Cool and unsettled weather ahead
Thursday, September 21, 2017
An anomalously large trough of low pressure stretching from the central Canadian plains southwestward to almost Baja will affect our weather over the next week. Ahead of the trough, strong southwesterly flow has brought above average temperatures, sunny skies and wind to the Steamboat Springs area today.
There will be many moving pieces to the forecast as upstream Pacific energy contributes to several centers of circulation forming within the trough, with some of them being reabsorbed as they travel to the northeast, while others further stretch the trough to the southwest while reluctantly moving it eastward toward the Rockies.
Temperatures should stay warm through tomorrow morning ahead of gradually cooling temperatures through the weekend and into next week. The very slow movement of the trough will preclude any distinct cold front, but the slow cooling of the atmosphere combined with waves of energy moving over our area will contribute to an extended period of cool and showery weather.
There may be some showers Friday, though the heavier and more persistent precipitation will wait until Saturday and Saturday night when the trough is closer to our area and ejecting pieces of energy travel over Colorado.
There may be some dry air that mixes with the trough, possibly allowing for a break in the unsettled weather for a time on Sunday, before an unconsolidated center of circulation moves northeastward across Colorado later Sunday and Monday and brings another push of cooler air and storms.
Additional upstream Pacific energy crossing the West Coast regenerates the southern end of the trough early in the week, and though the coolest temperatures of the storm will occur over our area then, precipitation looks to become much lighter as the week progresses.
Right now, numerical models have the last push of cool air occurring around the end of the work week, and this finally moves the storm complex east of our area. A ridge of high pressure is advertised to bring much warmer and drier conditions for the following weekend.
Next storm first brings wind followed by precipitation heading into the weekend
Monday, September 18, 2017
Temporally sandwiched between hurricane Jose, currently threatening the New England Coast, and hurricane Maria, which may threaten a broader portion of the East Coast next week, a large and potent storm from the Gulf Of Alaska is currently crossing the Pacific Northwest coast.
After a relatively warm and dry Monday in the Steamboat Springs area, conditions will become breezy to windy from the west and southwest on Tuesday as the fairly dry first part of the splitting storm moves north of our area tomorrow afternoon or evening. Precipitation now looks to reach only as far south as the Wyoming border, so cooler temperatures with continued dry and breezy conditions are expected on Wednesday.
Several additional waves of energy will move through the storm, creating a complicated forecast that will likely evolve as we move toward the weekend. Right now, the first of these waves for midweek looks to largely keep the storm to our northwest, perhaps pulling in some drier and warmer air over Colorado for Thursday.
By Friday, another wave traveling around the storm to our northwest gets close enough to our area to increase the chance of storms for later in the day.
On Saturday and continuing into early next week, additional waves of energy move the storm to the east while elongating the storm to the southwest, which is forecast to bring several days of cool and showery conditions to the Yampa Valley with some snows at the higher elevations.
Seasonal changes on our doorstep
Thursday, September 14, 2017
The weather is generally cooperating with the last forecast as an unseasonably cold trough of low pressure over the Pacific Northwest escorts a storm system originally off the coast of California eastward across the Great Basin. Showers started around 1 pm in Steamboat Springs and will continue today, becoming moderate to heavy around mid-evening as the old California low moves across the northwestern corner of Colorado.
Precipitation should taper off after midnight before another weak round of showers forecast for early Friday morning moves through the our area. There should be some clearing from about mid-morning through early evening before the colder portion of the parent storm grazes northern Colorado Friday night. Precipitation will not be as heavy as forecast for tonight, but it will be significantly colder, with snowflakes likely on the upper reaches of Mt. Werner.
Showers may linger into a Saturday morning before the skies clear for the remainder of the day with seasonably cool temperatures. There may be some frost on Sunday morning, so it may be time to start covering the tomato plants.
Sunday and Monday should be spectacular fall-like days as drier air and average temperatures grace our area. Meanwhile, a larger and colder Gulf of Alaska storm crosses the Pacific Northwest coast late in the weekend. It looks like we will have an impressive cold front move through northern Colorado later Tuesday, though precise timing is uncertain, as the first of several waves rotate through our area. Though Wednesday looks relatively dry, additional waves rotating around the large storm look to keep cool and unsettled weather over our area for Thursday and heading into the next weekend.
Increasing moisture and decreasing temperatures after midweek
Monday, September 11, 2017
Lots to contend with this week, with now tropical storm Irma affecting the eastern third of the country, hurricane Jose spinning near Bermuda and possibly threatening the East Coast early next week, and, closer to home, a closed low pressure area off the California coast and a Pacific Northwest storm that will affect our weather starting around midweek.
There will be a chance of showers this afternoon and early evening as some moisture lingers over the Steamboat Springs area in continued above average temperatures. Tuesday will be as warm, but drier, before a strong storm in the Gulf of Alaska approaches the Pacific Northwest coast early Wednesday.
Seasonally building cold air in western Canada is forecast to mix with the storm, increasing its southern extent enough to incorporate the California low around midweek. Chances for showers increase again by Wednesday afternoon as energy and moisture from the storm complex moves toward the Great Basin and begins to affect our area.
Cooling temperatures and a much better chance of wetting rains for later Thursday and early Friday are likely as the old California low passes near or perhaps over northern Colorado. There is model disagreement with respect to the southern extent of this leading wave and how quickly a reinforcing wave of cold air moves over the area, but right now it looks like some drying for later Friday before we see another round of cooler and showery weather for the first half of the weekend.
Of note is the European ECMWF is much cooler with the reinforcing wave of cold air than the American GFS, possibly bringing some snowflakes to the upper elevations of Mt. Werner sometime this weekend if that model verifies.
Drier air and warming temperatures in southwest flow is advertised for later Sunday and the beginning of the next work week as the storm moves northeast of our area and another Gulf of Alaska storm approaches the Pacific Northwest coast.
Increasing moisture and decreasing smoke likely for the weekend
Thursday, September 7, 2017
A trough of low pressure approaching the Pacific Northwest will split today, with the southern piece forming a meandering closed low off the California coast and the northern piece moving eastward across the U.S. - Canadian border. The northern portion will move the ridge of high pressure currently over the western states east of the Steamboat Springs area by Friday afternoon, with weak southerly winds behind the ridge and ahead of the closed low off the West Coast directing moisture toward Colorado and smoke from the local wildfires to our northwest away from the city.
However, the southerly flow is not strong, so it is unclear how much smoke will be scoured from the area, though an improvement in air quality is very likely. Additionally, the weak flow will limit the amount of moisture that moves over our area, so the afternoon storms that may occur Friday, Saturday and possibly Sunday afternoons may produce more wind than rain.
By early in the work week, the western ridge partially reforms behind the eastward-moving wave forecast to be to our northeast, and this reintroduces drier air and weak northwesterly flow for northern Colorado. Therefore, if the local wildfires to our northwest are still producing smoke, we may once again have some smokey and hazy days next week.
Another Pacific wave approaches the West Coast midweek, and dislodges the California closed low. Models disagree on how strong the Pacific wave will be, but agree that the remnants of the closed low will move across the Great Basin and approach our area sometime around the end of the work week.
At this point, I would expect the possibility of some light showers ahead of the closed low near the end of the work week, with a much better chance of wetting rains around next weekend if the closed low moves over our area.
