Hot and showery weather ahead of our first cold front around Sunday night
Thursday, August 27, 2020
Temperatures in the mid-eighties and partly cloudy skies are over the Steamboat Springs area this Thursday mid-afternoon. We’ll see continued hot temperatures through the weekend, with afternoon and evening showers possible until the first cold front of the season passes through northern Colorado around Sunday night. And as if to highlight the coming of meteorological fall on Tuesday, the first of September, there may be some snowflakes at the highest elevations of Colorado around Sunday and Monday nights as we finally see temperatures drop to below average for a couple of days.
Currently, a ridge of high pressure over the central and southern Rockies is surrounded by rapidly weakening hurricane Laura to the southeast, storms to our north and a dry area of low pressure over northern California. Monsoonal moisture traveling northward along the western side of the Rockies ridge will remain over our area through the weekend, and portions of the storm to our north and then northern California will combine with the moisture for the chance of afternoon and evening storms. While most of the rain should be light and showery, there is the possibility of brief moderate to heavy downpours around the strongest cells.
A big pattern change comes to our area around Sunday night with the arrival of our first cold front of the season. A storm currently in the Gulf of Alaska is forecast to mix with some cold air from the North Pole and shift our winds to be from the current southwest to the west on Sunday and the northwest by Monday. There may be enough moisture around for some snowflakes at the highest elevations of Colorado, though it is not clear if that happens Sunday night and/or Monday night when a trailing wave passes through.
The most noticeable effect on our weather will be the much cooler temperatures on Monday and Tuesday, with lows in the thirties, below our average of 41 F, and highs falling from five to ten degrees above our average of 78 F before the first front to five to ten degrees below average after the front. Much drier air and breezy northwesterly winds will then invade our area as a stable ridge of high pressure builds over the Gulf of Alaska, keeping this pattern going through the work week.
And while daytime temperatures will warm back towards average starting around midweek, several waves of energy traveling along the eastern side of the ridge look to periodically mix cold air from northern Canada and keep cool morning temperatures in the thirties. After such a hot summer, next week should certainly have hints of fall.
The ridge of high pressure over the Gulf of Alaska is forecast to amplify by next weekend, which might enable Pacific energy traveling over the top of the ridge to again mix with cold Canadian air and bring another cold front through our area around the end of the following weekend or early the next work week.
I should have a better idea of whether we see any snow-dusted peaks early in the coming work week by my next regularly scheduled weather narrative on Sunday afternoon.
Moisture increases this week
Sunday, August 23, 2020
Another hot and hazy day is in store for Steamboat Springs this Sunday with the temperature already up to 84 F on this mostly sunny Sunday noon. Moisture from the southwest is forecast to increase over our area starting tomorrow and lasting for about a week. We need to make the best of what moisture will be available though, as it appears our first cool front, currently forecast for just before the first day of meteorological fall, September 1, will sweep any moisture over our area to the east.
A ridge of high pressure currently centered over the Four Corners will be suppressed to the south and nudged eastward over the upcoming week by a series of storms moving through the Gulf of Alaska and eventually the northern U.S. While the remnants of former-hurricane Genevieve look to skirt north of our area, the southwesterly flow on the western side of the ridge of high pressure will bring monsoonal moisture from the Mexican Plateau over our area. Unfortunately, it may also transport smoke from the Pine Gulch fire near Grand Junction and the Grizzly Creek fire near Glenwood Springs back to the region.
Though hurricane Marco, currently in the Gulf of Mexico and soon-to-be-hurricane Laura, currently over the Dominican Rebublic are forecast to threaten the Gulf Coast through the work week, our area will not be seeing any moisture from these tropical storms. We will have to rely on much more modest monsoonal moisture for the next week, and can expect at least some clouds that will help reduce our forecast high temperatures to around five degrees above our average high of 79 F.
The moisture will also insulate the surface during the night, so expect much warmer low temperatures around ten degrees or more above our average low of 42 F.
Chances for rain increase starting on Monday afternoon, though showers associated with the early part of a monsoon surge usually yield more wind than rain as it takes a day or two for the lower levels of the atmosphere to moisten. In any event, none of the work week days look to produce significant accumulations, though storms that develop could produce brief but locally moderate to heavy rain. Additionally, the moister atmosphere makes it more likely that we may see some rainfall overnight as well.
