Alert archive / Wyoming / Mesoscale Discussions in 2004

Mesoscale Discussion 1649

July 13, 2004Powder River County, Montana; 5 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jul 13, 2004, 3:50 PM MDT for Powder River County, Montana; 5 counties in Wyoming. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Jul 13, 2004, 3:50 PM MDT (21:50 UTC)
Expired: Jul 13, 2004, 5:45 PM MDT
In force: 115 min
Issued by: the Storm Prediction Center

Counties Powder River County, MT, Campbell County, WY, Crook County, WY, Johnson County, WY, Sheridan County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 229 km from the middle of the area, began a volume at 21:51 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 (KUNR), launched 12:00Z, 9.8 hours before the alert went out and 226 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: 3 J/kg
Mixed-layer CIN: -660 J/kg
Mixed-layer LCL: 1729 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: -11 m²/s²
0-3 km storm-relative helicity: 278 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

623 
ACUS11 KWNS 132151
SWOMCD
SPC MCD 132150 
SDZ000-MTZ000-WYZ000-132345-

MESOSCALE DISCUSSION 1649
NWS STORM PREDICTION CENTER NORMAN OK
0450 PM CDT TUE JUL 13 2004

AREAS AFFECTED...NERN WY...SERN MT

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 132150Z - 132345Z

ISOLATED SEVERE THUNDERSTORMS MAY DEVELOP ACROSS NORTHEAST WY DURING
THE NEXT FEW HOURS.  AREA IS BEING MONITORED FOR A POSSIBLE WW.

VISIBLE SATELLITE AND RADAR IMAGERY SHOW ISOLATED THUNDERSTORMS
BEGINNING TO DEVELOP ALONG THE BIG HORN MTNS IN SHERIDAN/JOHNSON
COUNTIES WY.  THIS AREA IS BENEATH FLAT UPPER RIDGE AXIS...BUT
WITHIN MODERATELY STRONG WESTERLY MID LEVEL WINDS /30-35 KNOTS AT
500MB/.  SOUTHEASTERLY LOW LEVEL WINDS IN THIS REGION AND SURFACE
DEWPOINTS IN THE LOW/MID 50S ARE PROVIDING A FAVORABLE THERMODYNAMIC
AND SHEAR ENVIRONMENT FOR ORGANIZED/SUPERCELL STORMS.  AREAL
COVERAGE AND EASTWARD EXTENT OF CONVECTIVE DEVELOPMENT REMAIN
UNCERTAIN AT THIS TIME.  HOWEVER...THIS AREA WILL BE MONITORED FOR
THE NEXT 1-2 HOURS FOR FURTHER INTENSIFICATION AND POSSIBLE WW
ISSUANCE.

..HART.. 07/13/2004

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

ATTN...WFO...UNR...CYS...BYZ...RIW...

44530713 45350690 45430536 45190465 44810413 43830405
43080434 43210627 43540693

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 13, 2:27 PM MDT	Mesoscale Discussion	SPC	Goshen, Laramie, Platte	3 hr
Jul 13, 3:10 PM MDT	Severe Thunderstorm Watch	SPC	Albany, Converse, Goshen, Laramie, Platte	6 hr

Nearby

Mesoscale Discussions in Wyoming, 2004 Mesoscale Discussions in Montana, 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.