Alert archive / Colorado / Red Flag Warnings in 2020

Red Flag Warning 28, NWS Denver/Boulder, CO

October 4, 202021 counties in Colorado

NWS Denver/Boulder, CO issued this red flag warning at Oct 4, 2020, 4:01 AM MDT for 21 counties in Colorado. It took effect at Oct 5, 2020, 12:00 AM MDT. It was in force for 18 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
Oct 4, 2020, 4:01 AM MDT (10:01 UTC)
In effect from
Oct 5, 2020, 12:00 AM MDT
Expired
Oct 5, 2020, 6:00 PM MDT
In force
18 hr
Issued by
NWS Denver/Boulder, CO
All 21 counties

Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Clear Creek County, CO, Denver County, CO, Douglas County, CO, Elbert County, CO, Gilpin County, CO, Grand County, CO, Jackson County, CO, Larimer County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Park County, CO, Phillips County, CO, Sedgwick County, CO, Summit County, CO, Washington County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 22 km from the middle of the area, began a volume at 10:03 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

Denver, CO (KDNR), launched 00:00Z, 10.0 hours before the alert went out and 118 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, Denver, CO at 00:00Z on 2020-10-04Temperature 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 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2020-10-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 32 square meters per square second.1939587897Sfc1 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
2331 m above ground
0-6 km bulk shear
58 kt
0-1 km storm-relative helicity
32 m²/s²
0-3 km storm-relative helicity
233 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

541 
WWUS85 KBOU 041001
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
401 AM MDT Sun Oct 4 2020

...Critical Fire Weather Conditions expected on Monday for the 
higher elevations of the northern mountains, North Park and Middle
Parks, and the northern plains...

.Increased flow along the Colorado-Wyoming border is expected to
begin after midnight tonight as mountain wave enhancement of the 
winds is likely across the east slopes of the Front Range 
Mountains of Jackson and Larimer Counties. The strongest winds are
expected before sunrise Monday and could gust to 50 mph in the 
most favored locations. There will also be poor relative humidity 
recovery over the Northern Front Range foothills tonight. 

After sunrise, the rest of the area will see gradually increasing
winds with strong mixing and full sun. Relative humidity will be 
below 15 percent and gusty winds are expected across the plains. 

COZ215-218-041815-
/O.UPG.KBOU.FW.A.0019.201005T0600Z-201006T0000Z/
/O.NEW.KBOU.FW.W.0028.201005T0600Z-201006T0000Z/
Larimer and Boulder Counties Between 6000 and 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
401 AM MDT Sun Oct 4 2020

...RED FLAG WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 6 PM MDT
MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR NORTH CENTRAL
MOUNTAINS AND NORTHERN FRONT RANGE FOOTHILLS...

The National Weather Service in Denver has issued a Red Flag
Warning FOR WIND AND LOW RELATIVE HUMIDITY, which is in effect
from midnight tonight to 6 PM MDT Monday. The Fire Weather Watch
is no longer in effect.

* Affected Area...Fire Weather Zones 215 and 218.

* Timing...Midnight tonight through 6 PM Monday.

* Winds...West 15 to 30 mph with gusts up to 50 mph.

* Relative Humidity...As low as 13 percent.

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.

&&

$$

COZ211>213-217-238-242-248-250-251-041815-
/O.UPG.KBOU.FW.A.0019.201005T1200Z-201006T0000Z/
/O.NEW.KBOU.FW.W.0028.201005T1200Z-201006T0000Z/
Jackson County Below 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Grand and Summit Counties Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Larimer County Below 6000 Feet/Northwest Weld County-
Northeast Weld County-Logan County-Sedgwick County-
Phillips County-
401 AM MDT Sun Oct 4 2020

...RED FLAG WARNING IN EFFECT FROM 6 AM TO 6 PM MDT MONDAY FOR
WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF NORTHERN
MOUNTAINS...HIGH VALLEYS...AND FAR NORTHERN PLAINS...

The National Weather Service in Denver has issued a Red Flag
Warning FOR WIND AND LOW RELATIVE HUMIDITY, which is in effect
from 6 AM to 6 PM MDT Monday. The Fire Weather Watch is no longer
in effect.

