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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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434 FXUS66 KMTR 071845 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1145 AM PDT Sun Jul 7 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 1236 AM PDT Sun Jul 7 2024 Day 6 of the inland heat wave. The peak of the event is finally behind us and some minor relief is on the way this week before a more substantial cool-down next weekend. && .UPDATE... Issued at 944 AM PDT Sun Jul 7 2024 No update to the forecast this morning. The Excessive Heat Warning remains in effect until Wednesday morning for most of our interior locations, with Heat Advisories still in effect for some locations closer to the coast. The Heat Advisory for the low lying areas of Santa Cruz was cancelled. Also, all Red Flag Warnings have expired, however the national hazards map still has them displayed. The issue is being worked on at the national level. && .SHORT TERM... (Today and tonight) Issued at 1236 AM PDT Sun Jul 7 2024 ACARS data from Oakland flights are showing the 850 mb temperature is 31C. The highest 850 mb temperature ever observed from the Oakland weather balloon is 31.0C. This means we are experiencing the hottest low level heat since records began 75 years ago. Inland areas reached triple digits yesterday with a few over 110. Higher elevations are seeing some of the hottest daily max and min temps on record. For example Pinnacles National Park reached 116 degrees yesterday (all time record 117 9/6/20), and Mallory Ridge (north of Livermore @ 1948 ft) only got down to 90 Saturday morning before jumping back up to 106 in the afternoon. Fortunately onshore winds and a shallow marine layer are keeping coastal areas cool. As the ridge axis moves across California, temperatures will begin to cool a bit Sunday. The only record we are threatening is at King City (105 forecast). Otherwise, most inland areas will stay out of the 100s today. Higher elevations are still seeing very warm conditions, but they will also begin to cool a few degrees Sunday. Coastal areas will be much cooler (similar to yesterday) with marine layer clouds breaking in the afternoon and returning in the evening. && .LONG TERM... (Monday through Saturday) Issued at 1236 AM PDT Sun Jul 7 2024 The cool-down will continue through Tuesday as the ridge continues to slide east. While this is certainly welcome, it is not a drastic improvement. To put it in perspective, the 850 mb temp is currently in the top 99.99% (30.2 C) of historical observations. We are anxiously awaiting it to drop back to the the 98% (25 C) by Tuesday. We are still going to be well above average this week with inland areas remaining in the 90s. By Wednesday, the cooling trend flattens, and temps may tick back up a few degrees Wed-Fri before a more substantial cool-down arrives this weekend. This heat wave has been going for 5 days now and we are just now getting on the back nine. The warm mornings and back-to-back record breaking temperatures can cause cumulative effects that make the situation more dangerous. Heat is the number 1 weather related killer in the United States. Unfortunately lives will be lost during this heat wave. Follow these tips to protect yourself, your loved ones, and your animals. -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. -Do not leave kids or pets in a parked car. You can put your cellphone/wallet or even your shoe in the back seat as a reminder. -Ensure pets and livestock have access to shade and water. && .AVIATION... (18Z TAFS) Issued at 1145 AM PDT Sun Jul 7 2024 Satellite and surface observations show nearly continuous stratus and fog /LIFR-IFR/ along the immediate coast, inland it`s MVFR-VFR with localized haze reducing surface visibilities. There may also be reduced slant range visibility due to wildfire smoke/haze aloft, otherwise recent high resolution rapid refresh model output shows general improvement in visibility from later today to tonight. The marine layer depth varies from a few hundred feet deep along the North Bay to approx 1000 feet deep Marin Headlands to the north Central Coast. Stratus and fog /LIFR-IFR/ return inland on onshore breezes prevailing tonight and Monday morning, currently the SFO-SAC pressure gradient is 2.2 mb, there`s an ongoing SMX-SFO pressure gradient currently 1.5 mb and the ACV-SFO northerly gradient is far less than it was since early last week, currently less than 1 mb and the STS-UKI gradient is currently 2.2 mb supporting a southerly breeze. Vicinity of SFO...VFR. West to northwest breezes increasing to 18 to 25 knots during the afternoon and evening, easing tonight and Monday morning to around 10 knots. SFO Bridge Approach...Similar to SFO. Reduced slant range visibility possible due to wildfire smoke/haze aloft, otherwise generally improving conditions per recent high resolution model output through later today and tonight. Monterey Bay Terminals...Stratus and fog /LIFR-IFR/ along the northern Monterey Bay, elsewhere it`s VFR. Stratus and fog /LIFR-IFR/ redeveloping and moving inland tonight and Monday morning. Stratus and fog mixing out by late Monday morning and/or early afternoon. West to northwest winds 5 to 15 knots with a few afternoon and early evening gusts nearing 20 knots. && .MARINE... (Today through Friday) Issued at 1109 AM PDT Sun Jul 7 2024 High pressure continues over the Pacific Ocean with gentle to moderate northwest winds persisting into the early work week. Fresh to the occasional strong gusts will briefly develop over the northern outer coastal waters Monday before diminishing into Tuesday. Widespread fresh to strong northwest winds return across the coastal waters by mid-week. Significant wave heights will build to 10-14 feet in the outer waters beginning Wednesday. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 11 PM PDT Wednesday for CAZ502>504- 506-510-512>518. Heat Advisory until 11 PM PDT Wednesday for CAZ508-528. PZ...Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Monday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...Flynn LONG TERM....Flynn AVIATION...Canepa MARINE...Canepa 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