Alert archive / Iowa / Mesoscale Discussions in 2007

Mesoscale Discussion 1849

August 22, 20074 states

The Storm Prediction Center issued this mesoscale discussion at Aug 22, 2007, 2:37 PM CDT for 4 states. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued
Aug 22, 2007, 2:37 PM CDT (19:37 UTC)
Expired
Aug 22, 2007, 4:00 PM CDT
In force
83 min
Issued by
the Storm Prediction Center
All 103 counties

Adair County, IA, Adams County, IA, Appanoose County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Buchanan County, IA, Cass County, IA, Cedar County, IA, Clarke County, IA, Dallas County, IA, Davis County, IA, Decatur County, IA, Fremont County, IA, Grundy County, IA, Guthrie County, IA, Hardin County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Linn County, IA, Lucas County, IA, Madison County, IA, Mahaska County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Monroe County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Van Buren County, IA, Wapello County, IA, Warren County, IA, Washington County, IA, Wayne County, IA, Brown County, KS, Doniphan County, KS, Jewell County, KS, Marshall County, KS, Nemaha County, KS, Phillips County, KS, Republic County, KS, Smith County, KS, Washington County, KS, Andrew County, MO, Atchison County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Grundy County, MO, Harrison County, MO, Holt County, MO, Mercer County, MO, Nodaway County, MO, Putnam County, MO, Schuyler County, MO, Sullivan County, MO, Worth County, MO, Adams County, NE, Buffalo County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Dawson County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Furnas County, NE, Gage County, NE, Gosper County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Jefferson County, NE, Johnson County, NE, Kearney County, NE, Lancaster County, NE, Merrick County, NE, Nemaha County, NE, Nuckolls County, NE, Otoe County, NE, Pawnee County, NE, Phelps County, NE, Polk County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thayer County, NE, Webster County, NE, York County, NE

The radar

The Omaha radar (KOAX), 50 km from the middle of the area, began a volume at 19:38 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

Omaha, NE (KOAX), launched 12:00Z, 7.6 hours before the alert went out and 50 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, Omaha, NE at 12:00Z on 2007-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1071 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, Omaha, NE at 12:00Z on 2007-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 128 square meters per square second.1939Sfc1 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
1071 J/kg
Mixed-layer CIN
-277 J/kg
Mixed-layer LCL
1229 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
128 m²/s²
0-3 km storm-relative helicity
89 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 221937
SWOMCD
SPC MCD 221937 
IAZ000-MOZ000-KSZ000-NEZ000-222100-

MESOSCALE DISCUSSION 1849
NWS STORM PREDICTION CENTER NORMAN OK
0237 PM CDT WED AUG 22 2007

AREAS AFFECTED...SRN NEB/NRN KS/SWRN AND CENTRAL IA/NRN MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 221937Z - 222100Z

CONVECTION IS INCREASING S OF ONGOING BAND OF STORMS OVER CENTRAL
AND NRN NEB/NWRN IA.  WHILE SEVERE THREAT IS FORECAST TO REMAIN
MARGINAL...COVERAGE MAY EVENTUALLY REQUIRE WW ISSUANCE.

SHOWERS AND SCATTERED THUNDERSTORMS ARE BEGINNING TO DEVELOP ATTM
FROM SRN NEB EWD INTO SRN IA/NRN MO...NEAR OUTFLOW ASSOCIATED WITH
MORE PERSISTENT CONVECTION TO THE N.  AIRMASS CONTINUES TO
HEAT/DESTABILIZE...WITH 2500 TO 3000 J/KG MEAN-LAYER CAPE NOW
INDICATED.  

DESPITE FAVORABLE INSTABILITY...MOST CONVECTION IS DEVELOPING NEAR
-- AND THEN BEING UNDERCUT BY -- SWD-MOVING CONVECTIVE OUTFLOW. 
THIS COMBINED WITH MARGINAL SHEAR AT BEST /LOW TO MID-LEVEL FLOW AOB
30 KT PER AREA PROFILERS/ SUGGEST THAT THE PRIMARY SEVERE THREAT
WILL REMAIN ISOLATED/GENERALLY LESS THAN 1 1/2 HAIL.  WHILE WW IS
NOT IMMINENT...ISSUANCE MAY BE REQUIRED IN THE NEXT COUPLE OF HOURS
IF SEVERE POTENTIAL APPEARS TO EXPAND IN COVERAGE/INTENSITY.

..GOSS.. 08/22/2007

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DVN...DMX...EAX...OAX...TOP...GID...LBF...GLD...

40310038 41019997 41249763 41349560 42429362 42569165
41909095 40659181 39829337 39679976

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 8:14 PM CDTSevere Thunderstorm WatchSPCAllamakee, Buchanan, Chickasaw, Clayton, Delaware, Dubuque and 5 more8 hr
Aug 21, 10:49 PM CDTMesoscale DiscussionSPCAllamakee, Audubon, Benton, Black Hawk, Boone, Bremer and 37 more86 min
Aug 22, 2:13 AM CDTMesoscale DiscussionSPCJackson62 min
Aug 22, 6:45 AM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Carroll, Cherokee, Clay, Crawford and 13 more60 min
Aug 22, 10:12 AM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Cherokee, Clay, Crawford, Humboldt and 8 more93 min
Aug 22, 3:20 PM CDTSevere Thunderstorm WatchSPCFremont, Harrison, Mills, Montgomery, Page, Pottawattamie and 1 more6 hr
Aug 22, 6:33 PM CDTMesoscale DiscussionSPCFremont, Harrison, Mills, Montgomery, Page, Pottawattamie and 1 more87 min
Aug 21, 8:28 PM CDTMesoscale DiscussionSPCCheyenne, Decatur, Ellis, Gove, Graham, Jewell and 15 more92 min
Aug 22, 6:48 PM CDTSevere Thunderstorm WatchSPCGreeley, Logan, Sherman, Wallace, Wichita5 hr
Aug 22, 5:31 PM CDTMesoscale DiscussionSPCArthur, Banner, Box Butte, Cheyenne, Deuel, Garden and 5 more89 min

Nearby

Mesoscale Discussions in Iowa, 2007Mesoscale Discussions in Nebraska, 2007Mesoscale Discussions in Missouri, 2007Every mesoscale discussion in 2007

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.