wxgeek's weather-Indian Summer Fall weather-Update 10/28

Update Tue Oct 28

More typical Fall feeling day today with temps slightly below seasonal average. Upper ridge beginning to build across the Great Basin today and will migrate east over CO later this week. This pattern will bring dry weather to CO as well as temps above seasonal norms from Wednesday through Saturday. Thursday and Friday look to be the warmest days this week with temps 5-15 degrees above seasonal norms.

Next system to impact CO will move into the West Coast Thursday and Friday, then move east into CO over the weekend. Models today are less robust with precip from this system over CO. Some precip may develop over western CO Saturday afternoon, mostly in showers and isolated thunderstorms with snow level above 10,000 ft. Cold front will move across CO on Sunday, with additional precip along and west of the Divide with snow level lowering to 7000-8000 ft, so some winter type driving conditions across higher passes west of the Divide on Sunday. Models today only suggest a slight chance for precip east of the Divide on Sunday afternoon and night, with snow level lowering to 5000-6000 ft Sunday, although little if any accumulation is expected in the foothills at this time. Models may change their tune, so will update with any changes. Models suggest a cool day on tap Monday, but only lingering flurries in the mountains expected.

Tuesday through Thursday next week looks dry and mild with temps climbing back above seasonal norms. Next system could impact CO by next Friday into Saturday. Models suggest this would be a colder system moving down from the northwest, so snow chances would be better for most of CO.

It appears we will end October with 5 inches of snow on Conifer Mountain, well below our average of 15 inches for October. November tends to be a dry month for much of CO, and it looks like that will be the case this year as well. November average snowfall on Conifer Mountain is around 14 inches, and unless the upper level pattern changes the latter half of November, we will be lucky to get close to average.

_________________
"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 Oct 27

Cold front passed through eastern CO last night bringing temps closer to seasonal norms today. Upper trough will pass over eastern today with a few lingering flurries in the mountains, and rain showers across the Urban Corridor and plains. By tonight, skies will clear and allow temps to drop to or below freezing in many areas, prompting NWS to issue a Freeze Warning for eastern CO below 6000 ft.

Upper ridge will build over CO the rest of this week which will allow for mostly dry conditions and temps at or above seasonal norms statewide. Warmest temps look to be Thursday through Saturday. A vigorous upper trough will move into CA Friday, and then east into CO by Sunday into Monday. Models at this time bring precip into western CO Sunday with snow level 7000-8000 ft. Precip is expected to spread east into eastern CO Sunday afternoon into Sunday night with snow level lowering to plains level overnight. Mountains could pick up 4-8 inches of snow from this system, with foothills getting a few inches. Showers may persist into Monday afternoon with snow level 5500-6500 ft.

Another upper ridge is expected to build back over CO later next week with fair and mild weather expected Tuesday through next Friday. Next precip chances will be next weekend as system moves across CO. Longer range models are suggesting that a long wave upper trough will develop along the west coast by mid November bringing much needed rain to CA. For CO, this would imply a chance for precip mostly over western CO as short wave systems move out of the long wave position. But during this time of year, models change their minds frequently.

_________________
"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 10-25
Finally back home after a lengthy international busines trip. Even traveled through 4 countries in one day on part of the journey (Italy, Germany, U.S. and Canada).

Some gorgeous weather the past few days as an upper ridge aloft provides warm and sunny weather over CO. We will see a slight bump in this pattern Sunday and Monday as an upper trough currently moving through the west coast moves inland across the central and northern Rockies. Biggest impact to CO will be increased clouds with a chance for precip mostly along and west of the Divide, and temps colling closer to seasonal norms. Precip is expected to move into western CO Sunday morning, with a slight chance of showers into the foothills by Sunday afternoon. Snow level is expected to remain above 12,000 ft. Cold front associated with upper trough will move through eastern CO Sunday evening, thus temps on Monday will be cooler with some gusty westerly winds Sunday night into Monday morning.

By Tuesday, upper ridge aloft builds back over CO creating dry and mild conditions through next Saturday. Temps likely to warm back above seasonal norms next week into Saturday. Next chance for precip looks to be next Sunday into Monday as an upper trough moves across CO. After that, more dry and mild weather expected into the following weekend.

For the long term, nothing significant on the horizon on long range models. The latest El Nino advisory still has the 3 month mean SST in the Pacific in the neutral ENSO range. Models suggest a 65% probability of a weak El Nino forming in the November to January time frame. The implications to this are that ENSO Neutral conditions are likely at least until the winter solstice. As we have seen the past 2 seasons, ENSO nuetral conditions favor a dry Fall for eastern CO, so snowfall seems likely to remain below average through December. If the weak El Nino does form, we could see heavier snow in the January to April time frame.

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

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