Alert archive / Florida / Mesoscale Discussions in 2011

Mesoscale Discussion 2263

October 18, 201115 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Oct 18, 2011, 8:39 PM EDT for 15 counties in Florida. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Oct 18, 2011, 8:39 PM EDT (00:39 UTC)
Expired: Oct 18, 2011, 9:45 PM EDT
In force: 66 min
Issued by: the Storm Prediction Center

Counties Broward County, FL, Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Highlands County, FL, Lee County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Okeechobee County, FL, Palm Beach County, FL, Saint Lucie County, FL

The radar

The Miami radar (KAMX), 113 km from the middle of the area, began a volume at 00:40 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 868Oct 18, 9:55 PM EDT

The nearest sounding before it

Miami, FL (KMFL), launched 00:00Z, 0.7 hours before the alert went out and 108 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: 3389 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 454 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 351 m²/s²
0-3 km storm-relative helicity: 417 m²/s²
Significant tornado parameter: 7.8
Supercell composite: 32.0

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
Oct 18, 9:54 PM EDT	Tornado Watch	SPC	Broward, Charlotte, Collier, Glades, Hendry, Highlands and 8 more	6 hr
Oct 19, 12:25 AM EDT	Mesoscale Discussion	SPC	Broward, Collier, Glades, Hendry, Martin, Miami-Dade and 2 more	95 min

Nearby

Mesoscale Discussions in Florida, 2011 Every mesoscale discussion in 2011

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.