Alert archive / California / Flash Flood Warnings in 1999
Flash Flood Warning 1, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this flash flood warning at Feb 8, 1999, 10:11 PM PST for San Mateo County, California. It was in force for 12 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 8, 1999, 10:11 PM PST (06:11 UTC)
- Expired
- Feb 9, 1999, 10:00 AM PST
- In force
- 12 hr
- Issued by
- NWS San Francisco Bay Area, CA
- Area
- Whole counties
County San Mateo County, CA
The nearest sounding before it
Oakland, CA (KOAK), launched 00:00Z, 6.2 hours before the alert went out and 35 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
- 25 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 502 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- 105 m²/s²
- 0-3 km storm-relative helicity
- 221 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KSFO 090615 FFWSFO CAC081-091805- BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE SAN FRANCISCO CA 1011 PM PST MON FEB 8 1999 THE NATIONAL WEATHER SERVICE IN SAN FRANCISCO HAS ISSUED A * FLASH FLOOD WARNING FOR AN UNCONTROLLED RELEASE IN... WEST CENTRAL SAN MATEO COUNTY IN CENTRAL CALIFORNIA * UNTIL 1000 AM PST * FORECACT RAINFALL OVERNIGHT IS EXPECTED TO CAUSE AN UNCONTROLLED RELEASE FROM PILARCITOS LAKE. SAN MATEO COUNTY OES AND SAN FRANCISCO WATER DISTRICT EXPECT THE UNCONTROLLED RELEASE WILL OCCUR SOMETIME EARLY TUESDAY MORNING. PEOPLE LIVING ALONG PILARCITOS CREEK SHOULD BEGIN TO TAKE ACTION TO EVACUATE THEIR HOMES IMMEDIATELY. MONITOR YOUR EMERGENCY MEDIA SOURCES FOR ANY EVACUATION INSTRUCTIONS. PEOPLE LIVING DOWNSTREAM FROM THIS LAKE ON PILARCITOS CREEK SHOULD TAKE IMMEDIATE ACTION. DO NOT WAIT UNTIL THE LAST MINUTE. ADDITIONAL STATEMENTS WILL BE ISSUED AS SOON AS NEW INFORMATION IS RECEIVED. HOFFMANN
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 8, 9:00 PM PST, 1 hour 11 minutes earlier.
Area forecast discussion, Feb 8, 9:00 PM PST, 1 hour 11 minutes before
SAN FRANCISCO BAY AREA/CENTRAL CALIFORNIA COAST FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO CA
900 PM PST MON FEB 8 1999
WAVE ON SURFACE FRONT NOW 250 NM W OF MONTEREY BAY. BACK EDGE OF
CLOUDS MOVING EAST AT 35 KT. LOTS OF WARM ADVECTION AHEAD OF THE
WAVE WITH LIGHT PRECIPITATION OVER MOST OF THE AREA AT THIS TIME.
RADAR SHOWS SHOWERS INCREASING OVER SAN FRANCISCO AND MARIN COUNTIES.
RAINFALL OVER THE PAST 6 HOURS LIGHT IN NORTH BAY COUNTIES .02 TO .80
IN SANTA CRUZ MOUNTAINS. RIVERS AND STREAMS SHOWING LITTLE RESPONSE
AT THIS TIME. ALSO FRONT OFFSHORE TAKING ON MORE NORTH/SOUTH
ORIENTATION AND MAY SLOW SOME AS IT APPROACHES THE COAST.
EXTRAPOLATION FROM SATELLITE SHOWS FRONT SHOULD REACH SFO ABOUT 12Z
AND SANTA CRUZ MOUNTAINS 12Z TO 14Z. COLD AIR CONTINUES TO PUSH
SOUTH NOW DOWN TO 33N AT 135W.
NEW NGM AND ETA CLOSE ON TIMING OF UPPER TROUGH THROUGH THE AREA BY
00Z TO 06Z. DIFFERENCE SEEMS TO OCCUR WITH FORECAST PRECIPITATION
AREAS. NGM SEEMS TO HAVE BETTER HANDLE ON SURFACE WAVE MOVING IT
ONSHORE NEAR SFO. PREFER NGM 700 MB OMEGA FIELD AS FRONT MOVES
ONSHORE. EVEN THOUGH PRECIPITATION MAX FORECAST OVER SFO BY
12Z...INCREASING MIDDLE/UPPER LEVEL DIVERGENCE...AND LOW LEVEL
UPSLOPE FLOW WHICH WILL ENHANCE VERTICAL MOTION AND PRECIPITATION.
THIS WOULD SUGGEST SANTA CRUZ MOUNTAINS AND SAN MATEO COAST SHOULD
GET MORE TOTAL PRECIP. WARM ADVECTION...OVERRUNNING PRECIP...ALREADY
PRODUCING MORE PRECIP THERE. AS FRONT ORIENTS MORE N/S A GOOD 2 TO 4
HOURS OF MODERATE TO HEAVY PRECIPITATION SHOULD REACH THE COAST SFO
TO MRY BY MORNING. DO NOT FEEL FLASH FLOOD WATCH IS NEEDED AT THIS
TIME SYSTEM WILL MOVE THROUGH QUICKLY...BUT WITH MODERATE TO HEAVY
PRECIP IN THE MORNING...URBAN AND SMALL STREAM ADVISORY MAY BE
NECESSARY BY NEXT FORECAST ISSUANCE.
LONGER RANGE...SHOWERS AND A FEW THUNDERSTORMS WILL FOLLOW SYSTEM
UNTIL TROUGH MOVE ONSHORE. CLEARING A COOLER WEATHER WILL FOLLOW WITH
COLDEST NIGHT ON WED NIGHT/THURS MORNING. NEXT SYSTEM APPROACHING
COAST LATE FRIDAY AND MOVING INLAND ON SATURDAY. MRF FCST SHOWS
LITTLE CHANGE IN GLOBAL PATTERN AND CONTINUES MEAN TROUGH POSITION
ALONG 130W TO 140W AND KICKS SHORT WAVE TROUGHS INTO WEST COAST
THROUGH THE PERIOD. SEE LITTLE CHANGE NEEDED IN THE FORECAST AT THIS
TIME.
STS +810 SFO/LVK +920 SJC ++20 MRY 9+20 HOFFMANN
.SFO...TNGT...SCA...PT ST GEORGE TO PT PIEDRAS BLANCAS INCLUDING
MRY BAY.The office that day
Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 9, 4:08 AM PST | Flash Flood Warning | MTR | Sonoma | 6 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.