Alert archive / Florida / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 67, NWS Miami, FL

May 20, 1999Hendry County, Florida

NWS Miami, FL issued this severe thunderstorm warning at May 20, 1999, 6:56 PM EDT for Hendry County, Florida. It was in force for 44 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
May 20, 1999, 6:56 PM EDT (22:56 UTC)
Expired
May 20, 1999, 7:40 PM EDT
In force
44 min
Issued by
NWS Miami, FL
Area
Whole counties

County Hendry County, FL

The radar

The Miami radar (KAMX), 129 km from the middle of the area, began a volume at 22:59 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

Miami, FL (KMFL), launched 12:00Z, 10.9 hours before the alert went out and 120 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, Miami, FL at 12:00Z on 1999-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 946 joules per kilogram.LCLLFCEL10008507005003002001001 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, Miami, FL at 12:00Z on 1999-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -1 square meters per square second.1939Sfc1 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
946 J/kg
Mixed-layer CIN
-35 J/kg
Mixed-layer LCL
1066 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
-1 m²/s²
0-3 km storm-relative helicity
32 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.

999 
WUUS1 KMIA 202258 RRA
SVRMIA
FLC051-202340-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MIAMI FL
656 PM EDT THU MAY 20 1999

THE NATIONAL WEATHER SERVICE IN MIAMI HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  NORTHWESTERN HENDRY COUNTY IN SOUTHERN FLORIDA

* UNTIL 740 PM EDT

* NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATES A SEVERE
  THUNDERSTORM OVER NORTHWEST HENDRY COUNTY. THIS THUNDERSTORM
  HAS LITTLE INDICATED MOVEMENT BUT HAS A HISTORY OF PRODUCING
  LARGE HAIL TO QUARTER SIZE. THE PUBLIC IS ADVISED TO SEEK
  SHELTER DUE TO FREQUENT LIGHTNING...LARGE HAIL...AND POSSIBLE
  STRONG WIND GUSTS IN EXCESS OF 50 MPH.


WHEN THUNDERSTORMS ARE OCCURRING...MOVE INSIDE A STRONG BUILDING.
DO NOT STAND BY WINDOWS. DO NOT USE TELEPHONES OR ELECTRICAL
APPLIANCES UNLESS IN AN EMERGENCY UNTIL THE STORM HAS PASSED.
MOTORISTS SHOULD NOT DRIVE INTO LOW WATER CROSSINGS.

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 55 MPH...
LARGE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. SEEK SHELTER
IN A STRONG BUILDING. STAY AWAY FROM WINDOWS. DO NOT USE TELEPHONES
OR ELECTRICAL APPLIANCES.

The office that day

Everything else NWS Miami, FL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 20, 2:20 PM EDTSevere Thunderstorm WarningMFLPalm Beach65 min
May 20, 3:35 PM EDTSevere Thunderstorm WarningMFLBroward60 min
May 20, 6:24 PM EDTSevere Thunderstorm WarningMFLCollier31 min

Nearby

Severe Thunderstorm Warnings in Florida, 1999Every severe thunderstorm 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.