Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 2199

December 20, 20125 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Dec 20, 2012, 7:54 PM EST for 5 counties in Florida. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
Dec 20, 2012, 7:54 PM EST (00:54 UTC)
Expired
Dec 20, 2012, 9:00 PM EST
In force
66 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Citrus County, FL, Hernando County, FL, Hillsborough County, FL, Pasco County, FL, Pinellas County, FL

The radar

The Tampa radar (KTBW), 61 km from the middle of the area, began a volume at 00:54 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 00:00Z, 0.9 hours before the alert went out and 61 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-pSkew-T log-p diagram, Tampa Bay, FL at 00:00Z on 2012-12-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 97 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Tampa Bay, FL at 00:00Z on 2012-12-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 203 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
97 J/kg
Mixed-layer CIN
-41 J/kg
Mixed-layer LCL
872 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
203 m²/s²
0-3 km storm-relative helicity
185 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.7

Open this sounding in Storm Lab

The text

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

773 
ACUS11 KWNS 210054
SWOMCD
SPC MCD 210054 
FLZ000-210200-

MESOSCALE DISCUSSION 2199
NWS STORM PREDICTION CENTER NORMAN OK
0654 PM CST THU DEC 20 2012

AREAS AFFECTED...PARTS OF THE IMMEDIATE W COAST OF THE FL PENINSULA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 210054Z - 210200Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A LOW PROBABILITY FOR A STRONG WIND GUST MAY DEVELOP NEAR
THE IMMEDIATE COAST OVER THE NEXT FEW HOURS AS A QLCS MOVES ASHORE
FROM THE ERN GULF OF MEXICO.

DISCUSSION...RADAR MOSAIC SHOWS A QLCS MOVING IN A GENERAL EWD
DIRECTION OVER THE ERN GULF OF MEXICO.  THIS CONVECTIVE LINE WILL
AFFECT CITRUS COUNTY IN THE IMMEDIATE TERM AND IN A FEW HOURS
FARTHER S IN THE TAMPA/ST. PETE VICINITY.  ADEQUATE FORCING FOR
ASCENT/DEEP LAYER FLOW WILL ACT TO MAINTAIN A QLCS STRUCTURE
--LARGELY SUB-SEVERE-- INTO CNTRL PORTIONS OF THE FL PENINSULA INTO
THE MID-EVENING HOURS.  YET...DESPITE MOIST LOW
LEVELS...CHARACTERIZED BY MID-UPPER 60S DEWPOINTS ALONG THE W
COAST...A MARGINAL THERMODYNAMIC PROFILE PER THE 00Z TBW RAOB /250
J/KG MUCAPE/ WILL ACT TO LIMIT UPDRAFT INTENSITY/SEVERE
POTENTIAL...WITH THE GREATEST CHANCE FOR A STRONG WIND GUST BEING
RELEGATED TO NEAR THE IMMEDIATE COAST.

..SMITH/CARBIN.. 12/21/2012

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

ATTN...WFO...TBW...

LAT...LON   27588287 28528277 28888270 29038243 28768229 27978230
            27548248 27588287

Nearby

Mesoscale Discussions in Florida, 2012Every 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; radar from the NEXRAD Level II archive.