Alert archive / Florida / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 94, NWS Tallahassee, FL

April 20, 20204 counties in Florida

NWS Tallahassee, FL issued this severe thunderstorm warning at Apr 20, 2020, 12:30 AM CDT for 4 counties in Florida. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Apr 20, 2020, 12:30 AM CDT (05:30 UTC)
Expired
Apr 20, 2020, 1:02 AM CDT
In force
32 min
Issued by
NWS Tallahassee, FL
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Bay County, FL, Jackson County, FL, Walton County, FL, Washington County, FL

The radar

The Eglin Afb radar (KEVX), 17 km from the middle of the area, began a volume at 05:32 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 19, 10:13 PM CDTTornado WatchSPC10 hr

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 00:00Z, 5.5 hours before the alert went out and 140 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, Tallahassee Rgnl, FL at 00:00Z on 2020-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2182 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, Tallahassee Rgnl, FL at 00:00Z on 2020-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 259 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
2182 J/kg
Mixed-layer CIN
-61 J/kg
Mixed-layer LCL
709 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
259 m²/s²
0-3 km storm-relative helicity
327 m²/s²
Significant tornado parameter
3.5
Supercell composite
17.9

Open this sounding in Storm Lab

The text

As transmitted.

964 
WUUS52 KTAE 200530
SVRTAE
FLC005-063-131-133-200630-
/O.NEW.KTAE.SV.W.0094.200420T0530Z-200420T0630Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Tallahassee FL
Issued by National Weather Service Houston/Galveston TX
1230 AM CDT Mon Apr 20 2020

The National Weather Service in Tallahassee has issued a

* Severe Thunderstorm Warning for...
  Southern Jackson County in the Panhandle of Florida...
  Northeastern Bay County in the Panhandle of Florida...
  East central Walton County in the Panhandle of Florida...
  Central Washington County in the Panhandle of Florida...

* Until 130 AM CDT.

* At 1230 AM CDT, severe thunderstorms were located along a line
  extending from 6 miles southwest of Chipley to 13 miles southeast
  of De Funiak Springs, moving east at 20 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Vernon, Bradford, Live Oak, Freeport, Alford, Wausau, Brock
  Crossroad, Red Bay, Orange Hill, Ridgetop, Greenhead, Red Head,
  Holmes Valley, Millers Ferry, Gilberts Mill, Round Lake, Simsville,
  Smyrna, Spring Hollow and Sunny Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 600 AM CDT for the Panhandle
of Florida.

For your protection move to an interior room on the lowest floor of a
building.

Intense thunderstorm lines can produce brief tornadoes and widespread
significant wind damage. Although a tornado is not immediately
likely, it is best to move to an interior room on the lowest floor of
a building. These storms may cause serious injury and significant
property damage.

&&

LAT...LON 3053 8617 3071 8559 3069 8502 3047 8576
TIME...MOT...LOC 0530Z 275DEG 18KT 3068 8559 3055 8602 

HAIL...<.75IN
WIND...60MPH
 
$$
1 follow-up statement
455 
WWUS52 KTAE 200602
SVSTAE

Severe Weather Statement
National Weather Service Tallahassee FL
Issued by National Weather Service Houston/Galveston TX
102 AM CDT Mon Apr 20 2020

FLC005-063-131-133-200611-
/O.CAN.KTAE.SV.W.0094.000000T0000Z-200420T0630Z/
Jackson FL-Bay FL-Walton FL-Washington FL-
102 AM CDT Mon Apr 20 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN JACKSON...
NORTHEASTERN BAY...EAST CENTRAL WALTON AND CENTRAL WASHINGTON
COUNTIES IS CANCELLED...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning has been cancelled.  However gusty winds are 
still possible with these thunderstorms. Additionally, there is a 
second severe line of storms in Walton County that will eventually 
enter this same area. See the bulletin for Severe Thunderstorm 
Warning 96 for more details.

A Tornado Watch remains in effect until 600 AM CDT for the Panhandle
of Florida.

Remember, a Severe Thunderstorm Warning still remains in effect for
Walton County with the incoming line of severe storms.

