Summary: October 22 2019
The last seven day period started out warm and dry across the IMW [Intermountain West], but another dose of winter has hit in the northern half of the region. The Tetons, northern Wasatch, and northern Colorado Rockies received 0.50-1.50″ of precipitation in the last several days, mostly in the form of snow. Totals in the valleys, were mostly below 0.25″. Southern mountains did not fair as favorably. The San Juans, La Sals, and Sangre de Cristos received little to no precipitation.
In general, the IMW is balancing the impacts of a hot, dry July-September against a remarkably cool and wet February through June. Results may vary by exact location. From an impacts standpoint, this dichotomy manifests itself as normal to above normal streamflows and reservoir storage, but below normal root zone soil moisture, and above normal plant stress. The wettest areas in winter, such as high elevations on Colorado’s west slopes, are most likely to have holdover soil moisture from winter/spring, and are showing less plant stress via satellite metrics, such as ESI. Areas that are climatologically drier in winter, and benefit from monsoon season rains have been hit hard.
Having had our second round of below freezing temperatures, the growing season is now mostly over for the IMW. However, from an agricultural standpoint, recent dryness has had an adverse and important impacts on pasture range conditions, and winter wheat planting. New Mexico (Arizona) pasture range conditions are ranked as 33% (40%) poor, and 9% (20%) very poor respectively. Percent of area poor and very poor is lower in Utah and Colorado, and much lower in Wyoming. Colorado winter wheat has mostly been planted, though it needed to be drilled over SE CO due to dry conditions. Winter wheat planted in the latter half of the planting season has not emerged, and recent dry, windy conditions may lead to subpar emergence.
A cold frontal passage diving out of the north on Wednesday and Thursday will bring a big temperature drop, and mostly light precipitation, to eastern Wyoming and Colorado. After that, the area will warm back up briefly. The CPC is predicting an increased chance of below normal temperatures for the 8-14 day period, but cooler air entering the region will be low in moisture content. The western IMW has an increased chance of below normal precipitation. The southeast portion of the IMW has an increased chance of above normal precipitation.