Alert archive / Iowa / Mesoscale Discussions in 2012
Mesoscale Discussion 817
The Storm Prediction Center issued this mesoscale discussion at May 15, 2012, 2:51 PM CDT for 13 counties in Illinois; 18 counties in Iowa; 6 counties in Wisconsin. It was in force for 54 min.
The area
The outline as issued.
The facts
- Issued
- May 15, 2012, 2:51 PM CDT (19:51 UTC)
- Expired
- May 15, 2012, 3:45 PM CDT
- In force
- 54 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 37 counties
Benton County, IA, Cedar County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Mahaska County, IA, Muscatine County, IA, Poweshiek County, IA, Scott County, IA, Washington County, IA, Boone County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Jo Daviess County, IL, Kane County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Rock Island County, IL, Stephenson County, IL, Whiteside County, IL, Winnebago County, IL, Dane County, WI, Green County, WI, Jefferson County, WI, Lafayette County, WI, Rock County, WI, Walworth County, WI
The radar
The Quad Cities radar (KDVN), 52 km from the middle of the area, began a volume at 19:49 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
Davenport, (KDVN), launched 12:00Z, 7.9 hours before the alert went out and 52 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
- 2205 m above ground
- 0-6 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- -8 m²/s²
- 0-3 km storm-relative helicity
- 25 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
400
ACUS11 KWNS 151951
SWOMCD
SPC MCD 151951
ILZ000-WIZ000-IAZ000-152045-
MESOSCALE DISCUSSION 0817
NWS STORM PREDICTION CENTER NORMAN OK
0251 PM CDT TUE MAY 15 2012
AREAS AFFECTED...ERN IA / NRN IL / SRN WI
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 151951Z - 152045Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...ISOLD-WIDELY SCTD STORMS EXPECTED TO DEVELOP 21-00Z. SOME
RISK FOR GUSTY WINDS MAY DEVELOP WITH THE STRONGER STORMS. OVERALL
SEVERE THREAT WILL SEEMINGLY BE LIMITED BY QUALITY OF MOISTURE /LACK
THEREOF/...RENDERING THE PROBABILITY OF WATCH ISSUANCE LOWER THAN
PERCEIVED EARLIER. THE SLIGHT RISK WILL BE DOWNGRADED TO A SEE TEXT
HIGHLIGHT FOR THE UPCOMING 20Z CONVECTIVE OUTLOOK ISSUANCE.
DISCUSSION...VISIBLE SATELLITE IMAGERY SHOWS A CLUMPING CU FIELD
ALONG THE FRONT EXTENDING FROM 30 MI N DSM INTO NERN IA. STRONG
SURFACE HEATING AHEAD OF THE FRONT HAS YIELDED TEMPS IN THE
MID-UPPER 80S AND 40-50 DEG TEMP/DEWPOINT SPREADS. OF
NOTE...VARIOUS MORNING MODEL SOLUTIONS HAVE BEEN OVERLY AGGRESSIVE
REGARDING THE QUALITY OF BOUNDARY LAYER MOISTURE ACROSS THE AREA.
OBSERVED GPS PW/S IN FAR ERN IA NEAR THE IL BORDER AND OVER NERN IA
/0.4 TO 0.5 INCH --RESPECTIVELY/...ARE 0.25-0.5 INCH LOWER THAN
VARIOUS OPERATIONAL MODELS. AS SUCH...UPDRAFTS WILL SEEMINGLY BE
INHIBITED TO A DEGREE BY DRY AIR ENTRAINMENT...DESPITE FRONTAL
FORCING AIDING IN CONVECTIVE DEVELOPMENT. WITH ONLY WEAK
INSTABILITY /A FEW HUNDRED J/KG SBCAPE/...STORM COVERAGE WILL LIKELY
REMAIN ISOLD TO WIDELY SCTD...YIELDING PERHAPS A FEW STRONG WIND
GUSTS.
..SMITH/HART.. 05/15/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...MKX...DVN...ARX...DMX...
LAT...LON 42109250 43398888 42788802 41838802 40979204 41349268
42109250SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 15, 4:58 PM CDT | Mesoscale Discussion | SPC | Boone, Carroll, Jo Daviess, McHenry, Ogle, Stephenson and 1 more | 62 min |
Nearby
Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Illinois, 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.