Alert archive / Florida / Mesoscale Discussions in 2004

Mesoscale Discussion 293

April 8, 200417 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2004, 12:42 PM EDT for 17 counties in Florida. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 8, 2004, 12:42 PM EDT (16:42 UTC)
Expired: Apr 8, 2004, 2:45 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Alachua County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Flagler County, FL, Gilchrist County, FL, Hernando County, FL, Lafayette County, FL, Lake County, FL, Levy County, FL, Marion County, FL, Orange County, FL, Putnam County, FL, Saint Johns County, FL, Seminole County, FL, Sumter County, FL, Volusia County, FL

The radar

The Tampa radar (KTBW), 151 km from the middle of the area, began a volume at 16:44 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 12:00Z, 4.7 hours before the alert went out and 151 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: 134 J/kg
Mixed-layer CIN: -206 J/kg
Mixed-layer LCL: 1145 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 188 m²/s²
0-3 km storm-relative helicity: 247 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

508 
ACUS11 KWNS 081643
SWOMCD
SPC MCD 081642 
FLZ000-081845-

MESOSCALE DISCUSSION 0293
NWS STORM PREDICTION CENTER NORMAN OK
1142 AM CDT THU APR 08 2004

AREAS AFFECTED...CENTRAL/NRN FL

CONCERNING...SEVERE THUNDERSTORM WATCH 54...

VALID 081642Z - 081845Z

SEVERE REMAINS POSSIBLE BOTH IN CONJUNCTION WITH TSTM LINE ACROSS
CENTRAL FL AND WITH ANY NEW DEVELOPMENT THAT MAY OCCUR BEHIND LINE. 
WW SHOULD BE MAINTAINED IN ORIGINAL ENTIRETY FOR TIME
BEING...HOWEVER THREAT MAY BE DIMINISHING OVERALL.  IF WEAKENING
TRENDS CONTINUE WW MAY BE CANCELLED BEFORE SCHEDULED 21Z EXPIRATION.


BROKEN LINE OF TSTMS FROM SRN FLAGLER/NRN VOLUSIA COUNTIES SWWD TO
HERNANDO COUNTY COASTAL WATERS -- AS OF 1630Z -- IS MOVING INTO
WEAKER KINEMATIC ENVIRONMENT PER DIAGNOSTICS OF TBW-MLB VWP.  ONLY
WEAK MOIST AXIS WITH MID 60S DEW POINTS REMAINS FROM MARION/LAKE
COUNTIES SWWD ACROSS TBW AREA...AHEAD OF SRN PORTION OF LINE. 
FARTHER NE...INSOLATION-RELATED MIXING IS OFFSETTING WEAK MOIST
ADVECTION IN MAINTAINING RELATIVELY LOW SFC DEW POINTS.  EXPECT NRN
TSTM CLUSTER -- OVER PORTIONS VOLUSIA/LAKE COUNTIES AS OF 1630Z --
TO MOVE OVER ATLANTIC WITH GRADUAL DISORGANIZATION IN MEANTIME. 
NARROW ZONE EXISTS IMMEDIATELY BEHIND THIS ACTIVITY WHICH APPEARS TO
HAVE BEEN TEMPORARILY STABILIZED BY OUTFLOW -- BASED ON CLOUD
ABSENCE IN VIS IMAGERY AND EVIDENT SUBSIDENCE. HOWEVER...WILL
MAINTAIN WW FOR TIME BEING BEHIND LINE BECAUSE OF DESTABILIZATION
FARTHER W TOWARD FL COASTAL BEND -- WHERE GREATER AMOUNT OF LOW
LEVEL MOISTURE REMAINS AND SFC HEATING CONTINUES.  VERTICAL SHEAR
PROFILES ACTUALLY ARE MORE FAVORABLE FOR SUPERCELLS OVER THIS AREA
THAN WITHIN/AHEAD OF ONGOING CONVECTIVE LINE...BUT MAIN NEGATIVE
FACTOR IS LACK OF STRONG LOW LEVEL LIFT.

..EDWARDS.. 04/08/2004

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

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

28398269 30038326 30018126 28398073

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 8, 9:50 AM EDT	Mesoscale Discussion	SPC	Calhoun, Gadsden, Holmes, Jackson, Jefferson, Leon and 5 more	85 min
Apr 8, 10:10 AM EDT	Severe Thunderstorm Watch	SPC	Escambia, Gadsden, Hamilton, Holmes, Jackson, Leon and 5 more	7 hr
Apr 8, 10:16 AM EDT	Mesoscale Discussion	SPC	Alachua, Bradford, Citrus, Clay, Duval, Flagler and 13 more	119 min
Apr 8, 10:45 AM EDT	Severe Thunderstorm Watch	SPC	Alachua, Bradford, Citrus, Clay, Flagler, Gilchrist and 11 more	6 hr
Apr 8, 1:11 PM EDT	Mesoscale Discussion	SPC	Escambia, Gadsden, Hamilton, Holmes, Jackson, Leon and 5 more	2 hr
Apr 8, 3:35 PM EDT	Mesoscale Discussion	SPC	Brevard, Hardee, Highlands, Hillsborough, Indian River, Okeechobee and 6 more	55 min
Apr 8, 3:40 PM EDT	Mesoscale Discussion	SPC	Nassau	65 min

Nearby

Mesoscale Discussions in Florida, 2004 Every mesoscale discussion in 2004

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.