Alert archive / Colorado / Dense Fog Advisories in 2021

Dense Fog Advisory 5, NWS Denver/Boulder, CO

May 24, 20218 counties in Colorado

NWS Denver/Boulder, CO issued this dense fog advisory at May 24, 2021, 6:23 AM MDT for 8 counties in Colorado. It was in force for 3 hr.

The area

The counties it named.

The facts

Issued
May 24, 2021, 6:23 AM MDT (12:23 UTC)
Expired
May 24, 2021, 9:00 AM MDT
In force
3 hr
Issued by
NWS Denver/Boulder, CO

Counties Elbert County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 109 km from the middle of the area, began a volume at 12:26 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.

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 0.4 hours before the alert went out and 257 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 2021-05-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2021-05-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -95 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1599 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
-95 m²/s²
0-3 km storm-relative helicity
111 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 dense fog advisory 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 dense fog advisory went out at May 23, 3:19 PM MDT, 15 hours 4 minutes earlier.

Area forecast discussion, May 23, 3:19 PM MDT, 15 hours 4 minutes before
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Hazardous weather outlook, May 23, 11:14 AM MDT, 19 hours 9 minutes before
Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1114 AM MDT Sun May 23 2021

COZ030>051-241715-
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-
1114 AM MDT Sun May 23 2021

...SEVERE THUNDERSTORMS WITH A FEW TORNADOES EXPECTED ACROSS
NORTHEAST COLORADO...

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

.DAY ONE...This Afternoon and Tonight

Severe thunderstorms with large hail, damaging winds, and a few
tornadoes are expected across northeast Colorado this afternoon
and early evening. The dryline has been slow to push eastward, and
thus the severe weather threat has shifted further west.

While a few showers and storms will occur over the Front Range and
I-25 Corridor, the highest threat of severe storms today will be
east of a line from Cheyenne, Wyoming to around Greeley and then
southward to near Denver International Airport and Kiowa. Large
hail up to golfball sized hail and damaging winds up to 70 mph can
be expected from most severe storms, while a couple storms will be
capable of producing longer track tornadoes and baseball sized
hail.

Drier conditions and gusty southwest winds will develop from west
to east across the mountains and I-25 Corridor later this
afternoon, behind the above mentioned dryline. Storms will be
ending from west to east, exiting the far northeast corner of the
state around 7 or 8 pm.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Monday through early Wednesday will be drier with near normal
temperatures, then expect an increasing threat of afternoon and
evening storms Wednesday afternoon and Thursday, especially across
the northeast plains.

Drier again with only a slight chance of late day storms for the
Friday through Saturday period. Temperatures will be above normal
with readings around 80 degrees.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be required across the plains by noon.

The office that day

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

IssuedProductOfficeCountiesLasted
May 23, 6:19 PM MDTSevere Thunderstorm WarningBOUPhillips, Sedgwick41 min

Nearby

Dense Fog Advisories in Colorado, 2021Every dense fog advisory in 2021

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.