Latest Seasonal Assessment -
The Outlook was revised on October 6 as the combination of the remains of Tropical Storm Tammy and an
eastward-sweeping cold front were forecast to dump 2 to 6 inches or rain on the drought area extending from the
Carolinas to New England during October 6-9. This will end drought over most of the region. Lesser rainfall
amounts over western Pennsylvania, southern Ohio, and eastern Kentucky will lead to more limited improvement in
these areas. Elsewhere, some drought improvement during October-December is expected in Texas and the Plains, as
well as parts of the Pacific Northwest. The Great Lakes region will see minor to more significant
improvement. Lingering areas of drought in the Southwest are not likely to see significant change during this
Tools used in the Drought Outlook
included the official CPC long-lead precipitation outlook for October-December, the
drought termination and amelioration probabilities for December, various medium and short-range forecasts and
models such as the 6-10 day and 8-14 day forecasts, and the soil moisture tools based on the
GFS model and the Constructed Analogues for the season.
The Outlook was amended on October 6 to account for the very heavy rains forecast across the Eastern Seaboard during October 6-9 from the combination of Tropical Storm Tammy and an eastward-moving cold front. The official HPC 5-day forecast for October 6-11 calls for over 2 inches of rain extending from northern Georgia to Maine, with over 3 inches across most of North Carolina, Virginia, Maryland, New Jersey, eastern Pennsylvania, eastern New York and nearly all of New England. Even higher amounts are forecast for parts of this region. Although accurate rainfall amounts in these situations are difficult to forecast, there seems little doubt that significant drought-breaking rains are imminent across the drought region, and the moisture will be enough to eradicate most of the D1-D2 drought areas depicted on the October 4 U.S. Drought Monitor. More limited relief is shown for the western fringes of the drought region extending from western Pennsylvania into eastern Kentucky, as 5-day totals are generally well under 2 inches in these areas and as little as 0.25 inches in the Kentucky drought area. It should be cautioned that even with 2-3 inches of rain across the drought region extending from the Carolinas to New England, 60-day rainfall deficits of 1-3 inches would remain, so drought-redevelopment later in the season cannot be ruled out if warm and dry weather returns. The next Outlook release on October 20 will consider the latest indications from the seasonal forecast tools to gauge the odds of drought returning to the region.
Elsewhere, Rita eliminated drought from Louisiana and Arkansas, so the forecast improvement shown in the September 15 Outlook has verified. Drought west of Rita’s rains has worsened in Texas, and this revised Outlook shows only some improvement for southeast Oklahoma and northeast Texas, as both short-term and long-term rainfall indicators do not look very optimistic for relief at this point. Likewise, the improvement area in South Texas was changed to more limited improvement. The Outlook will, of course, be revisited when the regularly-scheduled outlooks are issued on October 20.
In the West and Midwest, no more than minor changes have been made to the September 15 drought outlook, although improvements resulting from the recent storm across the Northwest and northern Rockies are reflected in slight changes to the baseline drought areas depicted on the map.