Alert archive / Florida / Mesoscale Discussions in 2015

Mesoscale Discussion 401

April 20, 201513 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2015, 4:29 PM EDT for 13 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 20, 2015, 4:29 PM EDT (20:29 UTC)
Expired: Apr 20, 2015, 6:30 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Brevard County, FL, Broward County, FL, Indian River County, FL, Lake County, FL, Martin County, FL, Miami-Dade County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Palm Beach County, FL, Saint Lucie County, FL, Seminole County, FL, Volusia County, FL

The radar

The Melbourne radar (KMLB), 118 km from the middle of the area, began a volume at 20:29 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

Cape Canaveral, FL (KXMR), launched 12:00Z, 8.5 hours before the alert went out and 156 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.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 20, 8:35 AM EDT	Mesoscale Discussion	SPC	Alachua, Baker, Bay, Bradford, Calhoun, Columbia and 16 more	2 hr
Apr 20, 11:04 AM EDT	Severe Thunderstorm Watch	SPC	Alachua, Baker, Bradford, Citrus, Clay, Columbia and 22 more	8 hr
Apr 20, 12:13 PM EDT	Mesoscale Discussion	SPC	Brevard, Broward, Indian River, Lake, Martin, Okeechobee and 7 more	2 hr
Apr 20, 1:03 PM EDT	Severe Thunderstorm Watch	SPC	Brevard, Broward, Indian River, Lake, Martin, Miami-Dade and 7 more	6 hr
Apr 20, 2:44 PM EDT	Mesoscale Discussion	SPC	Alachua, Bradford, Citrus, Clay, Duval, Flagler and 12 more	91 min
Apr 20, 5:24 PM EDT	Mesoscale Discussion	SPC	Broward, Hillsborough, Indian River, Manatee, Martin, Okeechobee and 4 more	96 min

Nearby

Mesoscale Discussions in Florida, 2015 Every mesoscale discussion 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.