Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 57, NWS San Francisco Bay Area, CA

February 20, 2017San Benito County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 20, 2017, 8:56 AM PST for San Benito County, California. It was in force for 6 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, 8:56 AM PST (16:56 UTC)
Expired
Feb 20, 2017, 2:45 PM PST
In force
6 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County San Benito County, CA

The radar

The San Francisco radar (KMUX), 86 km from the middle of the area, began a volume at 16:58 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, 4.9 hours before the alert went out and 152 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°0°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.

557 
WGUS56 KMTR 201656
FFWMTR
CAC069-202245-
/O.NEW.KMTR.FF.W.0057.170220T1656Z-170220T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

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

* Flash Flood Warning for...
  Central San Benito County in central California...

* Until 245 PM PST

* At 848 AM PST, the San Benito River near Willow Creek School
  stream gage indicated rapidly rising water levels well above the
  established flood stage.  Flood stage is 10 feet.  Current water
  level is 11.18 feet and rapidly rising.

* Flash flooding will remain over mainly rural areas of central San
  Benito County.  Impacts are expected to be minor unless local
  roadways are flooded, including Route 25 (Airline Highway).

LAT...LON 3665 12120 3653 12106 3651 12109 3657 12119
      3664 12127 3672 12130 3673 12127

$$

MWS
1 follow-up statement
844 
WGUS76 KMTR 202240
FFSMTR

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

CAC069-202246-
/O.EXP.KMTR.FF.W.0057.000000T0000Z-170220T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
San Benito CA-
240 PM PST MON FEB 20 2017

...THE FLASH FLOOD WARNING FOR CENTRAL SAN BENITO COUNTY WILL EXPIRE
AT 245 PM PST...

Heavy rain has ended across the warned area and water levels are
beginning to recede along the San Benito River. Therefore, the flash
flood warning will be allowed to expire at 2:45 pm. Please continue
to heed any remaining road closures. Renewed rainfall is likely
later this afternoon and evening, and new warnings may be needed. 

LAT...LON 3665 12120 3653 12106 3651 12109 3657 12119
      3664 12127 3672 12130 3673 12127

$$

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, 8:14 AM PSTFlash Flood WarningMTRMarin, Sonoma4 hr
Feb 20, 8:22 AM PSTAreal Flood WarningMTRSonoma60 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.