wxgeek's weather-Storm Forecast Mar 7

Wed Mar 7

Finally some concensus amongst the models today. Cold front pushed south across northeast CO this morning ushering in low clouds, fog, freezing drizzle and some light snow which will continue into the early afternoon hours. Driving down 285 this morning found roads wet, but ice accumulating on the windhshield. Warmer with less ice down in the Urban Corridor although temps still hovering at the freezing mark.

Upper low currently over southern UT will drift slowly to the 4 Corners region this afternoon and then is forecast to move into southern NM on Thursday and meander over northeast NM on Friday into Saturday morning before moving east into the southern Plains late Saturday into Sunday. The result will be for snow chances to increase this afternoon into tonight across the Palmer Divide and foothills south of I-70. I currently expect 1-3 inches across most of these areas, with up to 4-6 inches over higher foothills and areas farther south into southern JeffCo and Teller county. Snow should end by Thursday morning and move into southern CO south of US 50. Areas of south central and southeast CO could receive up to a foot of snow through Friday. Foothills and northeast Plains should see clearing skies later on Thursday and into Friday with temps near seasonal norms. There is a chance for an isolated flurry Thursday into Friday as enough instability could produce a few showers over higher terrain, but no additional accumulation.

The weekend is currently looking very nice across the state, with temps at or above seasonal norms. As this current system moves east this weekend, I can see good potential for a large severe weather outbreak across portions of OK, TX, AR, LA and MO. Warm and dry conditions are expected to persist across CO into most of next week. Next chance for precip looks to be late next week into next weekend.
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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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Tue Mar 6

Well, I must say, one of the most difficult storm forecasts I have seen while I have lived out here. I really should have titled this "Storm Guess, Maybe".

Upper trough is currently moving along the West Coast and digging into the Great Basin, this much is for certain. A cold front is currently in WY and will move south into northern CO early Wednesday morning. As the cold front moves south, shallow upclope flow will bring low clouds and a combination of freezing drizzle and ligh snow to northeast CO Wednesday morning, primarily north of the Palmer Divide and into the foothills up to about 8500-9500 ft. So the drive down the hill Wednesday morning may have fog, low clouds, and some freezing drizzle or light snow which could make roads slippery all the way down into the Urban Corridor. Because temps have been so warm this week, initial precip likely to melt on road surfaces, but with temps dropping during the day and below freezing, moisture could re-freeze on roads by late afternoon/evening.

Unfortunately there is horrible model concensus and even run to run consistency, so forecast confidence is quite low. In the short term, models agree the upper trough will become a closed upper low and dig to near the NV/UT/AZ border by Wednesday morning. Upper low is forecast to move slowly east on Wednesday to near the 4 Corners region by Wednesday evening and to north central NM by Thursday morning. From here there is a lot of disagreement on the future track. Faster GFS moves the upper low quickly east into TX/OK by Thursday evening, while the NAM, UK Met and ECMWF all keep the low hanging around somewhere between southeast CO to east central AZ by Friday morning. Hence, depending on where the low tracks will determine how much snow and where. In order to provide some form of guidance, I will use the NAM model as it has had about the best consistency of any of the models. Given that, here is the best I can come up with at the moment:

Low clouds, fog, freezing drizzle and light snow will move into northeast CO Wednesday morning, but any accumulation would be very light, less than 1/2 inch. Heavier and more steady snow looks like it will move into the foothills, mostly south of I-70, by Wednesday afternoon and persist into Thursday morning. Majority of snow then looks to move south of US 50 during the day on Thursday and remain over southeast CO into Friday morning. There is a chance for light snow or flurries across the foothills on Thursday south of I-70, but little if any additional accumulation. So total accumulation forecast currently looks like 3-7 inches for the foothills south of I-70 and the Palmer Divide, with 1-4 inches for the Urban Corridor and Banana Belt areas. Southeast CO could see heavier amounts. Skies should be clearing over most of CO on Friday and should be dry and mild by this weekend.

Caviet - If the upper low tracks a little farther north and stalls over northern NM or southeast CO like some models suggest, we could see a much more significant snowstorm in eastern CO and the foothills with snow totals in the 10-20 inch range from Wednesday through Friday. Even with GFS solution, we could see a pretty heavy band of snow Wednesday night. We could also see less than 2 inches on some models. There is just too much uncertainty right now to forecast anything with confidence. NWS is in the same boat and holding off on any winter advisories until there is better model concensus. Hopefully models get a better handle on this thing Wednesday and the forecast will have more clarity.
_________________
"Climatology is what you expect, Weather is what you get".

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

Bump for Wed Mar 7 Update