AS OF MONDAY JAN 20

The Idaho snowpack again failed to grow this week.  In some basins the snowpack declined by 1% of the peak snowpack.  Without the snowpack growing, as it normally does this time of year, the percent of normal snowpack has continued to decline.  On a statewide basis the percent of median snowpack as an average of all basins is 94% (just below normal = 100%).  The percent of peak snowpack is 52% (the same as last week).  The average percentile of all basins is 44%.  Two basins the Little Lost and Henrys Fork have snowpack percentiles below 20%, which places them in the moderate drought category for snowpack.  Based on the upcoming forecast, next week several more basins will join this category.  A persistent high-pressure ridge continues to block moisture from the Pacific Ocean from bolstering our snowpack.  We may start seeing a more familiar La Nina pattern emerge with higher-than-normal precipitation forecast in the northern Idaho at the 8 to 14 day Outlook.  But the next two weeks appear like they will be drier than normal in southern Idaho and the central mountains.  Hopefully more moisture will be arriving in February.  In the last Idaho Drought Committee meeting, folks from the National Weather Service indicated that climate conditions over the Pacific Ocean may be lining up for some atmospheric river events in February.  A few big atmospheric events coming out of the southwest, could pull the lost basins out of drought categories quickly and re-establish a strong snowpack. 

IDWR Hydrologist David Hoekema