Alert archive / Arkansas / Mesoscale Discussions in 2012
Mesoscale Discussion 2065
The Storm Prediction Center issued this mesoscale discussion at Oct 17, 2012, 3:44 PM CDT for 5 states. It was in force for 61 min.
The area
The outline as issued.
The facts
- Issued
- Oct 17, 2012, 3:44 PM CDT (20:44 UTC)
- Expired
- Oct 17, 2012, 4:45 PM CDT
- In force
- 61 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 45 counties
Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Clay County, AR, Cleburne County, AR, Cleveland County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Greene County, AR, Independence County, AR, Jackson County, AR, Jefferson County, AR, Lawrence County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Mississippi County, AR, Monroe County, AR, Phillips County, AR, Poinsett County, AR, Prairie County, AR, Pulaski County, AR, Randolph County, AR, Sharp County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Morehouse Parish, LA, Dunklin County, MO, Pemiscot County, MO, Bolivar County, MS, Coahoma County, MS, Tunica County, MS, Washington County, MS, Lake County, TN, Shelby County, TN, Tipton County, TN
The radar
The Little Rock radar (KLZK), 85 km from the middle of the area, began a volume at 20:44 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
Little Rock, AR (KLZK), launched 12:00Z, 8.7 hours before the alert went out and 138 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
- 843 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 328 m²/s²
- 0-3 km storm-relative helicity
- 347 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted, in the capitals the NWS used until 2016.
410
ACUS11 KWNS 172044
SWOMCD
SPC MCD 172044
TNZ000-MOZ000-ARZ000-MSZ000-LAZ000-172145-
MESOSCALE DISCUSSION 2065
NWS STORM PREDICTION CENTER NORMAN OK
0344 PM CDT WED OCT 17 2012
AREAS AFFECTED...PARTS OF CENTRAL AND ERN AR/FAR NERN LA/FAR NWRN
MS/FAR WRN TN/MO BOOTHEEL
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 172044Z - 172145Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...SHORT TERM MODEL TRENDS CONTINUE TO SUGGEST TSTMS WILL
DEVELOP ALONG A PRE-FRONTAL TROUGH/DIFFERENTIAL HEATING BOUNDARY
EXTENDING FROM NORTH CENTRAL-NERN AR TO SOUTH CENTRAL AR BETWEEN
22-23Z. ADDITIONAL STORMS SHOULD ALSO FORM ALONG THE COLD FRONT AS
IT REACHES CENTRAL AR LATE THIS AFTERNOON/EARLY EVENING. A
MOISTENING BOUNDARY LAYER AND STRENGTHENING...VERTICALLY VEERING
WINDS WILL SUPPORT A TORNADO THREAT...IN ADDITION TO DAMAGING WINDS.
DISCUSSION...18Z SOUNDINGS AT LZK/SHV BOTH INDICATED MOISTENING OF
THE BOUNDARY LAYER BENEATH A CAP BASED AROUND 850 MB WHICH FOR NOW
IS MAINTAINING SURFACE-BASED INHIBITION. ADDITIONAL MOISTURE RETURN
INTO THE NRN EXTENT OF THE LOWER MS VALLEY COMBINED WITH SURFACE
HEATING...WHICH HAS BEEN STRONGEST ACROSS SRN/ERN AR PER VISIBLE
SATELLITE IMAGERY AND SURFACE OBSERVATIONS...WILL FURTHER
DESTABILIZE THE AIR MASS /MLCAPE APPROACHING 1000 J/KG OVER SRN-SERN
AR LATE THIS AFTERNOON/. THE 18Z SOUNDINGS ALSO INDICATED 850-700
MB LAYER WINDS HAD BACKED SOME SINCE 12Z AND STRENGTHENED...WITH AN
INCREASE IN WLY MIDLEVEL WINDS ALSO NOTED. THESE KINEMATICS ARE
SUSTAINING LOW LEVEL HODOGRAPH CURVATURE WITH SURFACE-1 KM SHEAR
AROUND 40 KT FOR A TORNADO THREAT AND EFFECTIVE BULK SHEAR OF 40-50
KT FOR STORM ORGANIZATION.
UNCERTAINTIES REMAIN ABOUT THE DEGREE OF DESTABILIZATION AND AMOUNT
OF FORCING FOR ASCENT ATTENDANT TO A DIGGING NWLY MID-UPPER LEVEL
JET AND TROUGH TO SUPPORT TSTM DEVELOPMENT ACROSS THE DISCUSSION
AREA. HOWEVER...TRENDS IN SHORT TERM MODELS /HRRR AND 12Z 4 KM
WRF-NMM/NSSL/ CONTINUE TO SUGGEST FACTORS WILL BECOME JUXTAPOSED
ACROSS CENTRAL AR BETWEEN 22-23Z...WITH ADDITIONAL STORM DEVELOPMENT
ALONG THE COLD FRONT BY EARLY EVENING ACROSS CENTRAL AR.
..PETERS/THOMPSON.. 10/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...MEG...JAN...LZK...SGF...SHV...
LAT...LON 34119273 35459216 36509166 36568987 36438943 35398977
33999057 32979103 32759160 32959248 32999295 34119273SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 17, 12:55 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Marion | 95 min |
| Oct 17, 5:21 PM CDT | Tornado Watch | SPC | Arkansas, Baxter, Boone, Bradley, Calhoun, Carroll and 57 more | 7 hr |
| Oct 17, 6:29 PM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Chicot, Columbia, Drew and 5 more | 91 min |
| Oct 17, 11:45 AM CDT | Mesoscale Discussion | SPC | Audrain, Lewis, Lincoln, Marion, Monroe, Montgomery and 7 more | 90 min |
| Oct 17, 1:58 PM CDT | Severe Thunderstorm Watch | SPC | Audrain, Barry, Boone, Callaway, Camden, Christian and 41 more | 6 hr |
| Oct 17, 6:19 PM CDT | Mesoscale Discussion | SPC | Carter, Iron, Madison, Oregon, Perry, Reynolds and 3 more | 56 min |
Nearby
Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Mississippi, 2012Mesoscale Discussions in Tennessee, 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.