Alert archive / Florida / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 9, NWS Melbourne, FL

April 20, 2015Okeechobee County, Saint Lucie County, Florida

NWS Melbourne, FL issued this severe thunderstorm warning at Apr 20, 2015, 1:06 PM EDT for Okeechobee County, Saint Lucie County, Florida. It was in force for 39 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, 2015, 1:06 PM EDT (17:06 UTC)
Expired: Apr 20, 2015, 1:45 PM EDT
In force: 39 min
Issued by: NWS Melbourne, FL
Area: Storm-based polygon

Counties Okeechobee County, FL, Saint Lucie County, FL

The radar

The Melbourne radar (KMLB), 91 km from the middle of the area, began a volume at 17:08 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 watch it was issued in

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

Issued	Product	Office	Lasted
Apr 20, 1:03 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Cape Canaveral, FL (KXMR), launched 12:00Z, 5.1 hours before the alert went out and 133 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: 841 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 1041 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 16 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

365 
WUUS52 KMLB 201706
SVRMLB
FLC093-111-201745-
/O.NEW.KMLB.SV.W.0009.150420T1706Z-150420T1745Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MELBOURNE FL
106 PM EDT MON APR 20 2015

THE NATIONAL WEATHER SERVICE IN MELBOURNE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WESTERN ST. LUCIE COUNTY IN EAST CENTRAL FLORIDA...
  SOUTHEASTERN OKEECHOBEE COUNTY IN EAST CENTRAL FLORIDA...

* UNTIL 145 PM EDT

* AT 105 PM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM
  CAPABLE OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN EXCESS
  OF 60 MPH. THIS STORM WAS LOCATED OVER FOUR SEASONS ESTATES...OR
  NEAR TREASURE ISLAND...AND MOVING NORTHEAST AT 35 MPH.

* LOCATIONS IMPACTED INCLUDE...
  TREASURE ISLAND...OKEECHOBEE...TAYLOR CREEK...FOUR SEASONS ESTATES
  AND COUNTRY HILLS ESTATES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...DESTRUCTIVE HAIL...
DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR YOUR PROTECTION...MOVE TO
AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY
RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER
COVERS THE ROAD.

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
ALTHOUGH A TORNADO IS NOT IMMEDIATELY LIKELY...IF ONE IS SPOTTED...
ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY STRUCTURE...
SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...EXCESSIVE CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY. LIGHTNING IS ONE OF NATURES LEADING KILLERS. REMEMBER...
IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY
LIGHTNING.

&&

LAT...LON 2721 8079 2721 8081 2730 8090 2755 8059
      2739 8038 2718 8074
TIME...MOT...LOC 1705Z 232DEG 31KT 2728 8077 

$$

KELLY

2 follow-up statements

535 
WWUS52 KMLB 201731
SVSMLB

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MELBOURNE FL
131 PM EDT MON APR 20 2015

FLC093-111-201745-
/O.CON.KMLB.SV.W.0009.000000T0000Z-150420T1745Z/
ST. LUCIE FL-OKEECHOBEE FL-
131 PM EDT MON APR 20 2015

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 145 PM EDT
FOR WESTERN ST. LUCIE AND EAST CENTRAL OKEECHOBEE COUNTIES...

AT 131 PM EDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE
OF PRODUCING QUARTER SIZE HAIL AND DAMAGING WINDS IN EXCESS OF 60
MPH. THIS STORM WAS LOCATED 7 MILES NORTHEAST OF FOUR SEASONS
ESTATES...OR 9 MILES NORTHEAST OF TREASURE ISLAND...MOVING NORTHEAST
AT 30 MPH.

THIS SEVERE THUNDERSTORM WILL REMAIN OVER MAINLY RURAL AREAS OF
WESTERN ST. LUCIE AND EAST CENTRAL OKEECHOBEE COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WINDS...DESTRUCTIVE HAIL...
DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR YOUR PROTECTION MOVE TO AN
INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR HOME OR BUSINESS. HEAVY
RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE INTO AREAS WHERE WATER
COVERS THE ROAD.

