Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 2154

December 11, 201211 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Dec 11, 2012, 4:55 PM EST for 11 counties in Florida. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: Dec 11, 2012, 4:55 PM EST (21:55 UTC)
Expired: Dec 11, 2012, 6:30 PM EST
In force: 95 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Broward County, FL, DeSoto County, FL, Glades County, FL, Hendry County, FL, Highlands County, FL, Indian River County, FL, Martin County, FL, Okeechobee County, FL, Osceola County, FL, Palm Beach County, FL, Saint Lucie County, FL

The nearest sounding before it

Miami, FL (KMFL), launched 12:00Z, 9.9 hours before the alert went out and 139 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: 1813 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 537 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 124 m²/s²
Significant tornado parameter: 1.0
Supercell composite: 5.3

Open this sounding in Storm Lab

The text

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

423 
ACUS11 KWNS 112155
SWOMCD
SPC MCD 112155 
FLZ000-112330-

MESOSCALE DISCUSSION 2154
NWS STORM PREDICTION CENTER NORMAN OK
0355 PM CST TUE DEC 11 2012

AREAS AFFECTED...SRN/CNTRL FL PENINSULA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 112155Z - 112330Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THREAT FOR ISOLATED DAMAGING WIND GUSTS AND PERHAPS LARGE
HAIL WILL EXIST OVER PORTIONS OF THE SRN/CNTRL FL PENINSULA THIS
EVENING. IT IS UNCERTAIN WHETHER STORM COVERAGE WILL WARRANT A
WW...BUT TRENDS WILL CONTINUE TO BE MONITORED.

DISCUSSION...MESOANALYSIS AT 21-22Z SHOWS THAT TEMPERATURES NEAR 80F
AND DEWPOINTS IN THE LOW 70S ARE FOCUSING A LOW-LEVEL THETA-E AXIS
FROM FAR SRN FL INTO THE E-CNTRL PENINSULA. THIS WARM/MOIST BOUNDARY
LAYER COMBINED WITH MIDLEVEL TEMPERATURES NEAR 8C IS AIDING IN
SBCAPE VALUES RANGING FROM 1500-3500 J/KG. THOUGH LARGE-SCALE AND
MESOSCALE FORCING FOR ASCENT APPEARS TO BE WEAK...A CONFLUENT
SURFACE FLOW REGIME AND MODEST BOUNDARY LAYER DESTABILIZATION IS
YIELDING ISOLATED THUNDERSTORM DEVELOPMENT FROM HIGHLANDS COUNTY
E-SEWD TO THE ATLANTIC COAST. MOST LIKELY SCENARIO IS FOR STORMS TO
REMAIN ISOLATED DURING THE EVENING...WHICH MAY PRECLUDE THE NEED FOR
A WW. HOWEVER...TBW VWP SHOWS 35 KT OF 0-6 KM BULK SHEAR...WHICH IS
SUFFICIENT FOR STRONG/SVR MULTICELL THUNDERSTORMS POSING A THREAT
FOR ISOLATED DAMAGING WIND GUSTS AND PERHAPS LARGE HAIL.

..GARNER/HART.. 12/11/2012

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

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

LAT...LON   25908064 26198162 27318184 28248143 28218062 26608001
            25908064

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 10, 7:51 PM EST	Mesoscale Discussion	SPC	Osceola, Polk	84 min
Dec 10, 11:34 PM EST	Mesoscale Discussion	SPC	Collier	86 min

Nearby

Mesoscale Discussions in Florida, 2012 Every mesoscale discussion in 2012

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.