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.
