Summary: March 13, 2018
March has started off dry for much of the Intermountain West region. Most of the Upper Colorado River Basin has received less than 0.25 inches this month. Eastern Colorado, extending into eastern Wyoming and eastern New Mexico, has mainly seen no precipitation, with up to 0.10" along the divide. The dryness is troublesome in March since precipitation amounts are expected to start increasing this time of year and winter wheat will start coming out of dormancy, zapping what little moisture is left in the soil.
SPIs show the continued lack of precipitation. In the Four Corners and much of eastern Utah, SPIs are between -1 and -2.5 for the 90 day. Much of western Colorado shows up in the 0 to -1.5 range for the 90 day. Eastern Colorado is a bit of a mix, with extreme northeastern CO is on the wet end of the scale, towards the Divide SPIs dry out to the 0 to -1.5 range and southeastern Colorado is mainly between -1 and -2.5. The longer term SPIs for much of the UCRB shows much more dryness through the area, with the Four Corners and western Colorado worsening. Eastern Colorado improves, with more SPIs in the normal range. Southeastern Colorado is even in the +1 to -1 range. It should be noted, these better SPIs in the southeast are a result of precipitation in early October. It has been very dry since.
As expected with lack of precipitation this winter, snowpack numbers are terrible in Colorado, Utah, Arizona and New Mexico. Northern Colorado snowpack ranges from 82% in the South Platte, to 78% of the median in the Yampa and Colorado Mainstem. Southern Colorado ranges from 59% in the Arkansas Basin, to 49% in the San Juan basin. The majority of basins in Utah are below 55% of normal, decreasing in the south and eastern portions of the state. Wyoming has the best snowpack of the IMW region, with many basins above 100%, lower amounts in the southern part of the state.
Saving this year from being a terrible year is the water supply. Most of the major reservoirs in the UCRB are near or above normal, bringing enough water for the growing season.
Temperatures for this month have been above normal for most of Colorado and New Mexico and near to slightly below normal for the rest of the IMW region.
UCRB: It is recommended D3 be expanded in central Utah into western Emery County and eastern Sanpete and Sevier counties. SPIs in western Emery on the 90 day are below -1.5, mixed with precipitation and snowpack percentiles at the SNOTEL stations below the 5th percentile should justify this degradation. We also suggest the drought monitor take a look and extending D2 and D3 west of the UCRB in Utah where SNOTEL percentiles are just as low.
We are OK with how the rest of the UCRB looks this week.
Eastern Colorado: D3 is recommended in Baca, Prowers and Bent counties, catching a bit of Las Animas County to smooth the transition. FSA has confirmed that conditions in these counties are bad enough to introduce D3. Soil moisture is not doing well, and once the grasses and winter wheat come out of dormancy, which will be soon giving the warm temperatures, what little soil moisture is left will be quickly zapped. Several producers have said they might have a week left on their wheat before it dries up and fails. The D3 line is drawn based on Water Year to Date precipitation (less than 30% of normal) and 120-day SPI (below -2 SPI).
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