Tools used in the revised U.S. Monthly Drought Outlook (MDO) included the official Climate Prediction Center (CPC) temperature and precipitation outlooks for February 2018, various short- and medium-range forecasts and models such as the 7-day quantitative precipitation forecast (QPF) totals from the Weather Prediction Center (WPC), the 6-10 day and 8-14 day CPC extended-range forecasts (ERFs), the CPC Week 3-4 outlooks, the daily runs of the CFSv2 monthly precipitation and temperature probability forecasts, the 384-hour total precipitation forecasts from several runs of the GFS, 240-hour total precipitation forecasts from the ECMWF, climatology for February, initial conditions (the U.S. Drought Monitor valid on January 23, 2018). La Niña conditions are predicted to continue, and monthly forecasts from various sources generally agree that conditions reflecting a canonical La Niña response should continue this month.
Basin snow water content values have a sharp north-south gradient across the interior West, with near to above-average snowpack conditions over the northern Rockies and Intermountain West, and much below-normal snowpack conditions over the southern Rockies. Numerous locations from eastern Nevada through the central Four Corners region are reporting record or near-record low water content in the snowpack, indicating broadscale deterioration since the start of the year. Although an upper-level ridge is expected to prevail across the West through mid-month, periods of snow are expected across the northern tier of the region during the first week of the month. Farther south, from California and southern Oregon (where this is a relatively wet time of year) eastward through the southern Four Corners Region, odds favor subnormal precipitation month-long. Above-normal temperatures are expected through the month outside Montana. All indicators considered, the drought across central and southern parts of the region should persist, and expand northward into more of California, Nevada, and Utah. Indicators for February are mixed for the drought area in northeast Oregon, but with the first half of the month looking dry, this drought area should generally persist except on the eastern fringe, where higher elevations have been receiving more precipitation than other areas. In contrast, most indicators point toward cool and wet conditions across Montana throughout the month, which should result in further erosion and improvement of the drought area from the West.
Forecast confidence for the Western region is High outside Oregon, where confidence is moderate.
Drought persisted and slightly expanded in the southern tier of the region this past month, while lower temperatures and sufficient precipitation kept drought in the northern Plains essentially unchanged. This is a relatively dry time of year, so drought tends to change little in February, and the forecast calls for persistence regionwide, with some limited expansion expected in southeast Kansas where temperatures are relatively high and the climatology is slightly wetter. Farther north, most indicators lean wetter and cooler than normal for at least middle and late February in the Dakotas, but given the time of year and the dry climatology, noticeable improvement seems unlikely. Still, the wet consensus of indicators lowers confidence.
Forecast confidence for the High Plains region is moderate in southern areas and low in northern areas.
January was considerably drier than normal through most of the Southern region, with only a few tenths of an inch if any falling from central Oklahoma and Texas westward. Precipitation deficits were less extreme in the lower Mississippi Valley and Tenessee, but were still generally below normal outside southern Louisiana and adjacent Texas. Most indicators point toward continued subnormal precipitation region-wide outside Tennessee and small adjacent areas. Moderate precipitation (1.0 to 1.5 inches) is possible early in the month in eastern reaches of the region, but odds lean toward dryness thereafter. The consensus of these factors leads to a persistence forecast for almost the entire drought region save a small part of central Louisiana and adjacent Texas, where rainfall early in the period should improve this area of marginal drought. Further, given initial conditions and the strong indicators for continued dryness, drought expansion through western Texas seems likely. Drought development is also forecast in northeastern Texas and adjacent areas, though with less confidence. In eastern parts of Tennessee more closely related to the drought conditions in the Southeast climate region, the consensus of indicators points toward drought persistence and some limited northward expansion, though with less confidence.
Forecast confidence for the Southern region is moderate to high outside eastern Tennessee, where there is low forecast confidence.
Drought is more sparse in the Midwest than in most other climate regions, limited to the middle Mississippi Valley adjacent to the broad drought coverage farther south and west. February is somewhat drier than most other times of the year, especially in western and northern sections of the drought region. The first couple weeks of the forecast period should feature light precipitation at best here, and thereafter indicators are mixed, favoring neither dryness nor wetness overall. Given the non-committal consensus of indicators, some credence was given to drier than normal conditions indicated in late GFS and ECMWF runs, resulting in a low confidence forecast of drought persistence. Some expansion into adjacent areas is expected due to dryness early in the month.
Forecast confidence for the Midwestern region is moderate to low.
As in the Midwest, drought coverage is relatively small in the Northeast climate region, restricted to parts of Maryland and eastern Pennsylvania. A few weak storm systems could bring moderate precipitation to the drought region in early February, and longer-term indicators point toward wetter than normal weather for the month as a whole. However, February is slightly drier than most other times of the year in these regions, and there is nothing pointing toward widespread heavy precipitation; therefore, drought persistence seems slightly more likely than improvement or removal.
Forecast confidence for the Northeast region is low.
Near- to above-normal precipitation is favored across the South Atlantic Coastal states through the middle of the month, with surplus precipitation continuing to March in Virginia. Precipitation should be sufficient to remove drought from the central Carolinas to Virginia. Farther south, below-normal precipitation is expected for the month as a whole from the central Carolinas southward despite the potentially wetter-than-normal start to the month. The early-month precipitation should remove drought from small areas where drought was marginal as the forecast period began, but persistence is favored through most of the region, with limited northward expansion where antecedent conditions were somewhat dry.
Forecast confidence for the Southeast region is moderate near the Gulf Coast, and low elsewhere.
Small areas of drought persist along the leeward portions of Hawaii's larger islands. February is a fairly wet time of year across Hawaii, and additionally, odds favor surplus precipitation. Therefore, drought persistence remains the best bet. No drought currently exists or is forecast for Alaska and Puerto Rico.
Forecast confidence for Hawaii is moderate.
Forecaster: Rich Tinker
Next Monthly Outlook issued: February 28, 2018 at 3 PM EST