April 2013: Dry streaking

April was the fourth consecutive month of subpar precipitation for the inland northwest, and while only 4 days into May, the extended forecast bodes well for keeping the streak alive. To put the calendar year to-date precipitation in perspective here is how 2013 so far ranks relative to the 1895-present record.


Pretty much the entire West being in the hole. Northern California and parts of western Oregon at the bottom of the pit. Early May wildfire activity in Northern and Southern California foretells of the climate impacts of what could seem like the endless summer for some. Back in the inland northwest, we’ve had the driest beginning of a calendar year since at least 2001. The dryness is accentuated by the recent soggy springs of 2011 and 2012. Strong ridging over the region for the next week to 10 days will provide some inertia for maintaining the dry streak into May.

Screen shot 2013-05-05 at 8.44.22 AM

The usual suspects of the El Nino-Southern Oscillation and the Pacific North American pattern haven’t enabled this dry spell. Rather,   strong ridging directly upstream off the coast of the PNW has redirected the storm track well northward keeping the West dry.

Temperatures were below normal in April for the inland northwest.  Several record low temperatures were set from mid-to-late month include a 19 in Moscow on April 16th, 15 in Missoula on the 22nd and 13 in Pocatello on the 18th.  NCDC extremes shows a total of 76 coldest daily minimum temperatures broken or tied in April in Idaho, compare to only 3 warmest daytime high temperatures.


Snowpack numbers as of May 4th were close to normal across the northern half of the region, with numbers dropping precipitously south of the 45th parallel. With a string of warm temperature across much of the region the next couple weeks, we should see snowpack numbers decline from the Cascades eastward to the Bitterroots.


Despite several non-accumulating snowfall episodes in Moscow in April, no snow was reported leaving the water year total at 39.8″. Technically, snow has been officially measured in May. But given that 90% of May’s are snowless in Moscow, and we’ll be shutout the first half of the month and I’m 95% sure that our snowfall total will stay put.

This means that the winner of the 2012-2013 Snowcast is firegirl who forecasted 36.2″ of snow in Moscow and 18.1″ of Apr 1 SWE in Bogus Basin. This is particularly humbling since I will hear about this for quite some time. Being 2nd to last in forecasting skill in my undergraduate weather analysis and forecasting class at UC Davis, I am used to being humbled.

Screen Shot 2013-04-09 at 5.10.13 PM

This entry was posted in Uncategorized by John Abatzoglou. Bookmark the permalink.

About John Abatzoglou

John is an associate professor of Geography at the University of Idaho. John's interests are centered around climate and weather of the American West and their impacts to people and natural resources of the West. John and his Applied Climate Science Lab at the University of Idaho have published nearly 100 papers and book chapters on climate science, meteorology, and applied climate science connecting climate to water resources, wildfire and agriculture. The research group also develops web-based climate services that connect climate data with decision makers to help improve climate readiness of societies and ecosystems.

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