Wet Monday and Tuesday followed by warming and drying
Sunday, August 1, 2021
Comfortable temperatures in the mid-seventies and mostly sunny skies are over the Steamboat Springs area early this Sunday afternoon. We’ll see a downturn in rain chances today before they increase substantially for Monday and Tuesday ahead of warmer and drier weather that is forecast to last into next weekend.
As has been the case for much of the summer, a ridge of high pressure over the West is sandwiched between areas of low pressure located over the Gulf of Alaska and the Hudson Bay region. However, the orientation of the ridge since this past Wednesday has allowed moisture associated with the North American Monsoon to infiltrate our area as it travels northward along the backside of the ridge, leading to some rain over our region each day. Additionally, an eddy from a storm off the Northeast coast last weekend has slowly traveled across the Gulf Coast states last week and near our area these last few days, providing increased lift and a focus for storms.
In fact, some of the daily rainfall observations have been impressive, but inconsistent, as some areas received good rainfall one day only to see the best rainfall shift to another area the following day, which is usual during monsoon season. Luckily, the regional totals since last Wednesday are more evenly distributed, with generally around a half inch near town and around twice that in some areas in north and south Routt county.
Rainfall chances will decrease for today, though still be present later this afternoon and through the evening as the ridge of high pressure is nudged westward by a storm currently traveling through the Great Lakes that is associated with that Hudson Bay area of low pressure. This shift temporarily moves the monsoonal moisture plume to our west for the day and results in a decreased chance of showers.
However, rainfall chances increase on Monday, and even more so on Tuesday as that eddy originally from the east mixes with some energy ejecting out of the Gulf of Alaska low pressure area and nudges the ridge of high pressure back to the east. This allows the monsoonal moisture stream to move back overhead, and combined with the forcing from the eddy, could produce periods of moderate to heavy rainfall from Monday afternoon through Tuesday night.
Around Wednesday, energy that had earlier ejected out of a strong storm in the Bering Sea will begin moving pieces of that Gulf of Alaska storm eastward, with the southern part of the storm crossing the northern California coast midweek and the remaining part crossing the Pacific Northwest coast early in the weekend.
The first piece of the storm will nudge the ridge of high pressure to the east and bring dry air overhead, warming temperatures and substantially decreasing rain chances, with storm activity relegated back to its usual afternoon and evening time slot.
Even warmer temperatures closer to and a bit above our average of 82 F are forecast for the rest of the work week and the beginning of the weekend, with only small chances for late-day storms. Incidentally, our average daily temperature, shown in the Local Temperatures, Winds & Precipitation section on the SnowAlarm home page, took its first dip of the season today, indicating that, on average, the hottest part of the summer has passed.
Our weather could get more interesting again as soon as the end of next weekend as the northern piece of the Gulf of Alaska storm moves close enough to encourage moisture-rich flow from the south to move back over our area. The timing and evolution of this pattern will almost certainly change over the coming week, but right now it looks like good chances for precipitation later Sunday and overnight followed by cooler weather with continued shower chances to start the next work week.
I expect to again be reviewing good rainfall totals for the coming couple of days in my next regularly scheduled weather narrative on Thursday afternoon, as well discussing that evolving Gulf of Alaska storm and it’s effect on our late-weekend weather, so be sure to check back for the details.
Good rainfall chances through the weekend
Thursday, July 29, 2021
Temperatures are in the mid-eighties early this Thursday afternoon in the Steamboat Springs area as storm clouds begin to build. After another hot day today with the high temperatures once again approaching ninety degrees, a good chance for some rain appears for this evening. And even better chances for rain last from Friday afternoon through Saturday night, and again Monday as a well-established monsoonal moisture plume bringing moisture from the south remains overhead.
A broad ridge of high pressure currently centered over the eastern Colorado border extends northwestward into British Columbia and is sandwiched by deep areas of low pressure over the Gulf of Alaska and the Northeast. The North American Monsoon is likely peaking as moisture originally from the Gulf of Mexico is carried first westward and then northward in the clockwise flow around the high pressure, which means good chances for precipitation for our area in north-central Colorado.
Those chances start late this afternoon and last through the evening as a subtle upper level disturbance, likely the remnant of an eddy that formed to the south of an area of low pressure off the East Coast last weekend, interacts with the moistening air mass over our area. Rainfall could be moderate to heavy at times under the stronger cells, especially between around 8 pm and midnight tonight.
Even better chances for rainfall emerge starting Friday afternoon with showers possibly lasting through the night, again with some producing moderate to heavy rainfall. These higher chances persist through the day and night Saturday, with the most likely short-lived period for drier weather Saturday morning.
