Alert archive / Colorado / Severe Thunderstorm Warnings in 2023
Severe Thunderstorm Warning 328, NWS Denver/Boulder, CO
NWS Denver/Boulder, CO issued this severe thunderstorm warning at Jul 20, 2023, 5:43 PM MDT for 4 counties in Colorado. It was in force for 47 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Jul 20, 2023, 5:43 PM MDT (23:43 UTC)
- Expired
- Jul 20, 2023, 6:30 PM MDT
- In force
- 47 min
- Issued by
- NWS Denver/Boulder, CO
- Area
- Storm-based polygon
- Hail
- 1.5 in
- Wind
- 60.0 mph
Counties Arapahoe County, CO, Elbert County, CO, Lincoln County, CO, Washington County, CO
The radar
The Denver radar (KFTG), 73 km from the middle of the area, began a volume at 23:45 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 watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jul 20, 1:27 PM MDT | Severe Thunderstorm Watch | SPC | 9 hr |
The nearest sounding before it
N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.7 hours before the alert went out and 328 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.
- 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
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Denver/Boulder, CO wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 20, 5:39 PM MDT, 4 minutes earlier.
Area forecast discussion, Jul 20, 5:39 PM MDT, 4 minutes before
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Hazardous Weather Outlook National Weather Service Denver/Boulder CO 1013 AM MDT Thu Jul 20 2023 COZ030>051-211615- Jackson County Below 9000 Feet- West Jackson and West Grand Counties Above 9000 Feet- Grand and Summit Counties Below 9000 Feet- South and East Jackson/Larimer/North and Northeast Grand/ Northwest Boulder Counties Above 9000 Feet- South and Southeast Grand/West Central and Southwest Boulder/ Gilpin/Clear Creek/Summit/North and West Park Counties Above 9000 Feet-Larimer and Boulder Counties Between 6000 and 9000 Feet- Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear Creek/Northeast Park Counties Below 9000 Feet- Central and Southeast Park County- Larimer County Below 6000 Feet/Northwest Weld County- Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County- North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe Counties/East Broomfield County- Elbert/Central and East Douglas Counties Above 6000 Feet- Northeast Weld County-Central and South Weld County-Morgan County- Central and East Adams and Arapahoe Counties- North and Northeast Elbert County Below 6000 Feet/North Lincoln County- Southeast Elbert County Below 6000 Feet/South Lincoln County- Logan County-Washington County-Sedgwick County-Phillips County- 1013 AM MDT Thu Jul 20 2023 ...Strong to severe thunderstorms possible through this evening... ...Flood Watch in effect for eastern Elbert, Lincoln and Washington counties 2 PM to 10 PM this evening... This hazardous weather outlook is for northeast and north central Colorado. .DAY ONE...Today and Tonight An active period of thunderstorms will occur through this evening with storms becoming stronger and more numerous during the afternoon and evening hours. Some of these storms are expected to become severe across the plains with hail up to tennis ball size, damaging wind gusts, very heavy rain, and isolated tornadoes. The flash flood threat will be elevated in the burn scars this afternoon, with the greatest threat of flash flooding expected to be over Lincoln, Eastern Elbert and Washington counties. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Thunderstorm activity will decrease Friday with isolated to scattered thunderstorms. By Saturday, most areas will be dry with only a few high based showers and storms possible over the higher terrain. Temperatures will be increasing with highs reaching the mid 90s Sunday and into early next week. .SPOTTER INFORMATION STATEMENT... Spotter activation will be needed across the plains through this evening.
In the hours before
Local storm report, Jul 20, 3:49 PM MDT, 1 hour 54 minutes before
Preliminary Local Storm Report...Summary
National Weather Service Denver CO
349 PM MDT Thu Jul 20 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0343 PM Hail Simla 39.15N 104.08W
07/20/2023 E1.75 inch Elbert CO Trained Spotter
0250 PM Hail 4 E Kiowa 39.33N 104.38W
07/20/2023 M1.75 inch Elbert CO Trained Spotter
0213 PM Hail 4 ENE Ponderosa Park 39.41N 104.57W
07/20/2023 M1.00 inch Elbert CO Trained Spotter
Spotter: E561.
0208 PM Hail 1 NE Ponderosa Park 39.41N 104.62W
07/20/2023 E1.00 inch Elbert CO Public
Report from mPING: Quarter (1.00 in.).
0123 PM Hail 2 NW Castlewood Canyon 39.37N 104.80W
07/20/2023 E0.75 inch Douglas CO Public
Report from mPING: Dime (0.75 in.).
&&Special weather statement, Jul 20, 3:50 PM MDT, 1 hour 53 minutes before
Special Weather Statement
National Weather Service Denver CO
350 PM MDT Thu Jul 20 2023
COZ036-039-040-202215-
Boulder And Jefferson Counties Below 6000 Feet/West Broomfield County
CO-
North Douglas County Below 6000 Feet/Denver/West Adams and Arapahoe
Counties/East Broomfield County CO-
Jefferson and West Douglas Counties Above 6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet CO-
350 PM MDT Thu Jul 20 2023
...A strong thunderstorm will impact portions of north central
Douglas, southwestern Arapahoe, southwestern Denver and northern
Jefferson Counties through 415 PM MDT...
