Alert archive / Colorado / Mesoscale Discussions in 2012

Mesoscale Discussion 1664

July 31, 201219 counties in Colorado

The Storm Prediction Center issued this mesoscale discussion at Jul 31, 2012, 2:05 PM MDT for 19 counties in Colorado. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Jul 31, 2012, 2:05 PM MDT (20:05 UTC)
Expired: Jul 31, 2012, 3:00 PM MDT
In force: 55 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Adams County, CO, Arapahoe County, CO, Broomfield County, CO, Costilla County, CO, Crowley County, CO, Custer County, CO, Denver County, CO, Douglas County, CO, El Paso County, CO, Elbert County, CO, Huerfano County, CO, Jefferson County, CO, Las Animas County, CO, Lincoln County, CO, Morgan County, CO, Otero County, CO, Pueblo County, CO, Teller County, CO, Washington County, CO

The radar

The Pueblo radar (KPUX), 55 km from the middle of the area, began a volume at 20:07 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

Denver, CO (KDNR), launched 12:00Z, 8.1 hours before the alert went out and 139 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: 26 J/kg
Mixed-layer CIN: -414 J/kg
Mixed-layer LCL: 2225 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 63 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

347 
ACUS11 KWNS 312006
SWOMCD
SPC MCD 312005
COZ000-312100-

MESOSCALE DISCUSSION 1664
NWS STORM PREDICTION CENTER NORMAN OK
0305 PM CDT TUE JUL 31 2012

AREAS AFFECTED...PORTIONS OF CNTRL/ERN CO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 312005Z - 312100Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...INCREASING COVERAGE OF TSTMS OVER THE FRONT RANGE WILL
EVENTUALLY SPREAD EWD TOWARDS THE HIGH PLAINS OF CNTRL AND ERN CO.
AN ACCOMPANYING THREAT FOR DMGG WINDS AND LARGE HAIL MAY
MATERIALIZE. A WW IS NOT CURRENTLY BEING CONSIDERED...BUT MAY BE
NECESSARY IF TRENDS INCREASE.

DISCUSSION...A SMALL MCV NOTED ON VISIBLE SATELLITE IMAGERY WAS
PASSING THROUGH THE FRONT RANGE...POSITIONED W OF FCL AS OF
1930Z...AND IS CONTRIBUTING TO TSTM DEVELOPMENT OVER THE FRONT RANGE
THIS AFTERNOON. ONE SUCH STRONG STORM WAS MOVING EWD ACROSS THE
DENVER METRO AREA. MODERATE MIDLEVEL WLY FLOW ALONG THE NRN
PERIPHERY OF A SRN PLAINS ANTICYCLONE WILL SUPPORT SOME ORGANIZATION
OF TSTMS INTO SMALL CLUSTERS. BUT BOUNDARY LAYER MOISTURE IS
SOMEWHAT MARGINAL ACROSS THE HIGH PLAINS N/E OF DEN...WHERE
DEWPOINTS HAVE MIXED INTO THE UPPER 40S...LIKELY ONLY YIELDING
MLCAPE VALUES AROUND 500 J/KG. NONETHELESS...STEEP LOW-LEVEL LAPSE
RATES WILL SUPPORT AN ISOLATED THREAT FOR STRONG-SVR WIND
GUSTS...WHILE EFFECTIVE SHEAR AND MIDLEVEL LAPSE RATES ARE
MARGINALLY SUPPORTIVE FOR HAIL.

FARTHER S...TSTMS GENERALLY REMAIN ANCHORED TO THE HIGHER
TERRAIN...BUT SHOULD EVENTUALLY PROPAGATE EWD ONTO THE HIGH PLAINS.
SFC OBS REVEAL RICHER MOISTURE IS IN PLACE HERE /SFC DEWPOINTS IN
THE MID-UPPER 50S/...AND SUBSEQUENTLY...YIELDING MLCAPE VALUES NEAR
1000 J/KG. HOWEVER...WEAKER DEEP-LAYER FLOW MAY RESULT IN STORMS
STRUGGLING TO ORGANIZE...ALTHOUGH A COUPLE CLUSTERS COULD EVENTUALLY
DEVELOP DUE TO TSTM MERGERS/CONSOLIDATION AND POSE A LOCALIZED DMGG
WIND THREAT.

..ROGERS/CARBIN.. 07/31/2012

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

ATTN...WFO...GLD...PUB...BOU...

LAT...LON   40420323 39310313 38000345 37100368 36990445 37040506
            37280550 38690538 39790532 40210514 40480453 40560408
            40420323

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 30, 6:24 PM MDT	Mesoscale Discussion	SPC	Cheyenne, Kit Carson, Logan, Phillips, Washington, Yuma	36 min
Jul 30, 6:53 PM MDT	Severe Thunderstorm Watch	SPC	Cheyenne, Kit Carson, Yuma	4 hr

Nearby

Mesoscale Discussions in Colorado, 2012 Every 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.