Alert archive / Arkansas / Mesoscale Discussions in 2009

Mesoscale Discussion 657

May 1, 20094 states

The Storm Prediction Center issued this mesoscale discussion at May 1, 2009, 3:21 PM CDT for 4 states. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued
May 1, 2009, 3:21 PM CDT (20:21 UTC)
Expired
May 1, 2009, 4:15 PM CDT
In force
54 min
Issued by
the Storm Prediction Center
All 62 counties

Baxter County, AR, Boone County, AR, Carroll County, AR, Clay County, AR, Cleburne County, AR, Craighead County, AR, Crittenden County, AR, Cross County, AR, Fulton County, AR, Greene County, AR, Independence County, AR, Izard County, AR, Jackson County, AR, Johnson County, AR, Lawrence County, AR, Madison County, AR, Marion County, AR, Mississippi County, AR, Newton County, AR, Poinsett County, AR, Pope County, AR, Randolph County, AR, Searcy County, AR, Sharp County, AR, St. Francis County, AR, Stone County, AR, Van Buren County, AR, White County, AR, Woodruff County, AR, Fulton County, KY, Hickman County, KY, Barry County, MO, Butler County, MO, Carter County, MO, Dunklin County, MO, Howell County, MO, McDonald County, MO, Mississippi County, MO, New Madrid County, MO, Oregon County, MO, Ozark County, MO, Pemiscot County, MO, Ripley County, MO, Stoddard County, MO, Stone County, MO, Taney County, MO, Carroll County, TN, Chester County, TN, Crockett County, TN, Dyer County, TN, Fayette County, TN, Gibson County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Lake County, TN, Lauderdale County, TN, Madison County, TN, Obion County, TN, Shelby County, TN, Tipton County, TN, Weakley County, TN

The radar

The Little Rock radar (KLZK), 169 km from the middle of the area, began a volume at 20:24 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, 8.4 hours before the alert went out and 212 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.

Skew-T log-pSkew-T log-p diagram, Little Rock, AR at 12:00Z on 2009-05-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1720 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Little Rock, AR at 12:00Z on 2009-05-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 85 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1720 J/kg
Mixed-layer CIN
-19 J/kg
Mixed-layer LCL
482 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
85 m²/s²
0-3 km storm-relative helicity
176 m²/s²
Significant tornado parameter
0.5
Supercell composite
2.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 1, 12:45 AM CDTSevere Thunderstorm WatchSPCBenton, Carroll, Crawford, Madison, Washington6 hr
May 1, 3:00 AM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Crawford, Franklin and 10 more2 hr
May 1, 6:08 AM CDTMesoscale DiscussionSPCBenton, Boone, Carroll, Crawford, Franklin, Johnson and 3 more67 min
May 1, 7:26 AM CDTSevere Thunderstorm WatchSPCCrawford, Franklin, Johnson, Logan, Madison, Montgomery and 5 more7 hr
May 1, 10:32 AM CDTMesoscale DiscussionSPCCrawford, Franklin, Logan, Madison, Washington58 min
May 1, 1:22 PM CDTMesoscale DiscussionSPCCrawford, Franklin, Johnson, Logan, Montgomery, Polk and 3 more53 min
May 1, 3:36 PM CDTSevere Thunderstorm WatchSPCBaxter, Benton, Boone, Carroll, Clay, Cleburne and 34 more6 hr
May 1, 6:11 PM CDTMesoscale DiscussionSPCBaxter, Benton, Boone, Carroll, Clay, Cleburne and 30 more64 min
May 1, 1:18 PM CDTMesoscale DiscussionSPCBedford, Benton, Bledsoe, Cannon, Carroll, Chester and 34 more87 min
May 1, 2:23 PM CDTSevere Thunderstorm WatchSPCBedford, Cannon, Coffee, Franklin, Giles, Grundy and 13 more5 hr
May 1, 3:48 PM CDTMesoscale DiscussionSPCGiles, Hardin, Lawrence, Lewis, Lincoln, Wayne87 min
May 1, 6:41 PM CDTMesoscale DiscussionSPCBedford, Coffee, Franklin, Giles, Grundy, Hardin and 8 more64 min

Nearby

Mesoscale Discussions in Arkansas, 2009Mesoscale Discussions in Tennessee, 2009Mesoscale Discussions in Missouri, 2009Every mesoscale discussion in 2009

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.