Alert archive / Mississippi / Mesoscale Discussions in 2016
Mesoscale Discussion 1839
The Storm Prediction Center issued this mesoscale discussion at Nov 29, 2016, 12:38 PM CST for 19 parishes in Louisiana; 24 counties in Mississippi. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 29, 2016, 12:38 PM CST (18:38 UTC)
- Expired
- Nov 29, 2016, 2:45 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 43 counties
Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Richland Parish, LA, Tensas Parish, LA, Vernon Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Covington County, MS, Franklin County, MS, Hinds County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lawrence County, MS, Lincoln County, MS, Madison County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS
The radar
The Ft Polk radar (KPOE), 141 km from the middle of the area, began a volume at 18:40 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Jackson, MS (KJAN), launched 12:00Z, 6.6 hours before the alert went out and 162 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2018 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 179 m²/s²
- 0-3 km storm-relative helicity
- 254 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
287
ACUS11 KWNS 291838
SWOMCD
SPC MCD 291838
MSZ000-LAZ000-ARZ000-292045-
MESOSCALE DISCUSSION 1839
NWS STORM PREDICTION CENTER NORMAN OK
1238 PM CST TUE NOV 29 2016
AREAS AFFECTED...PARTS OF CENTRAL AND SOUTHERN LA INTO PARTS OF
CENTRAL AND SOUTHERN MS
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 291838Z - 292045Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A VERY GRADUAL INCREASE IN WARM-SECTOR CONVECTION ONGOING
AT THIS TIME MAY YIELD LOCAL/ISOLATED SEVERE RISK IN THE NEXT HOUR
OR SO. AT THIS TIME...IT APPEARS A WATCH WILL NOT BE NEEDED IN THE
IMMEDIATE TERM...BUT MAY BECOME INCREASINGLY NECESSARY ASSUMING A
CONTINUED/GRADUAL INCREASE IN CONVECTIVE COVERAGE.
DISCUSSION...LATEST VISIBLE SATELLITE AND RADAR LOOPS REVEAL GRADUAL
INCREASES IN CONVECTIVE COVERAGE/INTENSITY WITHIN HORIZONTAL
CONVECTIVE ROLLS...OCCURRING IN A MOIST (LOW 70S DEWPOINTS)
WARM-SECTOR THAT IS GRADUALLY HEATING/DESTABILIZING EARLY THIS
AFTERNOON. A COUPLE OF SHOWERS HAVE EVOLVED...ALONG WITH A LONE
THUNDERSTORM NOW ONGOING NEAR THE CATAHOULA/CONCORDIA PARISH LINE.
SHEAR PROFILES WITHIN THE WARM SECTOR -- THOUGH LACKING A BIT WITH
RESPECT TO LOW-LEVEL SHEAR -- REMAIN QUITE SUPPORTIVE OF
ORGANIZED/ROTATING UPDRAFTS...AS MID-LEVEL FLOW NEAR 75 KT FROM THE
SOUTHWEST REMAINS ATOP THE REGION. INDEED...THE AFOREMENTIONED
THUNDERSTORM HAS SHOWN WEAK ROTATION/SUPERCELL STRUCTURE ON RADAR...
AND EXPECT THAT ANY ADDITIONAL UPDRAFTS WHICH EVOLVE AND BECOME
SUSTAINED TO LIKEWISE ACQUIRE ROTATION. WHILE A WATCH IS NOT
IMMINENT DUE TO WHAT SHOULD REMAIN LIMITED STORM COVERAGE OVER THE
NEXT HOUR OR SO...THE CONTINUED/GRADUAL INCREASE IN STORMS/SEVERE
RISK MAY REQUIRE WATCH CONSIDERATION IN THE 19-20Z TIME FRAME.
..GOSS.. 11/29/2016
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LIX...LCH...SHV...
LAT...LON 30749346 31219351 32649242 33359069 32658935 31458925
31169002 30849229 30749346SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 28, 6:36 PM CST | Mesoscale Discussion | SPC | Saint Helena, Tangipahoa, Washington | 2 hr |
| Nov 28, 8:39 PM CST | Mesoscale Discussion | SPC | East Baton Rouge, East Feliciana, Livingston, Saint Helena, Tangipahoa, Washington and 1 more | 96 min |
| Nov 28, 11:38 PM CST | Mesoscale Discussion | SPC | Livingston, Saint Tammany, Tangipahoa, Washington | 3 hr |
| Nov 29, 9:51 AM CST | Mesoscale Discussion | SPC | Bienville, Caldwell, Catahoula, De Soto, Franklin, Grant and 10 more | 84 min |
| Nov 29, 1:48 PM CST | Tornado Watch | SPC | Caldwell, Catahoula, Concordia, East Carroll, Franklin, Grant and 12 more | 7 hr |
| Nov 29, 4:20 PM CST | Mesoscale Discussion | SPC | Caldwell, Catahoula, East Carroll, Franklin, LaSalle, Madison and 2 more | 55 min |
| Nov 29, 5:37 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Avoyelles, Beauregard, Calcasieu and 12 more | 2 hr |
| Nov 29, 3:08 PM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Bolivar, Calhoun, Chickasaw, Clay and 17 more | 2 hr |
| Nov 29, 3:48 PM CST | Tornado Watch | SPC | Alcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 12 more | 7 hr |
| Nov 29, 5:24 PM CST | Mesoscale Discussion | SPC | Itawamba, Tishomingo | 96 min |
Nearby
Mesoscale Discussions in Mississippi, 2016Mesoscale Discussions in Louisiana, 2016Every mesoscale discussion in 2016
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.