So after a hopefully partly soggy Saturday, Sunday should be drier, though still with a chance for afternoon and evening storms, as a wave travels down the east side of the ridge of high pressure over our area and nudges it to the west, briefly dragging some drier air overhead.
But good rainfall chances return for Monday afternoon and evening as some energy ejects out of the Gulf of Alaska storm and nudges the ridge of high pressure back to the east, bringing the monsoonal moisture plume back overhead.
While the weather forecast models agree that at least some of that Gulf of Alaska storm will eject eastward, the timing is uncertain and that may happen Tuesday or Wednesday. This is important for our weather since the flow of monsoonal moisture will be severed by the winds from the west when that happens, so it is unclear if drier weather appears earlier or later in the work week.
Furthermore, this wave of Pacific energy may indicate the end of this monsoon season for our area as the summertime ridge of high pressure grows weaker as the days grow shorter and cooler. In fact, the American GFS is hinting we may see our first fall-like cool front later next week, though the European ECMWF keeps more of that Gulf of Alaska storm off the coast and the ridge of high pressure over the West bruised, but still intact.
Stay tuned to my next regularly scheduled weather narrative on Sunday afternoon when I hope to to review some of the rainfall totals around our area as well as have a better idea on the fate of the ridge of high pressure over the West.
Precipitation chances briefly diminish to start the work week
Sunday, July 25, 2021
Temperatures in the upper seventies and mostly sunny but smokey skies are over the Steamboat Springs area this Sunday noon. While we will see a chance for precipitation this afternoon and evening, those chances become quite slim for Monday and most of Tuesday before increasing again for the rest of the upcoming week. And there is a possibility of heavier and more widespread rainfall heading into next weekend.
As has been usual this summer, there are deep areas of low pressure centered over the Gulf of Alaska and Hudson Bay, with the fast westerly flow between them across the Canadian border suppressing a broad area of high pressure over most of the West. The exception is that persistent eddy discussed a week ago Thursday that has slowly traveled from its original location in the Ohio River Valley ten days ago to its current location over Arizona. Last week there was hope that this would travel northward over our area, but the moisture associated with the eddy has been confined to areas to our south.
We did, however, see some winds associated with the eddy and its interaction with the high pressure from the north and northeast these last few days which transported smoke from wildfires into our area. Interestingly, while the haze was thick, there was no smell of smoke which indicates either the smoke came from far away, likely from fires in British Columbia, or from days-old smoke from the Morgan Creek fire that was dislodged from its usual downstream location relative to the fire, or both.
In any event, the smoke is expected to dissipate later tonight or tomorrow as the ridge of high pressure rebuilds over the West. Some drier air lurking to our northwest is beginning to infiltrate our area, with the chances of showers decreasing substantially on Monday and most of Tuesday as temperatures rise into the upper eighties for the warmest days of the week.
While weather forecast models have our winds turning to be more from the south while moving the plume of monsoonal moisture back over our area by Tuesday night or Wednesday, there is no well-defined trigger to focus precipitation, so we are left with a chance of showers for Wednesday and Thursday, similar to this past week where some areas saw precipitation and some saw none.
The European ECMWF keeps this going through the weekend while the American GFS draws an upper level low pressure area currently near Florida around the high pressure over the West and near or over our area around Friday and the weekend. The American GFS, therefore, is quite a bit wetter, and this signal has been present for the last couple of days. Remember that the American GFS had the right idea first with that eddy currently over Arizona, so there is hope it is also getting the wetter weekend right as well.
But we just won’t know till we get closer. So stay tuned to my next regularly scheduled weather narrative on Thursday afternoon to see if better chances for more widespread rain persist for the coming weekend.
Chances for rain continue during the upcoming week
Thursday, July 22, 2021
The skies have clouded over this Thursday mid-afternoon with the mid-eighties temperatures observed earlier in the afternoon decreasing to the upper seventies in the areas of town lucky enough to see a few drops of rain, like the mountain area. The monsoonal plume of moisture is forecast to remain over our area this week, with chances for precipitation remaining modest through the weekend and the beginning of next week before increasing, perhaps substantially, for the end of the work week.
A ridge of high pressure is currently centered over the Four Corners region and extends into the central Canadian Plains. An eddy, which I first talked about in last week’s weather narrative, is currently in west Texas while a storm from the Gulf of Alaska is located near the northern Alberta - Saskatchewan border. The eddy to our south is forecast to move across the Desert Southwest through the weekend and up the West Coast next week while the Canadian storm is forecast to deepen as it moves toward the Northeast next week.
The monsoonal moisture plume located on the western side of the ridge of high pressure will meander around through the week as the ridge deforms and jiggles around. Furthermore, the moisture content of the plume will vary as weather features pass near it (like that eddy and a possible tropical storm well to the south next week), leading to a somewhat low-confidence forecast in the days where we will see the best moisture over our area, even though each day of the coming week will see some chances for showers.
