Alert archive / Colorado / Mesoscale Discussions in 2019

Mesoscale Discussion 813

May 26, 20195 states

The Storm Prediction Center issued this mesoscale discussion at May 26, 2019, 2:07 PM MDT for 5 states. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued: May 26, 2019, 2:07 PM MDT (20:07 UTC)
Expired: May 26, 2019, 4:00 PM MDT
In force: 113 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 22 counties

Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Denver County, CO, Larimer County, CO, Morgan County, CO, Weld County, CO, Carter County, MT, Sioux County, NE, Butte County, SD, Custer County, SD, Fall River County, SD, Lawrence County, SD, Campbell County, WY, Converse County, WY, Crook County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY, Weston County, WY

The radar

The Cheyenne radar (KCYS), 120 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Tornado Watch 256May 26, 3:45 PM MDT

The nearest sounding before it

Rapid City, SD (KRAP), launched 12:00Z, 8.1 hours before the alert went out and 242 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1727 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 204 m²/s²
0-3 km storm-relative helicity: 282 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

285 
ACUS11 KWNS 262007
SWOMCD
SPC MCD 262007 
SDZ000-NEZ000-COZ000-MTZ000-WYZ000-262200-

Mesoscale Discussion 0813
NWS Storm Prediction Center Norman OK
0307 PM CDT Sun May 26 2019

Areas affected...portions of north-central CO...eastern WY...far
western NE...western SD and southeast MT

Concerning...Severe potential...Watch possible 

Valid 262007Z - 262200Z

Probability of Watch Issuance...40 percent

SUMMARY...Isolated strong to severe storms are expected by late
afternoon. The strongest storms could produce large hail and locally
damaging wind gusts. A watch may be needed later this afternoon.

DISCUSSION...Strong surface heating with temperature rises of around
4-8 degrees over the last 3 hours will continue this afternoon.
Isolated thunderstorms and showers have begun to develop over higher
terrain of southeast WY into north-central CO in southeasterly
upslope flow along a surface trough. Early day cloudiness is
persisting across parts of western NE and eastern CO, and has
probably resulted in somewhat slower erosion of midlevel capping
than suggested by some guidance. Modifying the 18z DNR RAOB for
current surface obs across the region suggest some areas are nearly
uncapped as of 19z. As additional heating and modest increase in
surface dewpoints occurs toward late afternoon, deep layer forcing
should increase with northward extent and additional convection is
expected to develop northward into southeast MT/western SD along the
surface trough. Strong vertical shear will support rotating updrafts
in the presence of steep midlevel lapse rates will support large
hail in strongest storms. While low level flow below 700 mb is
rather weak, high-based storms could produce some strong outflow
wind gusts. 

Some evidence of the Denver Cyclone was still apparent in 19z
surface analysis. This could increase landspout and/or weak tornado
potential if a storm takes advantage of enhanced low level shear in
this area.

..Leitman/Thompson.. 05/26/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...UNR...BOU...CYS...BYZ...

LAT...LON   39730537 39550519 39410497 39410460 39490426 39730385
            39940367 40310363 40940369 41400381 41850372 42350350
            43100319 43650302 44540299 45220318 45730363 46050432
            46020514 45770546 44790565 43310585 42250558 40250548
            39730537

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 26, 11:19 AM MDT	Mesoscale Discussion	SPC	Baca, Bent, Cheyenne, Kiowa, Kit Carson, Prowers	116 min
May 26, 12:27 PM MDT	Tornado Watch	SPC	Baca, Bent, Cheyenne, Crowley, Kiowa, Kit Carson and 4 more	9 hr
May 26, 2:43 PM MDT	Mesoscale Discussion	SPC	Baca, Bent, Cheyenne, Crowley, Kiowa, Kit Carson and 6 more	92 min
May 26, 3:46 PM MDT	Tornado Watch	SPC	Adams, Arapahoe, Denver, Elbert, Lincoln, Morgan and 2 more	4 hr
May 26, 5:04 PM MDT	Mesoscale Discussion	SPC	Baca, Bent, Prowers	86 min
May 26, 4:27 PM MDT	Mesoscale Discussion	SPC	Adams, Buffalo, Clay, Custer, Dawson, Fillmore and 19 more	63 min
May 26, 4:42 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Clay, Dawson, Fillmore, Franklin and 11 more	6 hr
May 26, 5:03 PM MDT	Mesoscale Discussion	SPC	Banner, Box Butte, Cheyenne, Kimball, Morrill, Scotts Bluff and 1 more	57 min

Nearby

Mesoscale Discussions in Colorado, 2019 Mesoscale Discussions in Wyoming, 2019 Mesoscale Discussions in South Dakota, 2019 Every mesoscale discussion in 2019

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.