Alert archive / Florida / Mesoscale Discussions in 2009

Mesoscale Discussion 2140

October 27, 200913 counties in Florida; 5 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Oct 27, 2009, 7:32 AM CDT for 13 counties in Florida; 5 counties in Georgia. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Oct 27, 2009, 7:32 AM CDT (12:32 UTC)
Expired: Oct 27, 2009, 9:00 AM CDT
In force: 88 min
Issued by: the Storm Prediction Center

Counties Bay County, FL, Calhoun County, FL, Franklin County, FL, Gadsden County, FL, Gulf County, FL, Jackson County, FL, Jefferson County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Wakulla County, FL, Walton County, FL, Washington County, FL, Brooks County, GA, Decatur County, GA, Grady County, GA, Seminole County, GA, Thomas County, GA

The radar

The Tallahassee radar (KTLH), 73 km from the middle of the area, began a volume at 12:35 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 776Oct 27, 8:10 AM CDT

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 0.5 hours before the alert went out and 325 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: 1086 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 451 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 189 m²/s²
0-3 km storm-relative helicity: 255 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.3

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 27, 8:14 AM CDT	Tornado Watch	SPC	Bay, Calhoun, Dixie, Franklin, Gadsden, Gulf and 13 more	8 hr
Oct 27, 10:24 AM CDT	Mesoscale Discussion	SPC	Bay, Calhoun, Gadsden, Gulf, Jackson, Jefferson and 5 more	2 hr
Oct 27, 1:57 PM CDT	Mesoscale Discussion	SPC	Jefferson, Leon, Madison, Wakulla	2 hr
Oct 27, 3:43 PM CDT	Mesoscale Discussion	SPC	Baker, Columbia, Dixie, Hamilton, Lafayette, Madison and 4 more	92 min
Oct 27, 2:43 PM CDT	Mesoscale Discussion	SPC	Bryan, Chatham, Liberty	2 hr
Oct 27, 5:56 PM CDT	Mesoscale Discussion	SPC	Chatham, Effingham	94 min
Oct 27, 6:08 PM CDT	Tornado Watch	SPC	Bryan, Chatham, Effingham	3 hr

Nearby

Mesoscale Discussions in Florida, 2009 Mesoscale Discussions in Georgia, 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.