Alert archive / California / Red Flag Warnings in 2021
Red Flag Warning 3, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this red flag warning at Jul 17, 2021, 1:47 PM PDT for 5 counties in California. It took effect at Jul 18, 2021, 11:00 AM PDT. It was in force for 16 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
- Jul 17, 2021, 1:47 PM PDT (20:47 UTC)
- In effect from
- Jul 18, 2021, 11:00 AM PDT
- Expired
- Jul 19, 2021, 3:02 AM PDT
- In force
- 16 hr
- Issued by
- NWS San Francisco Bay Area, CA
Counties Monterey County, CA, San Benito County, CA, San Mateo County, CA, Santa Clara County, CA, Santa Cruz County, CA
The radar
The San Francisco radar (KMUX), 33 km from the middle of the area, began a volume at 20:46 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Oakland, CA (KOAK), launched 12:00Z, 8.8 hours before the alert went out and 102 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1509 m above ground
- 0-6 km bulk shear
- 10 kt
- 0-1 km storm-relative helicity
- 10 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
160 WWUS86 KMTR 172047 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 147 PM PDT Sat Jul 17 2021 ...Dry lightning potential Sunday into Monday... .Upper level moisture will increase over the region Sunday morning through Monday morning from the south. The upper level moisture will accompany upper level instability increasing chances for thunderstorm activity. Thunderstorms will be a mix of dry and wet, but given how dry the fuels are any lightning strikes will be problematic. The threat for thunderstorms diminishes Monday afternoon as the moisture moves northward. CAZ517-518-180500- /O.UPG.KMTR.FW.A.0002.210718T1800Z-210719T1800Z/ /O.NEW.KMTR.FW.W.0003.210718T1800Z-210720T0000Z/ Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 147 PM PDT Sat Jul 17 2021 ...RED FLAG WARNING IN EFFECT FROM 11 AM SUNDAY TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONE 517 AND 518... The National Weather Service in San Francisco has issued a Red Flag Warning for dry lightning, which is in effect from 11 AM Sunday to 5 PM PDT Monday. The Fire Weather Watch is no longer in effect. * AFFECTED AREA...Fire Weather Zone 517 Santa Lucia Mountains and Los Padres National Forest and Fire Weather Zone 518 Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated to scattered dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. 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. && $$ CAZ507-511-512-180500- /O.UPG.KMTR.FW.A.0002.210719T0000Z-210719T1800Z/ /O.NEW.KMTR.FW.W.0003.210719T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- 147 PM PDT Sat Jul 17 2021 ...RED FLAG WARNING IN EFFECT FROM 5 PM SUNDAY TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONES 507 511 AND 512... The National Weather Service in San Francisco has issued a Red Flag Warning for lightning, which is in effect from 5 PM Sunday to 5 PM PDT Monday. The Fire Weather Watch is no longer in effect. * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains, Fire Weather Zone 511 East Bay Hills and the Diablo Range and Fire Weather Zone 512 Santa Cruz Mountains. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
5 follow-up statements
482 WWUS86 KMTR 180357 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 857 PM PDT Sat Jul 17 2021 ...Dry lightning potential Sunday into Monday... .Upper level moisture will increase over the region Sunday morning through Monday morning from the south. The upper level moisture will accompany upper level instability increasing chances for thunderstorm activity. Thunderstorms will be a mix of dry and wet, but given how dry the fuels are any lightning strikes will be problematic. The threat for thunderstorms diminishes Monday afternoon as the moisture moves northward. CAZ517-518-181300- /O.CON.KMTR.FW.W.0003.210718T1800Z-210720T0000Z/ Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 857 PM PDT Sat Jul 17 2021 ...RED FLAG WARNING IN EFFECT FROM 11 AM SUNDAY TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONE 517 AND 518... * AFFECTED AREA...Fire Weather Zone 517 Santa Lucia Mountains and Los Padres National Forest and Fire Weather Zone 518 Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated to scattered dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. 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. && $$ CAZ507-511-512-181300- /O.CON.KMTR.FW.W.0003.210719T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- 857 PM PDT Sat Jul 17 2021 ...RED FLAG WARNING IN EFFECT FROM 5 PM SUNDAY TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONES 507 511 AND 512... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains, Fire Weather Zone 511 East Bay Hills and the Diablo Range and Fire Weather Zone 512 Santa Cruz Mountains. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
874 WWUS86 KMTR 181245 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 545 AM PDT Sun Jul 18 2021 ...Dry lightning potential Sunday into Monday... .Upper level moisture will increase over the region today into Monday from south to north. This moisture will accompany upper level instability increasing chances for thunderstorm activity. Thunderstorms will be a mix of dry and wet, but given how dry the fuels are any lightning strikes will be problematic. The threat for thunderstorms diminishes Monday afternoon as the moisture moves northward. CAZ517-518-182045- /O.CON.KMTR.FW.W.0003.210718T1800Z-210720T0000Z/ Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 545 AM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONE 517 AND 518... * AFFECTED AREA...Fire Weather Zone 517 Santa Lucia Mountains and Los Padres National Forest and Fire Weather Zone 518 Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated to scattered dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. 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. && $$ CAZ507-511-512-182045- /O.CON.KMTR.FW.W.0003.210719T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- 545 AM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONES 507 511 AND 512... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains, Fire Weather Zone 511 East Bay Hills and the Diablo Range and Fire Weather Zone 512 Santa Cruz Mountains. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
