Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 63, NWS San Francisco Bay Area, CA

February 20, 2017Santa Clara County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 20, 2017, 5:03 PM PST for Santa Clara County, California. It was in force for 87 min. 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, 5:03 PM PST (01:03 UTC)
Expired
Feb 20, 2017, 6:30 PM PST
In force
87 min
Issued by
NWS San Francisco Bay Area, CA
Area
Storm-based polygon
Flood severity
None

County Santa Clara County, CA

The radar

The San Francisco radar (KMUX), 27 km from the middle of the area, began a volume at 01:07 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 00:00Z, 1.1 hours before the alert went out and 50 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 00:00Z on 2017-02-21Temperature 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 00:00Z on 2017-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 111 square meters per square second.1939587897117136156Sfc1 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
521 m above ground
0-6 km bulk shear
99 kt
0-1 km storm-relative helicity
111 m²/s²
0-3 km storm-relative helicity
565 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

517 
WGUS56 KMTR 210103
FFWMTR
CAC085-210230-
/O.NEW.KMTR.FF.W.0063.170221T0103Z-170221T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

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

* Flash Flood Warning for...
  Northwestern Santa Clara County in northern California...

* Until 630 PM PST

* At 457 PM PST, a stream gage on the Upper Penitencia Creek near
  Alum Rock Park indicated minor flooding was occurring.

* Some locations that will experience flooding include...
  Neighborhoods along Upper Penitencia Creek.

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.

Please report flooding to your local law enforcement agency when you
can do so safely.

&&

LAT...LON 3738 12185 3739 12186 3740 12179 3738 12179
      3739 12182

$$

Blier
1 follow-up statement
293 
WGUS76 KMTR 210238
FFSMTR

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

CAC085-210243-
/O.EXP.KMTR.FF.W.0063.000000T0000Z-170221T0230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Clara CA-
638 PM PST MON FEB 20 2017

...THE FLASH FLOOD WARNING FOR NORTHWESTERN SANTA CLARA COUNTY HAS
EXPIRED...

Rain rates are diminishing across the warned area and water levels
are beginning to recede. Therefore, the flash flood warning for the
Upper Penitencia Creek near Alum Rock Park has been allowed to
expire. Please continue to heed any remaining road closures.

LAT...LON 3738 12185 3739 12186 3740 12179 3738 12179
      3739 12182

$$

Blier

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 20, 4:13 PM PSTFlash Flood WarningMTRSan Benito, Santa Clara6 hr
Feb 20, 4:34 PM PSTFlash Flood WarningMTRAlameda116 min
Feb 20, 5:02 PM PSTRiver Flood WarningMTRMonterey24 hr
Feb 20, 5:29 PM PSTFlash Flood WarningMTRSan Mateo2 hr
Feb 20, 6:02 PM PSTFlash Flood WarningMTRSanta Cruz4 hr
Feb 20, 6:03 PM PSTAreal Flood AdvisoryMTRSan Mateo4 hr
Feb 20, 6:18 PM PSTAreal Flood AdvisoryMTRMonterey12 hr
Feb 20, 6:36 PM PSTFlash Flood WarningMTRAlameda4 hr
Feb 20, 6:54 PM PSTFlash Flood WarningMTRAlameda3 hr
Feb 20, 7:17 PM PSTFlash Flood WarningMTRSan Mateo3 hr
Feb 20, 9:15 PM PSTAreal Flood WarningMTRSanta Clara8 hr
Feb 20, 10:00 PM PSTFlash Flood WarningMTRSanta Cruz4 hr
Feb 20, 10:01 PM PSTFlash Flood WarningMTRAlameda3 hr
Feb 20, 10:15 PM PSTFlash Flood WarningMTRSan Mateo3 hr
Feb 20, 10:16 PM PSTAreal Flood WarningMTRSan Benito, Santa Clara12 hr
Feb 20, 10:34 PM PSTAreal Flood AdvisoryMTRAlameda12 hr
Feb 20, 10:42 PM PSTAreal Flood WarningMTRAlameda12 hr
Feb 20, 11:38 PM PSTAreal Flood WarningMTRSanta Clara12 hr
Feb 21, 12:14 AM PSTAreal Flood WarningMTRMonterey12 hr
Feb 21, 1:09 AM PSTAreal Flood WarningMTRSan Mateo6 hr
Feb 21, 5:38 AM PSTAreal Flood WarningMTRSan Benito, Santa Clara15 hr
Feb 21, 8:41 AM PSTSmall Craft Advisory for Hazardous SeasMTR12 hr
Feb 21, 11:29 AM PSTAreal Flood WarningMTRSanta Clara36 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.