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<\/a><\/p>\nThis afternoon’s water vapor image of the eastern Pacific and western North America shows a high amplitude pattern over and to the west of Colorado. A high amplitude pattern sometimes implies that disturbances will be slow to move eastward, and such is the case today. The strong trough<\/span> that has now entered the western US coast will very slowly trek eastward and provide a long duration precipitation event (Event #1) for most of Colorado. In addition, a particularly moist airmass has developed over the US Central Plains. Precipitable Water<\/span> (PW<\/span>) values up to 2 inches will stream northward into OK, KS and NE. While we certainly do not expect these kind of values to make it into Colorado (which would be record highs even during the summer), some of this moisture will be available to draw from.<\/p>\n Thus, we expect a very active period over the next 5 days or so. Initially, there will be an elevated fire danger across central CO due to high winds and low relative humidity. By Saturday, colder air will slowly over take the state from the northwest. Friday and Saturday (and possibly Sunday) will feature elevated chances of severe weather across the far eastern Plains, and possibly as far west as the Palmer Ridge. By Sunday, much cooler\/colder air will overtake most of the state, changing the dominant precipitation to stratiform, as opposed to convective, rain and snow showers.<\/p>\n In terms of the flood threat, the forecasted PW<\/span> plumes at Denver and Grand Junction, below, show a very large moisture gradient developing by this weekend. For example, by late Saturday, Denver’s PW<\/span> could be as high as 0.9 inches while Grand Junction is expected to remain below 0.6 inches.<\/p>\n In fact, just these two sites do not tell the entire story. The forecasted PW<\/span> at Lamar (below) shows values as high as 1.4 inches. While there is no long-term record of PW<\/span> here, data from Goodland, KS (which is almost always moister than Lamar) shows that during late September, the 90th<\/sup> percentile of PW<\/span> is about 1.1 inches. Thus, it is safe to say that the forecast values are well above average and likely close to record values. In addition, due to the slow movement of the trough<\/span>, we expect a high potential of thunderstorm training<\/span>. Although the higher flood threat remains just to the east of CO into KS and OK, an elevated flood threat will exist for southeast CO on Friday, Saturday and possibly Sunday for isolated<\/span> flash flooding<\/span> in southeast Colorado. Check back for our daily Flood Threat Bulletins for the most updated information.<\/p>\n<\/a><\/p>\n<\/a><\/p>\n