Alert archive / Mississippi / Mesoscale Discussions in 2007
Mesoscale Discussion 2129
The Storm Prediction Center issued this mesoscale discussion at Oct 22, 2007, 1:58 PM CDT for 23 parishes in Louisiana; 43 counties in Mississippi. It was in force for 92 min.
The area
The outline as issued.
The facts
- Issued
- Oct 22, 2007, 1:58 PM CDT (18:58 UTC)
- Expired
- Oct 22, 2007, 3:30 PM CDT
- In force
- 92 min
- Issued by
- the Storm Prediction Center
All 66 counties
Acadia Parish, LA, Ascension Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Iberia Parish, LA, Iberville Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Madison Parish, LA, Pointe Coupee Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Bolivar County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lawrence County, MS, Leake County, MS, Leflore County, MS, Lincoln County, MS, Madison County, MS, Montgomery County, MS, Neshoba County, MS, Oktibbeha County, MS, Pike County, MS, Pontotoc County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Sunflower County, MS, Tallahatchie County, MS, Walthall County, MS, Warren County, MS, Washington County, MS, Webster County, MS, Wilkinson County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 86 km from the middle of the area, began a volume at 19:00 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, 7.0 hours before the alert went out and 79 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
- 279 J/kg
- Mixed-layer CIN
- -46 J/kg
- Mixed-layer LCL
- 581 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 191 m²/s²
- 0-3 km storm-relative helicity
- 202 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
000 ACUS11 KWNS 221858 SWOMCD SPC MCD 221858 MSZ000-LAZ000-ARZ000-222030- MESOSCALE DISCUSSION 2129 NWS STORM PREDICTION CENTER NORMAN OK 0158 PM CDT MON OCT 22 2007 AREAS AFFECTED...SRN/ERN LA INTO MS CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 221858Z - 222030Z A GRADUAL INCREASE IN THUNDERSTORM DEVELOPMENT IS EXPECTED THROUGH THE PEAK AFTERNOON HEATING. TRENDS ARE BEING MONITORED FOR AN INCREASING SEVERE THREAT AND THE POSSIBILITY OF A WW. IN A RELATIVELY NARROW PRE-FRONTAL CORRIDOR ACROSS THE LOWER MISSISSIPPI VALLEY...BREAKS IN CLOUD COVER HAVE ALLOWED SUFFICIENT SURFACE HEATING TO REDUCE INHIBITION TO NEGLIGIBLE LEVELS. AND THIS...IN CONJUNCTION WITH LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH WEAK WARM ADVECTION...APPEARS TO BE SUPPORTING INCREASING THUNDERSTORM ACTIVITY ACROSS SOUTH CENTRAL LOUISIANA INTO SOUTHWESTERN MISSISSIPPI. WHILE THIS IS STILL GENERALLY TO THE NORTH OF EXTENSIVE CONVECTIVE DEVELOPMENT OVER THE NORTH CENTRAL GULF OF MEXICO INTO CENTRAL GULF COASTAL AREAS...WHICH IS CUTTING OFF INFLUX OF MID/UPPER 70S F DEW POINTS INTO INLAND AREAS...DEW POINTS ACROSS THE LOWER MISSISSIPPI VALLEY ARE GENERALLY IN THE LOWER 70S. GIVEN AT LEAST MODEST CLOCKWISE-CURVED HODOGRAPHS BENEATH 20-30 KT SOUTHERLY 850 FLOW...THE BOUNDARY LAYER WITH HIGH MOISTURE CONTENT AND HIGH RELATIVE HUMIDITIES APPEARS FAVORABLE FOR THE DEVELOPMENT OF ISOLATED TORNADOES. MIXED LAYER CAPE IS ONLY ON THE ORDER OF 500 J/KG DUE TO WEAK MID-LEVEL LAPSE RATES AHEAD SLOWLY DIGGING UPSTREAM TROUGH. BUT...DEEP LAYER SHEAR BENEATH 50 KT CYCLONIC 500 MB FLOW IS STRONG AND FAVORABLE FOR SUPERCELLS...AS ACTIVITY SPREADS NORTH NORTHEASTWARD THIS AFTERNOON. ..KERR.. 10/22/2007 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MEG...JAN...LIX...LCH...SHV... 30579264 31869182 32789135 33829092 34298981 34238881 32758890 31378989 30389047 29459196
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 21, 11:48 PM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Iberia, Jefferson, Lafourche, Orleans and 10 more | 2 hr |
| Oct 22, 3:37 AM CDT | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 2 more | 83 min |
| Oct 22, 4:38 PM CDT | Mesoscale Discussion | SPC | Saint Bernard | 2 hr |
| Oct 22, 5:11 PM CDT | Tornado Watch | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 3 more | 8 hr |
| Oct 22, 6:51 PM CDT | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Saint Bernard, Saint Tammany | 114 min |
Nearby
Mesoscale Discussions in Mississippi, 2007Mesoscale Discussions in Louisiana, 2007Every mesoscale discussion in 2007
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.