Alert archive / Florida / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 11, NWS Melbourne, FL

April 20, 2021Orange County, Seminole County, Florida

NWS Melbourne, FL issued this severe thunderstorm warning at Apr 20, 2021, 7:46 AM EDT for Orange County, Seminole County, Florida. It was in force for 29 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Apr 20, 2021, 7:46 AM EDT (11:46 UTC)
Expired: Apr 20, 2021, 8:15 AM EDT
In force: 29 min
Issued by: NWS Melbourne, FL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Orange County, FL, Seminole County, FL

The radar

The Melbourne radar (KMLB), 73 km from the middle of the area, began a volume at 11:49 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.

What was reported inside it

Time	Report	Where	Remark
Apr 20, 7:52 AM EDT	HAIL 0.75	2 E Azalea Park, FL	SEVERAL REPORTS OF HAIL OF DIME TO PENNY SIZE WERE REPORTED IN THE ORLANDO AREA NEAR UNION PARK BY PUBLIC AND BROADCAST MEDIA.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Cape Canaveral, FL (KXMR), launched 00:00Z, 11.8 hours before the alert went out and 61 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 103 J/kg
Mixed-layer CIN: -138 J/kg
Mixed-layer LCL: 956 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 5 m²/s²
0-3 km storm-relative helicity: 49 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

789 
WUUS52 KMLB 201146
SVRMLB
FLC095-117-201215-
/O.NEW.KMLB.SV.W.0011.210420T1146Z-210420T1215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Melbourne FL
746 AM EDT Tue Apr 20 2021

The National Weather Service in Melbourne has issued a

* Severe Thunderstorm Warning for...
  Southeastern Seminole County in east central Florida...
  Central Orange County in east central Florida...

* Until 815 AM EDT.

* At 746 AM EDT, a severe thunderstorm was located over Orlando
  Executive Airport, or over Azalea Park, moving northeast at 30 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Orlando, Oviedo, Winter Springs, Winter Park and Casselberry. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2879 8118 2878 8118 2878 8117 2864 8100
      2863 8099 2862 8099 2862 8098 2861 8098
      2861 8097 2858 8094 2858 8095 2844 8131
      2853 8144
TIME...MOT...LOC 1146Z 230DEG 26KT 2853 8133 

HAIL...1.00IN
WIND...60MPH
 
$$

Combs

2 follow-up statements

590 
WWUS52 KMLB 201154
SVSMLB

Severe Weather Statement
National Weather Service Melbourne FL
754 AM EDT Tue Apr 20 2021

FLC095-117-201215-
/O.CON.KMLB.SV.W.0011.000000T0000Z-210420T1215Z/
Seminole FL-Orange FL-
754 AM EDT Tue Apr 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 AM EDT
FOR SOUTHEASTERN SEMINOLE AND CENTRAL ORANGE COUNTIES...

At 754 AM EDT, a severe thunderstorm was located over Union Park, or
near University Of Central Florida, moving northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Orlando, Oviedo, Winter Springs, Winter Park and Casselberry. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2879 8118 2878 8118 2878 8117 2864 8100
      2863 8099 2862 8099 2862 8098 2861 8098
      2861 8097 2858 8094 2858 8095 2848 8124
      2858 8136
TIME...MOT...LOC 1154Z 234DEG 31KT 2857 8124 

HAIL...1.00IN
WIND...60MPH
 
$$

Combs

689 
WWUS52 KMLB 201207
SVSMLB

Severe Weather Statement
National Weather Service Melbourne FL
807 AM EDT Tue Apr 20 2021

FLC095-117-201215-
/O.CON.KMLB.SV.W.0011.000000T0000Z-210420T1215Z/
Seminole FL-Orange FL-
807 AM EDT Tue Apr 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 AM EDT
FOR SOUTHEASTERN SEMINOLE AND EAST CENTRAL ORANGE COUNTIES...

At 806 AM EDT, a severe thunderstorm was located over Chuluota,
moving northeast at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
Oviedo, Bithlo, University Of Central Florida, Chuluota and Geneva. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 2864 8100 2863 8099 2862 8099 2862 8098
      2861 8097 2852 8116 2861 8125 2875 8113
TIME...MOT...LOC 1206Z 234DEG 31KT 2864 8112 

HAIL...1.00IN
WIND...60MPH
 
$$

Combs

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 7:41 AM EDT	Special Weather Statement	MLB	Orange	34 min
Apr 20, 7:58 AM EDT	Special Weather Statement	MLB	Lake	32 min
Apr 20, 8:13 AM EDT	Special Weather Statement	MLB	Seminole	32 min
Apr 20, 8:22 AM EDT	Special Weather Statement	MLB	Orange	23 min
Apr 20, 8:26 AM EDT	Special Marine Warning	MLB		49 min
Apr 20, 8:48 AM EDT	Special Weather Statement	MLB	Seminole	27 min
Apr 20, 9:08 AM EDT	Special Weather Statement	MLB	Brevard	52 min
Apr 20, 9:26 AM EDT	Special Marine Warning	MLB		64 min
Apr 20, 11:09 AM EDT	Special Weather Statement	MLB	Okeechobee	36 min
Apr 20, 11:47 AM EDT	Special Weather Statement	MLB	Indian River	43 min
Apr 20, 12:28 PM EDT	Special Marine Warning	MLB		3 hr
Apr 20, 1:35 PM EDT	Areal Flood Advisory	MLB	Orange, Osceola	3 hr
Apr 20, 2:00 PM EDT	Special Marine Warning	MLB		3 hr
Apr 20, 2:10 PM EDT	Areal Flood Advisory	MLB	Brevard, Orange	3 hr
Apr 20, 2:14 PM EDT	Special Weather Statement	MLB	Osceola	46 min
Apr 20, 2:53 PM EDT	Special Weather Statement	MLB	Brevard, Osceola	37 min
Apr 20, 4:26 PM EDT	Special Weather Statement	MLB	Osceola	49 min
Apr 20, 4:44 PM EDT	Special Weather Statement	MLB	Indian River	46 min

Nearby

Severe Thunderstorm Warnings in Florida, 2021 Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.