wxgeek's weather-Forecast for thurs-nxt wk-Update 4/17

Update Thurs April 17

Clearing with temps nearly back to seasonal norms Thursday afternoon. Friday looks mostly sunny with temps climbing well above seasonal norms, but some gusty west to southwest winds developing in the afternoon with speeds of 20-45 mph possible. Slight chance for a few late afternoon and evening showers developing from the Divide east into the foothills and adjacent plains with snow level above 12,000 ft.

On Saturday, an upper level trough from the Desert Southwest will slowly move across CO and bring good chances for showers and isolated thunderstorms in the afternoon and evening. Showers will develop across the High Country initially, then spread east into the foothills and plains. Snow level remains above 12,000 ft, so should be all liquid except for some small hail possible in thunderstorms. Most areas should see less than 0.10 inches of rain, but in heavier showers isolated areas could see up to 0.25 inches. Activity should die down after sunset. Sunday should be mostly sunny with temps above seasonal norms, but with residual moisture and some instability, isolated showers will be possible Sunday afternoon and evening over the High Country and foothills, with some moving onto adjacent plains. Precip amounts should remain under 0.10 inches.

For next week, pretty confident Monday and Tuesday will be dry and warm. Models then include some unsettled weather mid to late in the week, although GFS and ECMWF differ on timing and intensity of next upper trough. GFS is faster and moves the upper trough to our north, while the ECMWF is slower and moves the upper trough farther south. Either way, expect cooler temps from Wednesday into next Friday, with the chance for precip Thursday and Friday. Wednesday could be windy ahead of the system. There is the potential for heavy snow above 7000-8000 ft as well, so our Spring snow may not be done yet.

_________________
"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 Tue Apr 15

A blood moon on tax day, seems appropriate. Generally nice day across the state with temps near seasonal norms. Mountain wave cloud has formed along the Front Range as upper level winds increase. Some gusty west to southwest winds this afternoon into Wednesday morning with speeds in the 15-35 mph range in the foothills, and 10-30 mph on the plains.

Forecast for Wednesday and Thursday rather complex, and remains uncertain. Upper level trough that will pass over CO rather weak, yet models insist on robust precip output, especially south of the Palmer Divide. Some models such as the WRF have little if any precip north of the Palmer Divide, while the NAM and GFS have lower amounts into the northern foothills and mountains. So, any forecast is a guess, and this one contains more uncertainty than most guesses. I am still not convinced given the upper level pattern that southern foothill and Palmer Divide areas will see as much precip as models suggest. General consensus is that showers will develop over the northern and central mountains this evening and tonight with snow level 6000-7000 ft, but any accumulation to be light. Showers then re-develop Wednesday morning over the mountains, and spread east into the foothills by Wednesday afternoon with snow level around 8000 ft. Precip increases Wednesday evening and night, diminishing after midnight, and snow level lowers to 5000-6000 ft. Amounts and coverage are the hard part. My best guess is that northern and central mountains will see 2-6 inches of snow. For the foothills, areas north of I-70 may see 1/2 to 2 inches, while areas between I-70 and the Palmer Divide could see 2-5 inches, while southern foothill areas and the Palmer Divide could see 4-9 inches. Models put a bulls eye over the Pikes Peak area with up to 12 inches, but I still see that as doubtful. South Central mountain areas could see 5-10 inches of snow. Latest models bring precip in sooner on Wednesday, so roads could be wet for the evening commute, but I do not think there will be any snow or ice accumulation until after 6 pm and only above 8000-9000 ft. Roads could become slick above 8000 ft Wednesday night into early Thursday morning, but based on the uncertainty in snow amounts and warm pavement, roads could remain just wet with some slush. Urban Corridor could see some snow Wednesday night, but believe roads will remain just wet. Plains not expected to see much if any precip from this event, although southeast plains could see some rainfall.

Conditions improve Thursday. By Friday, temps warm back to or above seasonal norms, but as a weak upper trough approaches from the southwest, chance for showers Friday afternoon and evening over the High Country and foothills, mostly south of I-70. Snow level looks to remain above 10,000 ft. As upper trough moves across CO on Saturday, precip chances increase statewide with isolated thunderstorms possible Saturday afternoon and evening. Snow level remains above 10,000 ft, but small hail and graupel possible in heavier showers. heaviest precip expected in areas south of I-70. Upper trough moves slowly east on Sunday, so temps should be warmer with more sun, but enough instability and moisture remain to create isolated showers Sunday afternoon and evening, mostly over the High Country and foothills with snow level above 12,000 ft.

Monday and Tuesday next week look mostly dry and warm, but models suggest another upper trough will move across CO mid to late next week, increasing precip chances with the potential for some heavy snow above 8000-9000 ft. Will have to wait and see how this evolves, but Spring is the time of year for these wandering upper level troughs to move across the Southwest and into CO.

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

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

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System Sunday brought generally 6-14 inches for foothills areas, with lesser amounts along the Urban Corridor. Get ready for round 2. Prior to our next round of snow, Tuesday looks to be mostly sunny and warm with temps back to seasonal norms.

Models appear to be in good agreement that next system will drop down from the northwest and bring precip to CO beginning Wednesday afternoon with snow level around 8000 ft. Precip will begin along and west of the Divide and spread east into the foothills and Urban Corridor by late afternoon/early evening with snow level lowering to near 6000 ft by 6 pm Wednesday. Precip becomes moderate to heavy Wednesday night into Thursday morning with snow level lowering to plains level overnight and precip spreads across most of CO. Snow continues Thursday morning, and begins to diminish Thursday afternoon. Models are currently pretty robust with snowfall amounts, on par with our recent system from Sunday. Hence, mountain and foothill areas could see another 6-12 inches of snow from this system, with 2-6 inches for Urban Corridor and 1-3 inches on the plains. If current models are correct, I would say the Wednesday evening commute back up the hill should be mostly ok, as Tuesday will be mostly sunny and warm, road temps will be warm enough to melt any initial snow. By Wednesday night though, temps drop as snowfall increases, so roads will become ice and snow packed and remain that way into the Thursday morning commute. As snow mostly ends by Thursday afternoon, commute back up Thursday should be ok.

This system is not as impressive looking as Sunday's in the upper levels, so there is some doubt in my mind that it will yield as much snow, but with Spring comes more lower level moisture to work with, so until models change their tune, will stick with the above forecast. I will certainly monitor future model runs to see if there are any changes to the forecast, but for now be prepared for another round of winter driving conditions this week.

Models continue to paint a more pleasant picture for Easter weekend, with some mountain showers, but mostly dry and warm in the foothills and plains. Longer range models indicate chances for more precip next week and towards the end of the month, so April has been a good month for moisture for us keeping fire danger low. We can only hope May will follow, but traditionally May is when fire danger begins to rise into the moderate to high range.

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

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

Bump for 4/15 update

Bump for 4/17 update