LAT...LON 3053 8617 3071 8559 3069 8502 3047 8576
TIME...MOT...LOC 0559Z 275DEG 18KT 3067 8542 3054 8585 

$$

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Tallahassee, FL wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 19, 10:29 PM CDT, 2 hours 1 minute earlier.

Area forecast discussion, Apr 19, 10:29 PM CDT, 2 hours 1 minute before
Area Forecast Discussion
National Weather Service Tallahassee FL
1129 PM EDT Sun Apr 19 2020

...Severe Threat Rapidly Increasing Across The Region...

.UPDATE...

Tornado Watch is now in effect for the entire area until 7AM EDT
or 6 AM CDT. A line of strong storms is now sliding to the
northwest of Coffee County AL although the southern end may clip
the county. Latest surface analysis shows the warm front north of
Dothan and Enterprise AL, stretching east to just north of
Thomasville, GA. The atmosphere south of the warm front is
extremely unstable with the TLH 02z sounding showing 3000 J/KG of
surface CAPE which is consistent with SPC mesoanalysis. Otherwise,
the near term from below is still on track from a mesoscale
perspective. The southern end of the line is passing through
Slidell, LA and starting to move into far SW AL. This will be the
main severe threat later this evening.

&&

.PREV DISCUSSION [844 PM EDT]...

.NEAR TERM [Through Tonight]...

Clearly, the airmass over our western area remains very unstable
- while over portions of South Central, GA, it will be a little
longer before this boundary starts moving northward

The 00z TAE sounding shows the kinematic fields continue to
increase with near 60 kt of deep layer shear and the 850 mb winds
now up to 45 knots. RAP analysis of 850 mb winds in our western
counties already show the presence of winds around 50 kt at that
level. Further west, the KLIX VWP is showing 50 kt winds at 3000
ft. Clearly, the wind fields moving into the region are more than
supportive for significant severe weather. While the low level
flow is not sufficiently curved, even across Srn Alabama and the
Western Florida Panhandle, there still appears to be enough low
level shear present to maintain the tornado risk through the night.
Moreover, the presence of the surface frontal boundary across a
portion of our forecast area could be a significant factor in
tornado potential later tonight, especially if this boundary is
slow to recede northward. Storms nearing this boundary would
encounter enhanced low level shear as the winds back near the
boundary, thus increasing tornado potential. This risk is greatest
across Southeast Alabama and into extreme SW Georgia over the
next 2-4 hours.

Through 9 pm CDT, storms that are over South Central Alabama will
be moving eastward toward our northern SE AL counties as well as
approaching Quitman/Clay Counties in extreme SW Georgia. With the
boundary beginning to retreat northward, it is possible that
these storms will remain surface-based moving into the area and
present the risk of all severe hazard types as they move through.
As the storms move further east of Clay/Quitman Counties, the
storms should become increasingly elevated and present more of a
large hail threat into South Central Georgia, as long as they are
not overtaken by the frontal boundary, should this occur, the
storms would continue to present a risk for all severe hazards.

After midnight CDT - a large cluster of storms, now across
Southern Mississippi will be nearing our western CWA boundary.
This particular complex of storms a cross Southern Mississippi
is especially intense, with a relatively untouched airmass ahead
of it that is incredibly favorable for the continued maintenance
of the storms. 22z/23z HRRR output suggests this storm nears
Southeast Alabama around 1 am CT and will pose a risk for all
severe hazards. This storm and others in the main line would then
progress across the region throughout the early morning hours on
Monday.

Key Point:

1. A moderate risk for severe weather continues across the region
tonight. Storms are expected to increase in coverage and severity
later tonight in our region and pose a risk for all severe
weather hazards: destructive winds, tornadoes, and large hail.

.SHORT TERM [Monday Night Through Wednesday]...

Dry weather with high pressure at the surface and confluent flow
aloft. Cool-ish partly cloudy mornings and warm mainly sunny
afternoons expected. Little change made to previous forecast.

.LONG TERM [Thursday Through Sunday]...

