Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 1699
The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2012, 1:09 PM CDT for 4 states. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Aug 4, 2012, 1:09 PM CDT (18:09 UTC)
- Expired
- Aug 4, 2012, 2:15 PM CDT
- In force
- 66 min
- Issued by
- the Storm Prediction Center
All 58 counties
Benton County, IA, Buchanan County, IA, Cedar County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Fulton County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McHenry County, IL, McLean County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Winnebago County, IL, Woodford County, IL, Clark County, MO, Green County, WI, Lafayette County, WI
The radar
The Quad Cities radar (KDVN), 51 km from the middle of the area, began a volume at 18:11 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
Davenport, (KDVN), launched 12:00Z, 6.2 hours before the alert went out and 49 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
- 1247 J/kg
- Mixed-layer CIN
- -144 J/kg
- Mixed-layer LCL
- 1158 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- 52 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.8
The text
As transmitted, in the capitals the NWS used until 2016.
401
ACUS11 KWNS 041809
SWOMCD
SPC MCD 041809
ILZ000-WIZ000-IAZ000-MOZ000-041915-
MESOSCALE DISCUSSION 1699
NWS STORM PREDICTION CENTER NORMAN OK
0109 PM CDT SAT AUG 04 2012
AREAS AFFECTED...SERN IA/NRN IL/FAR SRN WI
CONCERNING...SEVERE THUNDERSTORM WATCH 557...
VALID 041809Z - 041915Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 557
CONTINUES.
SUMMARY...A LINE OF TSTMS WILL CONTINUE PROGRESSING EWD ACROSS SERN
IA INTO NRN IL. PRIMARY SEVERE THREAT OF DAMAGING WINDS WITH THE LOW
PROBABILITY OF A FEW SEVERE HAIL REPORTS WILL EXIST AS LINE
CONTINUES EWD. A DOWNSTREAM WW WILL LIKELY BE NEEDED WITHIN THE NEXT
HOUR OR TWO.
DISCUSSION...RECENT DVN RADAR TRENDS HAVE SHOWN IMPROVED CONVECTIVE
STRUCTURE WITH INCREASED ORGANIZATION OVER THE PAST HOUR. DVN BASE
VELOCITY DATA HAS ALSO SHOWN AN INCREASING TREND WITH MAX WINDS
LOCATED ACROSS CEDAR COUNTY IA. ADDITIONALLY...RECENT SURFACE
OBSERVATIONS DEPICT A WELL-DEFINED RISE-FALL-RISE PRESSURE TREND
ALONG AND JUST BEHIND THE LINE...FURTHER VERIFYING THE
STRENGTH/MATURITY OF THE MCS. MLCAPE AOA 2000 J/KG...SUPPORTED BY
MOSTLY CLEAR SKIES...TEMPERATURES IN THE UPPER 80S/LOW 90S...AND
DEWPOINT VALUES IN THE UPPER 60S/LOW 70S...EXISTS DOWNSTREAM OF THE
LINE. LATEST MESOANALYSIS ALSO SUGGEST EFFECTIVE SHEAR VALUES IN
EXCESS OF 35 KTS ACROSS NRN IL. GIVEN THIS ENVIRONMENT...THE LINE IS
EXPECTED TO CONTINUE PROGRESSING EWD WITH A CONTINUED THREAT OF
DAMAGING WINDS AND SEVERE HAIL. CURRENT STORM MOTION IS ESTIMATED AT
250/45 WITH SOME DISCRETE PROPAGATION NOTED ACROSS CEDAR AND JONES
COUNTIES. THE LINE WILL LIKELY MOVE OUTSIDE OF WW 557 AND A
DOWNSTREAM WW WILL LIKELY BE NEEDED WITHIN THE NEXT HOUR OR TWO.
..MOSIER.. 08/04/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...ILX...MKX...DVN...ARX...
LAT...LON 40138938 40179031 40239129 40319182 40679203 41429218
42299203 42859179 42859060 42548841 41798800 41118805
40628826 40138938SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 4, 3:08 AM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Clinton, Greene, Jersey, Macoupin and 1 more | 2 hr |
| Aug 4, 10:26 AM CDT | Mesoscale Discussion | SPC | Adams, Boone, Brown, Bureau, Carroll, Cass and 46 more | 49 min |
| Aug 4, 10:50 AM CDT | Severe Thunderstorm Watch | SPC | Bureau, Carroll, Fulton, Hancock, Henderson, Henry and 16 more | 5 hr |
| Aug 4, 1:46 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more | 4 hr |
| Aug 4, 3:57 PM CDT | Mesoscale Discussion | SPC | Cook, Lake | 63 min |
| Aug 4, 6:12 PM CDT | Severe Thunderstorm Watch | SPC | Madison, Monroe, Randolph, Saint Clair | 6 hr |
| Aug 3, 7:33 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more | 6 hr |
| Aug 3, 10:33 PM CDT | Mesoscale Discussion | SPC | Worth | 87 min |
| Aug 4, 5:20 PM CDT | Mesoscale Discussion | SPC | Barry, Barton, Camden, Carter, Cedar, Christian and 38 more | 85 min |
| Aug 3, 10:57 PM CDT | Severe Thunderstorm Watch | SPC | Barron, Buffalo, Chippewa, Clark, Dunn, Eau Claire and 8 more | 4 hr |
| Aug 4, 1:41 AM CDT | Mesoscale Discussion | SPC | Clark, Iron, Jackson, La Crosse, Lincoln, Marathon and 6 more | 64 min |
Nearby
Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Wisconsin, 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.