Alert archive / Alabama / Mesoscale Discussions in 2017
Mesoscale Discussion 77
The Storm Prediction Center issued this mesoscale discussion at Jan 19, 2017, 6:11 PM CST for 11 counties in Alabama; 6 counties in Georgia. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 19, 2017, 6:11 PM CST (00:11 UTC)
- Expired
- Jan 19, 2017, 8:15 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
Counties Bullock County, AL, Chambers County, AL, Clay County, AL, Cleburne County, AL, Elmore County, AL, Lee County, AL, Macon County, AL, Montgomery County, AL, Randolph County, AL, Russell County, AL, Tallapoosa County, AL, Carroll County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Muscogee County, GA, Troup County, GA
The radar
The Maxwell AFB radar (KMXX), 44 km from the middle of the area, began a volume at 00:11 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
Peachtre/Fal Fld, GA (KFFC), launched 00:00Z, 0.2 hours before the alert went out and 118 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
- 27 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 1138 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 116 m²/s²
- 0-3 km storm-relative helicity
- 187 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
864
ACUS11 KWNS 200012
SWOMCD
SPC MCD 200011
GAZ000-ALZ000-200215-
Mesoscale Discussion 0077
NWS Storm Prediction Center Norman OK
0611 PM CST Thu Jan 19 2017
Areas affected...eastern Alabama through west central GA
Concerning...Severe potential...Watch unlikely
Valid 200011Z - 200215Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms will continue to pose a marginal risk for
isolated damaging wind and a brief tornado through 02Z as they move
through the remainder of eastern Alabama into far western Georgia.
Overall threat does not appear sufficient for a WW.
DISCUSSION...A line of thunderstorms with embedded bowing segments
and meso-vortices extends from northeast through south-central GA.
The line is moving east at 15-20 kt, while individual elements
within the line move more rapidly northeast. Objective analysis
indicates a marginally unstable warm sector with MLCAPE below 500
J/kg. The weak thermodynamic environment should remain the primary
limiting factor for a more robust severe threat especially as storms
continue east into GA as evidenced by the 00Z Atlanta raob. Based on
the VWP from Montgomery AL, low-level hodographs are not
particularly large with unidirectional deep-layer wind profiles.
However, effective bulk shear up to 40 kt is sufficient for storms
to organize with embedded bowing segments and weak supercell
structures. Some increase in the low-level jet is expected this
evening in response to the ejecting upper trough. However, storms
will begin to move east of the more unstable portion of warm sector
beyond 02Z, suggesting an overall diminishing trend by that time.
..Dial/Edwards.. 01/20/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FFC...BMX...MOB...
LAT...LON 32008649 32748614 33288591 33698578 34038556 33748505
33268476 32478474 31878549 32008649Nearby
Mesoscale Discussions in Alabama, 2017Mesoscale Discussions in Georgia, 2017Every mesoscale discussion in 2017
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.