Alert archive / South Dakota / Mesoscale Discussions in 2007
Mesoscale Discussion 1813
The Storm Prediction Center issued this mesoscale discussion at Aug 20, 2007, 1:03 AM MDT for 18 counties in South Dakota. It was in force for 57 min.
The area
The outline as issued.
The facts
- Issued
- Aug 20, 2007, 1:03 AM MDT (07:03 UTC)
- Expired
- Aug 20, 2007, 2:00 AM MDT
- In force
- 57 min
- Issued by
- the Storm Prediction Center
Counties Bennett County, SD, Buffalo County, SD, Campbell County, SD, Corson County, SD, Dewey County, SD, Haakon County, SD, Hughes County, SD, Hyde County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Potter County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD, Ziebach County, SD
The radar
The Rapid City radar (KUDX), 164 km from the middle of the area, began a volume at 07:05 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
Rapid City, SD (KRAP), launched 00:00Z, 7.1 hours before the alert went out and 169 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
- 1255 J/kg
- Mixed-layer CIN
- -193 J/kg
- Mixed-layer LCL
- 1275 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 22 m²/s²
- 0-3 km storm-relative helicity
- 64 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
000 ACUS11 KWNS 200703 SWOMCD SPC MCD 200703 SDZ000-NDZ000-NEZ000-200800- MESOSCALE DISCUSSION 1813 NWS STORM PREDICTION CENTER NORMAN OK 0203 AM CDT MON AUG 20 2007 AREAS AFFECTED...CENTRAL SD CONCERNING...SEVERE THUNDERSTORM WATCH 620... VALID 200703Z - 200800Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 620 CONTINUES. HAIL IS EXPECTED TO BE THE GREATEST THREAT WITH THE STRONGER TSTMS THROUGH THE OVERNIGHT TIME PERIOD. NEW WW IS NOT ANTICIPATED FOR DOWNSTREAM OF WW 620. WATER VAPOR IMAGERY INDICATED A SHORT WAVE TROUGH ADVANCING ENEWD ACROSS THE NRN ROCKIES TOWARD THE NRN HIGH PLAINS OF ERN MT/WY. DIFFLUENT UPPER LEVEL FLOW REGIME DOWNSTREAM OF THIS IMPULSE ACROSS SD...AND INCREASING LOW LEVEL WAA ALONG NOSE OF WRN NEB 30 KT LLJ WILL CONTINUE TO PROMOTE SUFFICIENT DEEP LAYER ASCENT FOR ADDITIONAL TSTM DEVELOPMENT INTO THE EARLY MORNING ACROSS SD. EFFECTIVE BULK SHEAR VALUES OF 45-55 KT AND ERN EXTENT OF STEEP LAPSE RATES /AROUND 7.5 C/KM/ ACROSS THIS REGION SUGGEST POTENTIAL FOR ORGANIZED TSTMS WITH HAIL. HOWEVER...STRONGER ASCENT AHEAD OF NRN ROCKIES TROUGH IS EXPECTED TO TRACK TO THE N OF SD ACROSS ERN MT/ND WHICH SHOULD LIMIT THE COVERAGE OF STRONGER MORE INTENSE TSTM ACTIVITY ACROSS SD. ..PETERS.. 08/20/2007 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...FSD...ABR...BIS...LBF...UNR... 43750143 44440170 45970193 45929950 44369902 43029939 42970187
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 7:46 PM MDT | Mesoscale Discussion | SPC | Bennett, Butte, Harding, Jackson, Meade, Oglala Lakota and 1 more | 59 min |
| Aug 19, 8:37 PM MDT | Severe Thunderstorm Watch | SPC | Bennett, Butte, Custer, Fall River, Haakon, Harding and 11 more | 5 hr |
| Aug 19, 9:29 PM MDT | Mesoscale Discussion | SPC | Bennett, Butte, Harding, Jackson, Meade, Oglala Lakota and 1 more | 61 min |
| Aug 20, 2:03 PM MDT | Mesoscale Discussion | SPC | Clay, Lincoln, Union, Yankton | 117 min |
Nearby
Mesoscale Discussions in South Dakota, 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.