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In Brief:
A short wave disturbance moves over the state Saturday which will kick off storms that rise to be marginally severe from I-25 eastward and Denver northward. That is replaced by a ridge for the start of the week bringing in low to mid 90's F highs and dry conditions. The pattern shifts a bit again mid-week bringing in a new flow of tropical moisture and a return to 80's F highs and daily afternoon storm.
Forecast Discussion:
The upper-level high is parked near El Paso today. A stream of tropical moisture is rotating around it, into the desert southwest, then up into the Rockies (green arrows Figure 1). An upper-level, low/disturbance over Utah is speeding up the moisture flow and providing additional lift on Saturday. That means that severe weather is possible from near I-25 (including most of Longmont) out onto the eastern plains (Figure 2). Late into the night going into Sunday, showers will linger in northern Colorado and out on the eastern Plains (Figure 3).
Rain chances peak between noon and 8 pm with Sunday warming to the lower 90's F. Rain chances drop to nearly zero. Sunday will be boring.
The Longer Range Forecast:
So will Monday- as the ridge and dry air travels over the state. The ridge only hangs around for about 3 days, then a trough digs into the Western U.S. and the high returns to a position (south central New Mexico) where it can pump moisture back into the state (Figure 5). Storm chances return and we drop from the mid 90's F Tuesday to the upper 80's F with daily afternoon storms (Figure 4).