* Affected Area...Fire Weather Zones 211, 212, 213, 217, 238, 
  242, 248, 250 and 251.

* Timing...6 AM to 6 PM Monday

* Winds...Northwest 15 to 25 mph with gusts up to 35 mph.

* Relative Humidity...As low as 12 percent.

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.

&&

$$

COZ240-241-243>247-249-041815-
/O.NEW.KBOU.FW.W.0028.201005T1700Z-201006T0000Z/
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
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-
Washington County-
401 AM MDT Sun Oct 4 2020

...RED FLAG WARNING IN EFFECT FROM 11 AM TO 6 PM MDT MONDAY FOR
WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF NORTHEAST PLAINS 
OF COLORADO...

The National Weather Service in Denver has issued a Red Flag 
Warning FOR WIND AND LOW RELATIVE HUMIDITY, which is in effect 
from 11 AM to 6 PM MDT Monday.

* Affected Area...Fire Weather Zones 240, 241, 243, 244, 245, 
  246, 247 and 249.

* Timing...11 am to 6 pm Monday

* Winds...North 15 to 25 mph with gusts up to 35 mph.

* Relative Humidity...As low as 9 percent.

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.

&&

$$
4 follow-up statements
905 
WWUS85 KBOU 042015
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
215 PM MDT Sun Oct 4 2020

...Critical Fire Weather Conditions expected on Monday for the
higher elevations of the northern mountains, North Park and
Middle Parks, and the northern plains...

.Increased flow along the Colorado-Wyoming border is expected to
begin after midnight tonight as mountain wave enhancement of the
winds is likely across the east slopes of the Front Range
Mountains of Jackson and Larimer Counties. The strongest winds
are expected before sunrise Monday and could gust to 50 mph in
the most favored locations. There will also be poor relative
humidity recovery over the Northern Front Range foothills
tonight.

After sunrise, the rest of the area will see gradually increasing
winds with strong mixing and full sun. Relative humidity will be
below 15 percent and gusty winds are expected across the plains.

COZ215-218-051200-
/O.CON.KBOU.FW.W.0028.201005T0600Z-201006T0000Z/
Larimer and Boulder Counties Between 6000 and 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
215 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO
6 PM MDT MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR NORTH
CENTRAL MOUNTAINS AND NORTHERN FRONT RANGE FOOTHILLS...

* Affected Area...Fire Weather Zones 215 and 218.

* Timing...Midnight tonight through 6 PM Monday.

* Winds...West 15 to 25 mph with gusts up to 45 mph.

* Relative Humidity...As low as 13 percent.

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.

&&

$$

COZ240-241-243>247-249-051200-
/O.CON.KBOU.FW.W.0028.201005T1700Z-201006T0000Z/
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
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-
Washington County-
215 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 11 AM TO 6 PM MDT
MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF
NORTHEAST PLAINS OF COLORADO...

* Affected Area...Fire Weather Zones 240, 241, 243, 244, 245, 
  246, 247 and 249.

* Timing...11 am to 6 pm Monday

* Winds...North 15 to 20 mph with gusts up to 35 mph.

* Relative Humidity...As low as 9 percent.

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.

&&

$$

COZ211>213-217-238-242-248-250-251-051200-
/O.CON.KBOU.FW.W.0028.201005T1200Z-201006T0000Z/
Jackson County Below 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Grand and Summit Counties Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Larimer County Below 6000 Feet/Northwest Weld County-
Northeast Weld County-Logan County-Sedgwick County-
Phillips County-
215 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 6 AM TO 6 PM MDT
MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF
NORTHERN MOUNTAINS...HIGH VALLEYS...AND FAR NORTHERN PLAINS...

* Affected Area...Fire Weather Zones 211, 212, 213, 217, 238, 
  242, 248, 250 and 251.

* Timing...6 AM to 6 PM Monday

* Winds...Northwest 15 to 25 mph with gusts up to 35 mph.

* Relative Humidity...As low as 12 percent.

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.

