Alert archive / Florida / Mesoscale Discussions in 2016

Mesoscale Discussion 111

February 16, 201611 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Feb 16, 2016, 1:54 AM EST for 11 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Feb 16, 2016, 1:54 AM EST (06:54 UTC)
Expired: Feb 16, 2016, 4:00 AM EST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Charlotte County, FL, DeSoto County, FL, Glades County, FL, Hardee County, FL, Highlands County, FL, Hillsborough County, FL, Lee County, FL, Manatee County, FL, Pinellas County, FL, Polk County, FL, Sarasota County, FL

The radar

The Tampa radar (KTBW), 55 km from the middle of the area, began a volume at 06:56 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 17Feb 16, 2:15 AM EST

The nearest sounding before it

Tampa Bay, FL (KTBW), launched 00:00Z, 6.9 hours before the alert went out and 55 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: 366 J/kg
Mixed-layer CIN: -8 J/kg
Mixed-layer LCL: 934 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 143 m²/s²
0-3 km storm-relative helicity: 203 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.2

Open this sounding in Storm Lab

The text

As transmitted.

308 
ACUS11 KWNS 160654
SWOMCD
SPC MCD 160654 
FLZ000-160900-

MESOSCALE DISCUSSION 0111
NWS STORM PREDICTION CENTER NORMAN OK
1254 AM CST TUE FEB 16 2016

AREAS AFFECTED...PORTIONS CENTRAL/SRN FL PENINSULA.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 160654Z - 160900Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...BAND OF TSTMS WILL MOVE ASHORE WRN FL PENINSULA WITHIN
NEXT FEW HOURS...OFFERING POTENTIAL FOR A FEW STG-SVR GUSTS...AND
PERHAPS A TORNADO OR TWO.  WW MAY BE REQUIRED SOON.

DISCUSSION...0650Z COMPOSITE REFLECTIVITY IMAGERY AND AVAILABLE SFC
DATA INDICATE TWO PRIMARY AREAS OF PRE-FRONTAL/LOW-LEVEL LIFT
SUPPORTING ORGANIZED CONVECTION:  
1. SERN GA SWWD ACROSS CTY AREA TO ABOUT 80 WNW PIE AND
2. OVER GULF...ROUGHLY 40 WSW PIE TO ABOUT 175 WSW FMY.

PRECIP INFLUENCES FROM GULF CONVECTION SHOULD CONTINUE TO STABILIZE
INFLOW REGION OF SRN PORTION OF FIRST BAND...CONSIDERABLY
SUPPRESSING SVR POTENTIAL N OF TBW REGION.  HOWEVER...SECOND/SRN
BAND WILL PROCEED EWD 30-35 KT...MOVING ASHORE FIRST AROUND TBW
REGION THEN FARTHER S ALONG W COAST TOWARD SRQ AND FMY.  00Z TBW
RAOB CONTAINED SOME STABLE LAYERS ALOFT STRONGLY LIMITING
BUOYANCY...HOWEVER COMBINATION OF LOW-LEVEL MOISTENING SINCE THEN
AND SOME STEEPENING OF MIDLEVEL LAPSE RATES HAS INCREASED BUOYANCY
OVER LAND.  ACCORDINGLY MODIFIED MODEL SOUNDINGS SUGGEST MLCAPE
AROUND 500-800 J/KG WITH SFC-BASED EFFECTIVE-INFLOW PARCELS ACROSS
CENTRAL FL...AMIDST 45-55 KT EFFECTIVE-SHEAR MAGNITUDES.  EFFECTIVE
SRH OVER REGION IS ESTIMATED AROUND 250-400 J/KG...BASED BOTH ON
THOSE MODEL SOUNDINGS AND ON OBSERVED VWP FROM TBW AND MLB.  MLCINH
APPEARS MINIMAL DESPITE SHALLOW/DIABATICALLY COOLED STABLE LAYER
NEAR SFC...AND THAT COOLING MAY BE OFFSET SOMEWHAT BY LOW-LEVEL
THETAE ADVECTION IN TERMS OF MAINTAINING SFC DEW POINTS MID-60S F
AND KEEPING CINH WEAK.  THIS ALSO MAY SUPPORT SOMEWHAT MORE DISCRETE
SUPERCELL POTENTIAL AHEAD OF PRIMARY SQUALL LINE...EVOLVING FROM
CURRENTLY WEAK CONVECTION INLAND NEAR COAST. 

THREAT FARTHER S AROUND MARCO ISLAND AND EWD ACROSS EVERGLADES TO S
FL METRO IS MORE DISTANT IN TIME AND UNCERTAIN GIVEN NEWD EJECTION
OF ERN CONUS LOW AND ASSOCIATED ISALLOBARIC FORCING AWAY FROM THIS
REGION...WITH ASSOCIATED WEAKENING/VEERING OF FLOW POSSIBLE BY
AROUND DAYBREAK.

..EDWARDS.. 02/16/2016

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

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

LAT...LON   28128273 28278226 28378165 27928121 27378105 26898118
            25808169 26328183 26458195 26398204 26488220 26768230
            26958234 27378263 27628275 27848286 28008280 28128273

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 15, 7:55 PM EST	Mesoscale Discussion	SPC	Bay, Calhoun, Franklin, Gadsden, Gulf, Holmes and 7 more	2 hr
Feb 15, 8:07 PM EST	Tornado Watch	SPC	Dixie, Franklin, Gadsden, Jefferson, Lafayette, Leon and 4 more	5 hr
Feb 15, 10:32 PM EST	Mesoscale Discussion	SPC	Dixie, Franklin, Gadsden, Jefferson, Lafayette, Leon and 5 more	58 min
Feb 16, 2:19 AM EST	Tornado Watch	SPC	Brevard, Charlotte, Collier, DeSoto, Glades, Hardee and 15 more	5 hr
Feb 16, 4:59 AM EST	Mesoscale Discussion	SPC	Hendry, Palm Beach	61 min
Feb 16, 7:36 AM EST	Mesoscale Discussion	SPC	Miami-Dade, Monroe	54 min

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.