Tuesday, May 31, 2016
Our transition to summer is still on track, and afternoon temperatures should be rising towards the weekend as a strong western ridge, not seen since the dry spell in February, builds over the Great Basin.
The main weather concern will be the usual afternoon showers that may appear Sunday and Monday afternoons as atmospheric moisture is trapped between a developing trough over the central to eastern US and and the western ridge.
Surprisingly though, an active jet stream continues across the Pacific, likely reinforced by still cold air in Siberia and northern Canada that rotates southward across the northern Pacific. The end result is a battle over the western US as a building ridge is moderated by incoming Pacific energy.
A weak Pacific storm forecast to cross the central California coast late in the weekend will be the first test of the resiliency of the ridge. There is model disagreement with the ECMWF keeping the storm west and north of our area as it rides up the western side of the ridge. The AVN, on the other hand, is now more aggressive in moving the storm through the ridge and over our area later Tuesday or Wednesday, bringing the chance of warm precipitation to the region.
Monday, May 30, 2016
Our persistently unsettled spring weather is finally on its way out, though an approaching storm currently over Montana as of Monday afternoon will bring several more cool waves of air to northern Colorado this afternoon through Wednesday.
The first cool front will bring a chance of afternoon and early evening showers today before spreading dry air over our region later tonight. The cool air will be reinforced on Tuesday leading to a cool but mostly sunny day.
A trailing wave of cool and dry air washes over our area Tuesday night, bringing another cool start to Wednesday, but the strong June sun will allow for warmer temperatures than we’ve seen in a while by the afternoon.
Summer looks to arrive in force on Thursday, and generally beautiful and warm summertime weather looks to finally hang around for more than a day or two. Other than a weak cool front that crosses the area Friday night and leads to a chilly start to Saturday, the main weather concern will be the usual afternoon showers that may begin to appear as soon as Saturday afternoon as atmospheric moisture is trapped between a developing trough over the central to eastern US and a weak southern Pacific storm forecast to cross the central California coast late in the weekend.
Surprisingly though, an active jet stream continues across the Pacific, likely reinforced by still cold air in Siberia and northern Canada that rotates southward across the northern Pacific. The end result is a battle over the western US as a building ridge is moderated by incoming Pacific energy. Current models keep the summertime weather over our area through the following work week, though there are indications that the Pacific energy will eventually penetrate the ridge and bring increasing chances of cooler air and precipitation after that.
Saturday, May 28, 2016
Our wet and cool spring looks to leave us around midweek after another pair of weakly connected storms pass through the area in the Monday through Wednesday time frame.
Before that, after a chance of light showers this afternoon, a weak storm off the central California coast will be dragged eastward by a stronger storm crossing the northern West Coast near the Canadian border that has already mixed with cool air from western Canada. The southern storm will bring increasing chances of stronger showers Sunday afternoon as moisture and atmospheric instability increase.
Some dry air may briefly pass over our area ahead of the pair of storms early in the day on Monday as they both move eastward. However, the dominant northern storm will bring a cool front through the area later Monday, again increasing the chance of afternoon storms.
By Monday night, pieces of energy from both storms will continue to eject over our area, possibly continuing showers into the nighttime. Additional cool air will filter into the area on Tuesday, though there is model disagreement on whether the air will be cool enough to preclude additional showers during the afternoon.
In any case, atmospheric moisture will gradually leave our area on Wednesday, even as the cool air hangs around for a cool and dry spring day.
Though Thursday may start out cool, rapid warming during the day combined with the drier airmass should bring beautiful and relatively summer-like weather that finally looks to hang around through next weekend as a western summertime ridge builds over the western third of the US.
Wednesday, May 25, 2016
A storm crossing the southern California coast this afternoon will be kicked northeastward by yet another storm traveling south from the Gulf of Alaska. Ahead of the southern storm, relatively dry air will keep only a slight chance of showers for later today.
The projected track of the southern storm brings it over southern Colorado by Thursday, along with a cool front and increasing moisture that will make stronger storms likely for Thursday afternoon, possibly lasting into the night.
As the storm moves east of the area by Friday, cool weather with another round of possibly strong storms are likely in the northwest flow behind the storm during the afternoon and early evening, with showers starting as soon as noon.
Meanwhile, the kicker storm from the northwest is forecast to cross the Northwest Coast on later Thursday or early Friday and spin over Idaho on Saturday and Sunday, mixing with some cool air from western Canada.
Pieces of energy are forecast to break away from the Idaho storm on Sunday and Monday, keeping the threat of afternoon and nighttime showers over our area for both Sunday and Memorial Day.
Additional Pacific energy kicks the Idaho storm across Montana on Tuesday, allowing some of that cool air originally from western Canada to move over our area later Tuesday. Additionally, some energy left behind in southern California is also dragged south of our area, and keeps the threat of unsettled weather with afternoon showers through at least midweek.
Monday, May 23, 2016
A storm just off the West Coast is producing a relatively dry southwest flow over our area from the desert southwest. There will still be a chance of light afternoon and early evening showers for today and Tuesday as numerous weak waves of energy travel over our area.
By Wednesday, the storm will be kicked eastward by another storm dropping south from the Gulf of Alaska, traveling across central Arizona and New Mexico by Thursday. This storm will be strong enough to bring a cool front through the area sometime on Thursday with an increasing chance of afternoon and evening showers.
As the storm moves east of the area by Friday, cool weather with stronger storms are likely in the northwest flow behind the storm during the afternoon and early evening, with showers starting as soon as noon.
Meanwhile, the kicker storm from the northwest is forecast to cross the Northwest Coast on Friday and spin over Idaho on Saturday and Sunday, keeping the cool and unsettled weather around for most the weekend.
There is uncertainty for later Sunday and Memorial Day as the ECMWF splits the the Idaho storm earlier than the GFS, with the northern stream moving just north of our area on Sunday while the GFS is about a day later. Currently, it appears that most of the weather will be north and east of our area when the storm moves past.