Alert archive / Colorado / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 310, NWS Denver/Boulder, CO

July 20, 2023Logan County, Weld County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 20, 2023, 9:28 AM MDT for Logan County, Weld County, Colorado. It was in force for 47 min. 1 report 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 20, 2023, 9:28 AM MDT (15:28 UTC)
Expired
Jul 20, 2023, 10:15 AM MDT
In force
47 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Logan County, CO, Weld County, CO

The radar

The Cheyenne radar (KCYS), 115 km from the middle of the area, began a volume at 15:28 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 20, 10:20 AM MDTHAIL 1.253 Se North Sterling Res, CODelayed report of large hail near the intersection of County Road 46 and County Road 37 with evidence of crop damage in this swath. Relayed reports estimate that the hail was quarter size but likely larger. Time estimated by radar.

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

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 3.5 hours before the alert went out and 248 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, N. Platte/Lee Bi, NE at 12:00Z on 2023-07-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 265 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, N. Platte/Lee Bi, NE at 12:00Z on 2023-07-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -42 square meters per square second.19395878Sfc1 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
265 J/kg
Mixed-layer CIN
-168 J/kg
Mixed-layer LCL
986 m above ground
0-6 km bulk shear
31 kt
0-1 km storm-relative helicity
-42 m²/s²
0-3 km storm-relative helicity
79 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

648 
WUUS55 KBOU 201528
SVRBOU
COC075-123-201615-
/O.NEW.KBOU.SV.W.0310.230720T1528Z-230720T1615Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Denver CO
928 AM MDT Thu Jul 20 2023

The National Weather Service in Denver Colorado has issued a

* Severe Thunderstorm Warning for...
  Northeastern Weld County in northeastern Colorado...
  Northwestern Logan County in northeastern Colorado...

* Until 1015 AM MDT.

* At 927 AM MDT, a severe thunderstorm was located 4 miles west of
  Westplains, or 25 miles northwest of Sterling, moving southeast at
  25 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
           vehicles is expected.

* This severe thunderstorm will be near...
  Westplains around 935 AM MDT.

Other locations in the path of this severe thunderstorm include North
Sterling Reservoir and Padroni.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4082 10373 4097 10364 4082 10311 4057 10337
TIME...MOT...LOC 1527Z 295DEG 21KT 4086 10358 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HIRIS
3 follow-up statements
902 
WWUS55 KBOU 201541
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
941 AM MDT Thu Jul 20 2023

COC123-201551-
/O.CAN.KBOU.SV.W.0310.000000T0000Z-230720T1615Z/
Weld CO-
941 AM MDT Thu Jul 20 2023

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN WELD COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 4082 10311 4062 10332 4079 10358 4091 10357
      4095 10356
TIME...MOT...LOC 1541Z 295DEG 20KT 4082 10349 

$$

COC075-201615-
/O.CON.KBOU.SV.W.0310.000000T0000Z-230720T1615Z/
Logan CO-
941 AM MDT Thu Jul 20 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 AM MDT
FOR NORTHWESTERN LOGAN COUNTY...

At 941 AM MDT, a severe thunderstorm was located near Westplains, or
21 miles northwest of Sterling, moving southeast at 25 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
         vehicles is expected.

Locations impacted include...
  North Sterling Reservoir and Padroni.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4082 10311 4062 10332 4079 10358 4091 10357
      4095 10356
TIME...MOT...LOC 1541Z 295DEG 20KT 4082 10349 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HIRIS
092 
WWUS55 KBOU 201552
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
952 AM MDT Thu Jul 20 2023

COC075-201615-
/O.CON.KBOU.SV.W.0310.000000T0000Z-230720T1615Z/
Logan CO-
952 AM MDT Thu Jul 20 2023

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 AM MDT
FOR NORTHWESTERN LOGAN COUNTY...

At 952 AM MDT, a severe thunderstorm was located 6 miles southeast of
Westplains, or 16 miles northwest of Sterling, moving southeast at 25
mph.

HAZARD...60 mph wind gusts and half dollar size hail.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees. Hail damage to 
         vehicles is expected.

