wxgeek's weather-Weather Outlook 9/24-10/3-Update 9/26

Update Thu Sep 26

Another warm, sunny and breezy to windy day across the state. Strongest winds currently west of the Divide, but I believe gusty southwest winds of 15-35 mph will make their way into the foothills once again this afternoon into tonight. Southern branch of western U.S. upper trough currently in the Great Basin and is forecast to move east across WY and CO Friday. This is a potent early season system, although the primary energy will stay north of CO in WY where 8-16 inches of snow will be possible across western portions of WY today into Friday. For CO, clouds will increase later today west of the Divide and lead to a chance for precip tonight. Snow level tonight will be 10,000 to 11,000 ft mostly west of Vail Pass and lower to near 8000 ft by Friday morning. Potential for 2-4 inches of snow west of the Divide above 9000 ft by Friday afternoon. Associated cold front will move into eastern CO Friday morning and bring a chance for precip to eastern CO. Precip chances best on the eastern plains Friday morning into Friday night, with some isolated thunderstorms. Best precip chances for the foothills will be Friday afternoon and evening, from about 3 pm through 9 pm as some brief upslope flow develops behind cold front and upper trough moves through. Snow level expected to lower to 8000-9000 ft Friday afternoon, with the possibility of lowering to 7500 ft Friday evening. Precip amounts for the foothills will be very light, less then 0.25 inches of liquid, and from a dusting to an inch of snow above 8000 ft, mostly on grassy surfaces as pavement will be too warm for snow accumulation. This may provide the first snow for many foothill areas. Slightly higher precip amounts possible across the far eastern plains where up to 0.50 inches possible. Precip should end by midnight across the state.

Cool start Saturday morning, but lots of sunshine will warm temps to near seasonal norms by afternoon. Sunday will be sunny and warmer with light winds and no precip across the state.

Models remain quite confused regarding weather next week. Monday through Wednesday will be warm and dry, but late next week models vacillating on bringing an upper trough down from the northwest across CO. Latest runs today have the upper trough and would bring precip and cold temps Thursday and Friday next week, with snow down to near plains level. Yesterday this trough was absent, so will have to wait and get better consistency in model runs before a more confident forecast can be made. At this time, suffice to say the potential for precip and snow down to low levels exists for late next week, but it is far from certain.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Update Wed Sep 25

Warm, dry and windy day across the state today. Upper low currently centered over the WA/OR border and is beginning to move slowly eastward pushing upper ridge to the east of CO. Southwest flow aloft will increase today through Friday morning across CO, which will create strong south to southwest surface winds across the state. High Wind Advisory in effect through 9 pm for most of western CO for winds up to 50 mph, and feel this will be extended into Thursday. Winds of 15-35 mph with gusts to 50 mph will be possible through the foothills today through Friday morning. If not for the recent rains, this would be a serious red flag scenario. However, due to saturated ground, trees will be more likely to fall, so the potential for downed trees and associated power outages will exist into Friday morning through the mountains and foothills.

Models continue to split the upper low into a northern and southern branch. Southern branch will move towards Salt Lake on Thursday then move northeast into WY. Because the majority of energy will remain north of CO, this system will not bring much precip to the state. Associated cold front will move into western CO late Thursday, and move into eastern CO during the day on Friday. Front will bring precip to western CO Thursday night west of the Divide with snow level 8000-9000 ft. Currently looks like 2-4 inches of snow possible above 8000 ft west of the Divide. As front moves into eastern CO Friday, some showers will be possible east of the Divide, but pretty limited moisture so do not expect much precip. Best chances will be far eastern plains Friday afternoon and evening where better surface mositure will exist. For the foothills, isolated showers possible Friday afternoon and evening with snow level around 9000 ft, but do not expect any accumulation at this time. West to northwest winds behind front Friday night, but winds should calm and temps will begin to warm Saturday. The rest of the weekend and now the remainder of next week look mild and dry across the state. Previously advertised system from yesterdays runs has washed out for next week, so looks dry with temps at or above seasonal averages through next weekend. Next chance for precip according to long range models is Oct 8-9.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Very nice early Fall weather across the state with temps back near or above seasonal norms and dry conditions expected through Thursday. Next upstream system continuing to evolve on models. Latest model runs continue to split the upper level energy into a northern branch that moves into the northern Plains, and a southern branch that hangs back across the Great Basin and then moves east across CO on Friday into Saturday. Upper trough still fairly deep for early Fall, and will have strong southwest winds aloft in advance, so strong south to southwest winds at the surface will reside across CO from Wednesday afternoon into Friday morning. Here is how the latest forecast evolution looks...

Warm temps and breezy south to southwest winds will give way Thursday to increasing clouds late in the day from west to east across the state. Precip will begin to develop Thursday evening across northwest CO and a cold front will move through CO Thursday night, with a surface low developing in southeast CO Friday morning. Snow level will begin above 12,000 ft Thursday evening, lowering to near 11,000 ft Friday morning. Snow level will continue to lower during the day on Friday to near 10,000 ft Friday evening. Further lowering to near 8000-9000 ft is possible Friday night. For precip, amounts currently looks very light across the state, with best chances across the northern mountains and foothills Friday into Friday night. NAM model currently has higher precip amounts than the GFS and ECMWF, but would still expect rainfall below 0.25 inches and any snow amounts to be less than 1 inch. Of course, forecast could change between now and then as system moves onshore from the Pacific Northwest.

Conditions should clear and begin to warm on Saturday, with mild and dry weather expected over the weekend and into at least the middle of next week. Latest GFS run brings a system from the northwest into CO late next week with precip and much cooler temps, so will need to watch how this system evolves. If current forecast is near accurate, this system late next week would certainly bring snow to the foothills and possibly down to the Urban Corridor and plains, but way to early to get too excited.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

Bump for 9/25 update

Bump for 9/26 update