Alert archive / California / Red Flag Warnings in 2021
Red Flag Warning 7, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this red flag warning at Sep 29, 2021, 10:27 AM PDT. It took effect at Sep 29, 2021, 11:00 PM PDT. It was in force for 9 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Sep 29, 2021, 10:27 AM PDT (17:27 UTC)
- In effect from
- Sep 29, 2021, 11:00 PM PDT
- Expired
- Sep 30, 2021, 8:17 AM PDT
- In force
- 9 hr
- Issued by
- NWS San Francisco Bay Area, CA
The text
As transmitted.
097 WWUS86 KMTR 291727 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 1027 AM PDT Wed Sep 29 2021 ...Gusty Offshore Winds and Dry Conditions for Interior North Bay Mountains Wednesday night through Thursday morning... .A shift towards a drier air mass and offshore flow will lead to locally critical fire weather conditions across the interior North Bay Mountains tonight through Thursday morning. Locally gusty north to northeast winds overnight will coincide with poor humidity recoveries. Winds are expected to diminish through the day Thursday, but widespread critically dry humidities will prevail throughout the day. The areas of greatest concern are locations in Napa County and into interior Sonoma County at or above 1000 feet including the Vaca and Mayacamas ranges. These areas will see the strongest winds, lowest humidity, have the driest fuels, and they received little to no wetting rainfall earlier this week. CAZ507-300130- /O.UPG.KMTR.FW.A.0006.210929T1800Z-211001T0100Z/ /O.NEW.KMTR.FW.W.0007.210930T0600Z-210930T1800Z/ North Bay Mountains- 1027 AM PDT Wed Sep 29 2021 ...RED FLAG WARNING IN EFFECT FROM 11 PM THIS EVENING TO 11 AM PDT THURSDAY FOR GUSTY OFFSHORE WINDS AND LOW HUMIDITY FOR INTERIOR NORTH BAY MOUNTAINS... The National Weather Service in San Francisco has issued a Red Flag Warning for gusty north to northeast winds and low humidity, which is in effect from 11 PM this evening to 11 AM PDT Thursday. The Fire Weather Watch is no longer in effect. * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains focused on the Vaca and Mayacamas ranges in Napa County and including the border area of Sonoma and Napa counties * TIMING...11 PM Wednesday to 11 AM Thursday. * WINDS...North 15 to 25 mph with gusts up to 35 mph. * RELATIVE HUMIDITY...As low as 8 to 15 percent during the day with poor recoveries overnight ranging only 15 to 30 percent. * TEMPERATURES...In the lower 70s. * IMPACTS...Any fire starts would likely see rapid spread due to dry fuels, low humidity and gusty winds in areas that did not receive wetting rains over the weekend. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
3 follow-up statements
383 WWUS86 KMTR 300124 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 624 PM PDT Wed Sep 29 2021 ...Gusty Offshore Winds and Dry Conditions for Interior North Bay Mountains tonight through Thursday morning... .A shift towards a drier air mass and offshore flow will lead to locally critical fire weather conditions across the interior North Bay Mountains tonight through Thursday morning. Locally gusty north to northeast winds overnight will coincide with poor humidity recoveries. Winds are expected to diminish through the day Thursday, but widespread critically dry humidities will prevail throughout the day. The areas of greatest concern are locations in Napa County and into interior Sonoma County at or above 1000 feet. These areas will see the strongest winds, lowest humidity, have the driest fuels, and received little to no wetting rainfall this month. CAZ507-301245- /O.CON.KMTR.FW.W.0007.210930T0600Z-210930T1800Z/ North Bay Mountains- 624 PM PDT Wed Sep 29 2021 ...RED FLAG WARNING REMAINS IN EFFECT FROM 11 PM THIS EVENING TO 11 AM PDT THURSDAY FOR GUSTY OFFSHORE WINDS AND LOW HUMIDITY FOR INTERIOR NORTH BAY MOUNTAINS... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains. Strongest winds over the Napa hills and downwind of Mount Saint Helena. * TIMING...11 PM Wednesday to 11 AM Thursday. * WINDS...North 15 to 25 mph with gusts up to 35 mph. * RELATIVE HUMIDITY...Poor recoveries overnight less than 30 percent with values 10-20 percent on Thursday. * IMPACTS...Any fire starts would likely see rapid spread due to dry fuels, low humidity and gusty winds. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
718 WWUS86 KMTR 301028 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 328 AM PDT Thu Sep 30 2021 ...Gusty Offshore Winds and Dry Conditions for Interior North Bay Mountains through Thursday morning... .Locally gusty north to northeast winds will coincide with poor humidity through this morning. Winds are expected to diminish through the day, but widespread critically dry humidities will prevail throughout the day. The areas of greatest concern are locations in Napa County and into interior Sonoma County at or above 1000 feet. These areas will see the strongest winds, lowest humidity, have the driest fuels, and received little to no wetting rainfall this month. CAZ507-301800- /O.CON.KMTR.FW.W.0007.000000T0000Z-210930T1800Z/ North Bay Mountains- 328 AM PDT Thu Sep 30 2021 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 11 AM PDT THIS MORNING FOR GUSTY OFFSHORE WINDS AND LOW HUMIDITY FOR INTERIOR NORTH BAY MOUNTAINS... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains. * TIMING...Through 11 AM this morning.. * WINDS...North 15 to 25 mph with gusts up to 35 mph, locally in excess of 45 mph in the highest peaks. * RELATIVE HUMIDITY...Poor recoveries overnight less than 30 percent with values 10-20 percent on Thursday. * IMPACTS...Any fire starts would likely see rapid spread due to dry fuels, low humidity and gusty winds. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
477 WWUS86 KMTR 301517 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 817 AM PDT Thu Sep 30 2021 CAZ507-301630- /O.CAN.KMTR.FW.W.0007.000000T0000Z-210930T1800Z/ North Bay Mountains- 817 AM PDT Thu Sep 30 2021 ...RED FLAG WARNING IS CANCELLED FOR North Bay Interior Mountains... The National Weather Service in San Francisco has cancelled the Red Flag Warning. Peak winds have come and gone while relative humidities will continue to lower through the day. $$
The office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 28, 5:50 PM PDT | Fire Weather Watch | MTR | 17 hr |
Nearby
Red Flag Warnings in California, 2021Every red flag warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.