&&

$$
795 
WWUS85 KBOU 050252
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
852 PM MDT Sun Oct 4 2020

...Critical Fire Weather Conditions expected on Monday for the
higher elevations of the northern mountains, North Park and
Middle Parks, and the northern plains...

.Increased flow along the Colorado-Wyoming border is expected to
begin late tonight as mountain wave enhancement of the winds is 
likely across the east slopes of the Front Range Mountains of 
Jackson and Larimer Counties. The strongest winds are expected 
before sunrise Monday and could gust to 50 mph in the most favored
locations. There will also be poor relative humidity recovery 
over the Northern Front Range foothills tonight.

After sunrise, the rest of the area will see gradually increasing
winds with strong mixing and full sun. Relative humidity will be
below 15 percent and gusty winds are expected across the plains.

COZ215-218-051100-
/O.CON.KBOU.FW.W.0028.201005T0600Z-201006T0000Z/
Larimer and Boulder Counties Between 6000 and 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
852 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO
6 PM MDT MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR NORTH
CENTRAL MOUNTAINS AND NORTHERN FRONT RANGE FOOTHILLS...

* Affected Area...Fire Weather Zones 215 and 218.

* Timing...Midnight tonight through 6 PM Monday.

* Winds...West 15 to 25 mph with gusts up to 45 mph.

* Relative Humidity...As low as 13 percent.

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.

&&

$$

COZ240-241-243>247-249-051100-
/O.CON.KBOU.FW.W.0028.201005T1700Z-201006T0000Z/
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
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-
Washington County-
852 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 11 AM TO 6 PM MDT
MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF
NORTHEAST PLAINS OF COLORADO...

* Affected Area...Fire Weather Zones 240, 241, 243, 244, 245, 
  246, 247 and 249.

* Timing...11 am to 6 pm Monday

* Winds...North 15 to 20 mph with gusts up to 35 mph.

* Relative Humidity...As low as 9 percent.

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.

&&

$$

COZ211>213-217-238-242-248-250-251-051100-
/O.CON.KBOU.FW.W.0028.201005T1200Z-201006T0000Z/
Jackson County Below 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Grand and Summit Counties Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Larimer County Below 6000 Feet/Northwest Weld County-
Northeast Weld County-Logan County-Sedgwick County-
Phillips County-
852 PM MDT Sun Oct 4 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 6 AM TO 6 PM MDT
MONDAY FOR WIND AND LOW RELATIVE HUMIDITY FOR REMAINDER OF
NORTHERN MOUNTAINS...HIGH VALLEYS...AND FAR NORTHERN PLAINS...

* Affected Area...Fire Weather Zones 211, 212, 213, 217, 238, 
  242, 248, 250 and 251.

* Timing...6 AM to 6 PM Monday

* Winds...Northwest 15 to 25 mph with gusts up to 35 mph.

* Relative Humidity...As low as 12 percent.

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.

&&

$$
492 
WWUS85 KBOU 050945
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
345 AM MDT Mon Oct 5 2020

...Critical Fire Weather Conditions expected today for the higher
elevations of the northern mountains, foothills, North Park and 
Middle Parks, and most of the northeastern plains...

.This morning is starting out warm, dry and windy in the east 
slopes of the Front Range Mountains of Jackson and Larimer 
Counties. Strong winds are gusting 40 to 50 mph in the most 
favored locations with poor relative humidity recovery near 20
percent.

After sunrise, the rest of the area will see gradually increasing
winds with strong mixing and full sun. Relative humidity will be
below 15 percent and gusty winds are expected across the plains.

COZ240-241-243>247-249-051800-
/O.CON.KBOU.FW.W.0028.201005T1700Z-201006T0000Z/
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
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-
Washington County-
345 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 11 AM THIS MORNING TO
6 PM MDT THIS EVENING FOR WIND AND LOW RELATIVE HUMIDITY FOR THE
PALMER DIVIDE AND PLAINS AREA ALONG AND SOUTH OF I-76...

* Affected Area...Fire Weather Zones 240, 241, 243, 244, 245, 
  246, 247 and 249.

