Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 1840
The Storm Prediction Center issued this mesoscale discussion at Aug 30, 2012, 12:57 PM CDT for 4 states. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Aug 30, 2012, 12:57 PM CDT (17:57 UTC)
- Expired
- Aug 30, 2012, 2:30 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
All 54 counties
Baldwin County, AL, Butler County, AL, Choctaw County, AL, Clarke County, AL, Conecuh County, AL, Dallas County, AL, Escambia County, AL, Lowndes County, AL, Marengo County, AL, Mobile County, AL, Monroe County, AL, Sumter County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Okaloosa County, FL, Santa Rosa County, FL, Washington Parish, LA, Attala County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Harrison County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Jackson County, MS, Jasper 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, Madison 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, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 103 km from the middle of the area, began a volume at 17:57 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, 6.0 hours before the alert went out and 113 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
- 107 J/kg
- Mixed-layer CIN
- -5 J/kg
- Mixed-layer LCL
- 501 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 473 m²/s²
- 0-3 km storm-relative helicity
- 650 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.8
The text
As transmitted, in the capitals the NWS used until 2016.
027 ACUS11 KWNS 301758 SWOMCD SPC MCD 301757 ALZ000-FLZ000-MSZ000-LAZ000-301930- MESOSCALE DISCUSSION 1840 NWS STORM PREDICTION CENTER NORMAN OK 1257 PM CDT THU AUG 30 2012 AREAS AFFECTED...MS...SERN LA...SWRN AL...WRN FL PANHANDLE CONCERNING...TORNADO WATCH 597... VALID 301757Z - 301930Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 597 CONTINUES. SUMMARY...GREATEST TORNADO THREAT MAY BEGIN TO SHIFT WEST INTO ERN MS OVER THE NEXT SEVERAL HOURS AS ISAAC DRIFTS INTO NWRN LA. DISCUSSION...REMNANTS OF ISAAC CONTINUE TO DRIFT WNWWD ACROSS NCNTRL LA WITH CENTER OF CIRCULATION NEAR THE CALDWELL/OUACHITA/JACKSON PARISH BORDER. OVER THE LAST FEW HOURS DISTINCT BREAKS IN CLOUD COVER HAVE DEVELOPED OVER ERN MS ALONG WRN FRINGE OF STRONGEST N-S CONVECTIVE BANDS. WHILE THE N-S CONVECTIVE BANDS HAVE STRUGGLED TO PROPAGATE WEST INTO THIS REGION NEW CONVECTION MAY ULTIMATELY EVOLVE OVER ERN MS WHERE ENHANCED BOUNDARY LAYER HEATING IS OCCURRING. EARLIER THIS MORNING MULTIPLE DISTINCT SUPERCELL STRUCTURES WERE EMBEDDED WITHIN THE N-S BAND ALONG THE MS/AL BORDER BUT THIS ACTIVITY HAS RECENTLY WANED IN INTENSITY. THERE IS REASON TO BELIEVE STRONGER SUPERCELL STRUCTURES WILL BEGIN TO SHIFT INTO THE AFOREMENTIONED CORRIDOR OF MS AS ISAAC SHIFTS WEST AND AIRMASS HEATS SLIGHTLY DUE TO BREAKS IN CLOUD COVER. ..DARROW.. 08/30/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...BMX...MOB...JAN...LIX... LAT...LON 33499062 32298652 29558652 30749063 33499062
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 29, 8:21 PM CDT | Mesoscale Discussion | SPC | Baldwin, Mobile, Washington | 84 min |
| Aug 29, 11:06 PM CDT | Mesoscale Discussion | SPC | Baldwin, Mobile, Washington | 84 min |
| Aug 29, 11:42 PM CDT | Tornado Watch | SPC | Mobile, Washington | 8 hr |
| Aug 30, 3:18 AM CDT | Mesoscale Discussion | SPC | Baldwin, Butler, Choctaw, Clarke, Coffee, Conecuh and 7 more | 117 min |
| Aug 30, 6:33 AM CDT | Mesoscale Discussion | SPC | Baldwin, Butler, Choctaw, Clarke, Coffee, Conecuh and 13 more | 117 min |
| Aug 30, 7:13 AM CDT | Tornado Watch | SPC | Autauga, Baldwin, Butler, Choctaw, Clarke, Conecuh and 15 more | 9 hr |
| Aug 30, 3:56 PM CDT | Tornado Watch | SPC | Choctaw, Greene, Sumter, Washington | 6 hr |
Nearby
Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Florida, 2012Every mesoscale discussion in 2012
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.