Alert archive / Georgia / Mesoscale Discussions in 2011

Mesoscale Discussion 2196

September 20, 2011Nassau County, Florida; 19 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Sep 20, 2011, 1:26 PM EDT for Nassau County, Florida; 19 counties in Georgia. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued
Sep 20, 2011, 1:26 PM EDT (17:26 UTC)
Expired
Sep 20, 2011, 2:30 PM EDT
In force
64 min
Issued by
the Storm Prediction Center

Counties Nassau County, FL, Appling County, GA, Atkinson County, GA, Bacon County, GA, Brantley County, GA, Camden County, GA, Charlton County, GA, Clinch County, GA, Coffee County, GA, Echols County, GA, Glynn County, GA, Jeff Davis County, GA, Lanier County, GA, Long County, GA, Lowndes County, GA, McIntosh County, GA, Pierce County, GA, Telfair County, GA, Ware County, GA, Wayne County, GA

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 5.4 hours before the alert went out and 121 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, Jacksonville, FL at 12:00Z on 2011-09-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2522 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, Jacksonville, FL at 12:00Z on 2011-09-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 28 square meters per square second.1939Sfc1 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
2522 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
481 m above ground
0-6 km bulk shear
14 kt
0-1 km storm-relative helicity
28 m²/s²
0-3 km storm-relative helicity
16 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0

Open this sounding in Storm Lab

The text

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

566 
ACUS11 KWNS 201727
SWOMCD
SPC MCD 201726
GAZ000-FLZ000-201830-

MESOSCALE DISCUSSION 2196
NWS STORM PREDICTION CENTER NORMAN OK
1226 PM CDT TUE SEP 20 2011

AREAS AFFECTED...SERN GA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 201726Z - 201830Z

CLUSTERS OF STORMS LIFTING NWD ACROSS SERN GA MAY ACQUIRE BRIEF
UPDRAFT ROTATION AND POSE A MARGINAL THREAT FOR SHORT-LIVED
TORNADOES. HOWEVER...THE SVR WEATHER THREAT IS EXPECTED TO BE TOO
LOW TO WARRANT A WW.

AT 17Z...COMPOSITE REFLECTIVITY SHOWED A CLUSTER OF STORMS LIFTING
NWD OVER SERN GA...WITH MORE DISCRETE ACTIVITY TRAILING SWD INTO FAR
NRN FL. STORMS OVER GA ARE MOVING ACROSS AN E-W ORIENTED LOW-LEVEL
BAROCLINIC ZONE...WITH WINDS S OF THE BOUNDARY OVER NRN FL
SELY...BACKING TO E-NELY OVER THE COOL SIDE OF THE BOUNDARY IN ERN
GA. STRONGLY VEERING VERTICAL WIND PROFILES MAY AID IN BRIEF UPDRAFT
ROTATION/SHORT-LIVED TORNADO THREAT AS VERY MOIST BOUNDARY LAYER
CONTINUES TO HEAT UP DURING THE AFTERNOON. HOWEVER...THE SVR WEATHER
THREAT IS EXPECTED TO BE VERY MARGINAL...PRECLUDING THE NEED FOR A
WW.

..GARNER.. 09/20/2011

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

ATTN...WFO...CHS...JAX...FFC...TAE...

LAT...LON   31988309 32058189 31588107 30488151 30578335 31988309

Nearby

Mesoscale Discussions in Georgia, 2011Mesoscale Discussions in Florida, 2011Every 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.