* Timing...11 am to 6 pm Monday

* Winds...North 15 to 20 mph with gusts up to 35 mph.

* Relative Humidity...As low as 9 percent.

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.

&&

$$

COZ215-218-051800-
/O.CON.KBOU.FW.W.0028.000000T0000Z-201006T0000Z/
Larimer and Boulder Counties Between 6000 and 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
345 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN FOOTHILLS AND
NORTHERN MOUNTAINS NEAR AND NORTH OF ROCKY MOUNTAIN NATIONAL PARK...

* Affected Area...Fire Weather Zones 215 and 218.

* Timing...Midnight tonight through 6 PM Monday.

* Winds...West 15 to 25 mph with gusts up to 45 mph.

* Relative Humidity...As low as 12 percent.

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.

&&

$$

COZ211>213-217-238-242-248-250-251-051800-
/O.CON.KBOU.FW.W.0028.201005T1200Z-201006T0000Z/
Jackson County Below 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Grand and Summit Counties Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Larimer County Below 6000 Feet/Northwest Weld County-
Northeast Weld County-Logan County-Sedgwick County-
Phillips County-
345 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR THE HIGH MOUNTAINS AND HIGH
VALLEYS OF JACKSON, GRAND AND SUMMIT COUNTIES AS WELL AS THE FAR
NORTHERN PLAINS...

* Affected Area...Fire Weather Zones 211, 212, 213, 217, 238, 
  242, 248, 250 and 251.

* Timing...6 AM to 6 PM Monday

* Winds...Northwest 15 to 25 mph with gusts up to 40 mph.

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

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.

&&

$$
907 
WWUS85 KBOU 051652
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
1052 AM MDT Mon Oct 5 2020

...Critical Fire Weather Conditions are occurring or about to 
occur for the higher elevations of the northern mountains, 
foothills, North Park and Middle Parks, and most of the 
northeastern plains...

.Morning inversions are already being eroded across the lee side 
of the Cheyenne Ridge in northeast Colorado, and across the 
foothills of the northern mountains. Expect winds to gust to 35 
mph or higher this afternoon across the northern plains and 
northern mountains and foothills and mixing continues. Minimum 
relative humidities should drop to around 8-12 percent across the
warned areas.

COZ240-241-243>247-249-060000-
/O.CON.KBOU.FW.W.0028.201005T1700Z-201006T0000Z/
North Douglas County Below 6000 Feet/Denver/West Adams and
Arapahoe Counties/East Broomfield County-
Elbert/Central and East Douglas Counties Above 6000 Feet-
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-
Washington County-
1052 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR THE PALMER DIVIDE AND
PLAINS AREA ALONG AND SOUTH OF I-76...

* Affected Area...Fire Weather Zones 240, 241, 243, 244, 245, 
  246, 247 and 249.

* Timing...Through 6 pm Today.

* Winds...North 10 to 20 mph with gusts up to 35 mph.

* Relative Humidity...As low as 9 percent.

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.

&&

$$

COZ215-218-060000-
/O.CON.KBOU.FW.W.0028.000000T0000Z-201006T0000Z/
Larimer and Boulder Counties Between 6000 and 9000 Feet-
South and East Jackson/Larimer/North and Northeast Grand/
Northwest Boulder Counties Above 9000 Feet-
1052 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR THE NORTHERN FOOTHILLS AND
NORTHERN MOUNTAINS NEAR AND NORTH OF ROCKY MOUNTAIN NATIONAL
PARK...

* Affected Area...Fire Weather Zones 215 and 218.

* Timing...Through 6 PM Today.

* Winds...Northwest 10 to 25 mph with gusts up to 35 mph.

* Relative Humidity...As low as 12 percent.

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.

