Warm and Breezy Start, Cold and Snow Later This Week
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Author:  wxgeek [ Oct 21, 2017 3:10 pm ]
Post subject:  Warm and Breezy Start, Cold and Snow Later This Week

Cool and breezy day across most of CO today in the wake of cold front that passed through last night. Some light snow to northern mountains last night, but mostly dry statewide today as temps will be below average. For Sunday, mostly sunny as temps climb back to seasonal norms or slightly above.

For the week ahead, upper level trough will develop across the eastern U.S. while an upper ridge builds over the astern Pacific off the Pacific Northwest coast. This will leave CO under a dry northwest flow aloft Monday through Wednesday. Tempe will be near to slightly above average Monday and Tuesday, then well above average on Wednesday. Expect some breezy northwest winds at times Sunday into Tuesday, which will keep fire danger elevated.

Big change later in the week as models advertise a upper level trough will dig from western Canada into CO late Thursday into Friday. This pattern will bring much cooler temps and a chance for snow to much of CO from Thursday afternoon into Friday morning. Models still figuring this out, but ECMWF is colder and wetter than GFS at this time which I tend to believe. Snow would fall down to plains level by Thursday evening and persist into Friday morning. Snow amounts at this time look to be in the 3-7 inch range for the foothills, but that could change lower or higher depending on how the pattern evolves. Friday temps would be cold with high temps remaining below freezing.

Models then keep CO under a dry northwest flow pattern with upper trough to our east and upper ridge to our west next weekend into the following week. Temps would be at to slightly above average with little to no precip through Friday Nov 3. Next precip chances look to be the weekend of Nov 4-5 for CO.

Author:  wxgeek [ Oct 22, 2017 2:33 pm ]
Post subject:  Re: Warm and Breezy Start, Cold and Snow Later This Week

Nice Fall day across the state today with temps slightly above average for most areas. We should see very similar weather to start the work week ahead Monday through Wednesday. No precip is expected statewide through Wednesday, and temps should remain at to slightly above average Monday and Tuesday, then well above average Wednesday. There may be some gusty west to northwest winds at times through Wednesday, which will keep fire danger elevated as ground fuels remain very dry.

Models continue to advertise a significant change in our weather for Thursday into Friday. Upper level trough is forecast to dig across the Central Rockies late Thursday which will bring much cooler temps and a chance for snow down to plains level. ECMWF continues to be the wetter model with over 0.50 inches of liquid forecast for our foothills, while the GFS keeps precip under 0.25 inches. I will continue to favor the European model for now, which would bring snow across much of CO late Thursday afternoon and continue into early Friday morning, then begin to clear. Using latest forecast, foothills could see 4-8 inches of snow, with 1-4 inches for the Metro Area and 1-2 inches for the plains. If upper trough slows and digs more, then we could see higher snow amounts, while if the upper trough stays farther north and moves through fast, amounts could be lower. Time will tell. Bottom line is expect more winter like conditions from Thursday afternoon into Friday morning. Temps will remain cold on Friday well below average, then begin to warm back towards average for the coming weekend, which looks dry statewide.

For next week, models suggest a mostly dry and mild pattern, with a slight chance for a few showers Tuesday, but otherwise dry statewide until next weekend whne precip chances return.

Author:  wxgeek [ Oct 23, 2017 1:46 pm ]
Post subject:  Re: Warm and Breezy Start, Cold and Snow Later This Week

A weak system passed to our north overnight, bringing in some low clouds to eastern CO this morning, but mostly clear this afternoon. Temps lower today across eastern CO due to low clouds and northeast flow, but near average along and west of the Divide. Upper ridge will build over CA next 48 hours leaving CO with a dry a mild north to northwest flow aloft through Wednesday. Temps should be near average Tuesday, then above average on Wednesday with no precip expected statewide.

