wxgeek's weather-Weather Outlkook Apr 5-14-Update 4/11

Update Fri Apr 11

Beautiful day across the state today with lost of sunshine and temps well above seasonal norms. As is pretty typical in Spring across the Rockies, things are gonna change.

Latest trends in models has been to delay the system on Sunday a bit. Models in good agreement and dig upper trough a bit farther west and slower, which means more snow for CO. Saturday will be a fairly pleasant day, sunny in the morning with showers in the afternoon and evening. Showers will develop west of the Divide late morning, and move east into the foothills and plains Saturday afternoon into evening. Isolated thunderstorms will be possible and snow level will remain above 12,000 ft, although small hail will be possible in thunderstorms. Models bring cold front into northern CO early Sunday morning and it puses south during the day. Snow level to begin around 7000-8000 ft Sunday morning lowering to plains level by around noon. Snow looks to begin in the mountains between midnight and 6 am, with precip beginning in the foothills and plains between 6 and 9 am. Heaviest precip will be from about 9 am through 6 pm Sunday in the foothills, with snow expected to persist until about midnight Sunday night. With snow lasting later, roads could be worse for the Monday morning commute. Amounts still looking fairly impressive:

Northern and Central Mountains: 6-12 inches
Foothills and Palmer Divide: 4-10 inches
Urban Corridor: 2-6 inches
plains: 1-4 inches

Expect NWS to issue some winter type advisories later today or Saturday for the mountains and foothills/Palmer Divide.

Since temps will be quite warm Saturday, initial snow likely to melt on roads, but as temps drop and heavy snow falls on top, roads likely to be come very slick by Sunday afternoon into Monday morning, especially above 7000 ft.

For next week, models adjusting. GFS now coming into agreement with ECMWF, so dry and warm conditions expected Monday and Tuesday, chance for precip Wednesday into Thursday morning, dry and warm Friday and Saturday, with models now indicating a chance for precip Easter Sunday into Monday. This time of year extended forecasts change frequently, so will have to see what transpires next week.

_________________
"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 Thu Apr 10

Mostly sunny with a few puffy CU around today, along with some decent westerly winds, so a pretty average April day in CO. Slight chance for a few showers to pop up over the mountains and eastern plains this afternoon, with very isolated thunderstorms a possibility. Snow level above 12,000 ft. Friday should see warmer temps with less wind and mostly sunny, so a very nice day in store.

As I have been mentioning, the weekend weather will not be nearly as nice. Saturday will be ok, mostly sunny in the morning then clouds build in the afternoon with showers likely from the Divide east to the plains, and isolated thunderstorms possible. Snow level remains above 12,000 ft, so higher foothill areas could see our first rain since last September. Attention then turns to a vigorous upper level trough that will approach from the northwest. Latest models in pretty good agreement now. Cold front will push south from near the WY border around midnight and move south to the Palmer Divide by around 6 am Sunday morning. Moist upslope flow will develop behind front as temps drop rapidly. Snow level at midnight will be around 10,000 ft across I-70, and lower to 7000-8000 ft by 6 am, and down to 5000-6000 ft by noon, and plains level in the afternoon. Precip moves south to I-70 by 6 am Sunday morning and pushes south through the day. Precip now looks to persist into Sunday evening, with lingering flurries through about midnight. Models continue to suggest robust precip totals, with up to an inch of liquid equivalent in some areas. Northern and central mountains along with the foothills and Palmer Divide will see the highest snowfall from this event. Currently looks like 4-10 inches possible in the mountains and foothills and Palmer Divide above 7500 ft. Below that initial precip will be a mix of rain and snow and initial snow will melt except on grassy surfaces. However, by late afternoon, lower elevations will see their share of accumulating snowfall. For areas below 7500 ft in the foothills and Urban Corridor, these areas could see 2-6 inches of snow, with 1-3 inches farther east on the plains. Roads likely to become slush and snow packed above 7500 ft by Sunday afternoon into early Monday morning, thus Monday morning commute could be slick in areas, especially above 7000 ft.

Conditions clear Monday with a return to near normal temps. Tuesday looks dry and warm as well. Models have some disagreement on intensity for system next week, but they all point towards precipitation from Wednesday to Friday, just a matter of how much and how cold. GFS is stronger and colder with next system, while ECMWF is weaker and warmer. Precip on Wednesday would be rain with snow level above 12,000 ft. If GFS is correct, snow level would lower to 6000-7000 ft by Thursday afternoon with heavy precip into Friday morning. ECMWF would have precip ending by Thursday evening and snow level around 8000 ft. Either way, expect some unsettled weather mid to late next week, with the potential for heavy snow.