&&

$$

COZ211>213-217-238-242-248-250-251-060000-
/O.CON.KBOU.FW.W.0028.000000T0000Z-201006T0000Z/
Jackson County Below 9000 Feet-
South and Southeast Grand/West Central and Southwest Boulder/
Gilpin/Clear Creek/Summit/North and West Park Counties Above
9000 Feet-Grand and Summit Counties Below 9000 Feet-
West Jackson and West Grand Counties Above 9000 Feet-
Larimer County Below 6000 Feet/Northwest Weld County-
Northeast Weld County-Logan County-Sedgwick County-
Phillips County-
1052 AM MDT Mon Oct 5 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM MDT THIS EVENING
FOR WIND AND LOW RELATIVE HUMIDITY FOR THE HIGH MOUNTAINS AND
HIGH VALLEYS OF JACKSON, GRAND AND SUMMIT COUNTIES AS WELL AS THE
FAR NORTHERN PLAINS...

* Affected Area...Fire Weather Zones 211, 212, 213, 217, 238, 
  242, 248, 250 and 251.

* Timing...Through 6 PM Today.

* Winds...Northwest 15 to 25 mph with gusts up to 35 mph.

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

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.

&&

$$

What forecasters said that day

The local office's own words before this red flag 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 red flag warning went out at Oct 4, 3:39 AM MDT, 22 minutes earlier.

Area forecast discussion, Oct 4, 3:39 AM MDT, 22 minutes before
Area Forecast Discussion
National Weather Service Denver/Boulder CO
339 AM MDT Sun Oct 4 2020

.SHORT TERM...(Today and tonight)
Issued at 330 AM MDT Sun Oct 4 2020

The upper ridge aloft which is just upstream from Colorado will
flatten somewhat today as a weak upper level wave now across the
Pacific Northwest moves into the flow. This will result in an
increasing west and northwest flow through the mid levels later
this afternoon and especially tonight. This will be advecting
warmer temperatures through the lower and mid levels of the
atmosphere as 700mb temperatures climb to around +11c. This will
result in temperatures 10-15 degrees warmer than yesterday as
afternoon temperatures approach 80 degrees across the plains. The
airmass will be very dry under sunny skies. There will be varying
amounts of smoke around today over the mountains and adjacent
plains, but main smoke plume will likely shift further north over
Larimer and Weld counties as the flow turns a bit more westerly
later this afternoon and tonight.

For tonight, main concern is the increasing fire danger over the
higher mountains and foothills as winds increase. (also see fire
weather discussion below). Cross sections showing increasing
cross barrier flow to 35-40kt after midnight tonight. Expect some
mountain wave amplification during the night so could see some
gusts up around 50kt or so later tonight over ridges and exposed
east slopes. Simulated water vapor imagery from WRF showing
increasing dryness/subsident flow this evening which will also
help increasing the winds. Main change to the forecast was to
increase winds tonight another 10-15kt increase from previous
forecast. Overnight low temperatures will also be warmer with the
downslope flow, especially in the exposed foothill locations.

.LONG TERM...(Monday through Saturday)
Issued at 330 AM MDT Sun Oct 4 2020

An upper trough will be dropping southeast along the Northern
Rockies with a tightening pressure gradient through the lower and
mid levels. The deepening surface trough will keep the downsloping
pattern across the Front Range mountains and foothills into the
adjacent plains, resulting in a warm and dry start to the morning.
As the jet max moves down on the backside of the upper trough, it
will put the forecast area in the front right exit region where
downward motion will mix some of the higher winds aloft down to
the surface. Gusts of 35 to 50 mph in the morning will lessen
slightly during the day in the higher terrain, while gusts will be
increasing across the plains into the 20 to 35 mph range.
Humidity will be very low throughout the day leading to critical
fire weather conditions. This will also lead to widespread smoke
from the active fires to spread across the area. Otherwise,
expect temperatures to be near 10 degrees above normal.

The upper ridge will then push east across the state on Tuesday to
bring continued dry weather and even warmer temperatures. Winds
will be less under the ridge, though the lee side trough will
still cause gusty winds in the mountains. Flow aloft will be more
westerly, so this will likely direct any of the smoke from the
local fires to go more easterly rather than southeast. A weak
upper trough will move onshore over the west coast Wednesday which
will push down 500 mb heights slightly, while a weak cool front
will slide south into the eastern plains. The result will be a
degree or two cooling over the forecast area, but continued warmer
than average and dry weather.

