Alert archive / Georgia / Mesoscale Discussions in 2012

Mesoscale Discussion 936

May 28, 2012Duval County, Nassau County, Saint Johns County, Florida; 17 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at May 28, 2012, 11:00 AM EDT for Duval County, Nassau County, Saint Johns County, Florida; 17 counties in Georgia. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued
May 28, 2012, 11:00 AM EDT (15:00 UTC)
Expired
May 28, 2012, 12:30 PM EDT
In force
90 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Duval County, FL, Nassau County, FL, Saint Johns County, FL, Appling County, GA, Bacon County, GA, Brantley County, GA, Camden County, GA, Charlton County, GA, Coffee County, GA, Glynn County, GA, Jeff Davis County, GA, Long County, GA, McIntosh County, GA, Montgomery County, GA, Pierce County, GA, Tattnall County, GA, Telfair County, GA, Toombs County, GA, Wayne County, GA, Wheeler County, GA

The radar

The Jacksonville radar (KJAX), 87 km from the middle of the area, began a volume at 14:59 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

Jacksonville, FL (KJAX), launched 12:00Z, 3.0 hours before the alert went out and 85 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 2012-05-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 39 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 2012-05-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 100 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
39 J/kg
Mixed-layer CIN
-3 J/kg
Mixed-layer LCL
464 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
100 m²/s²
0-3 km storm-relative helicity
136 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

318 
ACUS11 KWNS 281501
SWOMCD
SPC MCD 281500
GAZ000-FLZ000-281630-

MESOSCALE DISCUSSION 0936
NWS STORM PREDICTION CENTER NORMAN OK
1000 AM CDT MON MAY 28 2012

AREAS AFFECTED...SE GA...FAR NE FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 281500Z - 281630Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A MARGINAL TORNADO THREAT WILL LIKELY PERSIST INTO THE
AFTERNOON ACROSS FAR NE FL AND SERN GA. THE THREAT IS EXPECTED TO
REMAIN TOO ISOLATED TO WARRANT WW ISSUANCE.

DISCUSSION...THE NATIONAL HURRICANE CENTER PLACES TROPICAL
DEPRESSION BERYL ABOUT 60 STATUTE MILES WEST OF JACKSONVILLE FL.
MESOANALYSIS DATA CURRENTLY SHOWS PRECIPITABLE WATER VALUES AROUND
2.10 INCHES EXTENDING NEWD FROM BERYL'S CENTER ACROSS NE FL AND SE
GA WHERE 0-1 KM SHEAR VALUES ARE ESTIMATED FROM 20 TO 30 KT. THIS
ENVIRONMENT ALONG WITH FURTHER DESTABILIZATION LATE THIS MORNING
INTO EARLY THIS AFTERNOON SHOULD ALLOW FOR A FEW DISCRETE UPDRAFTS
TO EXHIBIT ROTATION. AS BERYL MOVES SLOWLY WWD...THE THREAT MAY
EXTEND FURTHER INLAND ESPECIALLY IF BREAKS IN THE CLOUD COVER CAN
RESULT IN SFC HEATING IN AREAS TO THE WEST AND NORTHWEST OF
JACKSONVILLE. STORMS THAT ROTATE MAY HAVE A MARGINAL TORNADO THREAT
IF GREATER INSTABILITY CAN DEVELOP IN THE NERN QUADRANT OF BERYL
THIS AFTERNOON.

..BROYLES.. 05/28/2012

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

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

LAT...LON   32238206 32308262 32218282 31938303 31578309 31288265
            30948225 30348185 29938175 29818140 29978107 30518083
            31178090 31938158 32238206

Nearby

Mesoscale Discussions in Georgia, 2012Mesoscale 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.