wxgeek's weather-Another blast of winter-Update 4/30

29 Apr 2013 06:02 #1 by RenegadeCJ
Update Wed May 1

Models have done a good job with this system. Banded precip brought heavy snow to areas north of I-70 overnight, with northern foothills receiving 8-14 inches of snow, and 16 inches at Long Draw reservoir with 4-8 inches along the I-25 corridor. Farther south, much lighter amounts overnight, however, models continue to predict heaviest snow south of I-70 will be during the day today and into this evening. Former snow amounts still look valid by tonight. Distinct band still across CO will change into a more classic upslope snow event today, with heaviest snow along the foothills south to the Palmer Divide. Roads mostly wet at this time below 8000 ft, but as heavier snow and colder temps move in today, that may change by the evening commute. Moderate to heavy snow to persist through about 8 pm, then light snow to persist into early Thursda morning, so the morning commute on Thursday could be slow and slick in spots.

Update 12:30 pm - Area of moderate to heavy snow beginning to move south of I-70 and will continue to move slowly south through this evening. Snowfall rates in this area up to 1-2 inches per hour. In addition, temps hovering around freezing along the Urban Corridor will begin to drop after 2 pm, so as snowfall rates increase and temps drop, roads previously wet will become slushy to icy this afternoon and evening, especially at higher elevations in the foothills. Snow will remain moderate to heavy through about 4-6 pm, then lighten in intensity. Light snow likely to persist past midnight, especially southern foothills and Palmer Divide. Should begin to clear by early Thursday morning, but roads could be slick in spots.

Models show warmer temps and mostly dry conditions across the state Thursday and Friday. By the weekend, current systenm cuts off over the Mississippi Valley and another cutoff upper low forms off the CA coast, with a ridge building in-between over CO. This translates to warmer temps, but afternoon and evening showers possible, mostly along and west of the Divide with snow level at or above 10,000 ft. By next week, the upper low off the CA coast is forecast to drift slowly east, so as it approaches, more afternoon and evening showers with isolated thunderstorms possible and snow level remains above 10,000 ft. Chances for showers across the foothills and plains increase by late next week as upper low gets closer. No more snow in the extended forecast at this time.

So we ended April with 35.75 inches of snow on Conifer Mountain, just below our April average of 38.75 inches. Season total now stands at 150 inches, which is 94% of normal for the end of April, and 87% of our seasonal norm. So although we are still slightly behind average, we have made up a lot of ground Feb-Apr, and have had a very quiet early fire season, for which we are all thankful. May and June still loom as our most dangerous fire months, but hopefully we continue to get moisture to keep the fire danger low.


Update Tue Apr 30

A last breath of Spring before Winter returns. Initial cold front went through northern CO this morning, which will keep temps warm today, but well below the past 2 days. Showers beginning to develop across northern CO this afternoon and this band will intensify and gradually move south through this evening. NWS has lots of winter warnings and advisories out. Winter Storm Warning now includes the foothills south to the Palmer Divide above 6000 ft, with a Winter Weather Advisory for the Urban Corridor and adjacent plains.

Models indicate there will be two distinct precip episodes with this system. The first episode will be banded type precip oriented from southwest to northeast associated with the jet stream entering CO. This band will primarily affect northern CO north of I-70 from this afternoon into tonight. Band is expected to slip south to the Palmer Divide by later tonight. Snowfall rates in this band could reach 1-2 inches per hour at times. The second episode will be Wednesday afternoon and evening caused by stronger upslope flow and the passing of the upper level trough. Models also indicate that the colder air will not move into CO until Wednesday during the day. Snow levels currently above 10,000 ft and expected to remain so through about midnight tonight. Second push of cold air begins after midnight with snow level lowering to near 6000 ft by 6 am Wednesday morning. Cold air continues to push south on Wednesday, so temps not expected to rise much during the day, and may actually lower Wednesday afternoon. Snow level will be down to plains level most of the day Wednesday, although with warm roads, snow only expected to accumulate on grassy and dirt surfaces below 6000 ft. Snow may begin to stick to road surfaces by Wednesday evening. For foothill areas above 7000 ft, expect snow and ice packed roads by Wednesday morning, and likely to remain that way into Wednesday night with some melting during the day on Wednesday on primary roads. Snow looks to persist now through midnight Wednesday night, dissipating by early Thursday morning.

For snow amounts, lots of uncertainty with this system, especially at lower elevations. Since much of initial snow melts even at higher elevations, amounts may be less than what NWS is thinking. Here is my latest guess:

Northern and Central Mountains: 7-14 inches (highest amounts north of I-70)
Foothills above 7000 ft and Palmer Divide: 5-12 inches (highest amounts north of I-70)
Foothills below 7000 ft and Banana Belt: 3-7 inches
Urban Corridor: 2-5 inches (highest amounts across northern, western and southern suburbs)
Eastern Plains: 1/2 to 2 inches (highest amounts north of I-70)

Wednesday morning commute above 7000 ft will be slow with snow and ice packed roads as well as wet and slushy roads. Below 7000 ft should be just wet. Wednesday evening commute could also be difficult now, with snow and ice packed roads from the plains all the way up. Even the Thursday morning commute could have some slick spots as temps will be in the teens to low 20's Thursday morning.

Conditions improve Thursday with slowly warming temps, but still way below seasonal norms. Mostly sunny and warmer Friday as well. Weekend should see temps near seasonal norms with the chance for afternoon and evening showers, mostly along and west of the Divide, but some showers possible across the foothills and Urban Corridor both days. Snow level should remain at or above 10,000 ft this weekend.

Next week continues to show near normal temps and increased chances for afternoon and eveneing showers as an upper level trough slowly moves across the Rockies.

