Latest Seasonal Assessment -
The ocean and atmosphere system remained consistent with La Niña in early February, although a transition from La Niña to ENSO-neutral is most likely during the Northern Hemisphere spring (55% chance of ENSO-neutral during the March-May season). La Niña is expected to continue affecting temperature and precipitation across the U.S. during the next few months, with above-normal temperatures and below-median precipitation favored across the southern tier of the U.S., and below- normal temperatures and above-median precipitation expected across the northern tier of the United States. Drought coverage (D1-D4) continued to increase across the contiguous States during the past month, going from just over 32 percent on January 9 to almost 40 percent as of February 6. Severe or worse drought (D2-D4) increased from 8.7 percent to 18.4 percent during the same time period. This increase was driven primarily by continued drought deterioration in the south-central Plains and the Southwest where extended dryness and warmth has led to areas of record or near-record low mountain snowpack in the latter region. Drought improvement and contraction primarily occurred in the western Corn Belt, lower Mississippi Valley, parts of the Southeast, and Hawaii.
With sub-median precipitation and above-normal temperatures favored during March and MAM, drought should persist in the southwestern quarter of the Nation, along with development in most of California and Nevada, south-central Oregon, and southern Texas. The odds for California to get to near-normal precipitation this Water Year are rapidly diminishing as the wet season normally ends in April. In central Oregon, below- to near-median precipitation during the next 1-2 months will probably not be enough to significantly increase the mountain snowpack that stood at 28-35 percent of normal as of February 14. Subnormal winter precipitation, minimal snow cover, and a dry climatology (until late April) in eastern sections of the northern Plains does not bode well for adequate soil moisture recharge, hence persistence was left there. In contrast, recent precipitation and the forecast for additional rainfall from the southern Great Plains and lower Mississippi Valley northeastward into New England tilts the odds toward improvement in the eastern third of the Nation. Similarly, improvement is likely in the western sections of the northern Plains where surplus fall and winter precipitation has built a decent snow pack to aid in soil moisture recharge during spring snow melt while March and MAM precipitation favor above-median totals. Removal is forecast for western portions of the Big Island of Hawaii while development is possible along the southeastern Alaskan Panhandle.
Forecaster: David Miskus
Next Seasonal Outlook issued: March 15, 2018 at 8:30 AM EDT
Seasonal Drought Outlook Discussion