Right now, modest chances for precipitation, similar to the last few days, will persist into the weekend before decreasing around the start of the work week and then increasing again, perhaps substantially, near the end of the work week. There is uncertainty in the forecast as soon as tomorrow as we will see some winds from the north on Friday as that Canadian storm flattens the ridge of high pressure and allows it rebuild to the west. While it is not clear if some drier air lurking to our northwest will invade the area and decrease shower chances, it does appear we will see some smoke from the Morgan Creek fire infiltrate town, according to the latest NOAA smoke plume model.
While areas to our south are far more likely to see precipitation this weekend, we could see drier weather if we see more of the dry air from the northwest, perhaps with some smoke from the Morgan Creek fire, or wetter weather if the flow from the south and southwest wins out.
Regardless of what happens during the weekend, it appears we will see slim, but not negligible, chances for precipitation to start the work week as the ridge of high pressure amplifies to the northwest and shifts the monsoonal moisture plume to the west. This is short-lived, however, as another Gulf of Alaska storm is forecast to move eastward and push the ridge of high pressure back to the east around midweek.
Not only will this shift the monsoonal moisture plume towards our area, but the plume may be enriched by some sort of tropical storm that injects some moisture into the flow from well to the south, though that is very uncertain as this time. But at least it looks like increasing precipitation chances after the start of the work week, with some storms becoming increasingly likely to produce periods of moderate to heavy rain.
And the American GFS, which produces a sixteen day forecast four times a day, has the wet pattern continuing into the first week of August as increasingly fast flow from the west pushes the ridge of high pressure eastward and keeps the monsoonal moisture plume on the backside of the ridge overhead. Stay tuned to my next regularly scheduled weather narrative on Sunday afternoon where I hope to have a better idea of our precipitation chances for next week.
Increasing rain chances this week
Sunday, July 18, 2021
Sunday is shaping up to be a hot day in the Steamboat Springs area as temperatures are already just above 80 F this Sunday noon. Less clouds than the last few days means upper eighties for today and likely the low nineties for tomorrow before we see a good chance of showers on a cooler Tuesday as a surge in monsoonal moisture moves overhead. Shower chances for the rest of the upcoming week are entirely dependent upon the vagaries of the location of the monsoonal moisture plume, though it is likely that at least some of the days will be favored for precipitation.
A ridge of high pressure centered over the central Rockies is sandwiched between areas of low pressure over the Gulf of Alaska and the Northeast. The ridge is forecast to amplify through Monday, keeping hot temperatures of five to ten degrees above our average of 82 F for the next two days with almost no chance for precipitation. Additionally, we may see some winds out of the north or northeast this afternoon which may briefly transport some smoke from the Morgan Creek wildfire into our area, though smoke concentrations predicted by the NOAA smoke model are quite light.
But this changes on Tuesday as some energy ejects out of the Gulf of Alaska low pressure area which reduces the amplitude of the ridge and tilts it to the east. This allows the monsoonal moisture plume associated with the southerly flow on the backside of the ridge of high pressure to move over our area for increased precipitation chances and decreased temperatures closer to average. And unlike the last couple of days, the showers are more likely to produce brief periods of moderate to heavy rain as the lower atmosphere moistens.
However, weather forecast models are not in complete agreement, even among themselves, in the exact location of this monsoonal moisture plume, with the latest run of the European ECMWF backing off on precipitation chances on Tuesday. While areas to our south are more certain to receive moisture, our northern location means we are more dependent upon the vagaries of the exact plume location.
More of the same continues through the rest of the work week, with precipitation possible but hardly certain as that Gulf of Alaska storm is forecast to move eastward in a couple of pieces and cross the British Columbia coast around midweek before trekking across the Canadian Plains for the weekend.
This will substantially interact with the ridge of high pressure over the central Rockies, changing the location of the monsoonal moisture plume, which may be beneficial for continued precipitation chances, or not. Interestingly, that eddy I talked about in the last weather narrative is still forecast to break away from the area of low pressure over the Northeast around Tuesday and meander westward across Texas before it is trapped under the ridge of high pressure over the central Rockies. This may or may not eventually move over our area around next weekend, with substantially increased precipitation chances if it does.
It is not unusual for an uncertain precipitation forecast during our monsoon season, but the North American Monsoon seems well established which means there are at least chances for precipitation for our area. And for what its worth, the American GFS strengthens the monsoonal signature over our area after next weekend and heading into August. Stay tuned to my next regularly scheduled weather narrative on Thursday afternoon to see if this monsoon signal persists and for a better idea of precipitation chances for next weekend.
