Alert archive / Florida / Mesoscale Discussions in 2009

Mesoscale Discussion 474

April 13, 20099 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 13, 2009, 10:35 PM EDT for 9 counties in Florida. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: Apr 13, 2009, 10:35 PM EDT (02:35 UTC)
Expired: Apr 14, 2009, 12:00 AM EDT
In force: 85 min
Issued by: the Storm Prediction Center

Counties Citrus County, FL, Flagler County, FL, Franklin County, FL, Hernando County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Putnam County, FL, Sumter County, FL

The radar

The Tallahassee radar (KTLH), 142 km from the middle of the area, began a volume at 02:39 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

Jacksonville, FL (KJAX), launched 00:00Z, 2.6 hours before the alert went out and 231 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: 611 J/kg
Mixed-layer CIN: -29 J/kg
Mixed-layer LCL: 616 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 136 m²/s²
0-3 km storm-relative helicity: 280 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 7.2

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 14, 3:47 AM EDT	Mesoscale Discussion	SPC	Citrus, Hernando, Levy, Pasco, Sumter	88 min
Apr 14, 6:15 AM EDT	Tornado Watch	SPC	Brevard, Citrus, Flagler, Hardee, Hernando, Hillsborough and 14 more	6 hr
Apr 14, 7:36 AM EDT	Mesoscale Discussion	SPC	Citrus, Hernando, Hillsborough, Lake, Levy, Manatee and 10 more	54 min
Apr 14, 8:47 AM EDT	Mesoscale Discussion	SPC	Brevard, Citrus, Flagler, Hernando, Hillsborough, Lake and 10 more	88 min
Apr 14, 11:52 AM EDT	Mesoscale Discussion	SPC	Charlotte, DeSoto, Glades, Hardee, Hendry, Highlands and 6 more	53 min

Nearby

Mesoscale Discussions in Florida, 2009 Every mesoscale discussion in 2009

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.