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In Brief:
Dry stabilizing air is moving in overnight Sunday into Monday cutting off storm chances. A giant ridge is forming across the southern U.S. turning off tropical moisture flow. We warm to the 90'sF this week with very small chances of an afternoon storm - and even then, only on some days.
11:30 am 8/13 update:
Some moisture has sneaked back into northern Colorado. With daytime heating and the direction that winds are coming from up through the atmosphere, there is a risk of a few supercell thunderstorms getting started along the Front Range this afternoon. The SPC has painted us with a Marginal Risk again (1 on a scale of 1-5 - Figure 2 update) and hail is the primary risk near Longmont and I-25 (Figure 3 update).
Further out on the Plains in the Slight and Enhanced risk (Figure 2 update) zones, high winds and tornadoes become a threat to watch for.
End 11:30am 8/13 update
2pm 8/12 Update:
Just to follow up on the promise made yesterday - here is the water vapor image from midday Monday (Figure 1 update) showing the river of dry air flowing over the state. Looking out the window - it is really clear out there as well.
End 2pm 8/12 Update.
Forecast Discussion:
The real storms formed out over eastern Colorado with only light rain around I-25 and westward. The Denver NWS was right to be concerned about the dampening effect of too much morning cloudiness in the Marginal Risk zone Sunday. Dry air is replacing the moisture (it will be really different water vapor satellite image in the next 24-48 hours (Figure 1)). We return to the 90's with a very small chance of rain Monday (Figure 2). The SPC doesn't even give us a chance of convection on Monday (Figure 3).
The Longer Range Forecast:
On Tuesday, healthy daytime heating will interact with what remaining moisture we still have in the atmosphere and a storm or two may form around I-25. Most will not see a drop fall (Figure 4). The dominant story is a big ridge over the western U.S. and a ridge stretching almost from Bermuda to Hawaii to our south (Figure 5). Say goodbye to rich moisture (or monsoon like) flow.
Because of this sudden onset of quiet hot weather, I'll turn to some family time and post double-day posts until things cool down and get moist again. The longer range does hint at a big cool down for later August. Wait for it!
