Alert archive / Florida / Mesoscale Discussions in 2015

Mesoscale Discussion 101

February 25, 201512 counties in Florida; 4 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Feb 25, 2015, 7:29 PM CST for 12 counties in Florida; 4 counties in Georgia. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Feb 25, 2015, 7:29 PM CST (01:29 UTC)
Expired: Feb 25, 2015, 9:00 PM CST
In force: 91 min
Issued by: the Storm Prediction Center

Counties Calhoun County, FL, Dixie County, FL, Gadsden County, FL, Hamilton County, FL, Jefferson County, FL, Lafayette County, FL, Leon County, FL, Liberty County, FL, Madison County, FL, Suwannee County, FL, Taylor County, FL, Wakulla County, FL, Brooks County, GA, Grady County, GA, Lowndes County, GA, Thomas County, GA

The radar

The Tallahassee radar (KTLH), 33 km from the middle of the area, began a volume at 01:32 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

Tallahassee Rgnl, FL (KTLH), launched 00:00Z, 1.5 hours before the alert went out and 30 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 483 m above ground
0-6 km bulk shear: 84 kt
0-1 km storm-relative helicity: 862 m²/s²
0-3 km storm-relative helicity: 966 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.3

Open this sounding in Storm Lab

The text

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

075 
ACUS11 KWNS 260130
SWOMCD
SPC MCD 260129 
FLZ000-GAZ000-260300-

MESOSCALE DISCUSSION 0101
NWS STORM PREDICTION CENTER NORMAN OK
0729 PM CST WED FEB 25 2015

AREAS AFFECTED...CENTRAL/EASTERN FL PANHANDLE AND SOUTHWEST GA

CONCERNING...TORNADO WATCH 4...

VALID 260129Z - 260300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 4 CONTINUES.

SUMMARY...TORNADO WATCH 4 CONTINUES UNTIL 05Z. THE POTENTIAL FOR
LOCALLY DAMAGING WIND GUSTS AND/OR A TORNADO OR TWO ARE EXPECTED TO
MODESTLY INCREASE/DEVELOP EAST-NORTHEASTWARD OVER THE NEXT COUPLE OF
HOURS /THROUGH 03-04Z OR 10-11 PM EST/ ACROSS THE EASTERN HALF OF
THE FL PANHANDLE/FAR SOUTHWEST GA.

DISCUSSION...A MODESTLY MOIST MARITIME AIR MASS CONTINUES TO
GRADUALLY MOVE INLAND ACROSS THE FL PANHANDLE EARLY THIS EVENING IN
ADVANCE OF A DEEPENING/NORTHEASTWARD-MOVING SURFACE LOW /999 MB/
THAT IS LOCATED NEAR TALLAHASSEE FL AS OF 01Z. LOWER/SOME MIDDLE 60S
F SURFACE DEWPOINTS HAVE NOW MOVED INLAND ACROSS THE EASTERN PART OF
THE FL PANHANDLE...AND THIS SAME GENERAL NORTH-NORTHEASTWARD
MOISTURE FLUX WILL CONTINUE OVER THE NEXT FEW HOURS ACROSS
ADDITIONAL PARTS OF NORTH FL/FAR SOUTHERN GA.

AS THE UPSTREAM SHORTWAVE TROUGH CURRENTLY OVER THE MID-SOUTH
CONTINUES TO QUICKLY APPROACH THE REGION...VERTICAL SHEAR IS AND
WILL REMAIN QUITE STRONG. THE 00Z OBSERVED SOUNDING FROM TALLAHASSEE
AND LATEST WSR-88D VWP DATA FROM KTLH SHOWS A LONG/CURVING LOW-LEVEL
HODOGRAPH WITH EXTREME /500+ M2 PER S2/ 0-1 KM SRH AND AROUND 80 KT
OF EFFECTIVE SHEAR. THAT SAID...THE RELATIVE MARGINALITY/NARROWNESS
OF THE INLAND MOISTURE FLUX THIS EVENING...AND RELATED WEAK BUOYANCY
WITHIN A MODEST MID-LEVEL LAPSE RATE ENVIRONMENT...IS LIKELY TO BE
AN OVERALL LIMITING FACTOR FOR A MORE CERTAIN/WIDESPREAD SEVERE
RISK. NONETHELESS...THE SCENARIO SHOULD SUPPORT A COMBINATION OF
INCREASINGLY ORGANIZED/PREVALENT SMALL-SCALE BOWS IN ADDITION TO
FAST-MOVING/TRANSIENT SUPERCELLS. LOCALLY DAMAGING WINDS AND A BRIEF
TORNADO OR TWO ARE POSSIBLE.

..GUYER.. 02/26/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAX...TAE...

LAT...LON   31018434 31078359 30528269 29688302 29378340 29808492
            30258564 31018434

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 25, 9:48 PM CST	Mesoscale Discussion	SPC	Baker, Columbia, Hamilton, Lafayette, Madison, Nassau and 2 more	87 min
Feb 26, 1:14 AM CST	Mesoscale Discussion	SPC	Alachua, Bradford, Citrus, Clay, Hernando, Hillsborough and 8 more	91 min

Nearby

Mesoscale Discussions in Florida, 2015 Mesoscale Discussions in Georgia, 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.