Alert archive / Colorado / Red Flag Warnings in 2021

Red Flag Warning 13, NWS Denver/Boulder, CO

August 28, 2021Grand County, Jackson County, Colorado

NWS Denver/Boulder, CO issued this red flag warning at Aug 28, 2021, 3:24 AM MDT for Grand County, Jackson County, Colorado. It took effect at Aug 28, 2021, 12:00 PM MDT. It was in force for 7 hr. 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 28, 2021, 3:24 AM MDT (09:24 UTC)
In effect from
Aug 28, 2021, 12:00 PM MDT
Expired
Aug 28, 2021, 7:00 PM MDT
In force
7 hr
Issued by
NWS Denver/Boulder, CO

Counties Grand County, CO, Jackson County, CO

The radar

The Cheyenne radar (KCYS), 147 km from the middle of the area, began a volume at 09:26 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

Grand Junction, CO (KGJT), launched 00:00Z, 9.4 hours before the alert went out and 239 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 00:00Z on 2021-08-28Temperature 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°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Grand Junction, CO at 00:00Z on 2021-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3684 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
18 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

983 
WWUS85 KBOU 280924
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
324 AM MDT Sat Aug 28 2021

COZ211-217-282200-
/O.NEW.KBOU.FW.W.0013.210828T1800Z-210829T0100Z/
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
324 AM MDT Sat Aug 28 2021

...RED FLAG WARNING IN EFFECT FROM NOON TODAY TO 7 PM MDT THIS
EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR MUCH OF JACKSON
COUNTY...FIRE WEATHER ZONES 211 AND 217...

The National Weather Service in Denver has issued a Red Flag
Warning for wind and low relative humidity, which is in effect
from noon today to 7 PM MDT this evening.

* Affected Area...Fire Weather Zones 211 and 217.

* Timing...Winds will increase with low humidity readings this
  afternoon. Conditions will improve by 7 pm as winds decrease.

* Winds...West 10 to 20 mph with gusts up to 30 mph.

* Relative Humidity...As low as 10 percent.

* Impacts...Fires will be able to start easily and spread quickly
  in the dry and breezy conditions. Avoid any burning or outdoor
  activity that may produce a spark. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$
1 follow-up statement
757 
WWUS85 KBOU 282057
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
257 PM MDT Sat Aug 28 2021

COZ211-217-290100-
/O.CON.KBOU.FW.W.0013.000000T0000Z-210829T0100Z/
Jackson County Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
257 PM MDT Sat Aug 28 2021

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 7 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR MUCH OF JACKSON COUNTY...
FIRE WEATHER ZONES 211 AND 217...

* Affected Area...Fire Weather Zones 211 and 217.

* Timing...Winds will increase with low humidity readings this 
  afternoon. Conditions will improve by 7 pm as winds decrease.

* Winds...West 10 to 20 mph with gusts up to 30 mph.

* Relative Humidity...As low as 11 percent.

* Impacts...Fires will be able to start easily and spread 
  quickly in the dry and breezy conditions. Avoid any burning or 
  outdoor activity that may produce a spark.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

Nearby

Red Flag Warnings in Colorado, 2021Every red flag warning 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.