Thursday, June 25, 2015
After a small threat of afternoon storms today that will likely produce mostly windy conditions due to the very dry lower atmosphere, temperatures soar to above normal by the weekend. A building ridge just west of us over the Great Basin will keep us hot and dry for at least the first half of the weekend. Some moisture is forecast to be drawn northward along the western periphery of the ridge and eventually move over our region, leaving a small chance of storms starting Sunday afternoon and extending through Tuesday.
By Wednesday, models forecast some cool air from the Canadian plains flattening the Great Basin ridge and allowing for the possibility of stronger storms from Wednesday afternoon and extending through the Fourth of July weekend. The American GFS has the cool air approaching our area around Wednesday while the European ECMWF minimizes this surge mid-week and delays the brunt of the cool air until later in the workweek or early in the weekend.
Longer-term, the continued surges of cool air will keep the ridge from rebuilding over our area, keeping seasonable temperatures in the forecast beyond the Fourth of July weekend.
Thursday, June 18, 2015
For the first time in about 6 weeks, the forecast is easy! Beautiful dry and seasonably warm to hot sunny days and cool nights should grace our area for the next week as this weekend’s forecast shortwave will end up passing well north of our area with no sensible effect on our weather.
By the end of the next workweek, models show the possibility of our summer monsoon season starting as moisture is drawn northwards over Colorado from Old Mexico. The possibility of afternoon storms will likely increase heading into next weekend as this moisture settles over our state.
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.
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.
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.