Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 56, NWS San Francisco Bay Area, CA

February 20, 2017Marin County, Sonoma County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 20, 2017, 8:14 AM PST for Marin County, Sonoma County, California. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Feb 20, 2017, 8:14 AM PST (16:14 UTC)
Expired
Feb 20, 2017, 12:15 PM PST
In force
4 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

Counties Marin County, CA, Sonoma County, CA

The radar

The Sacramento radar (KDAX), 85 km from the middle of the area, began a volume at 16:14 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, 4.2 hours before the alert went out and 65 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.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 12:00Z on 2017-02-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 12:00Z on 2017-02-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 364 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
515 m above ground
0-6 km bulk shear
75 kt
0-1 km storm-relative helicity
364 m²/s²
0-3 km storm-relative helicity
367 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

368 
WGUS56 KMTR 201614
FFWMTR
CAC041-097-202015-
/O.NEW.KMTR.FF.W.0056.170220T1614Z-170220T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
814 AM PST MON FEB 20 2017

The National Weather Service in The San Francisco Bay Area has issued
a

* Flash Flood Warning for...
  Southeastern Sonoma County in northern California...
  Northeastern Marin County in northern California...

* Until 1215 PM PST

* At 810 AM PST, Doppler radar and automated rain gauges indicated
  heavy rain falling across the Petaluma Basin and much of the North
  Bay. Flash flooding is already occurring at several gages
  locations within the watershed.  Water levels continue to rise.

* Some locations that will experience flooding include...
  Petaluma and Penngrove.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 3832 12259 3812 12246 3812 12248 3820 12259
      3824 12270 3830 12271

$$

MWS
1 follow-up statement
303 
WGUS76 KMTR 202007
FFSMTR

Flash Flood Statement
National Weather Service San Francisco CA
1207 PM PST MON FEB 20 2017

CAC041-097-202015-
/O.EXP.KMTR.FF.W.0056.000000T0000Z-170220T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sonoma CA-Marin CA-
1207 PM PST MON FEB 20 2017

...THE FLASH FLOOD WARNING FOR SOUTHEASTERN SONOMA AND NORTHEASTERN
MARIN COUNTIES WILL EXPIRE AT 1215 PM PST...

Flood waters have receded in Petaluma. Rejuvenated storm activity in
the North Bay is still possible, and a reissue of a Flash Flood
Warning is still possible. At this point it is being
cancelled. Please continue to heed any remaining road closures.

LAT...LON 3832 12259 3812 12246 3812 12248 3820 12259
      3824 12270 3830 12271

$$

MWS

The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 20, 3:53 AM PSTRiver Flood WarningMTRSanta Clara59 hr
Feb 20, 4:23 AM PSTFlash Flood WarningMTRMonterey3 hr
Feb 20, 5:03 AM PSTRiver Flood WarningMTRMonterey29 hr
Feb 20, 7:07 AM PSTFlash Flood WarningMTRMonterey6 hr
Feb 20, 7:35 AM PSTAreal Flood AdvisoryMTRMarin, Napa, City and County of San Francisco, San Mateo, Sonoma3 hr
Feb 20, 7:40 AM PSTFlash Flood WarningMTRSanta Cruz6 hr
Feb 20, 7:44 AM PSTAreal Flood AdvisoryMTRSan Mateo, Santa Clara, Santa Cruz3 hr
Feb 20, 8:22 AM PSTAreal Flood WarningMTRSonoma60 hr
Feb 20, 8:56 AM PSTFlash Flood WarningMTRSan Benito6 hr
Feb 20, 9:04 AM PSTFlash Flood WarningMTRSanta Cruz6 hr
Feb 20, 10:13 AM PSTFlash Flood WarningMTRSan Benito, Santa Clara6 hr
Feb 20, 10:26 AM PSTFlash Flood WarningMTRAlameda6 hr
Feb 20, 10:34 AM PSTAreal Flood AdvisoryMTRMarin, Napa, City and County of San Francisco, San Mateo, Sonoma3 hr
Feb 20, 10:48 AM PSTAreal Flood AdvisoryMTRSan Mateo, Santa Clara, Santa Cruz3 hr
Feb 20, 11:21 AM PSTAreal Flood AdvisoryMTRAlameda, Contra Costa, Santa Clara3 hr
Feb 20, 1:32 PM PSTAreal Flood AdvisoryMTRMarin, Napa, City and County of San Francisco, San Mateo, Sonoma3 hr
Feb 20, 1:48 PM PSTAreal Flood AdvisoryMTRSan Mateo, Santa Clara, Santa Cruz3 hr
Feb 20, 2:14 PM PSTAreal Flood AdvisoryMTRMonterey4 hr
Feb 20, 2:24 PM PSTSmall Craft AdvisoryMTR18 hr
Feb 20, 2:40 PM PSTAreal Flood AdvisoryMTRSan Mateo65 min
Feb 20, 3:23 PM PSTAreal Flood WarningMTRSanta Clara6 hr

Nearby

Flash Flood Warnings in California, 2017Every flash flood warning in 2017

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.