FXUS66 KMTR 240550 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1050 PM PDT Tue Jul 23 2024 ...New AVIATION... .SYNOPSIS... Issued at 1201 AM PDT Tue Jul 23 2024 Inland heat continues through mid-week. Excessive Heat Warnings and Heat Advisories are in effect through Wednesday evening for areas away from the coast. A cold front will bring significant relief by Friday. && .UPDATE... Issued at 858 PM PDT Tue Jul 23 2024 Severity of heat today and Wednesday has diminished slightly, therefore the Excessive Heat Warning has been downgraded to a Heat Advisory, and the Heat Advisory for the North Bay has been canceled. The remaining Heat Advisories still continue until 11 PM Wednesday night. && .SHORT TERM... (This evening through Wednesday) Issued at 222 PM PDT Tue Jul 23 2024 Today will see the peak in the latest wave of heat. The Excessive Heat Warning and Heat Advisory will remain in place for todays forecast, however decisions on continuing-downgrading or canceling of the current heat products in certain areas for tomorrow will be made during the evening shift for the sake of continuity in our messaging. Many of our inland locations, especially the more elevated spots are already in the upper 90s, with some locations in the North Bay Hills at 105 or more. There is a slight chance for elevated thunderstorms to produce dry lightning the for the remainder of today, tonight and tomorrow, but those chances are too low for mentioning in the official forecast attm. Overnight lows tonight will be very similar to what we saw this morning, mostly upper 60s to low 70s inland, cooler near the coastline. Overnight marine stratus and patchy fog will fill in later tonight, and mix out by late tomorrow morning. Please read below for tips to help beat the heat: 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. -Ensure pets and livestock have access to shade and water. && .LONG TERM... (Wednesday night through next Monday) Issued at 222 PM PDT Tue Jul 23 2024 Thursday marks the beginning of what will be a significant pattern change and cool down by the weekend. Highs on Thursday will be right around normal as an upper level low over the SE Pacific moves N/NE toward the central coast of California. By Friday, the upper low is overhead bringing much cooler temperatures aloft and at the surface. As the system moves overhead and farther inland over the course of the weekend, we'll see thicker marine layer cloud cover and deeper penetration into the inland valleys. High temperatures on Friday will be 5-10 degrees cooler than normal for most locations, and that trend looks to continue through the weekend into the beginning of next week, welcomed relief from the recent heat. && .AVIATION... (06Z TAFS) Issued at 1050 PM PDT Tue Jul 23 2024 VFR everywhere except MRY and SNS through the TAF period. The marine layer remains fairly well compressed which is helping to keep stratus confined closer to the coastline and confining direct impacts to MRY and SNS tonight. Low probability of stratus making it past the Golden Gate bridge but, even if some does, stratus is not expected to impact SFO/OAK. Light, variable winds continue overnight before moderate onshore winds return during the day tomorrow. Vicinity of SFO...VFR through the TAF period. Light winds continue overnight with offshore winds briefly possible mid tomorrow morning. Moderate onshore flow is expected to return tomorrow afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...VFR becoming LIFR overnight. Satellite shows stratus lingering directly along the coastline with moderate confidence that stratus will reach MRY within the next few hours. Stratus coverage may be slightly patchier at SNS overnight with LIFR CIGs temporarily developing. Potential for patchy fog development at MRY early tomorrow morning continues with low to moderate confidence that visibility will temporarily decrease to 1/2SM. Light, variable winds continue overnight before moderate onshore flow returns during the afternoon. && .MARINE... (Tonight through next Monday) Issued at 858 PM PDT Tue Jul 23 2024 Winds remain light to gentle in the coastal waters through Wednesday, with fresh to strong breezes in the northern outer waters creating continuing hazards to small craft, before slightly strengthening into the weekend. Significant wave heights will abate through the forecast period. A compressed marine layer will result in patches of dense fog along the coast tonight and Wednesday morning. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory until 11 PM PDT Wednesday for CAZ510-512>518. PZ...Small Craft Advisory until 9 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...JM LONG TERM....JM AVIATION...DialH/Kennedy MARINE...DialH 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