Alert archive / Colorado / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 356, NWS Denver/Boulder, CO

August 1, 2023Jefferson County, Colorado

NWS Denver/Boulder, CO issued this severe thunderstorm warning at Aug 1, 2023, 2:24 PM MDT for Jefferson County, Colorado. It was in force for 36 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
Aug 1, 2023, 2:24 PM MDT (20:24 UTC)
Expired
Aug 1, 2023, 3:00 PM MDT
In force
36 min
Issued by
NWS Denver/Boulder, CO
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

County Jefferson County, CO

The radar

The Denver radar (KFTG), 64 km from the middle of the area, began a volume at 20:26 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 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 Aug 1, 11:49 AM MDT, 2 hours 35 minutes earlier.

Area forecast discussion, Aug 1, 11:49 AM MDT, 2 hours 35 minutes before
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Hazardous weather outlook, Aug 1, 9:58 AM MDT, 4 hours 26 minutes before
Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
958 AM MDT Tue Aug 1 2023

COZ030>051-021600-
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-
958 AM MDT Tue Aug 1 2023

...FLOOD WATCH FOR THE I-25 URBAN CORRIDOR, FRONT RANGE
FOOTHILLS, NORTHEAST PLAINS, AND PORTIONS OF THE NORTHERN
MOUNTAINS NOON TODAY UNTIL MIDNIGHT TONIGHT...

This hazardous weather outlook is for northeast and north central
Colorado.

.DAY ONE...Today and Tonight

The threat of flash flooding will remain in the forecast this
afternoon and evening as another round of storms with very heavy
rainfall move across the area. Numerous thunderstorms will
develop over the mountains in the early to mid afternoon hours,
spreading east across the I-25 Corridor through the late afternoon
hours and over the northeast plains this evening.

The strongest storms will be capable of producing 1.5 to over 2
inches of rain in 45 minutes or less. A couple storms may also
become severe with strong winds greater than 60 mph and hail up to
1.5 inches in diameter. The greatest threat of severe thunderstorms
appears to be along and Palmer Divide south and east of Denver.

Never drive through flooded roads or water of unknown depth. Avoid
recreational activities in or near burn areas today, have
multiple ways to receive warnings, and be ready to take action and
move to higher ground if a warning is issued for your area.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday

The flash flood threat will continue on Wednesday afternoon and
evening. Storms that develop will be capable of producing locally
heavy rain and flash flooding.

Thursday and Friday will have decreased storm coverage, though
there will still be a low threat of flash flooding and a few
severe storms. Increased thunderstorm activity is possible again
over the weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today and tonight. However,
any reports of heavy rainfall, flooding, hail, and strong winds
will be appreciated.

In the hours before

Special weather statement, Aug 1, 2:17 PM MDT, 7 minutes before
Special Weather Statement
National Weather Service Denver CO
217 PM MDT Tue Aug 1 2023

COZ036-012100-
Jefferson and West Douglas Counties Above  6000 Feet/Gilpin/Clear
Creek/Northeast Park Counties Below 9000 Feet CO-
217 PM MDT Tue Aug 1 2023

...A strong thunderstorm will impact portions of central Jefferson
County through 300 PM MDT...

At 217 PM MDT, Doppler radar was tracking a strong thunderstorm over
Pine Junction, or 28 miles southwest of Denver, moving east at 10
mph.

HAZARD...Winds in excess of 40 mph and nickel 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...
Morrison, Tiny Town, Buffalo Creek, Conifer, Pine Grove, South
Platte, Aspen Park, Pine Junction and Indian Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3951 10546 3952 10544 3950 10542 3952 10543
      3953 10542 3951 10541 3952 10539 3950 10534
      3952 10534 3956 10540 3964 10518 3939 10512
      3938 10544
TIME...MOT...LOC 2017Z 256DEG 8KT 3948 10538

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

DANIELSON

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 6:09 PM MDTSevere Thunderstorm Warning Considerable damage threatBOUWeld36 min
Jul 31, 6:35 PM MDTAreal Flood AdvisoryBOUDouglas2 hr
Jul 31, 6:38 PM MDTSevere Thunderstorm WarningBOUBoulder, Jefferson37 min
Jul 31, 6:40 PM MDTSevere Thunderstorm WarningBOULarimer, Weld50 min
Jul 31, 6:46 PM MDTSpecial Weather StatementBOUDouglas44 min
Jul 31, 7:10 PM MDTFlash Flood WarningBOUDouglas110 min
Jul 31, 7:23 PM MDTSpecial Weather StatementBOUArapahoe52 min
Jul 31, 7:30 PM MDTSevere Thunderstorm WarningBOULarimer, Weld45 min
Jul 31, 7:37 PM MDTFlash Flood WarningBOULarimer3 hr
Jul 31, 7:52 PM MDTSevere Thunderstorm WarningBOUElbert38 min
Jul 31, 8:12 PM MDTFlash Flood WarningBOULarimer3 hr
Jul 31, 8:14 PM MDTFlash Flood WarningBOULarimer3 hr
Jul 31, 8:38 PM MDTSpecial Weather StatementBOUAdams, Arapahoe52 min
Jul 31, 9:26 PM MDTRiver Flood WarningBOUDouglas6 hr
Jul 31, 9:34 PM MDTSpecial Weather StatementBOUElbert26 min
Jul 31, 9:49 PM MDTSpecial Weather StatementBOUElbert26 min
Jul 31, 10:49 PM MDTSpecial Weather StatementBOUWashington41 min
Jul 31, 10:51 PM MDTSevere Thunderstorm WarningBOUWashington24 min
Aug 1, 2:17 PM MDTSpecial Weather StatementBOUJefferson43 min
Aug 1, 2:58 PM MDTSevere Thunderstorm WarningBOUDouglas, Jefferson32 min
Aug 1, 3:23 PM MDTFlash Flood WarningBOUJefferson3 hr
Aug 1, 3:27 PM MDTSevere Thunderstorm WarningBOUDouglas, Jefferson19 min
Aug 1, 3:58 PM MDTSpecial Weather StatementBOUWashington32 min
Aug 1, 4:06 PM MDTSevere Thunderstorm WarningBOUAdams, Arapahoe, Washington24 min
Aug 1, 4:10 PM MDTSpecial Weather StatementBOUDenver35 min
Aug 1, 4:19 PM MDTSevere Thunderstorm WarningBOULarimer, Weld26 min
Aug 1, 4:28 PM MDTSevere Thunderstorm Warning Considerable damage threatBOUArapahoe, Washington47 min
Aug 1, 5:05 PM MDTSpecial Weather StatementBOUBoulder25 min
Aug 1, 5:13 PM MDTFlash Flood WarningBOUBoulder3 hr
Aug 1, 5:15 PM MDTSevere Thunderstorm WarningBOUAdams30 min
Aug 1, 5:37 PM MDTAreal Flood AdvisoryBOUWashington3 hr
Aug 1, 5:40 PM MDTSpecial Weather StatementBOUBroomfield50 min
Aug 1, 5:43 PM MDTSevere Thunderstorm WarningBOUWeld32 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; radar from the NEXRAD Level II archive.