Alert archive / California / Flash Flood Warnings in 1999
Flash Flood Warning 2, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 9, 1999, 4:08 AM PST for Sonoma 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 counties it named.
The facts
- Issued
- Feb 9, 1999, 4:08 AM PST (12:08 UTC)
- Expired
- Feb 9, 1999, 10:00 AM PST
- In force
- 6 hr
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Whole counties
County Sonoma County, CA
The radar
The Sacramento radar (KDAX), 108 km from the middle of the area, began a volume at 12:07 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 12:00Z, 0.1 hours before the alert went out and 109 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.
- Mixed-layer CAPE
- 62 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 847 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- 400 m²/s²
- 0-3 km storm-relative helicity
- 470 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KSFO 091210 FFWSFO CAC097-091800- BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE SAN FRANCISCO CA 408 AM PST TUE FEB 9 1999 THE NATIONAL WEATHER SERVICE IN SAN FRANCISCO HAS ISSUED A * FLASH FLOOD WARNING FOR... SOUTHERN SONOMA COUNTY IN NORTH CENTRAL CALIFORNIA * UNTIL 1000 AM PST * AT AT 400 AM PST...AUTOMATED RAIN GAUGES INDICATED HEAVY RAIN OVER SOUTHERN SONOMA COUNTY. * RAIN RATES APPROACHING A HALF AN INCH PER HOUR HAVE BEEN OCCURRING OVER SONOMA COUNTY DURING THE PAST TWO HOURS. SATELLITE AND RADAR DATA INDICATE THAT MODERATE TO HEAVY RAIN WILL FALL ACROSS THE WARNING AREA FOR THE NEXT SEVERAL HOURS. SINCE THE GROUND IS ALREADY SATURATED FROM RECENT HEAVY RAIN...FLASH FLOODING IS LIKELY IN URBAN AREAS AND SMALL STREAMS. SOME OF THE TOWNS AFFECTED WILL BE...PETALUMA. SOME OF THE SMALL STREAMS THAT WILL FLOOD ARE...THE PETALUMA RIVER AND SMALL STREAMS OF THE PETALUMA DRAINAIGE. DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE WATER COVERS THE ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY AND THE ROAD BENEATH MAY NOT BE INTACT. VEHICLES CAUGHT IN RISING WATER SHOULD BE ABANDONED QUICKLY. IT ONLY .TAKES A FOOT OR TWO OF FLOWING WATER TO WASH MOST CARS AWAY. REMEMBER... MOST DEATHS IN FLASH FLOODING OCCUR IN AUTOMOBILES. CARROLL
What forecasters said that day
The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Francisco Bay Area, CA wrote its last area forecast discussion before this flash flood warning went out at Feb 9, 3:30 AM PST, 38 minutes earlier.
Area forecast discussion, Feb 9, 3:30 AM PST, 38 minutes before
SAN FRANCISCO BAY AREA/CENTRAL CALIFORNIA COAST FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
330 AM PST TUE FEB 9 1999
STRONG STORM SYSTEM DEVEOPING RIGHT OFF NORTHERN AND CENTRAL
CALIFORNIA COAST ALREADY BRINGING STRONG WINDS AND HEAVY RAIN TO MANY
PARTS OF DISTRICT. WIND ADVISORY ISSUED FOR ALL ZONES AND GALE
WARNINGS ALL WATERS OUR CWA. HEAVY PRECIP OCCURING NORTH BAY COUNTIES
AND MOVING INTO SFO WHILE HAS TEMPORARILY TAPERED OFF TO THE SOUTH.
WITH HEAVY RAINS THAT OCCURRED THIS PAST WEEKEND...GROUND IS
SATURATED AND HYDROMET SHOWS RIVER AND STREAM LEVELS NORTH BAY
STARTING TO RISE RAPIDLY. HAVE ISSUED A FLOOD WATCH FOR RUSSIAN
RIVER IN SONOMA COUNTY AND NAPA RIVER IN NAPA COUNTY...AND A FLASH
FLOOD WATCH FOR ALL OTHER RIVERS AND STREAMS IN NAPA...SONOMA...AND
MARIN COUNTIES.
MODELS ARE GENERALLY OUT TO LUNCH WITH THIS SYSTEM...THOUGH NGM AT
LEAST CONTAINS HINTS OF NATURE OF WAVE DEVELOPMENT ACTUALLY
OCCURRING...SO AM BASING SHORT TERM FORECASTS LARGELY ON
INTERPRETATION OF SATELLITE...RADAR...AND SURFACE OBSERVATIONS. AM
THEREFORE HITTING HARD ON HEAVY PRECIP UNTIL FRONT MOVES THROUGH
NORTH BAY LATER THIS MORNING AND SOUTH PART OF CWA MIDDAY OR EARLY
AFTERNOON. WITH MODEL STRUCTURE AND EVOLUTION SO FAR OFF...MODEL
SOUNDINGS ALSO FAIL TO INDICATE RISK OF CONVECTION. STRONG LOW LEVEL
SHEAR AND HELICITY DEVELOPING AHEAD OF THE FRONT...ALONG WITH
COMPARATIVELY WARM AND MOIST AIR MASS. HAVE ALREADY PUT CHANCE
THUNDERSTORMS WITH SMALL HALL IN ZONES AND WILL NEED TO PAY CAREFUL
ATTENTION TO POSSIBILITY OF SEVERE WEATHER DEVELOPING.
VERY COLD AIR BEHIND THIS SYSTEM WILL RESULT IN FALLING TEMPERATURES
AND SNOW LEVELS IN THE AFTERNOON. SNOW LEVELS COULD GET AS LOW AS
1000 FEET NORTH BAY COUNTIES AND 2500 FEET MONTEREY BAY AREA DURING
THE EVENING. SHOWERS AND THUNDERSTORMS BEHIND THE FRONT SHOULD END
DURING THE EVENING AND NIGHT FROM NORTH TO SOUTH...WITH COOL AND
PARTLY CLOUDY WEATHER ON WEDNESDAY.
IN EXTENDED...DRY FOR AT LEAST A COUPLE OF DAYS...THEN SIGNIFICANT
DIFFERENCES BETWEEN MODELS ON NEXT SYSTEM...BUT NO TIME TO LOOK IN
DETAIL AT THAT NOW.
STS +40 SFO/LVK +40 SJC +40 MRY +60 BLIER
.SFO...TODAY...GLW...PT REYES TO PT PIEDRAS BLANCAS INCLUDING
SFO AND MRY BAYS.
SCA...PT ST GEORGE TO PT REYES.
WIND ADVISORY...ALL ZONES THIS MORNING.
FLOOD WATCH...NAPA AND SONOMA RIVERS.
FLASH FLOOD WATCH...NAPA...SONOMA...MARIN COUNTIES.The office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 8, 10:11 PM PST | Flash Flood Warning | MTR | San Mateo | 12 hr |
Nearby
Flash Flood Warnings in California, 1999Every flash flood warning in 1999
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.