Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 1815

August 1, 20049 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2004, 12:11 PM CDT for 9 counties in Iowa. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: Aug 1, 2004, 12:11 PM CDT (17:11 UTC)
Expired: Aug 1, 2004, 1:15 PM CDT
In force: 64 min
Issued by: the Storm Prediction Center

Counties Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Crawford County, IA, Greene County, IA, Ida County, IA, Pocahontas County, IA, Sac County, IA

The radar

The Des Moines radar (KDMX), 136 km from the middle of the area, began a volume at 17:12 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

Omaha, NE (KOAX), launched 12:00Z, 5.2 hours before the alert went out and 156 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1981 J/kg
Mixed-layer CIN: -120 J/kg
Mixed-layer LCL: 919 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 109 m²/s²
0-3 km storm-relative helicity: 27 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.8

Open this sounding in Storm Lab

The text

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

651 
ACUS11 KWNS 011712
SWOMCD
SPC MCD 011711 
IAZ000-011815-

MESOSCALE DISCUSSION 1815
NWS STORM PREDICTION CENTER NORMAN OK
1211 PM CDT SUN AUG 01 2004

AREAS AFFECTED...WESTERN IA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL 

VALID 011711Z - 011815Z

MARGINALLY SEVERE HAIL AND HEAVY RAINS ARE POSSIBLE ACROSS PORTIONS
OF WRN IA DURING THE NEXT COUPLE OF HOURS. NO WATCH IS ANTICIPATED
UNTIL LATER THIS AFTERNOON...WHEN SURFACE BASED STORMS ARE EXPECTED
TO DEVELOP WEST/NORTH OF THE CURRENT CLUSTER OF STORMS. 

A FEW ELEVATED STORMS HAVE DEVELOPED BETWEEN SUX AND DSM... ABOUT 25
MILES NORTH OF AN OUTFLOW BOUNDARY THAT STRETCHES E-W ACROSS IA AND
THEN NWWD INTO CENTRAL SD. A 25 KT LOW LEVEL JET FROM THE WSW IS
BEING LIFTED OVER THE BOUNDARY...FUELING THE STORMS WITH MUCAPE
VALUES AROUND 2500 J/KG. THIS AMOUNT OF INSTABILITY MAY BE
SUFFICIENT FOR THESE STORMS TO PRODUCE 1/2 TO 1 INCH SIZE HAIL
DURING THE NEXT HOUR OR SO. ALTHOUGH MID LEVEL WINDS ARE FROM THE
WNW AT 25 KT...STRONG BACKWARD PROPAGATION WILL RESULT IN THE STORMS
TO MOVE VERY SLOWLY ESEWD. GIVEN THE SLOW MOTION AND STRONG UPDRAFTS
WITHIN A MOIST ENVIRONMENT...RAINFALL RATES OF 2 TO 4 INCHES PER
HOUR WOULD ALSO BE POSSIBLE.

..IMY.. 08/01/2004

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

ATTN...WFO...DMX...FSD...OAX...

41749507 42029586 42209583 42429577 42809576 43039557
43029501 42859464 42629424 42219420 41889450

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 31, 8:19 PM CDT	Mesoscale Discussion	SPC	Dickinson, Emmet, Lyon, Osceola, Winnebago	56 min
Jul 31, 9:45 PM CDT	Severe Thunderstorm Watch	SPC	Buena Vista, Cherokee, Clay, Dickinson, Emmet, Hancock and 10 more	5 hr
Jul 31, 11:41 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Calhoun, Cerro Gordo, Cherokee, Chickasaw, Clay and 19 more	64 min
Aug 1, 1:59 AM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Boone, Carroll, Cass and 24 more	91 min
Aug 1, 5:56 AM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Audubon, Boone, Bremer and 59 more	94 min
Aug 1, 1:48 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Calhoun, Carroll, Cherokee, Clay, Crawford and 17 more	117 min
Aug 1, 2:17 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Cass, Clarke, Dallas and 15 more	58 min

Nearby

Mesoscale Discussions in Iowa, 2004 Every mesoscale discussion in 2004

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.