Cool start to the Independence Day weekend before hot and dry weather returns
Thursday, June 29, 2017
A trough of low pressure over the northern plains has brought cooler temperatures to the Steamboat Springs area today. A trailing wave will bring the last cool front in this series through the area overnight, leading to a chilly morning with even the possibility of some frost. The National Weather Service forecast for the Park Range even has the mention of snow flurries for tonight! Still-tender plants in low-lying areas might need to be protected tonight and Friday night with the unseasonably cool temperatures.
As the trough moves eastward, a ridge of high pressure will return to the western states, bringing drier air and strongly warming temperatures for the weekend.
Meanwhile, another Gulf of Alaska storm has mixed with some subtropical moisture and will weaken as it crosses the Great Basin on Sunday. By the time the trough moves over Colorado later Sunday into Monday, the increased moisture and upward motion associated with the trough will bring increasing chances of showers, with the associated clouds moderating the hot temperatures.
A western ridge rebuilds behind the early week storm, bringing hot temperatures for Independence Day. There may be a chance of some afternoon showers, but they should be isolated and brief.
By midweek, the numerical models disagree with the evolution of the western ridge. The American GFS insists on further amplification, bringing even hotter and drier weather to the western states for the rest of the work week, while the European ECMWF has a weakening ridge which allows some Pacific energy to move inland. This would result in more seasonable temperatures with the possibility of afternoon showers starting around midweek.
Early week warmth moderates by midweek with continued dry conditions
Monday, June 26, 2017
A ridge of high pressure over the Intermountain West will allow temperatures to rise above normal for today and Tuesday with very little chance for precipitation. A storm currently in southern British Columbia will mix with some cool western Canadian air as correctly forecast by the American GFS last week and bring a series of cool fronts through the Steamboat Springs area starting Wednesday and persisting through the first part of the weekend.
These fronts will be dry, with some breezy westerly to northwesterly afternoon winds. Temperatures will be close to or slightly below normal leading to gorgeous and comfortable summer days with cool nights for the rest of the work week and heading into the weekend.
A transient ridge of high pressure is forecast to translate over the western states for the second half of the weekend, allowing hot temperatures to return around Sunday and heading into the new work week. There is also a weak subtropical disturbance moving through this ridge, leading to a slightly better chance of clouds and possibly some precipitation on Sunday.
With summer weather firmly entrenched, I’ve been looking at the longer-range forecast models to get an idea of when our summer monsoon season might arrive. While there currently is some moisture pooling around the Sonoran Desert, it appears it won’t get here until around the following weekend when southwesterly flow is predicted to become better established over the western states.
Temperatures moderate for the weekend before turning hot again early next week
Thursday, June 22, 2017
Some cooler air will wash over the Steamboat Springs area starting early Friday and extending through the weekend, and possibly again around mid-next week. For the rest of today, similar to yesterday, there may be a chance of a mostly windy afternoon storm. The locally strong and gusty winds around these storms are caused by evaporating precipitation (virga) which cools the air before it reaches the ground. This cooler air creates strong downdrafts which then spread out horizontally when colliding with the surface.
For Friday and Saturday, a couple of waves moving southward along the western flank of a storm in the southern Canadian Plains will introduce cooler air over our area, knocking temperatures back towards the normal range and making for some very pleasant early summer days. These cool fronts will be dry, and with less moisture predicted to be in the atmosphere as compared to the last few days, precipitation chances will be close to nil.
Temperature will warm a bit Sunday, but the warming will occur in earnest on Monday and Tuesday as a transient ridge brings hot temperatures over the western states. We may have a slightly better chance of afternoon storms then as some energy from a tropical wave interacts with energy from a storm in the Gulf of Alaska and moves over our area later Monday and Tuesday.
By Wednesday, significant differences appear in the numerical forecast models, with the American GFS having the Gulf of Alaska storm mixing with some cool western Canadian air before digging it into the Great Basin. This forecast is a change from the last few days and would bring a series of cool fronts through the area for the end of the next work week. The more consistent European ECMWF, however, keeps this storm further north and faster moving which leaves most of the cool air north of our area.
Summer heat arrives just in time for the Summer Solstice
Monday, June 19, 2017
It is appropriate that a blast of summer heat will arrive by the Summer Solstice, which will occur on Tuesday, 20 June 2017 at 10:24pm. A ridge of high pressure is currently centered over the desert southwest, and this will move towards the Steamboat Springs area on Tuesday bringing very warm summertime temperatures.
Concurrently, a storm in the Gulf of Alaska will move eastward and mix with some cool air from the western Canadian plains. While the bulk of the storm will stay well to our north, the cool air moving southward will battle the warm air under the ridge, suppressing the ridge southward and bringing some cooling, clouds and winds for Wednesday. There is a small chance of some afternoon storms that would likely bring more wind than rain due to the dry lower atmosphere, especially at the higher elevations.
Thursday will be similar to Wednesday before disagreement between the numerical forecast models appears for Friday and the weekend. While both the American GFS and the European ECMWF have another wave of cool air traveling mostly north of us, the American GFS brings this through on Friday with most of the cool-down experienced on the Front Range, while the European ECMWF keeps Friday warm and brings the cooler air and breezy conditions further west through the mountains on Saturday.
After that, both models agree on a building ridge of high pressure over the Intermountain West by the second half of the weekend, which will bring a return to hot and dry conditions heading into the next work week.
Quiet weather for this week
Thursday, June 15, 2017
The jet stream will stay mostly north of the Steamboat Springs area for the next week leading to mostly warm and dry days. However, embedded waves in the predominantly westerly flow will force the jet to sag south on Saturday and again near the end of the next work week, leading to some slight cooling, some clouds and the possibility of afternoon showers and breezy to windy westerly winds.
Between Saturday and Thursday, a growing ridge of high pressure over the western states will lead to very summery weather heading into and around the Summer Solstice on Tuesday, 20 June 2017 at 10:24pm.
Around Thursday, the jet stream is forecast to again sag to the south, and this will re-introduce some cooling and clouds with breezy westerly afternoon winds and the chance of afternoon thunderstorms for the remainder of the work week.