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.