Locations impacted include...
Padroni and North Sterling Reservoir. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4078 10351 4091 10346 4088 10331 4082 10311
      4064 10330
TIME...MOT...LOC 1552Z 295DEG 21KT 4081 10341 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HIRIS
313 
WWUS55 KBOU 201617
SVSBOU

Severe Weather Statement
National Weather Service Denver CO
1017 AM MDT Thu Jul 20 2023

COC075-201626-
/O.EXP.KBOU.SV.W.0310.000000T0000Z-230720T1615Z/
Logan CO-
1017 AM MDT Thu Jul 20 2023

...THE SEVERE THUNDERSTORM WARNING FOR NORTHWESTERN LOGAN COUNTY HAS
EXPIRED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been allowed to expire.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
Denver Colorado.

Remember, a Severe Thunderstorm Warning still remains in effect for
central Logan County until 1100 AM MDT.

LAT...LON 4078 10351 4091 10346 4088 10331 4082 10311
      4064 10330
TIME...MOT...LOC 1616Z 295DEG 21KT 4075 10324 

$$

HIRIS

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 20, 3:02 AM MDTFlood WatchBOUElbert, Lincoln, Washington21 hr
Jul 20, 7:38 AM MDTSpecial Weather StatementBOUWashington52 min
Jul 20, 8:09 AM MDTSevere Thunderstorm Warning Considerable damage threatBOUWashington51 min
Jul 20, 9:47 AM MDTAreal Flood AdvisoryBOULogan, Weld3 hr
Jul 20, 10:10 AM MDTSevere Thunderstorm WarningBOULogan50 min
Jul 20, 10:49 AM MDTSpecial Weather StatementBOULogan41 min
Jul 20, 12:23 PM MDTFlash Flood WarningBOULarimer3 hr
Jul 20, 1:13 PM MDTFlash Flood WarningBOULarimer3 hr
Jul 20, 1:34 PM MDTSpecial Weather StatementBOUArapahoe41 min
Jul 20, 1:58 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe32 min
Jul 20, 2:05 PM MDTSevere Thunderstorm WarningBOUDouglas, Elbert40 min
Jul 20, 2:17 PM MDTAreal Flood AdvisoryBOUDouglas, Elbert3 hr
Jul 20, 2:35 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Morgan25 min
Jul 20, 2:40 PM MDTSevere Thunderstorm Warning Considerable damage threatBOUElbert50 min
Jul 20, 2:56 PM MDTSevere Thunderstorm WarningBOUAdams, Morgan, Washington49 min
Jul 20, 3:23 PM MDTSevere Thunderstorm Warning Considerable damage threatBOUElbert52 min
Jul 20, 3:38 PM MDTAreal Flood AdvisoryBOUElbert3 hr
Jul 20, 3:50 PM MDTSpecial Weather StatementBOUJefferson25 min
Jul 20, 3:54 PM MDTSevere Thunderstorm WarningBOULincoln51 min
Jul 20, 3:59 PM MDTFlash Flood WarningBOUGrand117 min
Jul 20, 4:01 PM MDTSevere Thunderstorm WarningBOUArapahoe, Denver, Douglas, Jefferson44 min
Jul 20, 4:07 PM MDTSevere Thunderstorm WarningBOUElbert, Lincoln38 min
Jul 20, 4:16 PM MDTSevere Thunderstorm WarningBOUMorgan, Washington32 min
Jul 20, 4:25 PM MDTSevere Thunderstorm Warning Destructive damage threatBOULincoln50 min
Jul 20, 4:38 PM MDTSevere Thunderstorm WarningBOUAdams52 min
Jul 20, 4:43 PM MDTSevere Thunderstorm WarningBOUElbert, Lincoln47 min
Jul 20, 4:59 PM MDTAreal Flood AdvisoryBOUElbert, Lincoln3 hr
Jul 20, 4:59 PM MDTSpecial Weather StatementBOUWashington46 min
Jul 20, 5:05 PM MDTAreal Flood AdvisoryBOUMorgan, Washington3 hr
Jul 20, 5:10 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Washington50 min
Jul 20, 5:15 PM MDTSevere Thunderstorm WarningBOULincoln15 min
Jul 20, 5:27 PM MDTAreal Flood AdvisoryBOUAdams, Morgan3 hr
Jul 20, 5:28 PM MDTSevere Thunderstorm WarningBOUWashington47 min
Jul 20, 5:43 PM MDTSevere Thunderstorm WarningBOUArapahoe, Elbert, Lincoln, Washington47 min

Nearby

Severe Thunderstorm Warnings in Colorado, 2023Every severe thunderstorm warning in 2023

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.