Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 768

May 9, 201223 counties in Florida; 12 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at May 9, 2012, 6:01 PM EDT for 23 counties in Florida; 12 counties in Georgia. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: May 9, 2012, 6:01 PM EDT (22:01 UTC)
Expired: May 9, 2012, 7:30 PM EDT
In force: 89 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 35 counties

Alachua County, FL, Baker County, FL, Bradford County, FL, Clay County, FL, Columbia County, FL, Dixie County, FL, Duval County, FL, Franklin County, FL, Gilchrist County, FL, Hamilton County, FL, Jefferson County, FL, Lafayette County, FL, Leon County, FL, Levy County, FL, Madison County, FL, Marion County, FL, Nassau County, FL, Putnam County, FL, Saint Johns County, FL, Suwannee County, FL, Taylor County, FL, Union County, FL, Wakulla County, FL, Atkinson County, GA, Bacon County, GA, Brantley County, GA, Brooks County, GA, Camden County, GA, Charlton County, GA, Clinch County, GA, Echols County, GA, Lanier County, GA, Lowndes County, GA, Pierce County, GA, Ware County, GA

The nearest sounding before it

Jacksonville, FL (KJAX), launched 12:00Z, 10.0 hours before the alert went out and 106 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: 420 J/kg
Mixed-layer CIN: -52 J/kg
Mixed-layer LCL: 904 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 35 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.

008 
ACUS11 KWNS 092201
SWOMCD
SPC MCD 092201 
FLZ000-GAZ000-092330-

MESOSCALE DISCUSSION 0768
NWS STORM PREDICTION CENTER NORMAN OK
0501 PM CDT WED MAY 09 2012

AREAS AFFECTED...SERN GA...ERN FL PANHANDLE...NRN FL PENINSULA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 092201Z - 092330Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A FEW THUNDERSTORMS MAY PRODUCE MARGINALLY SVR HAIL/WIND
INTO EARLY EVENING.

DISCUSSION...CONVECTIVE CLUSTERS THAT INITIATED ALONG A COLD
FRONT...WHICH IS DRAPED ACROSS PARTS OF THE SERN STATES...WILL
CONTINUE TO MOVE EWD ACROSS THE AREA AMIDST A MODERATELY UNSTABLE
AIR MASS /MLCAPE VALUES OF 1000-1500 J PER KG/. WITH A NEARLY
UNIDIRECTIONAL WLY WIND PROFILE WITHIN THE 1-7-KM-AGL LAYER...A
BROKEN SQUALL LINE CONTINUES TO ORGANIZE FROM WEST OF WAYCROSS GA TO
SOUTH OF TALLAHASSEE FL...AND FORWARD-PROPAGATION WILL CONTINUE AS
ADDITIONAL CONVECTIVE DEVELOPMENT IS FOSTERED AT THE LEADING EDGE OF
ENHANCED COLD POOLS. MARGINALLY SVR WIND GUSTS WILL BE POSSIBLE WITH
THE STRONGEST/MOST ORGANIZED LINE SEGMENTS...AIDED BY STEEP
LOW-LEVEL LAPSE RATES...ALONG WITH TEMPERATURE-DEWPOINT SPREADS NEAR
30F ACROSS PORTIONS OF THE NRN FL PENINSULA. MARGINALLY SVR HAIL
WILL ALSO BE POSSIBLE IN EARLY STAGES OF REGENERATIVE CONVECTION.
HOWEVER...WITH ONLY 20-25 KT OF MID-LEVEL FLOW...DEEP-LAYER SHEAR IS
ONLY MODEST AND WILL MAINLY SUPPORT A MULTICELL CONVECTIVE MODE WITH
ONLY SPORADIC INSTANCES OF MARGINALLY SVR STORMS...AND A MORE
ORGANIZED/SUBSTANTIAL SVR THREAT IS NOT ANTICIPATED.
FURTHERMORE...THE DEVELOPMENT OF THE STABLE NOCTURNAL BOUNDARY LAYER
DURING THE NEXT FEW HOURS WILL RESULT IN A DOWNWARD-TREND IN
CONVECTIVE INTENSITY THROUGH THE EVENING.

..COHEN/HART.. 05/09/2012

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

ATTN...WFO...TBW...JAX...TAE...

LAT...LON   30948139 30518141 29748131 29118201 29218300 29638352
            29908420 29578506 30038533 30898345 31678238 31398162
            30948139

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 12:59 PM EDT	Mesoscale Discussion	SPC	Bay, Calhoun, Gadsden, Gulf, Hamilton, Jackson and 6 more	2 hr
May 9, 11:32 AM EDT	Mesoscale Discussion	SPC	Burke, Richmond	88 min
May 9, 2:00 PM EDT	Severe Thunderstorm Watch	SPC	Bryan, Bulloch, Candler, Chatham, Effingham, Evans and 4 more	5 hr
May 9, 4:54 PM EDT	Mesoscale Discussion	SPC	Bryan, Chatham, Liberty, Long, McIntosh, Wayne	96 min
May 9, 7:04 PM EDT	Mesoscale Discussion	SPC	Bryan, Chatham, Effingham, Liberty, Long, McIntosh	26 min

Nearby

Mesoscale Discussions in Florida, 2012 Mesoscale Discussions in Georgia, 2012 Every 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.