Drought Update - May 31st 2002

Nolan Doesken
Research Associate
nolan@ccc.atmos.colostate.edu

As May comes to an end there is not a lot of good news to report regarding our drought. The only good news was the big rain/wet snow on the 24th-25th here along the Front Range and indications that we may be in for another storm early next week. Thanks to last week's storm and a couple of early lesser storms, May precipitation totals are in the 1.8 to 3.2" range (near average) from Lakewood northward to Fort Collins, Wellington and Red Feather Lakes, with Boulder County having the largest May totals. This really helped calm the forest fire problems at least for a time. Elsewhere in the state, near-average May precipitation is hard to find, and it looks like most, if not all, of the remainder of the state has tallied another very dry month at a time of year where precipitation is especially important. Many monthly totals will likely be less than 0.50" with less than .20" over portions of southeastern Colorado. This is terrible.

This past week has provided only scant and widely scattered showers and thunderstorms. There have been threatening skies and some higher humidity especially along and east of the mountains, but clouds have been high-based and non productive. The hot weather that we have hoped would wait until some time in June arrived with a vengeance this week, with many areas seeing temperatures in the 90s the past two days. The Fruita COAGMET station report 100 deg F on Thursday and several readings up around 105 have been reported today in the Arkansas Valley.

The hot weather is leading to a surge of streamflow in some of the rivers and streams coming out of the mountains. This is a bit of good news since it indicates there is enough snow left to produce at least a brief snowmelt runoff peak flow. But despite that news, the predictions of the amount of surface water available this summer continue to drop. Back in early April we knew that water supplies were going to be poor on the rivers of southern and southwestern Colorado, but we were optimistic that there was enough snow and enough chance for spring rains that our northern rivers would fare much better. This is not the case, however. Based on information received today from very credible water resources experts, we are now on pace to set all-time low flows for the year on many rivers in all parts of the state. No one seems to be able to remember a year when the snowpack disappeared so quickly in April and May while producing so little water. This is what happens when abnormally warm and dry weather persist for several years.

No need to elaborate -- it is very dry throughout the state. Southeastern Colorado, which has enjoyed (and possibly without realizing it) a very wet recent two decades, is now exceptionally dry with many areas from Pueblo eastward showing less than 40% of their average precipitation since last August with only a few tenths of an inch of precipitation since February -- thus, lousy forage.

Each time as we look ahead we are optimistic -- foolish perhaps. A bit more moisture is heading our way again, and a strong push of chilly, moist air may arrive early next week with a chance of widespread precipitation, especially over northeastern Colorado. This extreme early heat will be pushed away, at least for a time. Klaus Wolter at the NOAA Climatic Diagnostics Center in Boulder continues to paint an optimistic forecast for summer precipitation, especially east of the mountains. He believes the developing El Nino gives us about a 60% chance of have near to above average summer precipitation over south central and eastern Colorado. All bets are off, however, for the Western Slope.