Alert archive / California / Flash Flood Warnings in 1998

Flash Flood Warning 34, NWS San Francisco Bay Area, CA

February 6, 1998Marin County, Sonoma County, California

NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 6, 1998, 11:45 AM PST for Marin County, Sonoma County, California. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Feb 6, 1998, 11:45 AM PST (19:45 UTC)
Expired
Feb 6, 1998, 2:45 PM PST
In force
3 hr
Issued by
NWS San Francisco Bay Area, CA
Area
Whole counties

Counties Marin County, CA, Sonoma County, CA

The radar

The Sacramento radar (KDAX), 104 km from the middle of the area, began a volume at 19:49 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, 7.8 hours before the alert went out and 84 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 1998-02-06Temperature 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 1998-02-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 210 square meters per square second.1939587897117Sfc1 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
1526 m above ground
0-6 km bulk shear
67 kt
0-1 km storm-relative helicity
210 m²/s²
0-3 km storm-relative helicity
448 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KSFO 061946
FFWSFO
CAC041-097-062245-
 
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
1145 AM PST FRI FEB 6 1998
 
THE NATIONAL WEATHER SERVICE IN SAN FRANCISCO HAS ISSUED A
FLASH FLOOD WARNING EFFECTIVE UNTIL  245 PM PST
FOR PEOPLE IN THE FOLLOWING LOCATIONSS...
 
IN CENTRAL CALIFORNIA
 
   ...MARIN COUNTY
 
IN NORTH CENTRAL CALIFORNIA
 
   ...SOUTHERN SONOMA COUNTY
 
RAINFALL OVER THE PAST SIX HOURS HAVE RANGED FROM ONE TO TWO INCHES OVER
PORTIONS OF THE NORTH BAY REGION. SHOWERS AND THUNDERSTORMS WILL
CONTINUE TO MOVE THROUGH THE WARNING AREA UNTIL ABOUT 1PM. THE GROUND IS
VERY SATURATED AND SMALL RIVERS ARE NEAR CAPACITY FROM THE STORM EARLY
THIS WEEK. ADDITIONAL RAINFALL FROM THESE STORMS WILL CAUSE SMALL
RIVER AND STREAMS TO OVERFLOW...ESPECIALLY THE PETALUMA RIVER. HIGH
TIDES THIS MORNING WILL ALSO INCREASE FLOODING OVER LOW LYING
AREAS. MUDSLIDES AND ROAD CLOSURES ARE ALSO POSSIBLE.
 
DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY.  THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO
CROSS SAFELY.  VEHICLES CAUGHT IN RISING WATER SHOULD BE
ABANDONED QUICKLY.  MOVE TO HIGHER GROUND.

The office that day

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

IssuedProductOfficeCountiesLasted
Feb 5, 4:00 PM PSTFlash Flood WarningMTRNapa, Sonoma8 hr
Feb 5, 4:00 PM PSTFlash Flood WarningMTRMarin8 hr
Feb 6, 8:42 AM PSTFlash Flood WarningMTRMonterey6 hr
Feb 6, 9:38 AM PSTFlash Flood WarningMTRSan Mateo, Santa Clara5 hr
Feb 6, 2:02 PM PSTSevere Thunderstorm WarningMTRSanta Clara, Santa Cruz58 min
Feb 6, 2:44 PM PSTFlash Flood WarningMTRSonoma3 hr
Feb 6, 2:44 PM PSTFlash Flood WarningMTRSan Mateo3 hr

Nearby

Flash Flood Warnings in California, 1998Every flash flood warning in 1998

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.