved ones, and animals during this extreme heat. Given that tomorrow is Independence Day, a holiday in which many activities take place outdoors (parades, picnics, BBQs, community gatherings, fireworks displays), extra caution is urged. For areas of Extreme Heat Risk, consider suspending outdoor events or modifying them to take place indoors in an air conditioned environment. Clearly, an event such as a parade cannot be moved inside, but modifications can be made to events to make it safer for everyone, be it moving it to a time much earlier in the morning when its still "cool" (though again, temps will likely already be in the 90s come the 9-10am hour), or perhaps if you can, moving the event indoors if possible, and if you cannot, taking into consideration canceling the outdoor event. Aside from these measures, there are many other things you can do to protect yourself, including staying hydrated by drinking HYDRATING beverages such as water or sports drinks with electrolytes, and avoiding DEHYDRATING beverages such as alcohol and caffeine-laden drinks. A few other heat safety tips: -Stay inside in an air conditioned environment between 10am and 7pm. -Suspend unnecessary outdoor activities during the extreme heat, but if you must be outdoors, take frequent breaks in the shade or AC and drink cool water. -Know the signs and symptoms of Heat Exhaustion vs. Heat Stroke! Heat Stroke can be deadly if not treated immediately by a medical professional. Call 911 if you suspect someone is suffering from Heat Stroke. -Wear a lifejacket, swim near a lifeguard, and check conditions before entering the water if going to a river or ocean to cool off. Rivers and the ocean are extremely cold, and Cold Water Shock can turn into paralysis and drowning if you are not careful. -Use a cool and damp towel on your body if you do not have AC and are feeling hot. Or, take a cool shower or bath. && .LONG TERM... (Thursday night through next Tuesday) Issued at 257 PM PDT Wed Jul 3 2024 By now you know the heat extends into the longer term, into next week, so we`ll focus on Fire Weather in the long term, seeing as those concerns extend over part of the weekend. With the extension of Red Flag Warnings this morning, and the upgrading of the Fire Weather Watch into a Red Flag for San Benito and Monterey Counties, conditions will be ripe for fire growth should a spark ignite something. The decision was made to extend the RFWs and to upgrade the Watch based off of very low RH values (generally dipping below 15% RH), critically dry fuels (ERC values exceeding or coming extraordinarily close to exceeding the max moving average for a number of regions), in addition to the final component of winds. Now you might be scratching your head at that final component. Where are the breezy, gusty winds you speak of? Well, with fuels this dry, and RHs down into single digits in some areas for daytime minimums, we don`t necessarily need winds to be breezy and gusty. At the bottom tier of the decision matrix, with daytime min RHs into the single digits, and nighttime max RHs in the teens to low 20% range, we only need winds about 6-11mph sustained to warrant issuing a Red Flag Warning. As it currently stands, we are forecast to meet those criteria, especially within Monterey and San Benito counties, and the East Bay Hills. North Bay mountains are a bit more marginal in regards to the RH recoveries, but nonetheless are forecast to meet the criteria. Additionally, fuels will continue to dry as we persist through this very long period of extraordinarily hot and dry weather as the ridge continues to build. Conditions are dangerous, and we urge extreme caution. Please rethink the use of any fireworks this year, including the safe and sane, or even those seemingly- innocuous sparklers and pop-its. Perhaps consider not lighting them off at all this year, and instead enjoy a professional display in your community, or even on TV. Its not worth the risk. Don`t Be the Spark! Additionally, check those chains and per our recent social media post: Keep those butts in the window! Don`t let your chains drag while towing, and do not toss cigarette butts out the window. Additionally, do not operate machinery or vehicles over dry vegetation. As a final note on this long AFD, none of this is meant to "fearmonger" or incite worry. Rather, we simply want people to be as safe as possible throughout the coming days. We are tasked with the protection of life and property, and we would be failing to accomplish this without mention of the risks and hazards that lie ahead, as well as the facts. Heat is the number one weather- related killer across the nation. We will likely come to learn of casualties in the coming weeks and days attributed to the heat. Have fun, and enjoy the holiday as well as these summer days. Just be safe, be careful, and make modifications as necessary to keep yourselves and others safe. We will be doing the same! && .AVIATION... (00Z TAFS) Issued at 419 PM PDT Wed Jul 3 2024 Clear skies and VFR across the board this evening as high pressure dominates. Areas of fog will develop along the coast overnight, but areas further inland are likely to remain clear. Light winds with not much impact overnight into the morning hours Thursday. After sunrise tomorrow, chance of reduced slant range visibility due to wildfire smoke. Vicinity of SFO...High confidence that VFR will prevail through the TAF period. Winds become light this evening into the morning. NW/W winds increase again Thursday afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR through the TAF period. Confidence is low that CIGs and low vis will occur. Will continue to monitor for any updates needed to the TAFs. && .MARINE... (Tonight through next Tuesday) Issued at 907 PM PDT Wed Jul 3 2024 Light moderate winds continue into the weekend with possible gusty and strong winds in the northern outer waters that will pose hazardous to small crafts into tonight before easing. Waves start to diminish Thursday morning, bringing relatively calm conditions over the waters into Friday. && .FIRE WEATHER... Issued at 257 PM PDT Wed Jul 3 2024 Northerly winds are gusting in the 20-30 mph range mph overnight, with Mt. St Helena gusting as high as 64 mph and Mount Diablo at 54 mph early this morning. While winds will begin to diminish over the next few days, these RFW extend through 9 PM Saturday evening due to the critically dry conditions. In fact, 10 and 100 hour fuels are near historic levels in the Santa Cruz, Diablo and North Bay Mountains in regard to the energy release component going into the weekend. In addition to the hot, dry weather, the 4th of July Holiday may lead to new starts from stray fireworks. Further south, things start to dry out more this weekend. && .BEACHES... Issued at 1224 AM PDT Wed Jul 3 2024 Beaches will be a popular destination over the Holiday and as one of the few places to escape the oppressive inland temperatures. Fortunately the waves are relatively low energy, but that doesn`t alleviate all beach safety concerns. Ocean temperatures are in the mid-50s. This cold water may catch some off-guard. Cold water shock can set in very quickly. Wear a life jacket, dress appropriately, limit time in the water, swim near a lifeguard and follow their instructions. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Coastal Flood Advisory until 5 AM PDT Friday for CAZ006-506-508. Heat Advisory until 7 PM PDT Thursday for CAZ006. Excessive Heat Warning until 11 PM PDT Wednesday for CAZ502>504- 506-510-512>518. Red Flag Warning until 5 AM PDT Friday for CAZ502-503. Red Flag Warning until 9 PM PDT Saturday for CAZ504-512-515. Heat Advisory until 11 PM PDT Wednesday for CAZ508-528-529. Red Flag Warning from 9 AM Friday to 9 PM PDT Saturday for CAZ516>518. PZ...Small Craft Advisory until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM. && $$ UPDATE...RGass SHORT TERM...AC LONG TERM....AC AVIATION...Behringer MARINE...Behringer FIRE WEATHER...RGass BEACHES...Flynn 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