Front Range Foothills / Denver Metro Weather Briefing – 23 June 2012 – 0640 hrs MDT

Synopsis: Elevated and extreme fire danger will exist today and fire starts could exhibit moderate to rapid growth.

For the metro it will be hot with high temps above 100 degrees and dry again today however the winds are expected to be lighter with afternoon gusts up to 20 mph.

For the Foothills, the Red Flag Warning remains in effect until 2000 hours with temps in the 80’s and 90’s and RH in the single digits.

For the next seven days, expect temps in the 80’s and 90’s with a slight increase in moisture, but not much. In the Foothills, thunderstorms are possible with dry lightning.


Watches & Warnings:



Red Flag Warnings remain in effect for the Front Range Mountains and Foothills through 2000 hours.

* Timing...Another day of near record heat is expected with very low humidities today.

* Winds...Southwest 10 to 20 mph with gusts up to 35 mph...winds will decrease after sunset.

* Relative humidity...In the single digits.

* Impacts...The increasing winds...combined with the warm and dry conditions could create extreme fire behavior on already existing fires and make any new ignitions difficult to control with possible high rates of spread.


Hazardous Weather Outlook for Today: Extreme fire danger will continue today through this evening over the higher terrain due to gusty winds and very low humidity. Over northeast Colorado it will continue hot with highs at or above 100 degrees in many areas. An isolated late afternoon or early evening thunderstorm will be possible over Park County otherwise it will remain dry.

For Sunday through Friday: Hot weather is expected to continue through the week with temperatures 10 to 15 degrees warmer than average. There will be a slight chance of thunderstorms each afternoon, mainly over the mountains. However, the storms are not expected to produce any beneficial rains at this time. While the warm and dry conditions persist over the mountains and northeast Colorado, there will continue to be a significant risk of wildfire starts.




Front Range Foothills Forecast

Today: Sunny, with a high near 90. West southwest wind 6 to 9 mph becoming east southeast. Winds could gust as high as 15 mph.

Tonight: Partly cloudy, with a low around 58. North northwest wind between 5 and 7 mph.

Sunday: A 20 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 87. West wind at 10 mph becoming east. Winds could gust as high as 16 mph.

Sunday Night: A 20 percent chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 56. North northwest wind between 6 and 8 mph.

Monday: A 10 percent chance of showers and thunderstorms after noon. Mostly sunny, with a high near 89. West southwest wind 6 to 11 mph becoming south southeast. Winds could gust as high as 17 mph.

West Denver Metro Forecast

Today: Sunny and hot, with a high near 102. Southwest wind 6 to 8 mph becoming east southeast.

Tonight: Partly cloudy, with a low around 66. East southeast wind at 7 mph becoming west.

Sunday: Mostly sunny and hot, with a high near 98. West wind between 4 and 7 mph becoming calm.

Sunday Night: A 20 percent chance of showers and thunderstorms before midnight. Mostly cloudy, with a low around 65. North northwest wind around 7 mph.

Monday: Mostly sunny and hot, with a high near 99. West wind 6 to 11 mph becoming south southeast. Winds could gust as high as 16 mph.


Fire Weather for Zone 239 (Below 6000 feet) –

Today...


Sky/weather.........mostly sunny.

Max temperature.....97-103.
24 hr trend......1-2 degrees warmer.

Min humidity........4-8%.
24 hr trend......little change.

20-foot winds.......variable less than 8 mph becoming southwest 8-14 mph in the afternoon. Gusts up to 20 mph.

Haines index........6 high.

LAL.................1.

CWR.................0 percent.

10k ft free winds...west 30-40 mph.

Mixing height.......below 1000 ft agl until 0700. 15000-16000 ft agl after 1200.

Transport winds.....west 10-15 mph until 0900...then 20-25 mph until 1200...then 25-30 mph until 1600...then around 20 mph.

Smoke dispersal.....poor until 0800...then good until 1000...then excellent.


Tonight...


Sky/weather.........mostly clear.

Min temperature.....61-66.
24 hr trend......little change.

Max humidity........28-34%.
24 hr trend......7-10% wetter.

20-foot winds.......variable less than 8 mph becoming northwest 8-13 mph after midnight.

Haines index........6 high.

LAL.................1.

CWR.................0 percent.

10k ft free winds...southwest 15-25 mph.

Mixing height.......15500 ft agl until 2400...then below 1000 ft agl.

Transport winds.....west around 10 mph until 2400...then light and variable.

Smoke dispersal.....good until 2400...then poor.


Sunday...


Sky/weather.........mostly sunny until 1200...then mostly cloudy (50-60%).

Max temperature.....95-99.
24 hr trend......2-4 degrees cooler.

Min humidity........14-18%.
24 hr trend......7-10% wetter.

20-foot winds.......variable less than 8 mph becoming southeast 8-12 mph in the afternoon.

