Alert archive / Florida / Mesoscale Discussions in 2011

Mesoscale Discussion 2155

September 10, 201125 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Sep 10, 2011, 5:53 PM EDT for 25 counties in Florida. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Sep 10, 2011, 5:53 PM EDT (21:53 UTC)
Expired: Sep 10, 2011, 7:30 PM EDT
In force: 97 min
Issued by: the Storm Prediction Center

All 25 counties

Brevard County, FL, Broward County, FL, Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Hendry County, FL, Highlands County, FL, Hillsborough County, FL, Indian River County, FL, Lake County, FL, Marion County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Okeechobee County, FL, Orange County, FL, Osceola County, FL, Palm Beach County, FL, Polk County, FL, Saint Lucie County, FL, Seminole County, FL, Sumter County, FL, Volusia County, FL

The radar

The Melbourne radar (KMLB), 90 km from the middle of the area, began a volume at 21:53 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

Tampa Bay, FL (KTBW), launched 12:00Z, 9.9 hours before the alert went out and 109 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: 512 J/kg
Mixed-layer CIN: -89 J/kg
Mixed-layer LCL: 951 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 90 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

690 
ACUS11 KWNS 102154
SWOMCD
SPC MCD 102153
FLZ000-102330-

MESOSCALE DISCUSSION 2155
NWS STORM PREDICTION CENTER NORMAN OK
0453 PM CDT SAT SEP 10 2011

AREAS AFFECTED...CNTRL/SOUTH FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 102153Z - 102330Z

A FEW THUNDERSTORMS COULD PRODUCE GUSTY WINDS INTO THE EARLY EVENING
HOURS. A WW IS NOT NEEDED.

LATE AFTERNOON SFC MESOANALYSIS REVEALS A FEW FEATURES OVER PARTS OF
CNTRL/SOUTH FL THAT WILL CONTINUE TO FOCUS CONVECTION INTO THE EARLY
EVENING HOURS:

1. THE BAROCLINIC CIRCULATION IN ASSOCIATION WITH A REMNANT/STALLED
FRONTAL ZONE -- MARKING A PRONOUNCED SFC DEWPOINT GRADIENT -- DRAPED
FROM NEAR DAYTONA BEACH TO SW OF OCALA...
2. A SUBTLE CONFLUENCE AXIS LYING FROM NEAR MELBOURNE TO SARASOTA
AND FARTHER SW INTO THE OFFSHORE WATERS OF THE ERN GULF...EVIDENT IN
THE MOTION OF CLOUD ELEMENTS PER RECENT VISIBLE SATELLITE IMAGES...
3. THE EAST COAST SEA BREEZE BOUNDARY /AROUND 1.5-KM DEEP PER MIAMI
VWP DATA/ EXTENDING FROM NEAR MELBOURNE TO THE ERN PARTS OF LAKE
OKEECHOBEE TO WELL WSW OF MIAMI...AND
4. THE WEST COAST SEA BREEZE BOUNDARY EXTENDING FROM ENE OF SARASOTA
TO ENE OF FORT MYERS TO WELL WSW OF MIAMI.

AS THE WEST AND EAST COAST SEA BREEZE BOUNDARIES CONTINUE
PROPAGATING INLAND...THE MAINTENANCE OF SFC CONVERGENCE AMIDST
MLCAPE VALUES OF 1500-2500 J/KG WILL PROMOTE REGENERATIVE CONVECTION
OVER PRIMARILY INTERIOR SECTIONS OF THE CNTRL/SRN FL PENINSULA.
CONVERGENCE WILL BE AUGMENTED INVOF THE CONFLUENCE AXIS...WHERE
CONVECTIVE ACTIVITY MAY BE LOCALLY ENHANCED. HOWEVER...WITH ONLY 11
KT OF 0-6-KM SHEAR PER MIAMI VWP...PULSE CONVECTION WILL BE THE
PREDOMINATE MODE. MODESTLY INCREASED DEEP-LAYER SHEAR INVOF THE
REMNANT FRONT COULD PROMOTE MULTICELLULAR CONVECTION FARTHER NORTH
IN CNTRL FL. WITH PW VALUES OF 1.90-2.25 INCHES PER GPS
DATA...WATER-LOADING PROCESSES COULD SUPPORT GUSTY OUTFLOW WINDS AS
STORMS COLLAPSE. HOWEVER...THE ABSENCE OF STRONGER VERTICAL WIND
SHEAR WILL LIMIT THE OVERALL CONVECTIVE ORGANIZATION. STORMS SHOULD
BEGIN WEAKENING BY 00Z AS DIABATIC COOLING COMMENCES.

..COHEN.. 09/10/2011

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

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

LAT...LON   29328112 27758039 26048008 25298040 25298110 26608192
            27628243 28848254 29378199 29328112

Nearby

Mesoscale Discussions in Florida, 2011 Every mesoscale discussion in 2011

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.