Mon Feb 20

Well, last forecast was a big bust, sorry about that. Upper low tracked farther north so we had westerly winds with no upslope. I really hate being wrong, but it is a hazard of the profession, so like a relief picther in baseball who just gave up a run in the ninth to lose the game, on to the next game (forecast). At least with these forecasts hopefully there is no one using these for life and death situations. In my professional forecasting career, when you're wrong you can put people's lives in danger.

Blizzard conditions on the eastern Plains should ease up later this afternoon and evening with snow moving east into KS/NE. Our focus now turns to high wind events this week. Combination of strong northwest upper level winds combined with strong surface pressure will create very strong west to northwest winds across the foothills tonight into Wednesday evening. Atmospheric profile tonight and Tuesday night into Wednesday morning is conducive for an enhanced mountain wave which will bring very strong downslope winds along the mountains east of the Divide and especially the foothills. NWS has issued a High Wind Watch for the period from 7 am Tuesday thrugh 7 am Thursday. This is likely to become a High Wind Warning for Tuesday night into Wednesday evening.

For Monday night into Tuesday morning, winds will strengthen and become strong especially between 10 pm Monday and 8 am Tuesday. Wind speeds of 25-50 mph likely with gusts to 60 mph possible. Winds will remain strong during the day on Tuesday with speeds of 20-45 mph likely. Very strong winds will once again develop Tuesday evening into Wednesday morning with speeds of 30-60 mph with gusts to 75 mph possible. Some of the winds Tuesday night into Wednesday morning could be damaging and cause power outages. Winds will remain strong Wednesday with speeds of 25-50 mph into Wednesday evening. So expect a prolonged period this week of strong and gusty west to northwest winds that may cause blowing and drifting snow as well as damage to structures and power outages. High winds should be confined to mountain areas and foothills, with only breezy to windy conditions east of C-470/CO93. Because of the downsloping winds, temps will remain relatively mild Monday through Wednesday, especially at night.

The mountains west of the Divide and north of I-70 will see periods of snow from Monday night through Wednesday, but only a few inches of accumulation each day. The next storm system will move from the northern Rockies south into CO Wednesday night into Thursday. Strong cold front will push south into northern CO Wednesday night and reach the I-70 corridor by early Thursday morning. This front will bring a chance for snow along with gusty northerly winds and much cooler temps. Currently lokks like light amounts, so maybe a dusting to an inch or two of accumulation from this system for the foothills and Plains. If the front moves through during the Thursday morning commute, could cause slower speeds. Snow should be done by about noon, but cold temps expected Thursday night.

Models then build a brief upper ridge into CO Friday and Saturday with mostly dry conditions across the state, and temps should rebound to near seasonal norms, and maybe above on Saturday. Long range models bring the next Pacific system into CO on Saturday night into Sunday which would bring another chance for snow and colder temps across the state. This system has the potential to bring several inches to the foothills on Sunday. Models keep this same pattern active into early March.

Tue Feb 21

High Wind Warning goes into effect at 11 pm today and remains in effect through 5 am Thursday for foothills, adjacent Plains and mountain areas east of the Divide from the WY border to the southern end of Jeffereson County. In addition, Winter Storm Warning in effect for the northern mountains today through Noon Wednesday for 12-18 inches of additional snow.

High Wind Event - Strong upper level northwest winds combining with tight surface pressure gradient across CO to cause strong downslope winds east of the Divide to I-25. Strongest winds will be in the high mountains above 9000 ft and along the eastern slopes of the foothills. I believe strongest winds will be north of I-70, but very strong winds will exist south of I-70 as well. Winds crank up tonight after about 10 pm and remain very strong into Wednesday night. West to northwest winds with sustained speeds of 30-65 mph will exist for an extended period, and gusts in the 80-100 mph range will be likely over exposed and favored high wind areas. The combination of prolonged high wind speeds and high gusts will likely cause some structural damage and power outages. Anything not anchored down will become airborne. Driving will be difficult in this area, especially for any high profile type vehicles that will be prone to being blown over. I believe strongest winds will occur between 10 pm Tuesday night and 10 pm Wednesday night. Temps will remain mild during this event due to adiabtaic heating of the downslope winds. Temps Wednesday on the Plains will be near 60 degrees F.

