Here's the forecast high temperatures for Monday:
The cool weather (blue and green colors) are largely confined to the western US, while the southern and eastern states have warmer weather (yellow and orange colors). But then look at what will happen by Friday:
The map is flipped. Now warmer weather is found in the western US, while the eastern US will experience a cool-down. This isn't unusual. What's happening in one half of the country is often opposite of the other half.
Here is a meteogram of forecast temperatures for the next 7 days at Spokane Airport:
The various colored lines are forecasts from different computer models. The green line is the official NWS forecast. As you can see, Monday through Thursday will see a warming trend of about 7 degrees each day. So, Monday's high should be about 55, Tuesday 62, Wednesday near 70, and Thursday into the mid 70s. The NAM model (in red) is actually going for a high on Thursday close to 80F.
Now technically Spokane hasn't seen it's first 70F day yet this spring. On April 8th the airport topped out at 69F, while most other sensors in the metro area reached 70F or better. While Wednesday will be close, Thursday is a slam dunk as far as having our first 70F day of the spring. So you're probably asking yourself, is this first 70F day early or late this year? Well, here's the statistics:
Average: 17 April
Earliest: 9 March 1889
Latest: 21 May 1896
Thus technically, we'll be later than normal for our first 70F day (by 15 days), but nowhere close to the record of 21 May. And since you maybe wondering what the numbers are for the first 80F day at Spokane, here they are:
Average: 12 May
Earliest: 7 Apr 1977
Latest: 22 Jun 2011
So on the outside chance that we actually reach 80F at Spokane with this warm-up, it would be ahead of schedule by about 10 days.