Conditions still looking nice for Easter weekend with warm temps and dry. More precip the following week possible.

_________________
"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 8

Beautiful Spring day across the state today with temps generally 5-10 degrees above seasonal norms. Wednesday is looking even warmer, but gusty westerly winds are expected to develop during the day into the evening with speeds of 20-45 mph possible. This has prompted a Red Flag Warning from Noon through 8 pm for the far eastern plains and south central CO as RH values expected to be below 15%. Basically anywhere snow is gone has an increased fire danger right now as the "green up" has started at lower elevations, but still a lot of dry ground fuels present. Temps Wednesday expected to be 10-15 degrees above seasonal norms. Winds are in response to a fast moving system to our north, which will bring a slight chance for afternoon showers to the foothills and Urban Corridor Thursday afternoon. Snow level is expected to be 10,000 - 12,000 ft, so any precip likely to be of the liquid variety. Very isolated thunderstorms possible. Friday looks to remain dry and mild with temps remaining above seasonal norms.

Weather will take a turn this weekend. Saturday will start out nice, with isolated showers possible Saturday afternoon and evening, with snow level remaining above 10,000 ft. Isolated thunderstorms possible as well. GFS model has come into alignment with the ECMWF as expected, so upper trough will move into CO from the northwest on Sunday. Associated cold front will move south across the area early Sunday morning, and bring cooler upslope flow to eastern CO during the day on Sunday. Precip is likely and will move from the WY border early Sunday morning south to the Palmer Divide by late morning and persist into Sunday evening. Snow level will lower behind cold front to 5000-6000 ft, so snow at higher elevations and a mix at plains level. Amounts look to remain on the light side, with maybe a few inches above 7000 ft accumulating. Paved roads may remain just wet, but could see some slush and snow on secondary roads.

For next week, Monday looks dry. Next system moves across CO rather slowly, so precip chances remain from Tuesday afternoon through Thursday morning across much of CO. heaviest precip look to be from Wednesday afternoon into Thursday morning, with snow level lowering to 7000-8000 ft Wednesday night. Some decent accumulations could occur above 8000 ft from this system. Models suggest things dry out next Friday, then precip chances return next weekend and continue into the early portion of the following week, so some good moisture opportunities look to continue over the Easter weekend and beyond.

Some interesting developments in the Pacific Ocean. The ENSO (El Nino Southern Oscillation) observations have shown a dramatic warming of the Nino 3.4 region (south of Hawaii) and depict some very warm sub-surface water across much of the central Equatorial Pacific. This is usually an indication of a building El Nino pattern, but we will have to wait and see how this develops. The last time this much sub-surface warm water was present was before the 1997-1998 El Nino, which turned out to be one of the strongest El Nino's on record. If this pattern continues and a strong El Nino develops, this would spell good news for next seasons snowfall for eastern CO. A building El Nino can also correlate with a heavier than usual Monsoon season, which would also be good news for CO, as the fire season remains critical until the North American Monsoon begins, then fire danger usually goes way down with increased precipitation and higher humidity.

_________________
"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 Mon Apr 7

After a little burst of snow this morning across the foothills, generally clearing skies but breezy this afternoon with temps remaining below seasonal norms. Mountain flurries may persist into this evening, but should end after sunset. Upper level ridge will move over the region beginning Tuesday which will warm temps above seasonal norms Tuesday through Friday. Warmest day of the week looks to be Wednesday, but will be accompanied by gusty westerly winds. Temps will likely make it into the lower 70's on the plains. Upper ridge flattens some on Thursday as a weak system passes to the north, so temps will be slightly lower, and a chance for some afternoon showers and isolated thunderstorms. Snow level will be above 10,000 ft on Thursday, so mostly liquid precip except over the High Country. Friday should return to dry and mild conditions statewide.

For the weekend, there is disagreement between the GFS and ECMWF on the timing and intensity of our next system. The GFS brings a fast moving system through CO late Saturday that would bring only light precip to eastern CO Saturday afternoon into Sunday morning. The ECMWF is slower and brings a much stronger system into CO on Sunday. ECMWF solution would keep Saturday mostly dry, but brings more precip with colder temps into all of CO Sunday into Monday morning. Tool early to tell which model has the more likely solution, but usually the GFS comes into agreement with the European model. Either way, expect a chance for some unsettled weather this weekend with cooler temps.

Beyond the weekend, models continue to suggest more precip chances next week Tuesday through Thursday. In general, longer range models keep some precip chances, but tend to dry things out towards the latter half of April.

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

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

Bump for 4/8 update

Bump for 4/9 update

Bump for 4/11 update