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
ALTHOUGH A TORNADO IS NOT IMMEDIATELY LIKELY...IF ONE IS SPOTTED...
ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY STRUCTURE...
SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

IF YOU ARE IN THE PATH OF THIS STORM...PREPARE IMMEDIATELY FOR LARGE
HAIL AND DAMAGING WINDS. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING AND AWAY FROM WINDOWS.

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...FREQUENT CLOUD TO 
GROUND LIGHTNING IS OCCURRING WITH THIS STORM.  MOVE INDOORS 
IMMEDIATELY. LIGHTNING IS ONE OF NATURES LEADING KILLERS. 
REMEMBER... IF YOU CAN HEAR THUNDER...YOU ARE CLOSE ENOUGH TO BE 
STRUCK BY LIGHTNING.

&&

LAT...LON 2723 8074 2731 8080 2755 8059 2739 8038
      2721 8069
TIME...MOT...LOC 1731Z 237DEG 25KT 2730 8066 

$$

KELLY

974 
WWUS52 KMLB 201744
SVSMLB

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MELBOURNE FL
144 PM EDT MON APR 20 2015

FLC093-111-201754-
/O.EXP.KMLB.SV.W.0009.000000T0000Z-150420T1745Z/
ST. LUCIE FL-OKEECHOBEE FL-
144 PM EDT MON APR 20 2015

...THE SEVERE THUNDERSTORM WARNING FOR WESTERN ST. LUCIE AND EAST
CENTRAL OKEECHOBEE COUNTIES WILL EXPIRE AT 145 PM EDT...
                
THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.
THEREFORE THE WARNING WILL BE ALLOWED TO EXPIRE. HOWEVER GUSTY WINDS
AND HEAVY RAIN ARE STILL POSSIBLE WITH THIS THUNDERSTORM.

LAT...LON 2723 8074 2731 8080 2755 8059 2739 8038
      2721 8069
TIME...MOT...LOC 1741Z 232DEG 31KT 2730 8066 

$$

KELLY

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 12:27 PM EDT	Special Weather Statement	MLB	Saint Lucie	48 min
Apr 20, 12:42 PM EDT	Special Weather Statement	MLB	Saint Lucie	63 min
Apr 20, 12:47 PM EDT	Special Marine Warning	MLB		58 min
Apr 20, 1:22 PM EDT	Special Marine Warning	MLB		83 min
Apr 20, 1:47 PM EDT	Special Weather Statement	MLB	Saint Lucie	58 min
Apr 20, 1:58 PM EDT	Special Weather Statement	MLB	Orange	62 min
Apr 20, 2:11 PM EDT	Areal Flood Advisory	MLB	Okeechobee	2 hr
Apr 20, 2:44 PM EDT	Special Marine Warning	MLB		91 min
Apr 20, 2:48 PM EDT	Special Marine Warning	MLB		57 min
Apr 20, 2:50 PM EDT	Special Weather Statement	MLB	Indian River, Martin, Okeechobee, Saint Lucie	55 min
Apr 20, 2:58 PM EDT	Special Weather Statement	MLB	Lake	62 min
Apr 20, 3:00 PM EDT	Special Weather Statement	MLB	Seminole	60 min
Apr 20, 3:06 PM EDT	Severe Thunderstorm Warning	MLB	Brevard	39 min
Apr 20, 3:10 PM EDT	Severe Thunderstorm Warning	MLB	Lake, Orange, Seminole	41 min
Apr 20, 3:14 PM EDT	Special Weather Statement	MLB	Osceola	31 min
Apr 20, 3:32 PM EDT	Special Weather Statement	MLB	Orange	43 min
Apr 20, 3:34 PM EDT	Special Weather Statement	MLB	Lake	56 min
Apr 20, 3:42 PM EDT	Special Weather Statement	MLB	Okeechobee	33 min
Apr 20, 3:59 PM EDT	Special Weather Statement	MLB	Brevard	46 min
Apr 20, 4:17 PM EDT	Special Marine Warning	MLB		58 min
Apr 20, 4:42 PM EDT	Special Weather Statement	MLB	Indian River	48 min

Nearby

Severe Thunderstorm Warnings in Florida, 2015 Every severe thunderstorm warning in 2015

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.