Alert archive / Alabama / Mesoscale Discussions in 2021

Mesoscale Discussion 1973

December 9, 2021Baldwin County, Mobile County, Alabama; Escambia County, Florida

The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2021, 9:45 PM CST for Baldwin County, Mobile County, Alabama; Escambia County, Florida. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Dec 9, 2021, 9:45 PM CST (03:45 UTC)
Expired
Dec 9, 2021, 10:45 PM CST
In force
60 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Baldwin County, AL, Mobile County, AL, Escambia County, FL

The radar

The Mobile radar (KMOB), 37 km from the middle of the area, began a volume at 03:45 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

Slidell Radar S, LA (KSIL), launched 00:00Z, 3.8 hours before the alert went out and 180 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-pSkew-T log-p diagram, Slidell Radar S, LA at 00:00Z on 2021-12-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1405 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Slidell Radar S, LA at 00:00Z on 2021-12-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 150 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
1405 J/kg
Mixed-layer CIN
-5 J/kg
Mixed-layer LCL
577 m above ground
0-6 km bulk shear
48 kt
0-1 km storm-relative helicity
150 m²/s²
0-3 km storm-relative helicity
213 m²/s²
Significant tornado parameter
1.2
Supercell composite
5.5

Open this sounding in Storm Lab

The text

As transmitted.

691 
ACUS11 KWNS 100345
SWOMCD
SPC MCD 100345 
FLZ000-ALZ000-100445-

Mesoscale Discussion 1973
NWS Storm Prediction Center Norman OK
0945 PM CST Thu Dec 09 2021

Areas affected...southern Alabama into the western Florida
Panhandle.

Concerning...Severe potential...Watch unlikely 

Valid 100345Z - 100445Z

Probability of Watch Issuance...5 percent

SUMMARY...There will be a brief tornado threat across southern
Alabama and the western Florida Panhandle for the next 1 to 2 hours.

DISCUSSION...Deepening convection has moved in off the Gulf of
Mexico and is currently merging with the ongoing convective cluster
across southern Alabama. This merger, in close proximity to the warm
front, has led to a small area of low-level rotation near Mobile.
This will likely be very short lived given the messy storm mode and
marginal thermodynamic environment. However, a similar airmass
exists into the western Florida Peninsula and therefore, additional
storm mergers and strengthening cells in close proximity to the warm
front could lead to other areas of low-level rotation exhibiting a
brief tornado threat.

..Bentley/Grams.. 12/10/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MOB...

LAT...LON   30828822 30838769 30718712 30468706 30258744 30278792
            30358825 30648838 30808836 30828822

Nearby

Mesoscale Discussions in Alabama, 2021Mesoscale 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.