wxgeek's weather-Cool and Dry Start to 2013-Update Jan 4

Update Fri Jan 4

Beautiful day across the state, although our lack or moisture tempers the beauty just a bit. Temps will continue to gradually rise as upper ridge moves across CO this weekend, so temps near to slightly above seasonal norms for the weekend, and continued dry across the state. Some breezy south to southwest winds possible Sunday into Monday.

For next week, models beginning to come into better agreement. GFS and Euro now both split an upper trough and close off an upper low early next week and track it across northern Mexico/southern NM. Euro slower with this, but the outcome for CO will be the same, no precip. The NAM is the only model showing some precip for CO on Monday, but with all other models driving the upper low to our south, I tend not to believe the NAM at this time. Euro model in general is the best medium range model, it tends to have the favored solution that other models adapt. So, some clouds possible, especially south of US 50, but does not look like any precip for CO until later next week. As this system moves east it could be a significant system across TX and then as it moves into the mid and lower Mississippi Valley and eventually into the eastern US.

GFS and Euro now in pretty good agreement on the system for later next week. Both models now bring a deep upper trough into the Great Basin on Thursday and move it across CO next Friday/Saturday. Latest runs bring snow to western CO early Friday, and develop snow across the entire state by Friday afternoon and persist snow across eastern CO on Saturday. If this system holds together, could be a decent snow maker for the foothills and plains. If the current timing holds, it would also mean a very snowy and cold game for the Broncos next Saturday. Still way to early to bank on this, but certainly a system to keep an eye on next week.

Longer range models then build a high amplitude upper ridge in the eastern Pacific, which would bring very cold air down into CO the following week along with some light upslope snow for eastern CO.
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"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 Jan 3

Cool, clear and dry is the forecast through the weekend. Temps will gradually warm into the weekend, but still cold nights with temps in the single digits most areas. High temps should rise back to near seasonal norms by the weekend.

There is now some differences in medium range models for next week. Latest GFS runs now bring an upper trough across CO on Monday, which would include a chance for snow most areas of the state. The Euro keeps the upper low well to our south so would not include any precip for CO. Both models have changed from a cutoff low over southern CA to a more progressive solution, so not sure what the eventual system will be, but given the recent change, we could see some snow early next week. Models also disagree on pattern later next week. GFS has been consistent in bringing an upper trough across CO next Thursday which would bring snow to most of CO. Euro model much slower with this system, which would delay the trough through CO until at least Friday. Since the GFS has been more consistent with each pattern, I am currently leaning more towards believing the GFS solutions, so chances for snow next Monday and Thursday are looking possible. Higher amounts west of the Divide, with mostly light amounts for our foothills at this time. Temps look to remain at or below seasonal norms next week.

For the football fans out there, games on Saturday:

Houston - Slight chance of rain during the game, temps in the low to mid 50's, light north winds.

Green Bay - Dry, with temps in the low 20's to upper teens, westerly winds of 5-10 mph, bringing wind chills in the low teens.

On Sunday:

Baltimore and Washington - Dry, with temps in the low to mid 40's, light westerly winds of 5-10 mph.
_________________
"Climatology is what you expect, Weather is what you get".

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

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Jan 2
CO currently remains under a cool and dry northwest flow aloft pattern, so temps will remain at or below seasonal norms and no precipitation is forecast across the state through the weekend. Temps may rise back to seasonal norms by the weekend as the upper ridge moves over the Inter-Mountain west.

Medium range models continue to suggest that our next chance for precip will be next week Wednesday through Friday. First chance will come as a cutoff low ejects from southern CA across northern NM. Best precip chances from this system will be next Wednesday mostly south of US 50. Then an upper trough will move over CO from the northwest and bring better chances for snow across the entire state next Thursday/Friday. After this, models indicate the upper ridge will retrograde westward into the eastern Pacific leaving CO under a cool northwest flow aloft, but systems moving southeast in this flow mayt bring additional snow chances to CO next weekend and into the following week. Under this pattern, the mountains will receive the bulk of snow, especially the northern and central mountains, while the foothills and plains remain cool but mostly dry, with only chances for light snow. However, if the upper ridge remains in the eastern Pacific, systems can dig down the east side of the ridge and create cutoff lows in the desert southwest that can bring snow to eastern CO. Will have to wait and see how things progress. In general, the upper level pattern is a dry pattern for most of the western U.S. as the upper ridge dominates, so I would currently expect a drier than average January across CO. This is not unusual, as January tends to be one of our drier months in eastern CO. Conifer Mountain averages 15 inches of snow in January, and 6 days with snow.
_________________
"Climatology is what you expect, Weather is what you get".

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

Bump for Jan 4th update