Fire Weather Watch 9, NWS Denver/Boulder, CO

019 
WWUS85 KBOU 060855
RFWBOU

URGENT - FIRE WEATHER MESSAGE
National Weather Service Denver/Boulder CO
255 AM MDT Fri Aug 6 2021

COZ250-251-061000-
/O.CAN.KBOU.FW.A.0009.210807T1900Z-210808T0100Z/
Sedgwick County-Phillips County-
255 AM MDT Fri Aug 6 2021

...FIRE WEATHER WATCH IS CANCELLED FOR WIND AND LOW RELATIVE
HUMIDITY FOR SEDGWICK AND PHILLIPS COUNTIES...

The National Weather Service in Denver has cancelled the Fire
Weather Watch for Saturday.

While it will be breezy on Saturday with peak gusts of 20 to 30 
mph, humidities over the northeast corner of the state will only 
drop to around 25 percent, and not reach critical 15 percent
thresholds. 

$$

Area Forecast Discussion
National Weather Service Denver/Boulder CO
215 PM MDT Thu Aug 5 2021

.SHORT TERM...(This evening through Friday)
Issued at 211 PM MDT Thu Aug 5 2021

The upper level ridge has pushed in over the Great Basin and is
pulling northwest flow into the region. This is also bringing
increased levels of smoke down from fires across California and the
northwest. Some CU has developed across the higher elevations but
mid-level drying will help to keep convection at bay and conditions
dry for the late afternoon and evening. Current HRRR smoke
projections have elevated smoke sticking around through the evening
ahead of the incoming shortwave. This and the aforementioned upper
flow will keep overnight lows more mild in the mid-60s across the
plains.

Looking to Friday, a shortwave embedded in the upper flow aloft that
is currently pushing into western WY will move into CO during the
morning hours. There is some weak forcing associated with it that
will help to fire off some afternoon convection across the higher
terrain that will move onto the plains by the late afternoon. Model
upper air soundings indicate more high-based storms with DCAPE
values from 1400-1500 J/kg that will equate to more gusty wind
impacts then intense rainfall. Some storms could produce winds up to
50 mph with outflows into the evening hours. Outside of the storms
winds will stay elevated with subsidence increasing behind the
disturbance with gusting from 35 to 45 mph across the higher
elevations with mixing by the afternoon. In return, this will help to
scour out the low lying smoke and provide some relief over the next
few days. Highs will continue their upward climb with temperatures
in the mid to upper 90s across the lower elevations and 70s to low
80s in the mountains and high mountain valleys.

.LONG TERM...(Friday night through Thursday)
Issued at 211 PM MDT Thu Aug 5 2021

FRIDAY NIGHT INTO SATURDAY, AN UPPER LEVEL TROUGH OF LOW PRESSURE
WILL MOVE ACROSS THE NORTHERN AND CENTRAL ROCKIES WITH A DRY WEST TO
NORTHWESTERLY FLOW ALOFT OVER COLORADO. THIS PATTERN WILL BRING
MOSTLY DRY, COOLER AND BREEZY CONDITONS TO NORTH CENTRAL AND
NORTHEASTERN COLORADO WITH ONLY A FEW HIGH BASED SHOWERS POSSIBLE
MAINLY OVER THE MOUNTAINS and far northeastern plains. With low
relative humidity, gusty winds and dry fuels, fire danger will be
elevated across the far northeastern corner of Colorado.

FOR SUNDAY AND MONDAY, DRY WEATHER AND ABOVE NORMAL TEMPERATURES are
expected AS UPPER LEVEL HIGH PRESSURE DOMINATES THE SOUTHERN TIER OF
THE U.S and ANOTHER UPPER LEVEL TROUGH OF LOW PRESSURE MOVING ACROSS
THE NORTHERN ROCKIES.

For Tuesday through Thursday, upper level high pressure begins to
build over the Western U.S. with a northwesterly flow aloft over
Colorado. There is some differences between the models in how they
handle an upper level low pressure system over the Central Plains
States. The ECMWF shows an upper level low centered over the Black
Hills by 00Z Friday with the GEM solution having a deeper low
centered over Eastern South Dakota. The GFS solution shows no such
low and has an open trough covering much of the Central and Eastern
U.S. Both the ECMWF and GEM solutions show some increase in
subtropical moisture and QPF during this period, while the GFS keeps
things dry. For now will go with the forecast model blend and make
some tweaks to lower the pops somewhat.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 211 PM MDT Thu Aug 5 2021

VFR conditions are expected for the TAF period. Smoke is expected to
impact all terminals through the day prior to the shortwave passage
on Friday that could reduce slantwise visibility. Winds will remain
light with predominant direction out of the south that will
transition to the southwest then around to the northwest by 18z
Friday with a slight chance of showers and storms moving off the
higher terrain impacting area terminals toward the end of the TAF
period.

&&

.FIRE WEATHER...
Issued at 211 PM MDT Thu Aug 5 2021

Elevated fire weather conditions will be possible Friday afternoon
across the northeast plains with RH values dropping below 15% with
some wind gusts from 20 to 25 mph. Fuel status across the
northeastern plains counties are cured enough to promote fire
spread so caution is advised.

Dry fuels combined with gusty winds to 30 mph and low relative
humidity will lead to elevated fire danger across Sedgwick and
Phillips Counties on Saturday. Despite marginal relative humidity
values, have decided to go with a Fire Weather Watch for those
areas after coordinating with adjacent offices. The fire danger
will remain elevated through early next week.

&&

.HYDROLOGY...
Issued at 211 PM MDT Thu Aug 5 2021

The threat of burn area flash flooding will be quite low on Friday.
Only scattered but high based showers/storms can be expected.
Limited moisture, a dry and deep sub-cloud layer, and relatively
fast storm movement will support only light rainfall amounts (less
than 0.25 inch).

Mostly dry weather is expected through Monday with a slight
increase in shower and thunderstorm activity beginning on Tuesday.
With limited moisture available, the flash flood threat at this
time looks to limited.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for COZ250-251.

&&

SHORT TERM...Bowen
LONG TERM...Kalina
AVIATION...Bowen
FIRE WEATHER...Bowen/Kalina
HYDROLOGY...Bowen/Kalina

Hazardous Weather Outlook
National Weather Service Denver/Boulder CO
1103 AM MDT Thu Aug 5 2021

COZ030>051-061715-
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-
1103 AM MDT Thu Aug 5 2021

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

.DAY ONE...Today and Tonight

No hazardous weather is expected through the period.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Scattered showers and a few thunderstorms can be expected Friday
afternoon and early evening. They will produce only light rain
but strong, gusty winds to around 50 mph will be possible.

Fire danger will be elevated as we move into a three to four day
period of above normal temperatures and lower humidities through
this weekend and into early next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today or tonight.