Next strong system will approach Thursday with deep moisture and
decent shear in play. Severe weather possible along with an
excessive rain threat. Will have to see how the Friday-Sunday
period plays out as it looks like another system will move
through.  We'll look closer at that tmrw.

.AVIATION...
[Through 18Z Monday]

Return to VFR today outside of ABY/ECP where it will persist. Then
cigs lower to at least IFR tonight. A line of severe TSRA sweeps
across terminals overnight into Monday morning. Winds shift with
frontal passage on Monday gusting to 30 kt at times.

.MARINE...

Hazardous marine conditions are expected as a strong system moves
across the area. Winds and seas increasing this afternoon and
reaching SCA levels this evening into early Monday afternoon. A
Small Craft Advisory is now in effect. A cluster or line of
severe storms sweeps through overnight into Monday. After the
system departs, winds and seas gradually relax before ramping up
to cautionary/advisory levels again ahead of the next system on
Thurs.

.FIRE WEATHER...

Red flag conditions are not expected for the next several days.

.HYDROLOGY...

Thunderstorm outflow has reinforced the cool airmass to our north
and the warm front has come to a halt. This will focus a heavy
rain threat across much of our AL/GA counties...esply northern
sections...through tonight. Risk of flash flooding has increased in
these areas as has the potential for flooding on the Lee and
Lowndes County tributaries. River Flood warnings may be required
for these areas later today.

Thursday system still looks wet and after this system's rain we
will be much more susceptible to flooding. We're going to focus on
the short term for now but plan an ESF tomorrow to update
interests on our rivers about late week/weekend flood potential.
Stay tuned!

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur (while following all local, state, and CDC guidelines) by
calling the office or tweeting us @NWSTallahassee.

&&

.PRELIMINARY POINT TEMPS/POPS...

Tallahassee   72  84  58  84  57 /  70  50   0   0   0
Panama City   72  81  62  81  61 /  70  20   0   0   0
Dothan        67  78  55  80  55 /  90  10   0   0   0
Albany        64  79  56  80  54 /  90  20   0   0   0
Valdosta      69  81  58  81  55 /  60  70   0   0   0
Cross City    73  81  60  82  57 /  40  70   0   0   0
Apalachicola  72  79  63  79  61 /  60  40   0   0   0

&&

.TAE WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Tuesday morning for Coastal Bay-
     Coastal Franklin-Coastal Gulf-South Walton.

GA...Flash Flood Watch until 8 AM EDT Monday for Ben Hill-Lee-Quitman-
     Randolph-Terrell-Turner-Worth.

AL...None.
GM...Small Craft Advisory until 2 PM EDT /1 PM CDT/ Monday for
     Apalachee Bay or Coastal Waters From Keaton Beach to
     Ochlockonee River FL out to 20 Nm-Coastal Waters From
     Ochlockonee River to Apalachicola Fl out to 20 Nm-Coastal
     waters from Suwannee River to Keaton Beach FL out 20 NM-
     Coastal waters from Mexico Beach to Apalachicola FL out 20
     NM-Coastal waters from Mexico Beach to Okaloosa Walton
     County Line FL out 20 NM-Waters from Suwannee River to
     Apalachicola FL from 20 to 60 NM-Waters from Apalachicola
     to Mexico Beach FL from 20 to 60 NM-Waters from Mexico
     Beach to Okaloosa Walton County Line FL from 20 to 60 NM.

&&

UPDATE...LN
NEAR TERM...Godsey
SHORT TERM...Johnstone
LONG TERM...Johnstone
AVIATION...LF
MARINE...Johnstone
FIRE WEATHER...LF
HYDROLOGY...Johnstone

In the hours before

Local storm report, Apr 20, 12:21 AM CDT, 9 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
121 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1208 AM     TSTM WND GST     KINSTON                 31.22N 86.17W
04/20/2020  M56 MPH          COFFEE             AL   MESONET

            MESONET STATION IN KINSTON MEASURED A 56 MPH
            GUST.

&&

DH
Local storm report, Apr 20, 12:22 AM CDT, 8 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
122 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1224 AM     TSTM WND GST     1 NW CAIRNS AAF         31.28N 85.72W
04/20/2020  M54 MPH          DALE               AL   AWOS

            AWOS KOZR MEASURED A 54 MPH GUST.

