Summary: July 17, 2018
The monsoon has arrived, bringing moisture to many locations in Arizona and New Mexico, and periodically extending into southern Utah and southern Colorado. While dewpoints have increased and temperatures have decreased, the threat of new wildfires (and the spread of current ones) has settled down a bit. This pattern shift has also reduced the short-term evaporative demand throughout the Intermountain West. However, precipitation has still been a bit spotty, and widespread accumulations have not been enough yet to consider improvements to the D4 drought in the Four Corners area.
Streamflow conditions throughout the Upper Colorado River Basin remain in extremely poor condition, with 75% of the USGS streamgages reporting 7-day averaged flows below the 25th percentile. For a period of 17 days in June and July, not a single streamgage reported flows above the 75th percentile. Currently 7% of the gages are reporting record low 7-day averaged flows. What this likely means for the basin is that base flow for the new water year could start out lower than average, which will make it harder to accumulate near normal flows in the next water year, even if precipitation is near normal.
The one week outlook shows positive signs of the monsoonal moisture pushing into the IMW. Unfortunately, the two week outlook is a bit drier and warmer and will likely dry things out again fairly quickly. The next seasonal outlook will not be released by the Climate Prediction Center until later this week. The hope is that it still holds onto the strong monsoon so that we can begin to see some real improvement to this severe drought that has dominated the IMW since the beginning of the water year.
Improvement: We recommend a very small improvement from D1 to D0 (see blue contour) in southern Jefferson County in Colorado. The Cheesman COOP station reported 3.87" of precipitation on July 6, which appears to verify. This is the highest amount they've ever recorded in July, and is their 2nd highest daily amount ever, only behind April 15, 1921 when 3.97" was reported. SPIs there are positive on short time scales and only turn negative out 9 months.
Status quo is recommended for the rest of Colorado and the Upper Colorado River Basin. Due to widespread changes last week, nothing big enough has happened in the last 7 days to warrant any more changes. If the 7-day QPF pans out, we can expect to see some possible improvements recommended for next week's Drought Monitor depiction.
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