Haines index........6 high.

LAL.................1.

CWR.................0 percent.

10k ft free winds...south 15-20 mph.

Mixing height.......below 1000 ft agl until 0700. 14500-15500 ft agl after 1200.

Transport winds.....northwest around 10 mph until 0700...then light and variable until 1200...then southeast 10-15 mph.

Smoke dispersal.....poor until 1100. Excellent after 1300.


Fire Weather Zone 216 (Above 6000 Feet)


Today...


Sky/weather.........mostly sunny until 1300...then partly cloudy.

Max temperature.....85-95.
24 hr trend......little change.

Min humidity........5-9%.
24 hr trend......little change.

20-foot winds.......
Valleys / lower slopes...southwest 8-14 mph with gusts to 20 mph.
Ridges / upper slopes....southwest 9-15 mph.

Haines index........6 high.

LAL.................1.

CWR.................0 percent.

10k ft free winds...southwest 30-40 mph.

Mixing height.......below 1000 ft agl until 0700. 16500-17500 ft agl after 1000.

Transport winds.....west around 10 mph until 0700...then 20-25 mph until 0900...then 25-30 mph until 1400...then southwest 15-20 mph.

Smoke dispersal.....poor until 0700...then fair until 0800...then very good until 0900...then excellent.


Tonight...


Sky/weather.........partly cloudy.

Min temperature.....54-62.
24 hr trend......2-4 degrees warmer.

Max humidity........33-39%.
24 hr trend......7-10% wetter.

20-foot winds.......
Valleys / lower slopes...downslope / downvalley 2-8 mph.
Ridges / upper slopes....downslope/downvalley 2-8 mph.

Haines index........6 high.

LAL.................1.

CWR.................0 percent.

10k ft free winds...south 15-25 mph.

Mixing height.......16000 ft agl until 2400...then below 1000 ft agl.

Transport winds.....light and variable.

Smoke dispersal.....fair until 2400...then poor.


Sunday...


Sky/weather.........partly cloudy (30-35%) until 1200...then mostly cloudy (50-60%). Slight chance of thunderstorms...some dry...after 1200.

Max temperature.....82-92.
24 hr trend......2-4 degrees cooler.

Min humidity........14-18%.
24 hr trend......7-10% wetter.

20-foot winds.......
Valleys / lower slopes...upslope / upvalley 4-10 mph becoming east 8-13 mph in the afternoon.
Ridges / upper slopes....upslope / upvalley 4-10 mph becoming east 8-13 mph in the afternoon.

Haines index........5 moderate.

LAL.................1 until 1200...then 3.

CWR.................0 percent.

10k ft free winds...south 15-25 mph.

Mixing height.......below 1000 ft agl until 0700. 14500-15500 ft agl after 1100.

Transport winds.....light and variable until 1100...then southeast 10-15 mph.

Smoke dispersal.....poor until 1100. Excellent after 1300.



Other notable Colorado weather:

For Central and Western Colorado – Red Flag Warnings are in effect for Saturday.

Red Flag Warnings continue for the Front Range Foothills and Mountains on Sunday.

Discussion – For Sunday, dry lightning may start new fires Sunday afternoon and evening. High pressure will continue to bring hot temperatures and low humidities to Colorado. Gusty winds will also occur into this evening before diminishing shortly after sunset. On Sunday just enough moisture is expected to build under the upper level ridge to bring high based showers and thunderstorms to the mountains and foothills. Those storms are expected to produce lightning, strong gusty outflow winds, but little if any rainfall.

Red Flag Warnings are in effect from noon to 2200 hours Sunday for thunderstorms, mainly dry with strong gusty winds and low relative Humidity for the north central mountains, high valleys, and Front Range foothills.


* Timing...Gusty winds and extremely low humidities will continue through early this evening. Winds will decrease after sunset. On Sunday isolated to scattered dry thunderstorms with strong gusty winds are expected to develop in the afternoon and continue into the evening.


* Winds...Southwest 10 to 20 mph with gusts up to 35 mph diminishing to less than 15 mph by 9 pm this evening. On Sunday strong and gusty outflow winds up to 50 mph can be expected near any showers and storms. Otherwise lighter winds will prevail with a weaker pressure gradient over the region.

* Relative Humidity...Between 5 and 10 percent through this evening with only poor humidity recovery overnight. Then lowering to 15 percent or less Sunday.

* Thunderstorms...Isolated to scattered storm coverage Sunday afternoon and evening...highest coverage in mountains. Some storms will be dry with most storms producing strong gusty outflow winds.

* Impacts...The gusty winds and extremely low humidity through this evening will create extreme fire behavior on already existing fires and make any new ignitions difficult to control with high rates of spread. Numerous new fire starts will be possible Sunday afternoon and evening due to lightning.