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INTERMOUNTAIN WEST CLIMATE SUMMARY, JANUARY 2008 Seasonal Drought Outlook through April 2008 With the forecasted persistence of La Nina conditions into 2008, the current Drought Outlook (DO) is based on precipita- tion anomalies that typically occur during La Nina episodes. To develop the DO each month, CPC experts start with the designa- tions from the U.S. Drought Monitor (USDM, see p 7), and considers the latest short and medium range weather forecasts, climate outlooks from the Climate Prediction Center (see pages 13 and 14), climatological considerations, and initial drought conditions. This product projects changes in status of the USDM, which currently designates most of the western U.S. as in various categories of drought. The DO released January 21 st depicts general, large-scale trends through the end of April 2008 (3.5 months, Figure 12). Consistent with La Nina signal for above average precipitation in the Pacific Northwest and northern tier, the DO projects signifi- cant decrease in drought status across the drought areas in the interior Northwest and Great Basin, including western Wyoming and much of Utah. A Pacific storm in early January substantially boosted snow pack in California and other parts of the West, ~?,;'-l ~;.~~~} ~~~1 /~~. ;:JIJ. ,~. ... .. '" ~ ' l:, ~ .p:O ~~ ~ ~CC) )~ i I.- L~/ but below-average precipitation is expected during February - April for the Southwest, so the odds favor no change or limited decrease in drought status at best for this region. The next DO will be issued in two weeks, on January 31st. Notes The Seasonal Drought Outlook (DO) depicts general, large- scale trends from that date through the end of the forecast period (3 to 3.5 months, depending on the date of issue). The delineated areas in the (Figure 11) are defined subjectively based on expert assessment of numerous indicators, including outputs of short- and long-term forecasting models. Areas of continuing drought are schematically approximated from the Drought Monitor (D1 to D4). For weekly drought updates, see the latest Drought Monitor text on the website: http://www.drought.unl.edu/dm/monitor.html. NOTE: The green improvement areas imply at least a 1-category improvement in the Drought Monitor intensity levels, but do not necessarily imply drought elimination. < '--.. ,~.... Drought Outlook . Drought to persist or intensify . Drought ongoing, some improvements . Drought likely to improve, impacts ease D Drought development likely Figure 12. Long-lead national precipitation forecast for April - June 2008 (released January 17, 2008). On the Web · For more information, visit: http://www.drought.noaa.gov/. Forecasts of drought termination probabilities can be found at: http://www.ncdc.noaa.gov/oa/climate/ resea rch/ d ro u g ht/ cu rre nt. htm I FORECASTS 11 5