Latest models holding onto their differences regarding the system for Thursday into Friday. GFS brings an Alberta Clipper down across CO Thursday with much cooler temps, but little in the way of precip, while the ECMWF is slower and deeper with the upper level trough which would bring more precip to CO. I am now beginning to side with the GFS and think this system may remain farther north and just provide a brief shot of snow Thursday afternoon into evening from the Divide east. If the GFS is correct, snow amounts would only be a trace to an inch or two from Noon Thursday into Thursday evening. The ECMWF has lowered snow amounts from the past 2 days and would now bring in 2-5 inches for the foothills, so based on trending, now think foothill areas will only see 1-3 inches of snow, beginning between Noon and 3 pm and ending between 6 pm and 9 pm. Snow level will begin near 6000 ft Thursday morning lowering to 4000 ft by afternoon, thus do not think roads will be an issue below 6000 ft, but could see some snow and ice on roads for the commute back up the hill on Thursday. With warm temps on Wednesday, initial snow likely to melt on roads and then re-freeze, so any precip could cause slick roads. Cold front will come through early Thursday morning, so max temps Thursday will be early morning, then fall throughout the day. Temps Thursday night into Friday morning could be in the teens for foothill areas, with max temps on Friday struggling to reach freezing. Skies should be mostly sunny on Friday however. Another cold night on tap Friday night with low temps in the single digits by Saturday morning.

Weekend weather should be dry and temps will begin to moderate back towards seasonal norms on Sunday after a cool day on Saturday.

For next week, Monday looks dry and mild, then models indicate the chance for another quick hitting system out of the northwest on Tuesday into Wednesday with some snow possible for eastern CO. Later next week looks dry and mild then another chance for precip next weekend.

Author:  wxgeek [ Oct 24, 2017 2:24 pm ]
Post subject:  Re: Warm and Breezy Start, Cold and Snow Later This Week

Mostly sunny day across the state with temps near seasonal norms. Some gusty northerly winds will be possible at time this afternoon into tonight, especially on the eastern plains. Wednesday will also be mostly sunny with temps 5-15 degrees above average, so enjoy the warmth while you can.

Upper level trough and associated cold front will move south into CO early Thursday morning. Models coming into better agreement, with the GFS and ECMWF meeting in the middle. Cold front will be near the CO/WY border near sunrise and move quickly south across eastern CO Thursday morning. Temps will drop and northerly winds will develop behind front, so max temp for the day will be mid morning in the foothills. Precip will follow with snow developing near the CO/WY border between 6-9 am, and moving into the foothills and Urban Corridor between 9 am and Noon. Snow level will initially be near 6000-7000 ft Thursday morning, lowering to 4000-5000 ft Thursday afternoon. Heaviest snow will be along and east of the Divide into the foothills, with lighter amounts farther east. Latest models show 0.25 to 0.50 inches of liquid precip along the foothills. Snow amounts look as follows:

Mountains east of the Divide and Foothills: 2-6 inches with highest amounts in the favored areas
Urban Corridor: 1-3 inches with highest amounts at higher elevations west and south of the Metro area
Eastern plains: Trace - 2 inches with heaviest amounts north of I-70

Expect NWS will issue a Winter Weather Advisory for foothill areas, as roads will likely become slick Thursday afternoon and evening, so expect a slower and slick ride for the return commute on Thursday. Roads may have a layer of ice underneath due to very warm temps on Wednesday, so plan accordingly.

Snow should taper off between 6 pm and 9 pm Thursday, with clearing and cold temps overnight, so roads may have some slick spots early Friday morning.

Friday looks to be mostly sunny but cool, with temps struggling to get above freezing in the foothills.

For the weekend, another cool and mostly sunny day Saturday, then temps warm to near seasonal norms on Sunday under mostly sunny skies.

For next week, models not in very good agreement. GFS brings a significant system from the northwest across CO with cold temps and lots of snow, while the ECMWF brings more of a clipper system across CO with some light snow late Tuesday. Late next week looks mild and dry and these conditions should extend into next weekend. Models then suggest more precip early the following week.

