Alert archive / California / Flash Flood Warnings in 2017

Flash Flood Warning 13, NWS San Francisco Bay Area, CA

January 8, 2017Santa Clara County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Jan 8, 2017, 4:34 PM PST for Santa Clara County, California. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jan 8, 2017, 4:34 PM PST (00:34 UTC)
Expired
Jan 8, 2017, 7:30 PM PST
In force
3 hr
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), 25 km from the middle of the area, began a volume at 00:36 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.

What was reported inside it

TimeReportWhereRemark
Jan 8, 6:59 PM PSTFLOOD5 W Gilroy, CAHWY 152 CLOSED BOTH WAYS AT WATSONVILLE RD

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Oakland, CA (KOAK), launched 00:00Z, 0.6 hours before the alert went out and 91 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 2017-01-09Temperature 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 00:00Z on 2017-01-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 320 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
678 m above ground
0-6 km bulk shear
83 kt
0-1 km storm-relative helicity
320 m²/s²
0-3 km storm-relative helicity
361 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

372 
WGUS56 KMTR 090034
FFWMTR
CAC085-090330-
/O.NEW.KMTR.FF.W.0013.170109T0034Z-170109T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service San Francisco CA
434 PM PST SUN JAN 8 2017

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

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

* Until 730 PM PST

* At 431 PM PST, local law enforcement officials reported widespread
  flooding due to run-off from heavy rain throughout the day across
  the warned area. Flash flooding is already occurring, especially
  along the Uvas Creek and Llagas Creek west of Morgan Hill, Gilroy
  and San Martin. While precipitation will continue to diminish over
  the next several hours, run-off will continue to exacerbate
  flooding concerns in these areas. 

* Some locations that will experience flooding include...
  Gilroy and Morgan Hill. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, country roads, farmland, and other low lying
spots.

&&

LAT...LON 3691 12157 3696 12164 3699 12167 3703 12170
      3707 12172 3712 12177 3715 12179 3718 12173
      3710 12164 3702 12158 3695 12156

$$

RGass
1 follow-up statement
441 
WGUS76 KMTR 090328
FFSMTR

Flash Flood Statement
National Weather Service San Francisco CA
728 PM PST SUN JAN 8 2017

CAC085-090334-
/O.EXP.KMTR.FF.W.0013.000000T0000Z-170109T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Clara CA-
728 PM PST SUN JAN 8 2017

...THE FLASH FLOOD WARNING FOR SOUTH CENTRAL SANTA CLARA COUNTY WILL
EXPIRE AT 730 PM PST...

The heavy rain across the warned area continues to diminish this
evening. Flash flooding is no longer expected to pose a threat.
However, additional rainfall and run-off from earlier rains will
continue to pose an areal flood threat. Please continue to heed any
remaining road closures. 

LAT...LON 3691 12157 3696 12164 3699 12167 3703 12170
      3707 12172 3712 12177 3715 12179 3718 12173
      3710 12164 3702 12158 3695 12156

$$

RGass

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 8, 7:54 PM PSTAreal Flood WarningMTRSanta Clara3 hr
Jan 8, 8:21 PM PSTSpecial Marine WarningMTR24 min
Jan 8, 9:43 PM PSTSmall Craft AdvisoryMTR5 hr
Jan 8, 9:43 PM PSTSmall Craft AdvisoryMTR4 days
Jan 8, 10:45 PM PSTAreal Flood WarningMTRSanta Clara6 hr
Jan 8, 11:09 PM PSTFlash Flood WarningMTRMonterey3 hr
Jan 9, 2:44 AM PSTGale WarningMTR42 hr
Jan 9, 2:55 AM PSTCoastal Flood AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, Napa, City and County of San Francisco and 4 more3 days
Jan 9, 3:02 AM PSTHigh Wind WatchMTRMarin, City and County of San Francisco, San Mateo, Santa Clara, Santa Cruz, Sonoma11 hr
Jan 9, 2:17 PM PSTHigh Wind WarningMTRMonterey, San Mateo, Santa Clara, Santa Cruz34 hr
Jan 9, 2:17 PM PSTWind AdvisoryMTRAlameda, Contra Costa, Marin, Monterey, Napa, City and County of San Francisco and 4 more34 hr
Jan 9, 2:39 PM PSTFlash Flood WatchMTRMarin, Monterey, Napa, San Mateo, Santa Clara, Santa Cruz and 1 more37 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.