Snow will be nearly continuous in the central and northern mountains and combined with very strong winds will create near blizzard conditions today trhough Wednesday night. Travel will be difficult with delays and road closures likely. Avalanche danger remains high to extreme in mountain areas, and high winds are capable of causing avalanches through Thursday. Use extreme caution if traveling in the back country.

Next Pacific system will move down across CO late Wednesday night into Thursday morning. This system will bring increased snow to the northern and central mountains, and will bring a chance for brief snow to the foothills and adjacent Plains early Thursday morning. Any accumulation for the foothills looks light, between a half inch to 2 inches, with most areas closer to the half inch mark. Temps will be much colder on Thursday in the wake of a strong cold front. Snow likely to continue in the central and northern mountains through Thursday evening.

We should see a brief break across the state on Friday as an upper ridge moves across the state ahead of our next system. Temps will start cool but warm to near seasonal norms Friday afternoon.

Saturday will be a warm and breezy day ahead of the next Pacific system. Clouds will begin to increase by afternoon, and snow will move into western CO Saturday night and advance east with strong cold front to the Front Range by Sunday morning. Foothills and Plains may see a brief period of snow with the frontal passage early Sunday morning, but models currently keep any amounts on the light side with less than 2 inches, and mostly a dusting. Flurries and light snow will be possible through Sunday evening.

Long range models keep things cool and bring yet another upper trough over CO early next week, whcih will bring another round of snow to the mountains and possibly the foothills and Plains. Another system is forecast for next weekend.

Wed Feb 22

Strong winds to persist in the foothills and higher mountains through tonight. A brief lull this morning, but models indicate wind speeds will pick up again this afternoon into this evening. Highest wind reports so far have been outsode Boulder with a 88 mph gust at the NCAR Mesa lab around Noon. I expect we will continue to see gusts in the 80-100 mph range through about 9 pm tonight, with highest winds north of I-70. Conifer HS had a 63 mph gust this morning, so foothills south of I-70 will still see winds of 60-80 mph.

Winds should die down after midnight as cold front approaches from the north. Snow will increase over the northern mountains again tonight, combined with winds of 20-40 mph will create blizzard conditions. Winter Storm Warning remains in effect for the northern mountains through 11 am Thursday for an additional 12-18 inches of snow. Travel has become difficult to impossible there, and secondary roads remain unplowed with up to 4 feet of snow over the past week. A skiers delight, travelers nightmare. Winter Weather Advisory in effect for the Central Mountains for 8-14 inches of new snow through Thursday afternoon.

For the foothills and Urban Corridor, cold front will move across the area late tonight/early Thursday between 3 am and 6 am. Much colder air behind front and a brief shot of snow likely behind cold front. Winds aloft remain westerly, so I expect very little if any snow accumulation for the foothills, likely a dusting to a half inch most areas. Urban Corridor and Plains may see a half inch to an inch or two of snow early Thursday morning, right around commute time, so commute could be a tad slower Thursday morning. All snow should end around noon, with only some flurries in the mountains in the afternoon.

Cool temps Thursday night, but the entire state should be mostly sunny and dry on Friday with warmer temps in the afternoon. The next Pacific system moves into CO late Saturday. Models currently disagree on this system, with the GFS moving it quickly across the state with limited snow, while the Euro and NAM/WRF dig the system a little more and bring more snow to the mountains. I currently favor the slower solution which would bring snow to western CO Saturday afternoon and night, and brings a cold front across the foothills Saturday night, with a chance for light snow late Saturday night into Sunday morning. Any accumulation still looks light east of the Divide, likely less than an inch. Mountains could receive an additional 6-12 inches from this system west of the Divide.

Models then bring a secondary upper trough across CO on Monday night/Tuesday, which could bring a better chance for snow to the foothills and Plains on Tuesday. More snow chances for CO later next week and next weekend as the current pattern remains in place.