Alert archive / Florida / Mesoscale Discussions in 2021
Mesoscale Discussion 75
The Storm Prediction Center issued this mesoscale discussion at Feb 13, 2021, 9:58 AM EST for 6 counties in Florida. It was in force for 92 min.
The area
The outline as issued.
The facts
- Issued
- Feb 13, 2021, 9:58 AM EST (14:58 UTC)
- Expired
- Feb 13, 2021, 11:30 AM EST
- In force
- 92 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Brevard County, FL, Orange County, FL, Osceola County, FL, Polk County, FL, Seminole County, FL, Volusia County, FL
The radar
The Melbourne radar (KMLB), 65 km from the middle of the area, began a volume at 15:02 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
Cape Canaveral, FL (KXMR), launched 12:00Z, 3.0 hours before the alert went out and 72 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
- 121 J/kg
- Mixed-layer CIN
- -61 J/kg
- Mixed-layer LCL
- 1074 m above ground
- 0-6 km bulk shear
- 43 kt
- 0-1 km storm-relative helicity
- 139 m²/s²
- 0-3 km storm-relative helicity
- 155 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 2.3
The text
As transmitted.
054
ACUS11 KWNS 131459
SWOMCD
SPC MCD 131458
FLZ000-131630-
Mesoscale Discussion 0075
NWS Storm Prediction Center Norman OK
0858 AM CST Sat Feb 13 2021
Areas affected...portions of central Florida
Concerning...Severe potential...Watch unlikely
Valid 131458Z - 131630Z
Probability of Watch Issuance...20 percent
SUMMARY...A band of thunderstorms moving across central Florida at
this time may pose risk for a locally stronger/damaging wind gust or
two, and possibly a brief tornado, before moving offshore through
midday.
DISCUSSION...Latest radar loop shows a band of locally strong
thunderstorms moving across central Florida, just south of a cold
front extending from just north of Daytona to just south of Cross
City. South of the front, dewpoints in the upper 60s to low 70s but
rather weak lapse rates above 700mb are yielding only modest
instability (around 500 J/kg mixed-layer CAPE ahead of the
convective band). However, offsetting the modest instability, shear
across the region is sufficient for organized/stronger updrafts,
with flow veering weakly and increasing with height to 50 kt from
the southwest at mid levels. As such, and given increasingly linear
storm mode, gusty winds associated with small bowing segments or
areas of weak mesolow-type circulations can be expected, along with
risk for minor damage. Risk is expected to remain sufficiently
limited in time/intensity/area to preclude any need for WW issuance.
..Goss/Grams.. 02/13/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MLB...TBW...JAX...
LAT...LON 28218048 27658150 27548203 28318168 28988163 29388129
29008075 28218048SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 13, 5:38 AM EST | Mesoscale Discussion | SPC | Citrus, Hernando, Hillsborough, Lake, Marion, Pasco and 2 more | 3 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.