Alert archive / Colorado / Tornado Warnings in 2018

Tornado Warning 39, NWS Denver/Boulder, CO

July 28, 2018Logan County, Colorado

NWS Denver/Boulder, CO issued this tornado warning at Jul 28, 2018, 6:54 PM MDT for Logan County, Colorado. It was in force for 22 min. 7 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Jul 28, 2018, 6:54 PM MDT (00:54 UTC)
Expired
Jul 28, 2018, 7:16 PM MDT
In force
22 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Tornado
Radar indicated
Hail
2.75 in

County Logan County, CO

The radar

The Cheyenne radar (KCYS), 136 km from the middle of the area, began a volume at 00:56 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.

What was reported inside it

TimeReportWhereRemark
Jul 28, 7:02 PM MDTTORNADO7 W Sterling, COBRIEF TOUCHDOWN IN OPEN FIELD NEAR HWY 14. NO DAMAGE REPORTED. NO INJURIES.
Jul 28, 7:08 PM MDTHAIL 1.254 Nw Sterling, CO
Jul 28, 7:10 PM MDTHAIL 1.52 Ne Sterling, COEXTENSIVE CROP DAMAGE IN THE AREA BETWEEN STERLING AND ILIFF.
Jul 28, 7:13 PM MDTTSTM WND GST 633 W Sterling, CO
Jul 28, 7:13 PM MDTHAIL 1.5Sterling, CO
Jul 28, 7:13 PM MDTHAIL 1.753 W Sterling, CO
Jul 28, 7:17 PM MDTHAIL 1.751 Sse Sterling, CO

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jul 28, 5:40 PM MDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Denver, CO (KDEN), launched 00:00Z, 0.9 hours before the alert went out and 91 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-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2018-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 863 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2018-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 167 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
863 J/kg
Mixed-layer CIN
-114 J/kg
Mixed-layer LCL
1825 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
167 m²/s²
0-3 km storm-relative helicity
331 m²/s²
Significant tornado parameter
0.1
Supercell composite
6.4

Open this sounding in Storm Lab

The text

As transmitted.

783 
WFUS55 KBOU 290054
TORBOU
COC075-290130-
/O.NEW.KBOU.TO.W.0039.180729T0054Z-180729T0130Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Denver CO
654 PM MDT SAT JUL 28 2018

The National Weather Service in Denver Colorado has issued a

* Tornado Warning for...
  Southwestern Logan County in northeastern Colorado...

* Until 730 PM MDT.
    
* At 654 PM MDT, a severe thunderstorm capable of producing a tornado
  was located 5 miles north of Logan Corners, or 6 miles northwest of
  Sterling, moving south at 40 mph.

  HAZARD...Tornado and baseball size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* Locations impacted include...
  Sterling, Logan Corners, North Sterling Reservoir, Padroni and
  Atwood.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4080 10346 4082 10313 4052 10306 4050 10343
TIME...MOT...LOC 0054Z 347DEG 35KT 4070 10333 

TORNADO...RADAR INDICATED
HAIL...2.75IN

$$

RJK
1 follow-up statement
113 
WWUS55 KBOU 290116
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
716 PM MDT SAT JUL 28 2018

COC075-290124-
/O.CAN.KBOU.TO.W.0039.000000T0000Z-180729T0130Z/
Logan CO-
716 PM MDT SAT JUL 28 2018

...THE TORNADO WARNING FOR SOUTHWESTERN LOGAN COUNTY IS CANCELLED...
    
The tornado threat has diminished and the Tornado Warning has been
cancelled. However, large hail and damaging winds remain likely and a
Severe Thunderstorm Warning remains in effect for the area.

A Severe Thunderstorm Watch remains in effect until 100 AM MDT for
northeastern Colorado.

Remember, a Severe Thunderstorm Warning still remains in effect for 
southern and southeastern Logan County.   
**!

LAT...LON 4080 10346 4082 10313 4052 10306 4050 10343
TIME...MOT...LOC 0113Z 347DEG 35KT 4050 10327 

$$

RJK

The office that day

Everything else NWS Denver/Boulder, CO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 28, 6:28 PM MDTSevere Thunderstorm WarningBOULogan47 min
Jul 28, 7:13 PM MDTSevere Thunderstorm WarningBOULogan32 min
Jul 28, 7:50 PM MDTSevere Thunderstorm WarningBOUPhillips, Sedgwick40 min
Jul 28, 8:23 PM MDTSevere Thunderstorm WarningBOUPhillips52 min
Jul 29, 2:47 PM MDTTornado WarningBOUWeld28 min
Jul 29, 3:06 PM MDTSevere Thunderstorm WarningBOUWeld39 min
Jul 29, 3:16 PM MDTSevere Thunderstorm WarningBOULogan, Weld44 min
Jul 29, 3:32 PM MDTTornado WarningBOUWeld43 min
Jul 29, 3:44 PM MDTSevere Thunderstorm WarningBOUWeld46 min
Jul 29, 4:00 PM MDTTornado WarningBOUWeld30 min
Jul 29, 4:10 PM MDTTornado WarningBOULogan, Morgan, Washington, Weld35 min
Jul 29, 4:26 PM MDTTornado WarningBOUMorgan, Weld34 min
Jul 29, 4:31 PM MDTSevere Thunderstorm WarningBOUWeld29 min
Jul 29, 4:37 PM MDTTornado WarningBOULogan, Morgan, Washington23 min
Jul 29, 4:58 PM MDTSevere Thunderstorm WarningBOUMorgan25 min
Jul 29, 5:01 PM MDTTornado WarningBOUMorgan, Washington44 min
Jul 29, 5:32 PM MDTTornado WarningBOULincoln, Washington28 min
Jul 29, 5:54 PM MDTSevere Thunderstorm WarningBOULarimer51 min
Jul 29, 5:57 PM MDTSevere Thunderstorm WarningBOULincoln, Washington23 min

Nearby

Tornado Warnings in Colorado, 2018Every tornado warning in 2018Tornadoes in 2018

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.