Alert archive / Arkansas / Mesoscale Discussions in 2008
Mesoscale Discussion 2421
The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2008, 1:20 AM CST for 31 counties in Arkansas; 17 counties in Missouri; 7 counties in Oklahoma. It was in force for 25 min.
The area
The outline as issued.
The facts
- Issued
- Dec 9, 2008, 1:20 AM CST (07:20 UTC)
- Expired
- Dec 9, 2008, 1:45 AM CST
- In force
- 25 min
- Issued by
- the Storm Prediction Center
All 55 counties
Baxter County, AR, Benton County, AR, Boone County, AR, Carroll County, AR, Cleburne County, AR, Conway County, AR, Crawford County, AR, Faulkner County, AR, Franklin County, AR, Fulton County, AR, Garland County, AR, Independence County, AR, Izard County, AR, Johnson County, AR, Logan County, AR, Madison County, AR, Marion County, AR, Montgomery County, AR, Newton County, AR, Perry County, AR, Polk County, AR, Pope County, AR, Scott County, AR, Searcy County, AR, Sebastian County, AR, Sharp County, AR, Stone County, AR, Van Buren County, AR, Washington County, AR, White County, AR, Yell County, AR, Barry County, MO, Christian County, MO, Dent County, MO, Douglas County, MO, Greene County, MO, Howell County, MO, Lawrence County, MO, McDonald County, MO, Newton County, MO, Oregon County, MO, Ozark County, MO, Shannon County, MO, Stone County, MO, Taney County, MO, Texas County, MO, Webster County, MO, Wright County, MO, Adair County, OK, Cherokee County, OK, Delaware County, OK, Haskell County, OK, Latimer County, OK, LeFlore County, OK, Sequoyah County, OK
The radar
The Western Arkansas radar (KSRX), 80 km from the middle of the area, began a volume at 07:21 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
Springfield, MO (KSGF), launched 00:00Z, 7.3 hours before the alert went out and 143 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
- 809 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 648 m²/s²
- 0-3 km storm-relative helicity
- 738 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000
ACUS11 KWNS 090721
SWOMCD
SPC MCD 090720
MOZ000-ARZ000-OKZ000-090745-
MESOSCALE DISCUSSION 2421
NWS STORM PREDICTION CENTER NORMAN OK
0120 AM CST TUE DEC 09 2008
AREAS AFFECTED...ERN OK AND WRN AR
CONCERNING...SEVERE THUNDERSTORM WATCH 943...
VALID 090720Z - 090745Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 943
CONTINUES.
THREAT FOR DAMAGING WINDS PERSISTS ACROSS NRN PART OF 943...WITH
ATTENDANT FAST MOVING BOW. AN ISOLATED TORNADO THREAT MAY EXTEND N
OF TORNADO WATCH 942 INTO SWRN PORTION OF SEVERE THUNDERSTORM WATCH
943 DURING THE NEXT FEW HOURS.
FAST MOVING LINE SEGMENT/BOW LOCATED OVER FAR SWRN MO/NWRN AR IS
TRACKING ENEWD AT 50+ KT. ALTHOUGH INSTABILITY REMAINS WEAK
IMMEDIATELY DOWNSTREAM OF THIS BOW...STRONG DYNAMIC FORCING
ATTENDANT TO VIGOROUS OK SHORT WAVE TROUGH WILL MAINTAIN LINEAR
STRUCTURE...AT LEAST IN THE SHORT TERM...WITH THREAT FOR DAMAGING
WINDS REMAINING IMMINENT.
REGIONAL RADARS INDICATED A STORM LOCATED OVER NRN PUSHMATAHA/SERN
LATIMER/SRN LE FLORE COUNTIES...THAT HAD PRODUCED DAMAGE JUST AFTER
05Z IN GRAYSON COUNTY TX...CONTINUED TO SHOW SOME UPDRAFT ROTATION.
ALTHOUGH INSTABILITY IS WEAKER /MUCAPE 500-1000 J/KG/ OVER EAST
CENTRAL OK TO WRN AR...MOISTURE RETURN ACROSS THE WARM SECTOR
COMBINED WITH EFFECTIVE BULK SHEAR /40 KT/ AND EFFECTIVE SRH AROUND
250 M2/S2 SUGGEST A NON-ZERO POTENTIAL FOR STORMS MOVING NEWD INTO
ERN OK/WRN AR TO PRODUCE AN ISOLATED TORNADO.
..PETERS.. 12/09/2008
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...MEG...LSX...LZK...SGF...SHV...TSA...
LAT...LON 34389341 34309416 34599504 34779552 35399533 35999509
36749467 37129431 37609261 37739107 36139108 35069150
34609297 34389341SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 8, 11:31 PM CST | Tornado Watch | SPC | Little River, Miller | 7 hr |
| Dec 9, 12:10 AM CST | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Madison, Marion, Newton and 1 more | 35 min |
| Dec 9, 12:22 AM CST | Severe Thunderstorm Watch | SPC | Baxter, Benton, Boone, Carroll, Cleburne, Conway and 24 more | 4 hr |
| Dec 9, 2:17 AM CST | Mesoscale Discussion | SPC | Little River, Miller | 58 min |
| Dec 9, 3:41 AM CST | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia and 36 more | 64 min |
| Dec 9, 4:11 AM CST | Tornado Watch | SPC | Arkansas, Bradley, Calhoun, Clark, Cleveland, Columbia and 25 more | 7 hr |
| Dec 9, 7:41 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 21 more | 64 min |
| Dec 9, 9:32 AM CST | Tornado Watch | SPC | Ashley, Bradley, Chicot, Desha, Drew, Union | 6 hr |
| Dec 9, 10:12 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 10 more | 93 min |
| Dec 9, 2:18 PM CST | Mesoscale Discussion | SPC | Chicot | 87 min |
| Dec 8, 7:10 PM CST | Mesoscale Discussion | SPC | Bryan, Carter, Love, Marshall | 2 hr |
Nearby
Mesoscale Discussions in Arkansas, 2008Mesoscale Discussions in Missouri, 2008Mesoscale Discussions in Oklahoma, 2008Every mesoscale discussion in 2008
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.