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 Post subject: Weather Outlook Through Late September
Post Posted: Sep 18, 2018 2:03 pm 
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Yet another warm and dry day across the state. New record for consecutive 90 degree days in September this week, and another day with near record heat. The good news is that we finally have a chance for some precipitation this week and temps closer to normal.

After a warm start on Wednesday, a upper level trough will move to our north and bring up some moisture from the Southwest that will increase precip chances for most of CO on Wednesday into Thursday. Precip should move into western CO during the day on Wednesday, and then move into the foothills and eastern CO by Wednesday evening into Wednesday night. There will be isolated thunderstorms that will bring lightning and small hail, and even a chance for severe thunderstorms across northeast CO Wednesday evening. Precip could last into the overnight hours into Thursday morning, and amounts look to be mostly in the 0.10 to 0.25 inch range for most foothill areas, with isolated amounts up to 0.50 inches in heavier storms. Snow level may lower to 13,000 ft overnight so higher peaks may see a dusting.

Thursday will be cooler with temps closer to average and mostly dry statewide. Gusty northwest winds will be possible, especially over higher terrain of the mountains and foothills during the day on Thursday. Friday will be even cooler with temps near to slightly below average. There will be a slight chance for a few afternoon showers, mostly over higher terrain with precip amounts generally less than 0.10 inches.

The weekend looks to be mostly dry and temps rise to slightly above average for most areas.

For next week, models currently not in very good agreement. GFS and ECMWF both bring a upper level trough over the northern and central Rockies, but timing and intensity of the trough are different. GFS brings upper trough over late Tuesday into Wednesday and is much more vigorous with more precip and snow levels down to 6000 ft by Wednesday, while the ECMWF brings the trough over Tuesday and keep most energy north of CO with only a slight chance for any precip Tuesday afternoon with snow level near 9000 ft. So will have to wait and see how models resolve the forecast for next week. Late next week looks mostly dry and warm on both models.

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"Climatology is what you expect, Weather is what you get" - R. Heinlein.

"Sunshine is delicious, rain is refreshing, wind braces us up, snow is exhilarating; there is really no such thing as bad weather, only different kinds of good weather" - John Ruskin


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 Post subject: Re: Weather Outlook Through Late September
Post Posted: Sep 19, 2018 1:50 pm 
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Cold front has backed into northeast CO this afternoon with cooler temps and northeast winds which will prevent another 90 degree day for Denver, but temps are still running above average today for most areas of the state. Showers have developed across southwest CO this afternoon as moisture from a tropical depression in the Gulf of California is being sucked northeast by a upper level trough moving to our north today. Latest models bring precip into eastern CO from this evening through Thursday morning, but heaviest precip looks to remain mostly south of US 50. For foothill areas most models suggest less than 0.10 inches, so mostly a light rain event with a few isolated thunderstorms possible and up to 0.25 inches possible with heavier showers. Precip should begin to taper off early Thursday morning and move east.

Thursday will start out cloudy across much of northeast CO as upslope flow keeps low clouds across much of the plains with clouds pushing up into the foothills that may cause reduced visibility in fog Thursday morning below 9000-10,000 ft. It should remain mostly dry statewide with temps near average, and Friday should be very similar to Thursday with little if any precip expected statewide.

For the weekend expect dry conditions to prevail with temps rising back above average both days.

Models still not in very good agreement for next week on timing, but they both suggest much cooler temps and some precip early next week. ECMWF brings precip in Monday evening into Tuesday morning with snow level 8000-9000 ft, while GFS brings precip in Tuesday night into Wednesday morning with snow level down to 7000-8000 ft. Still too early to tell which model solution is better, but both suggest foothill areas may see our first dusting of snow next week. GFS clears thing out after Wednesday, while the ECMWF brings another shot of cooler temps and some precip into the foothills Wednesday night into Thursday morning with snow level 7000-8000 ft.

Both models then dry things out and warm temps up late next week into next weekend with temps near average.

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"Climatology is what you expect, Weather is what you get" - R. Heinlein.

"Sunshine is delicious, rain is refreshing, wind braces us up, snow is exhilarating; there is really no such thing as bad weather, only different kinds of good weather" - John Ruskin


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 Post subject: Re: Weather Outlook Through Late September
Post Posted: Sep 20, 2018 1:30 pm 
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Mostly sunny day today after some rain yesterday, although not much in foothill areas but over an inch in some Metro and plains areas. Some gusty northwest winds will be over higher terrain of the mountains and foothills today as temps hover near average for most areas. Friday looks to remain mostly sunny with temps near average and less wind.

Weekend looks to remain dry statewide as temps rise above average.

Models beginning to converge on a solution for early next week today. Both now have a upper level trough passing to our north Monday into early Tuesday. Showers will develop Monday afternoon with snow level near 12,000 ft. Some light precip may linger overnight after cold front has passed with snow level lowering to near 9000-10,000 ft. Thus our first snow seems less likely now. Temps will be near average Monday and below average Tuesday.

The period Wednesday through next weekend looks dry statewide with temps near average values. Fire danger will remain high as ground fuels continue to dry out. Models suggest precip will be possible towards the middle of the following week.

_________________
"Climatology is what you expect, Weather is what you get" - R. Heinlein.

"Sunshine is delicious, rain is refreshing, wind braces us up, snow is exhilarating; there is really no such thing as bad weather, only different kinds of good weather" - John Ruskin


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 Post subject: Re: Weather Outlook Through Late September
Post Posted: Sep 21, 2018 2:25 pm 
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Mostly sunny day today after a cool start temps should reach near average values for most areas. The weekend should remain dry statewide as temps rise above average each day. Fire danger will remain high until we either get significant rainfall or some snow. Sadly neither of those options appears likely anytime soon.

For next week, models continue to tweak the forecast each run. Decent agreement now between the GFS and ECMWF, although the ECMWF remains wetter. On Monday, upper level trough from the Pacific Northwest will move across the northern Rockies and into the Northern Plains on Tuesday. This will drag an associated cold front through eastern CO Monday evening. Some showers and a few isolated thunderstorms may develop along this front and move through the foothills Monday late afternoon/evening, but any precip would remain light. Temps on Monday should remain above average before front moves through. Models now bring a secondary upper trough from the northern Rockies into CO on Tuesday into Wednesday. Models suggest better precip chances with this impulse Tuesday afternoon into Wednesday morning. Precip amounts look to be in the 0.10 to 0.25 inch range according to the ECMWF, while the GFS only brings a trace of precip across CO. Snow level now looks to remain at or above 10,000 ft Tuesday night, but higher peaks could pick up a few inches of snow. Temps overall will be below average on Tuesday.

For the rest of next week, upper level pattern will feature a blocking ridge in the eastern Pacific and a large upper trough over the central U.S. with a dry northwest flow aloft over CO. This pattern looks to remain mostly in place through early October, which would keep CO mostly dry and towards the mild side. As systems move through this pattern, CO will see periodic dry cold fronts move across eastern CO which will temporarily cool temps, but then they warm back up quickly. Models do not suggest much if any precip until about Oct 5 in the extended range.

I have posted my snowfall forecast for the season in a separate topic labeled "Forecast for the Upcoming Snow Season". With a building El Nino, I am forecasting 180-220 inches of snow this season on Conifer Mountain, well above our average of 170 inches. I really hope this comes to fruition as we desperately need the moisture.

_________________
"Climatology is what you expect, Weather is what you get" - R. Heinlein.

"Sunshine is delicious, rain is refreshing, wind braces us up, snow is exhilarating; there is really no such thing as bad weather, only different kinds of good weather" - John Ruskin


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