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

"It is better to be roughly right than precisely wrong".
Update Mon Apr 29

Another warm and sunny day across the state today. Some gusty westerly winds will be present today, especially over the High Country and foothills in advance of our approaching system. Temps to remain 10-20 degrees above seasonal norms, which will create elevated fire danger in areas without snow on the ground, especially south of the Palmer Divide.

Tuesday will be another warm and breezy day into the early afternoon hours before the next system begins to impact the state. Upper level trough currently over British Columbia will dive into the Rockies on Tuesday, and bring an associated cold front south from WY into northern CO Tuesday afternoon/evening. Prior to the cold front, we will see very warm temps and gusty west to southwest winds which will create high fire danger in areas where snow is absent. Models have some minor differences regarding timing of the cold air and precip amounts, but are in overall good agreement on this system. Initial push of cold air behind cold front will push south from the WY border in the early afternoon hours on Tuesday. Cold front makes it to I-70 corridor by Tuesday evening around 3-6 pm, and continues south overnight. Showers will develop along and behind the cold front Tuesday afternoon into Tuesday evening, with isolated thunderstorms possible along the cold front. Snow level will be above 10,000 ft along and south of the cold front, but will drop rapidly behind the cold front. As the cold front moves south, northerly upslope flow will develop behind the front and create more continuous type precip across eastern CO (from the Divide east) Tuesday night into Wednesday evening. Snow level will be close to plains level by Wednesday morning and remain near plains level during the day on Wednesday as cold air continues to push south. Snow should begin to dissipate by Wednesday evening and clear by Wednesday night. Now for snow amounts. Very difficult system to predict snow amounts due to the very warm temps preceding this event, as much of the initial snow will melt. Latest models keep the highest precip amounts north of I-70 with this system, but decent amounts should still exist south to the Palmer Divide. So here is my latest guess at snow amounts:

Northern and Central Mountains: 6-12 inches (highest amounts north of I-70)
Foothills Above 7000 ft: 3-8 inches (with up to 10-12 inches north of I-70 close to the WY border)
Foothills Below 7000 ft and Banana Belt: 2-5 inches
Palmer Divide: 2-6 inches
Urban Corridor: 1-4 inches
Eastern Plains: 1/2 to 2 inches

Coldest air with this system happens during the day on Wednesday, and with high Spring sun angle, temps below 7000 ft will hover near or above freezing, so there may not be much accumulation below 7000 ft with this system. Roads certainly look to remain only wet below 7000 ft with accumulation on grass and dirt surfaces. Above 7000 ft, roads likely to be mostly wet, but ice and snow certainly possible early Wednesday morning especially at higher elevations. Roads likely to become mostly wet during the day on Wednesday with some slush. Wednesday morning commute could be the toughest, so expect a longer commute on Wednesday morning, should be ok by the evening commute.

Thursday and Friday should be dry with temps below seasonal averages. Temps climb back to near seasonal norms by the weekend, with showers both days mostly west of the Divide with snow level around 10,000 ft. Next week models suggest the chance for afternoon and evening showers as weak upper level system migrates across the area, with snow level at or above 10,000 ft.

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

"It is better to be roughly right than precisely wrong".
Spring in Colorado means diverse weather. We are currently enjoying some beautiful warm weather which will persist through Monday with temps 5-15 degrees above seasonal norms, and only slight chances for showers across the High Country Sunday and Monday, mostly north of I-70. Mother Nature appears to have a change of plans for the upcoming week. Latest model guidance brings a vigorous upper level trough and associated cold front barreling into CO from the northwest Tuesday. Cold front should move south from WY into northern CO by Tuesday afternoon, with precip developing north of I-70 shortly after Noon on Tuesday. Snow level will start out pretty high, around 10,000 - 12,000 ft Tuesday afternoon, but lower quickly as cold front brings much colder air across CO. Precip intensifies and pushes south Tuesday evening and Tuesday night. Snow level looks to drop to near 6000 ft by midnight, and down to plains level by Wednesday morning. Snow looks to persist all day Wednesday into Wednesday evening. Models currently outputting between 0.50 and 1.00 inches of liquid equivalent from this system, so snow amounts above 8000 ft could be in the 6-12 inch range. With very warm temps this weekend, snow amounts below 6000 ft uncertain, as much of the initial snow likely to melt, and snow falling during daytime hours Wednesday will have a hard time sticking below 6000 ft. However, above 7000-8000 ft, a more winter like picture is likely with snow and ice covered roads by Wednesday morning. I would expect winter type advisories or warning to be hoisted by NWS either later today or Monday for at least the mountains and foothills, and possibly the Urban Corridor.

Conditions improve with gradual warming on Thursday into next weekend, although medium range models showing a chance for showers next weekend with snow level 8000-9000 ft.

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

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

Too bad future generations aren't here to see all the great things we are spending their $$ on!!

Please Log in or Create an account to join the conversation.

29 Apr 2013 16:16 #2 by RenegadeCJ
Bump for April 29 update

Too bad future generations aren't here to see all the great things we are spending their $$ on!!

Please Log in or Create an account to join the conversation.

01 May 2013 05:54 #3 by RenegadeCJ
Bump for 4/30 Update

Too bad future generations aren't here to see all the great things we are spending their $$ on!!

Please Log in or Create an account to join the conversation.

01 May 2013 14:33 #4 by RenegadeCJ
Bump for may 1 update

Too bad future generations aren't here to see all the great things we are spending their $$ on!!

Please Log in or Create an account to join the conversation.

Time to create page: 0.127 seconds
Powered by Kunena Forum
sponsors
© My Mountain Town (new)
Google+