Alert archive / Alabama / Mesoscale Discussions in 2018

Mesoscale Discussion 41

January 22, 20187 counties in Alabama

The Storm Prediction Center issued this mesoscale discussion at Jan 22, 2018, 1:48 PM CST for 7 counties in Alabama. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 22, 2018, 1:48 PM CST (19:48 UTC)
Expired: Jan 22, 2018, 4:15 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Barbour County, AL, Bullock County, AL, Butler County, AL, Crenshaw County, AL, Macon County, AL, Montgomery County, AL, Pike County, AL

The radar

The Ft Rucker radar (KEOX), 84 km from the middle of the area, began a volume at 19:49 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

Birmingham, AL (KBMX), launched 12:00Z, 7.8 hours before the alert went out and 158 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1509 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 244 m²/s²
0-3 km storm-relative helicity: 229 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

942 
ACUS11 KWNS 221949
SWOMCD
SPC MCD 221948 
ALZ000-222215-

Mesoscale Discussion 0041
NWS Storm Prediction Center Norman OK
0148 PM CST Mon Jan 22 2018

Areas affected...southeast Alabama

Concerning...Severe potential...Watch unlikely 

Valid 221948Z - 222215Z

Probability of Watch Issuance...20 percent

SUMMARY...Storms may pose some risk for locally strong wind gusts
and perhaps a brief tornado over southeast Alabama next few hours.
Threat appears too marginal for a WW.

DISCUSSION...A cluster of storms with embedded circulations and
bowing segments has recently intensified over south-central AL.
Activity is forming within corridor of ascent along southern
extension of warm conveyor belt. Storms are approaching a minimum in
boundary-layer moisture with surface dewpoints around 56 F, and some
temporary weakening might occur as a result. However, low-level
theta-e advection should contribute to dewpoints rising to near 60F
across southeast AL next couple hours, and this should help to
sustain surface-based storms next few hours. Effective-bulk shear
around 40 kt and 0-1 km storm relative helicity from 200-300 m2/s2
is more than sufficient for transient embedded circulations and
bowing segments, but the weak thermodynamic environment is expected
to remain the primary limiting factor for a more robust severe
threat.

..Dial/Thompson.. 01/22/2018

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

ATTN...WFO...TAE...BMX...MOB...

LAT...LON   31498690 32078664 32368623 32428566 32068523 31518565
            31278665 31498690

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 22, 10:25 AM CST	Mesoscale Discussion	SPC	Choctaw, Washington	2 hr

Nearby

Mesoscale Discussions in Alabama, 2018 Every mesoscale discussion in 2018

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.