Alert archive / Mississippi / Mesoscale Discussions in 2017
Mesoscale Discussion 9
The Storm Prediction Center issued this mesoscale discussion at Jan 2, 2017, 10:17 AM CST for 4 counties in Alabama; 16 parishes in Louisiana; 31 counties in Mississippi. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Jan 2, 2017, 10:17 AM CST (16:17 UTC)
- Expired
- Jan 2, 2017, 12:15 PM CST
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 95%
All 51 counties
Baldwin County, AL, Clarke County, AL, Mobile County, AL, Washington County, AL, Ascension Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Slidell Radar S, LA (KSIL), launched 12:00Z, 4.3 hours before the alert went out and 98 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
- 1261 J/kg
- Mixed-layer CIN
- -29 J/kg
- Mixed-layer LCL
- 571 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 322 m²/s²
- 0-3 km storm-relative helicity
- 423 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 4.0
The text
As transmitted.
063
ACUS11 KWNS 021617
SWOMCD
SPC MCD 021617
ALZ000-MSZ000-LAZ000-021815-
Mesoscale Discussion 0009
NWS Storm Prediction Center Norman OK
1017 AM CST Mon Jan 02 2017
Areas affected...southeast Louisiana through southern Mississippi
Concerning...Severe potential...Tornado Watch likely
Valid 021617Z - 021815Z
Probability of Watch Issuance...95 percent
SUMMARY...The threat for damaging wind and a few tornadoes is
expected to increase from southeast Louisiana through southern
Mississippi into southwest Alabama from late morning into the
afternoon. A tornado watch will likely be issued for this region by
17Z.
DISCUSSION...This morning a coastal warm front extends from the FL
Panhandle through the MS boot heel into southeast and west central
Louisiana where it intersects a pre-frontal squall line. Widespread
clouds have been a limiting factor so far for a more robust severe
threat. However, the moist boundary layer south of the warm front is
destabilizing, primarily due to theta-e advection, but some cloud
breaks will be possible this afternoon supporting MLCAPE from
1000-1500 j/kg. The squall line will likely continue east next
several hours as it intercepts the moistening boundary layer along
and south of the warm front. Additional more discrete storms will
likely continue developing within pre-frontal confluence bands
within the destabilizing warm sector. Some strengthening of broad
southwesterly low-level jet will occur into the afternoon in
association with forcing for ascent accompanying the progressive
southern-stream shortwave trough. This will maintain sufficiently
large 0-2 km hodographs for a threat of low-level mesocyclones and a
few tornadoes, especially as discrete storms become surface-based
ahead of the line. Brief QLCS tornadoes in addition to damaging wind
will remain the primary threats within the squall line.
..Dial/Weiss.. 01/02/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MOB...JAN...LIX...
LAT...LON 32059183 32368987 31848767 30478764 30278928 29619032
30159126 32059183SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 2, 7:08 AM CST | Mesoscale Discussion | SPC | Bibb, Choctaw, Greene, Hale, Marengo, Perry and 3 more | 97 min |
| Jan 2, 11:22 AM CST | Tornado Watch | SPC | Baldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 8 more | 9 hr |
| Jan 2, 12:59 PM CST | Mesoscale Discussion | SPC | Autauga, Barbour, Bullock, Butler, Chambers, Chilton and 17 more | 2 hr |
| Jan 2, 2:03 PM CST | Mesoscale Discussion | SPC | Baldwin, Butler, Choctaw, Clarke, Coffee, Conecuh and 10 more | 117 min |
| Jan 2, 3:46 PM CST | Tornado Watch | SPC | Barbour, Bullock, Coffee, Dale, Geneva, Henry and 3 more | 8 hr |
| Jan 2, 5:36 PM CST | Mesoscale Discussion | SPC | Barbour, Bullock, Butler, Coffee, Covington, Crenshaw and 10 more | 114 min |
| Jan 2, 2:06 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Bienville, Calcasieu and 23 more | 114 min |
| Jan 2, 5:35 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Beauregard, Bienville, Bossier, Caddo and 18 more | 85 min |
| Jan 2, 6:12 AM CST | Tornado Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Bienville, Bossier and 27 more | 10 hr |
| Jan 2, 7:48 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Beauregard, Bienville, Bossier, Caddo and 19 more | 57 min |
| Jan 2, 11:09 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Caldwell, Cameron, Evangeline and 12 more | 96 min |
Nearby
Mesoscale Discussions in Mississippi, 2017Mesoscale Discussions in Louisiana, 2017Mesoscale Discussions in Alabama, 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.