Alert archive / California / Flash Flood Watches in 2021

Flash Flood Watch 2, NWS San Francisco Bay Area, CA

March 10, 2021Monterey County, San Benito County, California

NWS San Francisco Bay Area, CA issued this flash flood watch at Mar 10, 2021, 9:55 AM PST for Monterey County, San Benito County, California. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued
Mar 10, 2021, 9:55 AM PST (17:55 UTC)
Expired
Mar 10, 2021, 10:00 PM PST
In force
12 hr
Issued by
NWS San Francisco Bay Area, CA
Flood severity
None

Counties Monterey County, CA, San Benito County, CA

The radar

The San Francisco radar (KMUX), 103 km from the middle of the area, began a volume at 17:53 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, 5.9 hours before the alert went out and 171 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 2021-03-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 58 joules per kilogram.LCLLFCEL10008507005003002001001 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 2021-03-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 102 square meters per square second.19395878Sfc1 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
58 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
700 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
102 m²/s²
0-3 km storm-relative helicity
150 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

203 
WGUS66 KMTR 101755
FFAMTR

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service San Francisco CA
955 AM PST Wed Mar 10 2021

CAZ517-528-110600-
/O.NEW.KMTR.FF.A.0002.210310T1755Z-210311T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Lucia Mountains and Los Padres National Forest-Northern
Salinas Valley/Hollister Valley and Carmel Valley-
Including the cities of Salinas
955 AM PST Wed Mar 10 2021

...FLASH FLOOD WATCH FOR THE RIVER FIRE BURN AREA IN EFFECT THROUGH 
THIS EVENING...

The National Weather Service in San Francisco has issued a

* Flash Flood Watch for the River Fire burn area in a portion of 
  northern California, including the following areas, Northern 
  Salinas Valley/Hollister Valley and Carmel Valley and Santa Lucia 
  Mountains and Los Padres National Forest.

* Through this evening

* National Weather Service Meteorologists are forecasting additional 
  shower activity today into tonight with intermittent brief periods 
  of heavy rainfall over the River Fire burn area, which may lead to 
  flash flooding and debris flows. Local Officials have reported 
  mudslides have already occurred. Please remain vigilant.

* Additional shower activity today into tonight with intermittent 
  brief periods of heavy rainfall over the River Fire burn area is 
  expected up to and during the period of the watch. Residents near 
  the River Fire burn area should prepare for potential flooding 
  impacts. Be sure to stay up to date with information from local 
  authorities.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flash Flood Watch means that conditions may develop that lead to 
Flash Flooding. Flash Flooding is a very dangerous situation. You 
should monitor later forecasts and be prepared to take action should 
Flash Flood Warnings be issued.

Local emergency services are monitoring the situation and will issue 
a public statement as conditions warrant. PLAN NOW so you will know 
what to do in an emergency. Keep informed by listening to local 
radio and television for statements and possible warnings. Follow 
the advice of public safety officials.

&&

$$

BB
1 follow-up statement
334 
WGUS66 KMTR 110604
FFAMTR

Flood Watch
National Weather Service San Francisco CA
1004 PM PST Wed Mar 10 2021

CAZ517-528-110715-
/O.EXP.KMTR.FF.A.0002.000000T0000Z-210311T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Santa Lucia Mountains and Los Padres National Forest-Northern
Salinas Valley/Hollister Valley and Carmel Valley-
Including the cities of Salinas
1004 PM PST Wed Mar 10 2021

...FLASH FLOOD WATCH FOR THE RIVER FIRE BURN AREA HAS EXPIRED...

The Flash Flood Watch for a portion of northern California, 
including the following areas, Northern Salinas Valley/Hollister 
Valley and Carmel Valley and Santa Lucia Mountains and Los Padres 
National Forest has expired.

Showers are forecast to taper off overnight. Flooding is no longer 
expected to pose a threat. Please continue to heed any instructions 
from emergency services personnel.

$$

Dykema

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 9, 4:35 PM PSTSpecial Marine WarningMTR25 min
Mar 10, 11:36 AM PSTSpecial Weather StatementMTRAlameda39 min
Mar 10, 2:03 PM PSTSmall Craft AdvisoryMTR61 hr

Nearby

Flash Flood Watches in California, 2021Every flash flood watch 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.