Author:  wxgeek [ Oct 25, 2017 1:09 pm ]
Post subject:  Re: Warm and Breezy Start, Cold and Snow Later This Week

Near record warmth across much of eastern CO today under mostly sunny skies. Record temps at Denver today is 80, and current temp is 79, so record will likely be tied or broken. Not may other places you can have 80 degrees one day, followed by snow the next.

As upper level trough begins to move south tonight, gusty northwest winds will develop over the mountains and foothills, which will also keep temps above freezing. Latest models are now in good agreement on incoming system, so high confidence. Cold front will move towards the CO/WY border around sunrise and proceed south across eastern CO during the morning. As front passes, winds become northeasterly and low clouds develop and temps begin to drop. Models now suggest precip will move to the CO/WY border between 9 am and Noon with snow level near 6000 ft, and move south of I-70 between Noon and 3 pm with snow level lowering down to near 5000 ft. Heaviest snowfall will be along and north of I-70 from the Divide east into the foothills. Not much Precip is expected east of the I-25 corridor. Sow will persist through about 6 pm, then dissipate by 9 pm statewide. Overall models have diminished snowfall amounts, keeping in line with a quick hitting Clipper, and with such warm temps today, most roads may remain mostly wet, especially below 7000-8000 ft. Roads may become slushy to snow and ice packed above 8000 ft after 3-5 pm Thursday. For snow amounts, here is my latest thinking:

Mountains East of Divide and Foothills: 1-4 inches, with up to 6 inches northern foothills (north of I-70)
Palmer Divide and Urban Corridor: Trace to 2 inches, highest amount above 6000 ft west and south of Metro Area
Plains: no measurable now expected

Cold temps expected Friday under mostly sunny skies, with Saturday being slightly warmer, but remaining below seasonal norms. Overnight low temps will be in the 5-15 degree F range in the foothills both nights. Sunday will be mostly sunny with temps near seasonal norms, so overall a pretty nice weekend ahead.

For next week, models in better agreement today, bringing another Clipper from the northwest across CO on Monday.Models bring a cold front into eastern CO Sunday night into Monday morning which will usher in cooler temps along with low clouds, northeast winds and some light snow. Models currently limit snowfall to less than 2 inches all locations, with best chances for snow along the foothills with snow level near 6000 ft. Snow should en by Monday evening. Tuesday looks cold but dry, with cool conditions persisting into Wednesday. Late next week looks warm and dry as upper ridge moves over CO. Dr and mild weather is expected to persist into Saturday, with some precip possible into western CO next Sunday.

The following week models suggest a significant change in the upper level pattern, with a long wave upper trough developing along the West Coast, which will bring Pacific moisture into CO during the week.

Author:  wxgeek [ Oct 26, 2017 7:27 am ]
Post subject:  Re: Warm and Breezy Start, Cold and Snow Later This Week

Quick update on our system for today....

Cold front has moved through eastern CO early this morning bringing northerly winds to much of eastern CO. Precip remains near the CO/WY border at this hour. Latest HRRR models brings precip south during the morning hours and pushes south of teh I-70 corridor by around Noon, so expect local foothill areas to begin seeing snow around Noon to 2 pm. Snow may be moderate at times this afternoon with bursts of heavy snow through about 6 pm, then snow will diminish and should exit the state by 9 pm. Snow level will be 6000-7000 ft when precip begins around Noon, then lower to 5000-6000 ft by 3 pm, and down to 4000 ft by 6 pm. HRRR keeps heaviest precip along the foothills into the eastern slopes of mountains, with little precip east of I-25. Snow amounts still looking like 2-5 inches in the foothills, with highest amounts north of I-70, so generally 2-4 inches expected in our local foothill areas. Roads will likely remain mostly wet below 8000 ft through 3 pm, then roads may begin to accumulate snow with ice underneath after 3 pm, so roads may be slick at higher elevations for the return commute today. Hopefully everyone has properly prepared and equipped for winter driving conditions by this time. As conditions clear overnight, temps will drop into the 5-15 deg F range in the foothills, so any moisture left on roads will freeze, so secondary roads may have snow and ice Friday morning, while primary roads should be in good shape with crews clearing and treating.

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