Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 59
The Storm Prediction Center issued this mesoscale discussion at Feb 6, 2021, 7:41 PM EST for 17 counties in Florida. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 6, 2021, 7:41 PM EST (00:41 UTC)
- Expired
- Feb 6, 2021, 9:45 PM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 5
Counties Alachua County, FL, Bradford County, FL, Citrus County, FL, Clay County, FL, Dixie County, FL, Flagler County, FL, Gilchrist County, FL, Hernando 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 Jacksonville radar (KJAX), 139 km from the middle of the area, began a volume at 00:41 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Tampa Bay, FL (KTBW), launched 00:00Z, 0.7 hours before the alert went out and 181 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.
- Mixed-layer CAPE
- 1198 J/kg
- Mixed-layer CIN
- -24 J/kg
- Mixed-layer LCL
- 813 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 249 m²/s²
- 0-3 km storm-relative helicity
- 286 m²/s²
- Significant tornado parameter
- 1.8
- Supercell composite
- 7.7
The text
As transmitted.
423 ACUS11 KWNS 070041 SWOMCD SPC MCD 070041 FLZ000-070245- Mesoscale Discussion 0059 NWS Storm Prediction Center Norman OK 0641 PM CST Sat Feb 06 2021 Areas affected...Portions of northern/central Florida Concerning...Tornado Watch 5... Valid 070041Z - 070245Z The severe weather threat for Tornado Watch 5 continues. SUMMARY...Severe threat continues across ww005. DISCUSSION...Early-evening water-vapor imagery suggests a weak disturbance may be influencing deep convection that has migrated across the northern portions of FL over the last few hours. An expansive cluster of thunderstorms is moving off the northern FL Atlantic Coast with trailing convection, and scattered supercells, extending west-southwest north of the surface front. A secondary surface wave appears to be forming over the northern Gulf Basin ahead of the primary short-wave trough. This is likely the back edge of the severe threat which will shift toward the FL Gulf Coast later this evening. Much of the convection across the tornado watch is likely elevated with surface dew points only in the lower 60s. 00z sounding from TBW suggests upper 60s-70F dew points are needed for surface-based convection. If this air mass can advance north across ww005, ahead of the trailing surface wave, there may be an increase in near-surface based convection/supercells after 03-04z. ..Darrow.. 02/07/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MLB...TBW...JAX...TAE... LAT...LON 29828340 30178051 28588051 28238339 29828340
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 6, 9:48 PM EST | Mesoscale Discussion | SPC | Alachua, Citrus, Flagler, Hernando, Hillsborough, Lake and 10 more | 87 min |
| Feb 6, 10:58 PM EST | Tornado Watch | SPC | Brevard, Citrus, Flagler, Hardee, Hernando, Hillsborough and 14 more | 8 hr |
| Feb 7, 2:13 AM EST | Mesoscale Discussion | SPC | Brevard, Citrus, Flagler, Hardee, Hernando, Hillsborough and 14 more | 2 hr |
| Feb 7, 6:28 AM EST | Mesoscale Discussion | SPC | Brevard, Hardee, Hillsborough, Lake, Manatee, Orange and 7 more | 2 hr |
Nearby
Mesoscale Discussions in Florida, 2021Every mesoscale discussion in 2021
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.