Alert archive / Colorado / Flash Flood Watches in 2022

Flash Flood Watch 3, NWS Denver/Boulder, CO

July 27, 20229 counties in Colorado

NWS Denver/Boulder, CO issued this flash flood watch at Jul 27, 2022, 2:43 PM MDT for 9 counties in Colorado. It took effect at Jul 28, 2022, 11:00 AM MDT. It was in force for 10 hr.

The area

The counties it named.

The facts

Issued
Jul 27, 2022, 2:43 PM MDT (20:43 UTC)
In effect from
Jul 28, 2022, 11:00 AM MDT
Expired
Jul 28, 2022, 9:28 PM MDT
In force
10 hr
Issued by
NWS Denver/Boulder, CO
Flood severity
None

Counties Boulder County, CO, Clear Creek County, CO, Gilpin County, CO, Grand County, CO, Jackson County, CO, Jefferson County, CO, Larimer County, CO, Park County, CO, Summit County, CO

The radar

The Denver radar (KFTG), 102 km from the middle of the area, began a volume at 20:46 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 nearest sounding before it

Grand Junction, CO (KGJT), launched 12:00Z, 8.7 hours before the alert went out and 254 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, Grand Junction, CO at 12:00Z on 2022-07-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 48 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, Grand Junction, CO at 12:00Z on 2022-07-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 43 square meters per square second.1939Sfc1 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
48 J/kg
Mixed-layer CIN
-235 J/kg
Mixed-layer LCL
2016 m above ground
0-6 km bulk shear
6 kt
0-1 km storm-relative helicity
43 m²/s²
0-3 km storm-relative helicity
-11 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood watch 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 flash flood watch went out at Jul 27, 11:52 AM MDT, 2 hours 51 minutes earlier.

Area forecast discussion, Jul 27, 11:52 AM MDT, 2 hours 51 minutes before
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Hazardous weather outlook, Jul 27, 10:55 AM MDT, 3 hours 48 minutes before
Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1055 AM MDT Wed Jul 27 2022

COZ030>051-281700-
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-
1055 AM MDT Wed Jul 27 2022

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

.DAY ONE...Today and Tonight

There will be a chance of thunderstorms mainly over the northeast
plains late this afternoon and evening. A few storms may become
severe. Damaging wind gusts to 60 mph and heavy rainfall and
localized flash flooding. Hail up to quarter size is also possible
with a low tornado threat for the far northeast corner.

It is difficult to assess how all this will play out. It looks
like the best coverage will be over the northeast plains by early
this evening, with the potential for storms developing into the
urban corridor mid to late evening. Shower and thunderstorm
coverage will slowly decrease after midnight. There is a limited
risk of flash flooding primarily in the Cameron and Calwood burn
areas this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Numerous showers and thunderstorms are expected Thursday and
Friday. Heavy rain, small hail, and wind gusts to 50 mph will
accompany the stronger storms. The main threat will be heavy rain
that leads to flashing flooding in the burn areas. Heavy rain
will may also produce isolated flooding across the Front Range and
northeast Colorado. The amount of storms and storm intensity
decrease Saturday, but the flash flooding threat will linger for
the burn areas. A warmer and drier period is expect for Sunday and
early next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight but
rainfall reports would be greatly appreciated.

In the hours before

Special weather statement, Jul 27, 2:35 PM MDT, 8 minutes before
Special Weather Statement
National Weather Service Denver CO
235 PM MDT Wed Jul 27 2022

COZ041-045-046-272230-
Elbert/Central and East Douglas Counties Above 6000 Feet CO-
North and Northeast Elbert County Below 6000 Feet/North Lincoln
County CO-Central and East Adams and Arapahoe Counties CO-
235 PM MDT Wed Jul 27 2022

...Brief landspout tornadoes possible...

Conditions will be favorable for the development of landspout
tornadoes in eastern Douglas, northwest Elbert, and central Arapahoe
counties over the next couple of hours. At this time, it is unkown
which if any storm would produce a landspout. Any landspouts that
develop are expected to pose a limited threat.

HAZARD...Landspouts possible.

SOURCE...Radar indicated.

IMPACT...Landspout tornadoes can damage mobile homes, roofs,
         vehicles, and trees. Outdoor objects may be tossed about.

Locations impacted include...
Southeastern Castle Rock, Bennett, Elizabeth, Larkspur, Ponderosa
Park, Franktown, The Pinery and Strasburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

If a tornado is spotted seek shelter inside a sturdy building.

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

&&

LAT...LON 3925 10493 3961 10457 3961 10456 3958 10455
      3958 10453 3967 10451 3977 10441 3963 10419
      3913 10470
TIME...MOT...LOC 2032Z 240DEG 48KT 3944 10446

LANDSPOUT...POSSIBLE
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH

RODRIGUEZ

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 26, 6:29 PM MDTSpecial Weather StatementBOULincoln46 min
Jul 26, 6:41 PM MDTSevere Thunderstorm WarningBOULincoln34 min
Jul 26, 6:50 PM MDTAreal Flood AdvisoryBOUDouglas115 min
Jul 26, 7:24 PM MDTSpecial Weather StatementBOULincoln66 min
Jul 26, 8:28 PM MDTSpecial Weather StatementBOUBroomfield32 min
Jul 26, 8:45 PM MDTSpecial Weather StatementBOUDenver30 min
Jul 26, 9:37 PM MDTAreal Flood AdvisoryBOUDouglas, Jefferson3 hr
Jul 26, 10:48 PM MDTAreal Flood AdvisoryBOUAdams, Denver, Jefferson87 min
Jul 26, 11:12 PM MDTAreal Flood AdvisoryBOUDouglas2 hr
Jul 26, 11:22 PM MDTAreal Flood AdvisoryBOUArapahoe, Denver, Jefferson113 min
Jul 26, 11:30 PM MDTAreal Flood AdvisoryBOUBoulder, Weld105 min
Jul 27, 2:27 PM MDTAreal Flood AdvisoryBOULarimer3 hr
Jul 27, 2:35 PM MDTSpecial Weather StatementBOUArapahoe115 min
Jul 27, 4:15 PM MDTSpecial Weather StatementBOUArapahoe45 min
Jul 27, 4:24 PM MDTSevere Thunderstorm WarningBOUWeld51 min
Jul 27, 5:10 PM MDTSpecial Weather StatementBOUWeld50 min
Jul 27, 5:25 PM MDTSevere Thunderstorm WarningBOUWeld50 min
Jul 27, 5:58 PM MDTSevere Thunderstorm Warning Considerable damage threatBOUWeld29 min

Nearby

Flash Flood Watches in Colorado, 2022Every flash flood watch in 2022

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.