Alert archive / Mississippi / Mesoscale Discussions in 2012
Mesoscale Discussion 860
The Storm Prediction Center issued this mesoscale discussion at May 21, 2012, 4:35 PM CDT for Washington Parish, Louisiana; 47 counties in Mississippi. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- May 21, 2012, 4:35 PM CDT (21:35 UTC)
- Expired
- May 21, 2012, 5:30 PM CDT
- In force
- 55 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 48 counties
Washington Parish, LA, Amite County, MS, Attala County, MS, Carroll County, MS, Choctaw County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena 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, Leflore County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Perry 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, Washington County, MS, Wayne County, MS, Webster County, MS, Winston County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 12 km from the middle of the area, began a volume at 21:36 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 nearest sounding before it
Jackson, MS (KJAN), launched 12:00Z, 9.6 hours before the alert went out and 21 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
- 518 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 1663 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
880
ACUS11 KWNS 212135
SWOMCD
SPC MCD 212135
MSZ000-LAZ000-ARZ000-212230-
MESOSCALE DISCUSSION 0860
NWS STORM PREDICTION CENTER NORMAN OK
0435 PM CDT MON MAY 21 2012
AREAS AFFECTED...SRN/CNTRL MS...PORTIONS OF SERN LA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 212135Z - 212230Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...A LOCALIZED DMGG WIND/HAIL THREAT WILL EXIST ACROSS
PORTIONS OF SRN/CNTRL MS AND INTO SERN LA THROUGH THE NEXT 2-3 HRS.
A WW IS NOT CURRENTLY ANTICIPATED...BUT CONVECTIVE TRENDS WILL BE
MONITORED.
DISCUSSION...RADAR REFLECTIVITY FROM THE PAST HR SHOWS A MULTICELL
CLUSTER POSITIONED W OF KJAN...PROPAGATING SSEWD INTO SRN MS.
ADDITIONAL ISOLATED/DISCRETE TSTMS HAVE FORMED FARTHER N INTO
PORTIONS OF CNTRL MS. STRONG BOUNDARY LAYER HEATING HAS OCCURRED
THIS AFTERNOON ACROSS THE REGION...WITH SFC TEMPERATURES REACHING
THE UPPER 80S-LOWER 90S. ALTHOUGH THE AIR MASS IS NOT PARTICULARLY
MOIST...MODERATELY STEEP MIDLEVEL LAPSE RATES NEAR 6.5 C/KM COMBINED
WITH STRONG SFC HEATING HAVE YIELDED MLCAPE VALUES AROUND 1500 J/KG.
ADDITIONALLY...VWP DATA FROM DGX SHOWS 15-20 KTS OF NWLY FLOW ABOVE
3 KM AGL...WHICH SHOULD CONTINUE TO SUPPORT A FEW MULTICELL CLUSTERS
CAPABLE OF PRODUCING ISOLATED DMGG WIND GUSTS AND LARGE HAIL. THE
DOWNSTREAM ENVIRONMENT OVER SRN MS REMAINS UNPERTURBED...WITH A
CONTINUED ISOLATED THREAT THROUGH THE NEXT 2-3 HRS BEFORE DIURNAL
COOLING COMMENCES.
..ROGERS/MEAD.. 05/21/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MOB...MEG...JAN...LIX...
LAT...LON 31348864 30808913 30749055 31189132 32429104 32979112
33379107 33868956 33798890 33248848 31348864Nearby
Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Louisiana, 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.