278 WWUS86 KMTR 182022 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 122 PM PDT Sun Jul 18 2021 ...Dry lightning potential Sunday into Monday... .Upper level moisture will continue to increase over the region today into Monday from south to north. This moisture will accompany upper level instability increasing chances for thunderstorm activity. Thunderstorms will be a mix of dry and wet, but given how dry the fuels are any lightning strikes will be problematic. The threat for thunderstorms diminishes Monday afternoon as the moisture moves northward. CAZ517-518-190500- /O.CON.KMTR.FW.W.0003.000000T0000Z-210720T0000Z/ Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 122 PM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONE 517 AND 518... * AFFECTED AREA...Fire Weather Zone 517 Santa Lucia Mountains and Los Padres National Forest and Fire Weather Zone 518 Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday afternoon through early Monday afternoon. * LIGHTNING...Isolated to scattered dry thunderstorms will be possible Sunday afternoon through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. 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. && $$ CAZ507-511-512-190500- /O.CON.KMTR.FW.W.0003.210719T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- 122 PM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT FROM 5 PM THIS AFTERNOON TO 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONES 507 511 AND 512... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains, Fire Weather Zone 511 East Bay Hills and the Diablo Range and Fire Weather Zone 512 Santa Cruz Mountains. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely Sunday night through early Monday afternoon. * LIGHTNING...Isolated dry thunderstorms will be possible Sunday night through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
203 WWUS86 KMTR 190432 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 932 PM PDT Sun Jul 18 2021 ...Dry lightning potential overnight into Monday... .Upper level moisture will continue to increase over the region overnight into Monday from south to north. This moisture will accompany upper level instability increasing chances for thunderstorm activity. Thunderstorms will be a mix of dry and wet, but given how dry the fuels are any lightning strikes will be problematic. The threat for thunderstorms diminishes late Monday as the moisture exits northeastward. CAZ517-518-191300- /O.CON.KMTR.FW.W.0003.000000T0000Z-210720T0000Z/ Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 932 PM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONE 517 AND 518... * AFFECTED AREA...Fire Weather Zone 517 Santa Lucia Mountains and Los Padres National Forest and Fire Weather Zone 518 Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most likely overnight through early Monday afternoon. * LIGHTNING...Isolated to scattered dry thunderstorms will be possible overnight through early Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. 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. && $$ CAZ507-511-512-191300- /O.CON.KMTR.FW.W.0003.000000T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- 932 PM PDT Sun Jul 18 2021 ...RED FLAG WARNING REMAINS IN EFFECT UNTIL 5 PM PDT MONDAY FOR DRY LIGHTNING FOR HIGHER ELEVATIONS OF FIRE WEATHER ZONES 507 511 AND 512... * AFFECTED AREA...Fire Weather Zone 507 North Bay Mountains, Fire Weather Zone 511 East Bay Hills and the Diablo Range and Fire Weather Zone 512 Santa Cruz Mountains. * WIND...Given the potentially dry nature of thunderstorms gusty and erratic winds will be possible with developed storms. * TIMING...Thunderstorm threat most late overnight night through Monday afternoon. * LIGHTNING...Isolated dry thunderstorms will be overnight through Monday afternoon. * IMPACTS...Given the dry fuels over the higher elevations, any cloud to ground lightning strikes have the potential of starting new wildfires. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Red Flag Warning means that critical fire weather conditions are either occurring now...or will shortly. A combination of strong winds...low relative humidity...and warm temperatures can contribute to extreme fire behavior. && $$
804 WWUS86 KMTR 191002 RFWMTR URGENT - FIRE WEATHER MESSAGE National Weather Service San Francisco CA 302 AM PDT Mon Jul 19 2021 CAZ507-511-512-517-518-191115- /O.CAN.KMTR.FW.W.0003.000000T0000Z-210720T0000Z/ North Bay Mountains-East Bay Hills and the Diablo Range- Santa Cruz Mountains- Santa Lucia Mountains and Los Padres National Forest- Mountains Of San Benito County And Interior Monterey County Including Pinnacles National Park- 302 AM PDT Mon Jul 19 2021 ...RED FLAG WARNING IS CANCELLED FOR DRY LIGHTNING... The National Weather Service in San Francisco has cancelled the Red Flag Warning. Convection no longer looks favorable for the region so have cancelled the Red Flag Warning in coordination with neighboring NWS Forecast Offices. $$
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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.