&&

DH
Local storm report, Apr 20, 12:26 AM CDT, 4 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
126 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1217 AM     TSTM WND DMG     2 S MARLEY HILL         31.47N 85.69W
04/20/2020                   DALE               AL   EMERGENCY MNGR

            MULTIPLE TREES DOWN THROUGHOUT DALE COUNTY
            AND 2 REPORTS OF TREES ON HOUSES.

&&

DH
Local storm report, Apr 20, 12:28 AM CDT, 2 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
128 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1237 AM     TSTM WND GST     NAPIER FIELD            31.32N 85.45W
04/20/2020  M49 MPH          DALE               AL   ASOS

            KDHN IN DOTHAN MEASURED A 49 MPH GUST.

&&

DH
Local storm report, Apr 20, 12:29 AM CDT, 1 minute before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
129 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1215 AM     TSTM WND GST     SHELL ARMY FIELD        31.37N 85.85W
04/20/2020  M48 MPH          COFFEE             AL   AWOS

            AWOS STATION KSXS IN FT RUCKER REPORTED 48
            MPH GUST.

&&

DH
Local storm report, Apr 20, 12:30 AM CDT, 0 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TALLAHASSEE FL
130 AM EDT MON APR 20 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1226 AM     TSTM WND GST     HANCHEY FIELD           31.35N 85.65W
04/20/2020  M46 MPH          DALE               AL   AWOS

            AWOS STATION KHEY IN FT RUCKER MEASURED A 46
            MPH GUST.

&&

DH

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 19, 10:36 PM CDTSevere Thunderstorm WarningTAEHolmes, Walton84 min
Apr 19, 11:49 PM CDTSevere Thunderstorm WarningTAEHolmes, Jackson, Washington56 min
Apr 19, 11:55 PM CDTTornado WarningTAEHolmes, Jackson20 min
Apr 20, 12:26 AM CDTSevere Thunderstorm WarningTAEJackson, Washington34 min
Apr 20, 12:43 AM CDTSevere Thunderstorm WarningTAEHolmes, Walton, Washington47 min
Apr 20, 12:52 AM CDTSevere Thunderstorm WarningTAEGadsden, Jackson, Leon68 min
Apr 20, 1:24 AM CDTSpecial Marine WarningTAE2 hr
Apr 20, 1:35 AM CDTSevere Thunderstorm WarningTAEBay, Walton, Washington55 min
Apr 20, 2:32 AM CDTSpecial Weather StatementTAEGadsden, Leon, Liberty43 min
Apr 20, 2:33 AM CDTSpecial Marine WarningTAE57 min
Apr 20, 2:54 AM CDTSpecial Weather StatementTAEBay, Gulf, Liberty51 min
Apr 20, 3:05 AM CDTSpecial Marine WarningTAE3 hr
Apr 20, 3:07 AM CDTSpecial Weather StatementTAEWakulla38 min
Apr 20, 3:11 AM CDTSevere Thunderstorm WarningTAEBay, Franklin, Gulf, Liberty82 min
Apr 20, 3:47 AM CDTSevere Thunderstorm WarningTAEFranklin, Liberty, Wakulla43 min
Apr 20, 4:39 AM CDTSpecial Marine WarningTAE3 hr
Apr 20, 4:49 AM CDTSpecial Weather StatementTAESuwannee26 min
Apr 20, 4:52 AM CDTSpecial Weather StatementTAETaylor38 min
Apr 20, 5:13 AM CDTSevere Thunderstorm WarningTAEDixie, Lafayette, Taylor62 min
Apr 20, 5:35 AM CDTSevere Thunderstorm WarningTAEDixie, Taylor85 min
Apr 20, 7:00 AM CDTSevere Thunderstorm WarningTAEDixie15 min
Apr 20, 9:34 AM CDTRiver Flood WarningTAECalhoun, Franklin, Gulf, Liberty13 days

Nearby

Severe Thunderstorm Warnings in Florida, 2020Every severe thunderstorm warning in 2020

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.