As advertised here throughout this week, we saw a large temperature spread between the Northern Rockies and Lower Midwest with temperatures struggling to get much above the mid-30s while Missouri, Iowa up into Minnesota soared well into the 80s. One example I found was a 36 degree high at Yellowstone Lake, WY while it topped 88 in Des Moines, I’m sure there were a few 90s while it may have been even chillier in some tucked away communities within the N Rockies. Those are values ranging between 20-25 below to 15-20 above normal and a spread of 50-55 degrees.

The heavy snows continued to fall across parts of Idaho, western Montana and NW Wyoming with several locales receiving upwards of 1 to 1.5 feet and I’m sure when all is said and done there will be some who will have topped 2 feet.

Interestingly, today’s national snow cover was up at 3.7% while in fact is the highest for Sep 27 since 2003 according to WeatherNation.

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Here were today’s highs.

Here are the departures from normal.

Severe Threat Tonight

The current upper air pattern supports an unusually cold air mass within a trough that’s firmly placed over the Great Basin and Rockies.

Ahead of the cold front, strong SW surface winds, warm mid level air with cold air riding over top is producing showers and storms this evening and is expected to continue through tonight, raising concern for severe weather.

500mb pattern tonight.

5,000ft temps

Current dew points.

Though by no means is the situation explosive, there is some of the right ingredients converging and with storms firing along the cold front and with the thermal contrast in place, some of the Plains storms have a chance at turning severe with a few tornadoes possible tonight.

Here’s the current IR imagery.

Tonight’s severe risk according to SPC.

Record Rains Poised For Pacific Northwest Next 72 Hours!

As for the Pacific Northwest, we have a deepening Pacific storm over the Gulf of Alaska with pressure dropping sub-970mb which poses a concern for shipping throughout the northeast Pacific as winds could blow at 80+mph while 40ft+ waves are generated.

While this same never bodily comes ashore over BC or Washington, a ton of moisture will stream into the region and this poses a significant flood risk as a LOT of rain is expected to fall through this weekend. How much?

Here’s the 72 hour total rainfall expected from the ECMWF model.

Worse still is the QPF.

Keep in mind these are just 3 days worth of rain. The average for the entire month is between 1-3 inches and the record for many sites is just 4-6 inches so it looks highly likely that records will fall.

In Saturday’s post I shall look at not only the US upper pattern over the next 2 weeks but will discuss the potential pattern throughout October into November.

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Tags: Rockies September snow, Rockies Snow, severe weather