A big weather pattern shift will be in full swing on Thursday
across the western US, as a large Pacific trough will be pushing
east, ending the long standing upper ridge over that area for the
last couple weeks. Flow will begin coming from the southwest on
Thursday as an initial shortwave moves onshore. The main upper
trough will continue pushing onshore for Friday and into Saturday,
increasing the southwesterly flow aloft over Colorado, and by
Sunday, both the EC and GFS has enough moisture moving in and deep
enough to start seeing return of precipitation. While the GFS had
been the faster solution, the latest 00z ECMWF has taken its
place as well as a deeper solution. This isn't shown much in the
mean, however the EC is no stranger to catching on to the changes
sooner. The resulting chance of rain and snow into the area will
be a welcome change.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 330 AM MDT Sun Oct 4 2020

VFR with mainly clear skies. Still could see some smoke aloft and
will maintain FU in terminals today, but smoke should be shifting
further north tonight as the mountain flow turns more westerly.
South to Southwest surface winds will be shifting southeasterly
this afternoon.

&&

.FIRE WEATHER...
Issued at 330 AM MDT Sun Oct 4 2020

Will be upgrading the Fire Weather Watch to Red flag Warnings
starting later tonight initially for the northern mountains and
northern Front Range foothills. Concern will be increasing winds
after midnight tonight along with mountain wave amplification
which could lead to gusty winds to 50 mph over ridges and exposed
areas over the northern foothills. There will also be less
humidity recovery tonight with readings holding in the 20-35
percent range over the foothills.

Confidence has grown in the strong winds and low humidity
occurring into Monday, hence the upgrade of the Fire Weather
Watch to a Red Flag Warning. Have added most of the remaining
plains zones to the warning due the stronger winds expected to
spread south across that area during the afternoon. The exception
will be eastern Boulder County down into eastern Jefferson
County, as well as the southern foothills and South Park where
winds aren't expected to be as strong. Winds will be decoupling
late afternoon, with critical conditions easing by 6 pm.

Fire weather concerns will remain elevated for the rest of the
week as a dry and warm airmass remain over the region resulting
in daily RH minimums in the 8-20% range. Winds however will be
less, though will approach criteria again on Tuesday over the
northern mountains, and again on Thursday and
Friday...unfortunatelynear where the Cameron Peak and Mullen
fires are burning.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 6 AM to 6 PM MDT Monday for COZ211>213-217-
238-242-248-250-251.

Red Flag Warning from midnight tonight to 6 PM MDT Monday for
COZ215-218.

Red Flag Warning from 11 AM to 6 PM MDT Monday for COZ240-241-
243>247-249.

&&

SHORT TERM...Entrekin
LONG TERM...Kriederman
AVIATION...Entrekin
FIRE WEATHER...Entrekin/Kriederman
Hazardous weather outlook, Oct 3, 10:43 AM MDT, 17 hours 18 minutes before
Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1043 AM MDT Sat Oct 3 2020

COZ030>051-041645-
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-
1043 AM MDT Sat Oct 3 2020

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

.DAY ONE...Today and Tonight

No hazardous weather is expected today.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Sunday's temperatures will rise above normal, with downsloping
warm and dry conditions overnight. This will increase fire
weather concerns going into Monday when a dry weather system will
increase winds across most of the area. The northern mountains,
northern foothills and northern plains may experience near to
critical fire weather conditions.

Fire danger will remain elevated Tuesday through Thursday due to
persistent low humidity and gusty winds in the afternoons. Minimum
humidities will often be below 20 percent coincident with gusts
up to 20 mph. The danger is most persistent in the northern
mountains, foothills, and high mountain valleys, though it will
occasionally spread to the adjacent plains. Some relief may arrive
by Friday, however an upper trough will be breaking down the upper
ridge, resulting in increasing winds.

The area will also be repeatedly impacted by smoke from the
ongoing mountain fires, especially through Wednesday. Flow aloft
will begin switching to come out of the southwest Thursday and
Friday, which may help move the smoke away from the area.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Nearby

Red Flag Warnings in Colorado, 2020Every red flag warning in 2020

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.