Drought relief?

Computer forecast models are pointing to a change in the jet stream pattern over the coming week that could provide some drought relief to the southern half of the U.S., including eastern Texas, Oklahoma, and Arkansas. The jet stream so far in January has been blowing in a somewhat "zonal" fashion--straight across the U.S., from about Oregon to New England. The jet has had only modest dips to the south (troughs), associated with rain storms that have tracked rapidly across the northern tier of states. Beginning Saturday, however, the jet stream is expected to take on a more bowed pattern, bringing a sharp trough of low pressure all the way down to Mexico. This trough will bring cold air and moisture with it, giving southern California needed rains, and the first snows of winter to Flagstaff, AZ. Amazingly, Flagstaff had over 83 inches of snow fall by this time last year, but so far this winter has had none!

By Monday, as the trough moves across the country, the drought-ravaged areas of eastern Texas, Oklahoma, and Arkansas have a chance of up to .5 inches of rain. This would be the first significant rains in nearly 100 days in some areas. Another major trough is expected to follow about a week later, and indications are that this trough will also swing far enough south to bring rain and snow to portions of the southern U.S. in need of moisture. However, since there is no cold Arctic air in Canada for these troughs to tap into, only short periods of winter-like conditions are expected in the U.S. over the next ten days. The country remains on track to record our warmest-ever January.


Figure 1. Number of days since the last .25 inch rain for each county in Oklahoma.

Jeff Masters