At 350 PM MDT, Doppler radar was tracking a strong thunderstorm near
Red Rocks Park, or 13 miles west of Denver, moving southeast at 30
mph.
HAZARD...Winds in excess of 40 mph and penny size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Denver, western Aurora, Lakewood, southwestern Centennial, Highlands
Ranch, Littleton, Englewood, southwestern Wheat Ridge, Golden,
Greenwood Village, Evergreen, Sheridan, Morrison, Idledale, Tiny
Town, Chatfield Reservoir, Kittredge, Red Rocks Park, Indian Hills
and Louviers.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
A Severe Thunderstorm Watch remains in effect until 900 PM MDT for
central and northeastern Colorado.
&&
LAT...LON 3947 10501 3967 10534 3980 10526 3970 10481
3953 10496 3953 10497 3952 10498 3951 10498
TIME...MOT...LOC 2150Z 296DEG 27KT 3970 10521
MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH
HIRISLocal storm report, Jul 20, 4:10 PM MDT, 1 hour 33 minutes before
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</html>Local storm report, Jul 20, 4:27 PM MDT, 1 hour 16 minutes before
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</html>The office that day
Everything else NWS Denver/Boulder, CO issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 20, 3:02 AM MDT | Flood Watch | BOU | Elbert, Lincoln, Washington | 21 hr |
| Jul 20, 7:38 AM MDT | Special Weather Statement | BOU | Washington | 52 min |
| Jul 20, 8:09 AM MDT | Severe Thunderstorm Warning | BOU | Washington | 51 min |
| Jul 20, 9:28 AM MDT | Severe Thunderstorm Warning | BOU | Logan, Weld | 47 min |
| Jul 20, 9:47 AM MDT | Areal Flood Advisory | BOU | Logan, Weld | 3 hr |
| Jul 20, 10:10 AM MDT | Severe Thunderstorm Warning | BOU | Logan | 50 min |
| Jul 20, 10:49 AM MDT | Special Weather Statement | BOU | Logan | 41 min |
| Jul 20, 12:23 PM MDT | Flash Flood Warning | BOU | Larimer | 3 hr |
| Jul 20, 1:13 PM MDT | Flash Flood Warning | BOU | Larimer | 3 hr |
| Jul 20, 1:34 PM MDT | Special Weather Statement | BOU | Arapahoe | 41 min |
| Jul 20, 1:58 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe | 32 min |
| Jul 20, 2:05 PM MDT | Severe Thunderstorm Warning | BOU | Douglas, Elbert | 40 min |
| Jul 20, 2:17 PM MDT | Areal Flood Advisory | BOU | Douglas, Elbert | 3 hr |
| Jul 20, 2:35 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe, Morgan | 25 min |
| Jul 20, 2:40 PM MDT | Severe Thunderstorm Warning | BOU | Elbert | 50 min |
| Jul 20, 2:56 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Morgan, Washington | 49 min |
| Jul 20, 3:23 PM MDT | Severe Thunderstorm Warning | BOU | Elbert | 52 min |
| Jul 20, 3:38 PM MDT | Areal Flood Advisory | BOU | Elbert | 3 hr |
| Jul 20, 3:50 PM MDT | Special Weather Statement | BOU | Jefferson | 25 min |
| Jul 20, 3:54 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln | 51 min |
| Jul 20, 3:59 PM MDT | Flash Flood Warning | BOU | Grand | 117 min |
| Jul 20, 4:01 PM MDT | Severe Thunderstorm Warning | BOU | Arapahoe, Denver, Douglas, Jefferson | 44 min |
| Jul 20, 4:07 PM MDT | Severe Thunderstorm Warning | BOU | Elbert, Lincoln | 38 min |
| Jul 20, 4:16 PM MDT | Severe Thunderstorm Warning | BOU | Morgan, Washington | 32 min |
| Jul 20, 4:25 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln | 50 min |
| Jul 20, 4:38 PM MDT | Severe Thunderstorm Warning | BOU | Adams | 52 min |
| Jul 20, 4:43 PM MDT | Severe Thunderstorm Warning | BOU | Elbert, Lincoln | 47 min |
| Jul 20, 4:59 PM MDT | Areal Flood Advisory | BOU | Elbert, Lincoln | 3 hr |
| Jul 20, 4:59 PM MDT | Special Weather Statement | BOU | Washington | 46 min |
| Jul 20, 5:05 PM MDT | Areal Flood Advisory | BOU | Morgan, Washington | 3 hr |
| Jul 20, 5:10 PM MDT | Severe Thunderstorm Warning | BOU | Adams, Arapahoe, Washington | 50 min |
| Jul 20, 5:15 PM MDT | Severe Thunderstorm Warning | BOU | Lincoln | 15 min |
| Jul 20, 5:27 PM MDT | Areal Flood Advisory | BOU | Adams, Morgan | 3 hr |
| Jul 20, 5:28 PM MDT | Severe Thunderstorm Warning | BOU | Washington | 47 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.