Latest Seasonal Assessment -
El Niño has transitioned to ENSO-neutral, and ENSO-neutral conditions are most likely to continue through the Northern Hemisphere winter 2019-20 (50-55% chance). Drought coverage remains very low across the contiguous U.S. (CONUS). Across the West, as the summer monsoon season winds down in September, the West Coast rainy season will gradually ramp up. Drought currently in place across portions of the Northwest and western parts of New Mexico are favored to persist during the Sep-Oct-Nov (SON) 2019 season, mainly because significant, longer-term precipitation deficits are considered unlikely to be overcome. Over the Midwest, small areas of moderate drought (D1) were recently introduced to the U.S. Drought Monitor map, but these areas are expected to be removed during the SON season. In fact, heavy rainfall predicted during the next 1-2 weeks may be enough to wipe out budding drought in Iowa and northwestern Illinois. CPC's monthly and seasonal precipitation outlooks, valid for September and SON respectively, favor above normal precipitation for North Dakota, supporting drought removal there. Across the southern Great Plains, high temperatures and reduced precipitation have resulted in drought expansion. Drought development is also possible across southern Texas. In the Southeast, short-term rainfall may be enough to result in the improvement and/or removal of localized pockets of drought currently in place. The exception is southeastern North Carolina and adjacent parts of South Carolina, where 6-8 inch rainfall deficits have mounted over the past 3 months. In the eastern Interior of Alaska, moderate drought was removed from the U.S. Drought Monitor depiction this week. Autumnal westerlies are climatologically favored to strengthen and shift southward towards the southern coast of Alaska, helping to focus storm tracks and their associated precipitation patterns. This supports at least a one-category improvement in drought conditions across southern Alaska in SON. Farther south over the Central Pacific, the low-latitude trade winds are expected to strengthen now that the El Niño has ended, and result in increased rainfall across the Hawaiian Islands, especially windward areas. A seasonal increase in mid-latitude storm activity may also bring needed rainfall to the drier leeward slopes. For Puerto Rico, various dynamical model precipitation forecasts are at odds with the expected uptick in Atlantic hurricane activity for the SON season. With these conflicting indications, and in the absence of strong climate signals for either increased dryness or wetness, it is thought that drought persistence is most likely for the southern portion of Puerto Rico.
Forecaster: Anthony Artusa
Next Seasonal Outlook issued: September 19, 2019 at 8:30 AM EDT
Seasonal Drought Outlook Discussion