Our best chance for significant rain will likely wait until later next weekend as one of the Gulf of Alaska storm mixes with some cold air from the North Pole, bringing our first cool front since spring through our area around the beginning of the following work week. There is a lot of variability in the forecast strength and southern extent of this storm, with the American GFS bringing the storm across in several pieces while the European ECMWF has a more coherent storm that passes through earlier.
But both increase rain chances on Sunday before the passage of the cool front, and both eventually have much drier air behind the front as the westerly flow severs the monsoonal moisture tap, with longer-range models keeping the dry air around through at least the next work week.
So for the upcoming week, hope for rain and minimal smoke, and I’ll have more details about our first impending cool front of the season on my next regularly scheduled weather narrative on Thursday afternoon.
Significant rain likely about a week away
Thursday, August 20, 2020
Temperatures in Steamboat Springs are in the lower eighties early this Thursday afternoon, on their way towards ninety. As was the case yesterday, we may see a storm or two later today that would produce more wind than rain, but rain chances become almost nil with continued hot weather through the weekend. This continues into the next work week before good chances for moisture arrive starting midweek.
A ridge of high pressure currently stands firm over the western states, with light winds from the northwest bringing a modicum of moisture over our area today, similar to yesterday. But the lower atmosphere remains very dry, so while there may be some drops of rain, gusty winds and possibly dry lightning are the most likely outcome around any storms that form.
A continuing series of storms in the Gulf of Alaska is forecast to move the ridge of high pressure eastward and over the Rocky Mountains through the weekend. The resultant more westerly flow will eliminate whatever mid and upper-level moisture has been around these past two days, and keep high temperatures five to ten degrees above our average of 80 F. Fortunately, the insulating effects of the moisture at night will be lost with the dry air so expect nighttime lows to return to around our cool average of 43 F.
Our best hope for significant moisture since mid-July appears around the following midweek as current Hurricane Genevieve, located near the southern tip of the Baja peninsula, travels northward along the West Coast. The eventual remnants of this hurricane will merge with the southward-expanding storm complex over the Gulf of Alaska, and we will see our winds switch to be from the southwest early in the work week, bringing moisture-rich tropical and subtropical air over the Colorado mountains as early as Tuesday afternoon.
The interaction between the eventual former hurricane and the Gulf of Alaska storms will be complex, with current weather forecast models indicating that some of the hurricane will move ashore early in the work week while some will be left behind to be absorbed by another wave approaching the West Coast. Eventually, this second wave will move over our area by the end of the work week or the following weekend with even better chances of wetting rains than earlier in the week.
While the light westerly winds will keep the smoke from the Colorado wildfires away from our region, we may see some smokey haze from the California wildfires at times through the weekend. And while the winds turning to be from the southwest by Tuesday should bring desperately needed moisture to our area, it may also allow smoke from the Pine Gulch fire near Grand Junction to our southwest and the Grizzly Creek fire near Glenwood Springs to our south to once again infiltrate the Yampa Valley.
I’ll have a better idea by my next weather narrative, scheduled for Sunday afternoon, of the details surrounding this increase in moisture for the mountains of Colorado and the possible reintroduction of smoke to our area.
Broken record forecast continues for the week ahead
Sunday, August 16, 2020
Sunny skies devoid of smoke are over the Steamboat Springs area this Sunday noon as the temperature rises above 81 F. High temperatures in the upper eighties and lows in the lower forties continue this week, with a modicum of mid and upper level moisture forecast in our proximity starting midweek. However, with four wildfires partially encircling north-central Colorado, and continued dry lower levels of the atmosphere, this moisture may do more harm than good if it contributes to dry lightning and gusty, erratic winds.
Note: Even though I wrote this around noon on Sunday, internet issues delayed publication until Monday morning. Sorry for the inconvenience.
The fire situation around Steamboat Springs is not good; moving from southwest to east of our area is the Pine Gulch fire by Grand Junction at over 81,000 acres, the Grizzly Creek fire near Glenwood Springs at over 25,000 acres, the Williams Fork fire southwest of Fraser at 6,000 acres and finally the Cameron Pass fire east of our area and north of Rocky Mountain National Park at almost 11,000 acres.
The smoke plume forecasts I’ve been posting have done a good job over the weekend, predicting a clearing of smoke from Friday afternoon through today. Three of the fires could be clearly seen at the same time while I was on the upper mountain of the Steamboat Ski Area yesterday, with the distinctive pyrocumulus clouds, or cumulus clouds associated with a fire, clearly visible.
