Alert archive / Florida / Mesoscale Discussions in 2016

Mesoscale Discussion 21

January 15, 201614 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Jan 15, 2016, 8:53 AM EST for 14 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 15, 2016, 8:53 AM EST (13:53 UTC)
Expired: Jan 15, 2016, 11:00 AM EST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Charlotte County, FL, Citrus County, FL, DeSoto County, FL, Hardee County, FL, Hernando County, FL, Hillsborough County, FL, Lee County, FL, Manatee County, FL, Marion County, FL, Pasco County, FL, Pinellas County, FL, Polk County, FL, Sarasota County, FL, Sumter County, FL

The radar

The Tampa radar (KTBW), 29 km from the middle of the area, began a volume at 13:56 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 3Jan 15, 10:35 AM EST

The nearest sounding before it

Tampa Bay, FL (KTBW), launched 12:00Z, 1.9 hours before the alert went out and 29 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: 918 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 458 m²/s²
0-3 km storm-relative helicity: 518 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

552 
ACUS11 KWNS 151354
SWOMCD
SPC MCD 151353 
FLZ000-151600-

MESOSCALE DISCUSSION 0021
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CST FRI JAN 15 2016

AREAS AFFECTED...THE WESTERN FLORIDA PENINSULA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 151353Z - 151600Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...SCATTERED CONVECTION CONTINUES TO APPROACH THE WESTERN
FLORIDA PENINSULA AT THIS TIME...AND WILL POSE AN ISOLATED WIND
DAMAGE AND TORNADO THREAT.  A WW IS NOT ANTICIPATED FOR THIS
ACTIVITY.

DISCUSSION...A LINE OF CONVECTION IS APPROACHING THE WESTERN FLORIDA
PENINSULA...WITH ADDITIONAL SCATTERED/MORE CELLULAR CONVECTION NOTED
SOUTHWEST OF TBW ATTM.  THE ENVIRONMENT FOSTERING THIS DEVELOPMENT
IS CHARACTERIZED BY MEAGER INSTABILITY...WITH 250-500 J/KG NOTED
NEAR THE COAST AND OFFSHORE AHEAD OF THE CONVECTION /SLIGHTLY WEAKER
INLAND ACROSS CENTRAL FLORIDA.  FORCING FOR ASCENT ASSOCIATED WITH A
VIGOROUS SHORTWAVE OVER COASTAL MISSISSIPPI IS CONTRIBUTING TO
CONTINUED CONVECTIVE DEVELOPMENT THIS DEVELOPMENT THIS MORNING...AND
GIVEN VERY STRONG LOW AND DEEP SHEAR VALUES...AN ISOLATED DAMAGING
WIND GUST OR TORNADO CANNOT BE COMPLETELY RULED OUT.  ROTATION NOTED
IN CELLS SOUTHWEST OF TBW ALSO SUGGESTS AN ISOLATED
WATERSPOUT/TORNADO THREAT OVER THE NEXT COUPLE OF HOURS...AND
PERHAPS A SLIGHTLY GREATER TORNADO THREAT MAY EVOLVE ACROSS THE
SOUTHERN PENINSULA AS BREAKS IN THE CLOUD DECK AND CONTINUED
LOW-LEVEL ADVECTION RESULTS IN GRADUALLY INCREASING SURFACE-BASED
INSTABILITY. 

CONVECTIVE TRENDS CONTINUE TO BE MONITORED...ALTHOUGH A WW ISSUANCE
APPEARS UNLIKELY AT THIS POINT.

..COOK/THOMPSON.. 01/15/2016

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

ATTN...WFO...MFL...MLB...TBW...JAX...

LAT...LON   26148222 26498245 27518295 28398289 29238276 29538265
            29538230 29038190 27878161 26848159 26338159 26098176
            26038194 26148222

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 15, 6:17 AM EST	Mesoscale Discussion	SPC	Dixie, Taylor, Wakulla	88 min
Jan 15, 10:12 AM EST	Mesoscale Discussion	SPC	Broward, Charlotte, Collier, Glades, Hendry, Lee and 3 more	2 hr
Jan 15, 10:35 AM EST	Tornado Watch	SPC	Broward, Charlotte, Collier, DeSoto, Glades, Hendry and 8 more	6 hr

Nearby

Mesoscale Discussions in Florida, 2016 Every mesoscale discussion in 2016

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.