Alert archive / Florida / Mesoscale Discussions in 2003

Mesoscale Discussion 447

April 8, 200315 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2003, 11:32 AM EDT for 15 counties in Florida. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Apr 8, 2003, 11:32 AM EDT (15:32 UTC)
Expired: Apr 8, 2003, 2:30 PM EDT
In force: 3 hr
Issued by: the Storm Prediction Center

Counties Alachua County, FL, Bradford County, FL, Clay County, FL, Dixie County, FL, Flagler County, FL, Franklin County, FL, Gilchrist County, FL, Gulf County, FL, Lafayette County, FL, Levy County, FL, Marion County, FL, Putnam County, FL, Saint Johns County, FL, Taylor County, FL, Union County, FL

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 117Apr 8, 1:00 PM EDT

The nearest sounding before it

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 3.5 hours before the alert went out and 103 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: 38 J/kg
Mixed-layer CIN: -151 J/kg
Mixed-layer LCL: 688 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 244 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

050 
ACUS11 KWNS 081532
SWOMCD
SPC MCD 081532 
FLZ000-081830-

MESOSCALE DISCUSSION 0447
NWS STORM PREDICTION CENTER NORMAN OK
1032 AM CDT TUE APR 08 2003

AREAS AFFECTED...S-CENTRAL FL PANHANDLE...APALACHEE
BAY...NRN-MOST FL PENINSULA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 081532Z - 081830Z

ISOLATED STRONG-SEVERE TSTMS MAY MOVE OFF GULF AND PRODUCE
DAMAGING GUSTS/HAIL OVER PORTIONS GULF/FRANKLIN/LIBERTY/SERN BAY
COUNTIES NEAR AQQ BETWEEN 16Z-18Z.  WW NOT ANTICIPATED FOR THIS
REGION GIVEN SMALL SPATIAL/TEMPORAL COVERAGE OF THREAT.  HOWEVER
WW MAY BE REQUIRED WITHIN A FEW HOURS FOR NRN FL WHERE SEVERE
CONVECTION MAY DEVELOP BY EARLY AFTERNOON.

SURFACE MESOANALYSIS SHOWS BAROCLINIC ZONE FROM SRN DUVAL COUNTY
TO GNV THEN GENERALLY WWD ACROSS DIXIE COUNTY AND APALACHEE BAY
TO JUST INLAND FROM CAPE SAN BLAS.  THOUGH MINOR MESO-BETA SCALE
PERTURBATIONS ARE POSSIBLE...BOUNDARY SHOULD REMAIN
QUASISTATIONARY THROUGH MID-AFTERNOON AHEAD OF ANY CONVECTION
THAT FORMS.  EXPECT THERMAL CONTRAST AND ASSOCIATED ENHANCEMENT
TO LOW LEVEL VORTICITY TO BE MAINTAINED BY DIFFERENTIAL DIABATIC
HEATING ACROSS BOUNDARY OVER NEXT SEVERAL HOURS.  SOMEWHAT
STEEPER LOW-MIDLEVEL LAPSE RATES FROM 12Z TLH RAOB...COMPARED TO
JAX SOUNDING...SHOULD SPREAD OVER REGION AS BOUNDARY LAYER
CONTINUES WARMING AND CAPS WEAKEN.  MODIFIED RAOBS AND RUC
SOUNDINGS SUGGEST 1500-2500 J/KG MLCAPE WITH 80S/70S TEMP/DEW
POINTS RESPECTIVELY AT SFC.  THOUGH PRONOUNCED WEAKNESSES IN LOW
LEVEL FLOW AND LOW-MIDLEVEL SR WINDS WILL EXIST...DEEP-LAYER
KINEMATICS SUPPORT SMALL BOWS AND HP SUPERCELLS...WITH 40-50 KT
SHEAR FORECAST THROUGH 0-6 KM AGL LAYER.  


..EDWARDS.. 04/08/2003

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

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

30088565 30088365 30188246 30338137 29238106 28828273
29628530

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 7, 9:13 PM EDT	Mesoscale Discussion	SPC	Calhoun, Escambia, Gadsden, Jackson, Okaloosa, Santa Rosa and 2 more	62 min
Apr 8, 1:00 PM EDT	Severe Thunderstorm Watch	SPC	Alachua, Baker, Bradford, Clay, Columbia, Dixie and 15 more	5 hr
Apr 8, 2:32 PM EDT	Mesoscale Discussion	SPC	Alachua, Bradford, Clay, Dixie, Flagler, Franklin and 9 more	118 min
Apr 8, 4:51 PM EDT	Mesoscale Discussion	SPC	Alachua, Bradford, Clay, Dixie, Flagler, Franklin and 9 more	114 min

Nearby

Mesoscale Discussions in Florida, 2003 Every mesoscale discussion in 2003

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.