But the smoke model forecasts an increase in smoke for tonight and part of tomorrow as a ridge of high pressure over the Inter-mountain West amplifies. A small clockwise circulation is forecast to form to our north tonight that will produce some easterly winds, and this may force some smoke from both the Cameron Pass and Williams Fork fires over our area for some of Monday.
But winds are thankfully forecast to turn northerly, i.e from the north, later in the day, and this should once again clear smoke from our area. But the hot temperatures look to remain through the rest of the week.
Meanwhile, a series of storms in the Gulf of Alaska are forecast to deform the ridge of high pressure over the West through the week as a tropical storm passes to the south of Baja before eventually curving northward around the weekend. There is a chance that some of this moisture will make its way over our area starting midweek, though weather forecast models disagree on whether this moisture arrives Wednesday or Thursday and how long it stays around. However, there is agreement that the lower levels of the atmosphere will remain dry which means the possibility of dry lightning and gusty, erratic winds as the precipitation evaporates before reaching the ground.
The only good part of the forecast for fire weather concerns is that winds should be generally light through next weekend as we are underneath the ridge of high pressure, except around possible storms. I’ll have more details about some moisture returning to our area in my next regularly scheduled weather narrative on Thursday afternoon.
Hot and dry weather gets even hotter and drier
Thursday, August 13, 2020
Temperatures are in the mid-eighties early this Thursday afternoon with breezy westerly to southwesterly winds and skies almost completely cloud-free. While winds are forecast to ease through the weekend, temperatures are forecast to rise, likely reaching above ninety degrees through Monday. Some moisture may appear by mid-next week, though continued dry lower levels of the atmosphere may limit its effects to some clouds and mostly dry storms that would produce more wind than rain.
Currently, the southern portion of a storm well to our north is traveling across Montana tonight, briefly suppressing a ridge of high pressure over the West and leading to breezy conditions over our area. Our winds will shift to be more from the west by Friday, which should thankfully keep smoke from the two wildfires to our south and southwest at bay.
The wildfires near our area are continuing to grow, with the Pine Gulch fire northeast of Grand Junction reaching 58,000 acres by Wednesday evening, making it the sixth largest Colorado wildfire to date. Additionally, the Grizzly Creek wildfire by Glenwood Springs has reached over 4,600 acres, and both of these may contribute to smoke in our area this afternoon, likely heaviest in the South Yampa Valley.
For those interested, I have added a smoke plume forecast over Colorado to the numerical weather models I manage each day, available here.
I’ve posted an image of what the forecast looks like as of 4 pm today, and you can see the model forecasts some smoke overhead this afternoon. I don’t have any experience in using this product and can’t speak to its accuracy, but wanted to get these data to you in a timely fashion. If you animate the images, you’ll note that the smoke identifies the eddies in the atmosphere which would otherwise be invisible.
Note that the times as printed are applicable to the Eastern time zone, so subtract two hours for the Mountain time zone. While shown is the vertically integrated smoke, which sums all of the smoke in a column, there is also a product that shows the smoke concentrations expected at the surface.
The good news for our area is that our winds will shift to be more from the west by Friday as that Montana storm travels east, and this should keep the smoke generated in the southern fires away from Steamboat Springs.
But the ridge of high pressure will amplify over the West this weekend behind the departing storm to our north and ahead of a series of storms forecast to develop in the Gulf of Alaska and loiter off the British Columbia coast. Expect decreasing winds, but drier air over our area through Monday, with daytime temperatures approaching or even exceeding ninety, well above our our average high of 81 F. The dry air will, however, allow nighttime lows to fall five to ten degrees below our average low of 44 F, which could yield over a fifty degree temperature difference between the low and high of the day!
Weather forecast models agree that some moisture from the south may be carried over our area in the southerly flow between the Gulf of Alaska storms and the ridge of high pressure over the West by midweek, though lower levels of the atmosphere would remain dry. So while clouds may provide some heat relief, there may be gusty and erratic winds around any storms that form as the precipitation evaporates before reaching the ground.
There may be hope for wetting rains around the following weekend as a series of tropical storms travel south of the Baja peninsula. There is a possibility that some of the deeper moisture from these storms will be caught in the southerly flow to our west and eventually move over our area, and I hope to have more clarity on this by my next regularly scheduled weather narrative on Sunday afternoon.
