Alert archive / Mississippi / Mesoscale Discussions in 2015
Mesoscale Discussion 9
The Storm Prediction Center issued this mesoscale discussion at Jan 3, 2015, 10:24 AM CST for 20 parishes in Louisiana; 32 counties in Mississippi. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 3, 2015, 10:24 AM CST (16:24 UTC)
- Expired
- Jan 3, 2015, 12:30 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 52 counties
Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Pointe Coupee Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Amite County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Hancock County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne County, MS, Wilkinson County, MS, Winston County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 94 km from the middle of the area, began a volume at 16:26 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, 4.4 hours before the alert went out and 99 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
- 92 J/kg
- Mixed-layer CIN
- -86 J/kg
- Mixed-layer LCL
- 505 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 353 m²/s²
- 0-3 km storm-relative helicity
- 556 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 2.3
The text
As transmitted, in the capitals the NWS used until 2016.
823
ACUS11 KWNS 031624
SWOMCD
SPC MCD 031624
ALZ000-MSZ000-LAZ000-031830-
MESOSCALE DISCUSSION 0009
NWS STORM PREDICTION CENTER NORMAN OK
1024 AM CST SAT JAN 03 2015
AREAS AFFECTED...CNTRL/SRN MS...ERN LA
CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY
VALID 031624Z - 031830Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...PRE-FRONTAL TSTM DEVELOPMENT IS EXPECTED BY EARLY
AFTERNOON WITHIN AN ENVIRONMENT SUFFICIENT FOR ROTATING UPDRAFTS
WITH PRIMARY RISKS OF A COUPLE TORNADOES AND DAMAGING WINDS.
DISCUSSION...COMPOSITE CONVECTIVE OUTFLOW/COLD FRONT EXTENDED FROM
10 W UOX TO 20 W JAN TO 30 W HEZ TO 30 NW LFT AS OF 16Z. FROM THE
JAN AREA SWD TO THE GULF COAST AHEAD OF THIS BOUNDARY...A
DESTABILIZING AIR MASS CHARACTERIZED BY 65-70 DEG F SURFACE DEW
POINTS WAS PREVALENT. VISIBLE SATELLITE IMAGERY SUGGEST THAT WARM
SECTOR TCU/CBS HAVE INITIATED OFFSHORE S OF ATCHAFALAYA BAY. RECENT
HRRR RUNS AND CONVECTION-ALLOWING WRF GUIDANCE ARE CONSISTENT IN
SIMULATING STRENGTHENING OFFSHORE CONVECTION AS IT SPREADS INLAND
ACROSS PARTS OF THE LOWER MS VALLEY INTO THE AFTERNOON. THE HRRR
APPEARS A BIT MORE AGGRESSIVE IN TIMING/AMPLITUDE OF THIS WARM
CONVEYOR ACTIVITY.
DESPITE MOIST-ADIABATIC LAPSE RATES SAMPLED IN 12Z LCH/JAN
RAOBS...SLIGHT SURFACE HEATING IN THE 72-74 DEG F RANGE ACROSS ERN
LA IS ALREADY ADEQUATE FOR MLCAPE AROUND 750 J/KG. VEERED LOW-LEVEL
WINDS /STRONGER WITH NRN EXTENT/ SUGGEST HODOGRAPHS WILL NOT BE
OVERLY LARGE...BUT CERTAINLY SUFFICIENT FOR ROTATING UPDRAFTS
CAPABLE OF A COUPLE TORNADOES AND DAMAGING WINDS. THE MOST FAVORABLE
ENVIRONMENTAL CORRIDOR FOR TORNADOES SHOULD EVOLVE ACROSS ERN LA
INTO SRN MS BETWEEN ABOUT 19-22Z.
..GRAMS/HART.. 01/03/2015
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BMX...MOB...JAN...LIX...LCH...
LAT...LON 33068974 33108883 32878838 32498830 31928840 31188867
30228942 29469041 29399110 29679179 30209183 30829156
31689112 32459015 33068974SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 3, 11:04 AM CST | Tornado Watch | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 22 more | 7 hr |
| Jan 3, 12:00 PM CST | Mesoscale Discussion | SPC | Saint Bernard | 90 min |
| Jan 3, 1:43 PM CST | Mesoscale Discussion | SPC | East Baton Rouge, East Feliciana, Livingston, Saint Helena, Tangipahoa, Washington | 92 min |
| Jan 3, 5:31 PM CST | Mesoscale Discussion | SPC | Livingston, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington | 44 min |
| Jan 3, 2:54 PM CST | Mesoscale Discussion | SPC | Choctaw, Clarke, Clay, Covington, Jasper, Jefferson Davis and 16 more | 96 min |
Nearby
Mesoscale Discussions in Mississippi, 2015Mesoscale Discussions in Louisiana, 2015Every mesoscale discussion in 2015
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.