Gradual drying along with afternoon storms for the next week
Friday, June 12, 2015
Though it looks like our past few days of very wet weather will change today, we will still be susceptible to the typical summer afternoon thunderstorms through the next week. Storms may be limited today by the cool air left behind by the departing storm yesterday, but I would expect Saturday to have a good chance of afternoon storms.
Some dry air does sneak in here Sunday for a a downturn in the afternoon storm chances, but a wave traveling north of us along the Canadian border will allow some cool air to infiltrate the region on Monday and destabilize the atmosphere. This, along with additional ill-defined waves for Tuesday and Wednesday will delay the strong drying advertised in the last forecast and lead to a good chance of afternoon storms for each of those days.
The dry air is now timed to arrive around Thursday and last into at least part of the following weekend, limiting or even eliminating the chance of the summer afternoon thunderstorm. There is model disagreement near the middle of that weekend as forecasts are at odds with the degree of interaction between a Pacific wave entering the northwest coast and cool air over the Canadian plains, leading to an uncertain forecast for then.
Former hurricane Blanca influences our weather starting tomorrow
Tuesday, June 9, 2015
Former hurricane Blanca, currently in the Gulf of California, will travel northeastward across the Great Basin today and tonight as a Pacific storm crosses the West Coast tomorrow morning. It appears that the former hurricane will first move over our area tomorrow afternoon and evening before being quickly followed by what will end up being a slow-moving Pacific storm which may affect our weather through mid-weekend.
First, high clouds will invade our area tonight, and thicken and lower tomorrow before showers or a more persistent light to moderate rain arrives for the afternoon. Rainfall intensity will decrease overnight as I expect our heaviest precipitation to occur behind this initial event as a significant amount of moisture is left behind for the Pacific storm.
As the Pacific storm begins to move eastward towards our area on Thursday, some cool air from the Canadian plains mixes with the system, leading to a slower and stronger storm. There is some uncertainty when the cool air reaches our area, but current forecasts have moderate to heavy showers later Thursday and overnight before they diminish by early Friday. An additional surge of cool air is forecast to again increase the intensity and duration of showers by Friday afternoon and overnight.
Saturday looks to be cool with some light showers behind the finally-departing storm. Some dry air is forecast to sneak into parts of northern Colorado on Sunday, and this may lead to the typical afternoon thunderstorms after a sunny morning.
Monday looks to be very similar to Sunday before a much drier regime is advertised to occur over our area around Tuesday. The dry air may be interrupted by the end of next week as some models have a wave traveling to our north, but longer-term models keep this dry air mostly intact through next weekend and into the following week.
Update to yesterday’s forecast
Friday, June 5, 2015
As a storm currently along the West Coast draws moisture from once-hurricane Andres over our area. clouds will thicken during the day and showers will occur later this afternoon and through the evening. There will be a small break early Saturday before a lobe of energy is ejected over our area ahead of the eastward progressing West Coast storm, bringing another round of moderate to heavy rain for Saturday afternoon and extending into the night.
There may be another break early Sunday before the storm to our west lifts toward the northeast and travels across the Great Basin. Though the storm weakens considerably, there is still enough moisture and upward motion to to produce showers during the day.
We will still be under the influence of the weakened storm on Monday, leading to more showers, especially in the afternoon. Tuesday and Wednesday look to be the nicest days of next week, though there will still be the threat of the typical afternoon thunderstorm.
There is a wildcard for the forecast next week in the form of hurricane Blanca, which is forecast to move up the Baja coast early next week. Earlier model runs had the moisture moving over our area, but current runs keep most of the moisture to our south. However, models also forecast a complicated interaction between the former hurricane, another storm entering the West Coast around midweek, and a surge of cool air from the Canadian plains. These three entities may conspire to increase the threat of heavy rain by Thursday afternoon and lasting through Friday. That forecast will no doubt evolve as we get closer to the event.
After that, some models predict a far-western Caribbean storm that may help draw moisture northward and lead to a monsoonal-like surge of moisture over our area for late next weekend or early the following workweek. Furthermore, there will likely be additional Pacific energy crossing the West Coast keeping our June weather active.
More wet weather for Saturday and the end of next week
Thursday, June 4, 2015
The current warm and dry weather will end by tomorrow as a storm along the West Coast draws moisture from once-hurricane Andres over our area. Clouds will thicken during the day and showers will occur tomorrow afternoon and through the evening. There will be a small break early Saturday before a lobe of energy is ejected over our area ahead of the eastward progressing West Coast storm, bringing another round of moderate to heavy rain for Saturday afternoon.
There will be another break Sunday before the storm to our west lifts toward the northeast and travels across the Great Basin. Though the storm weakens considerably, there is still enough moisture and upward motion to to produce showers by Sunday afternoon.
We will still be under the influence of the weakened storm on Monday, leading to more showers, especially in the afternoon. Tuesday and Wednesday look to be the nicest days of next week, though there will still be the threat of the typical afternoon thunderstorm.
There is a wildcard for the forecast next week in the form of hurricane Blanca, which is forecast to move up the Baja coast early next week. Earlier model runs had the moisture moving over our area, but current runs keep most of the moisture to our south. However, models also forecast a complicated interaction between the former hurricane, another storm entering the West Coast around midweek, and a surge of cool air from the Canadian plains. These three entities may conspire to increase the threat of heavy rain by Thursday afternoon and lasting through Friday. That forecast will likely evolve as we get closer to the event.
After that, some models predict a far-western Caribbean storm that may help draw moisture northward and lead to a monsoonal-like surge of moisture over our area for late next weekend or early the following workweek.
Summer weather begins Saturday
Thursday, May 28, 2015
Our long-delayed summer weather begins on Saturday, but not before the wave currently affecting our area leaves more rain today and Friday. Rainfall should end by early Saturday as the wave moves east of our area.
Saturday should start out cool, but temperatures will begin to warm during the day. The cool airmass left behind will likely support storms of minimal strength and it’s possible we may even have a rain-free day for the first time in about 3 weeks, though that hope may be threatened by a very weak wave passing north of our area by late in the day and overnight.
The upper-elevation snowpack will see its first above-freezing low temperatures in three weeks Saturday night, signaling the beginning of its melting and contributing to increasing river flows, especially early next week as it may take a day for that water to make it to the Yampa river.
The warming temperatures will certainly make the weather feel summer-like, and yield typical summer afternoon thunderstorms Sunday through Tuesday.
A wave traveling across the northern third of the US will clip our area and knock temperatures back on Wednesday, as well as the strength of the afternoon storms. There is a possibility, however, that rain will be more persistent late in the day and overnight.
A much stronger storm crashes into the California coast around Thursday, though there is a significant amount of dry air ahead of the storm that will be brought over our area through the end of the workweek as the flow backs to the southwest. The evolution of this wave is complicated as it is not clear how much splitting will occur and how much of the cold air still in the Canadian plains will be drawn into the system, but this may threaten next weekend’s weather.
Generally, for the longer term, there is additional Pacific energy forecast to enter the West Coast as well as a westward expansion of the cool airmass over the Canadian plains. The combination of these is forecast to inhibit the West Coast ridge from building, keeping our weather on the seasonably wet side through at least mid-June.
