31.50% of the Lower 48 States are in Drought

Hurricane Helene dropped heavy to excessive amounts of rain on a large area from the Ohio Valley, central Appalachians, and mid-Atlantic Piedmont southward to the eastern Gulf Coast region. The storm moved inland across the Florida Panhandle and northward into the South Atlantic States, then slowed down and drifted westward as it interacted with an upper-level low pressure system, becoming quasi-stationary as it slowly dissipated. The heaviest rains fell where precipitation was orographically enhanced on the east side of the Appalachians. Part of the central North Carolina mountains received 20 to almost 30 inches of rain, with totals topping 10 inches over the rest of the North Carolina mountains as well as the central Blue Ridge in Virginia, part of central and western South Carolina, some patches in central Georgia, and near the landfall site. More than 4 inches soaked a broad area from the middle and lower Ohio Valley southward through eastern Alabama and eastward through the central and southern Appalachians and Piedmont, including most of the Carolinas and Georgia. Widespread flooding resulted, with devastating floods impacting the wetter areas, along with prolonged power outages. Helene is the deadliest tropical system to affect the Nation since Hurricane Katrina in 2005, with a death total was approaching 200 as of this writing.

At the same time, the intense rains dramatically improved or ended the various degrees of dryness and drought that had been affecting many of the areas impacted by Helene, especially from the Appalachians westward through the Ohio and Tennessee Valleys and southward to the central Gulf Coast, in addition to much of South Carolina and northern Georgia. Outside the broad area impacted by Helene, subnormal precipitation prevailed across most of the contiguous states. Precipitation was almost non-existent over a large area from the western Great Lakes and most of the Mississippi Valley westward to the Pacific Coast, with only scattered sites in the northern Intermountain West and areas from the northern Cascades to the Pacific Coast receiving over one-tenth of an inch. Above-normal temperatures accompanied the low precipitation totals, resulting in dryness and drought persisting or intensifying across this area covering a majority of the contiguous states. Farther east, the Northeast, mid-Atlantic region, and eastern Great Lakes recorded generally 0.5 to 2.0 inches of rain, with a little more reported in parts of western Michigan, southern and western Pennsylvania, and the higher elevations from upstate New York eastward across Vermont, New Hampshire, and western Maine.

Looking Ahead...

During the next five days (October 3 - 7), warm and dry weather will dominate the contiguous United States. Very little if any precipitation is expected across a vast majority of the Nation. The Florida Peninsula the immediate rim of the Gulf Coast are significant exceptions, where abundant tropical moisture is expected to feed heavy rainfall. There is some potential for tropical cyclone development over the Gulf later in the period. Over an inch is forecast across the Florida Peninsula and along parts of the immediate Gulf Coast from the Florida Panhandle through coastal southern Texas. Generally 1.5 to 3.0 inches are expected in a swath across the central Florida Peninsula and near the central Gulf Coast, with heavy amounts of 3 to 5 inches forecast on the Florida West Coast from the Tampa area southward through Ft. Myers, and across the Louisiana Bayou. Moderate amounts (0.5 to 1.5 inches) are forecast from the Cascades of Washington and northern Oregon westward to the Pacific Coast, and over parts of northern Idaho and adjacent Montana. Meanwhile, several tenths of an inch are expected across most of the Great Lakes region and the Northeast. Several tenths of an inch are also expected over most of Hawaii, with the largest totals forecast in central Lanai, eastern Maui, and part of the western Big Island. Between 2 and 3 inches are expected to fall on southeasternmost Alaska, where normals are relatively high. Near normal temperatures are expected in most areas east of the Mississippi River while well above-normal temperatures should prevail farther west. Daily maximum temperatures 10 – 15 deg. F above normal are anticipated from the central and northern Plains through most of the Rockies and Intermountain West to near the California Coast. Temperatures are expected to average closer to normal across Hawaii and southeastern Alaska.

The 6-10 day outlook (valid October 8 - 12) continues to favor warmer and drier than normal weather for most of the Nation. Above-normal rainfall is expected to continue across the Florida Peninsula, possibly spreading into southern Georgia. Meanwhile, marginally-enhanced chances for wetter than normal weather cover much of Maine, portions of the Far West from the Cascades westward, and west-central California. A much larger area with increased chances for drier-than normal weather stretch across the northern Rockies and from the High Plains eastward through the southern and middle Atlantic Coast. The best odds for subnormal rainfall extend from the Great Lakes southward through the lower Ohio and middle Mississippi Valleys. Surplus precipitation is expected in southeasternmost Alaska while totals over Hawaii are expected to be near normal. Meanwhile, warmer than normal weather is expected from the Great Lakes and the Mississippi Valley westward to the Pacific Coast, with odds for unusual warmth exceeding 80 percent over northern and central sections of the Rockies and Plains. Warmer than normal weather is also favored over the Florida Peninsula. In contrast, there are enhanced chances for subnormal temperatures along the Eastern Seaboard from Georgia through Maine, over most of the Appalachians, across the middle and upper Ohio Valley, and in the Tennessee Valley and adjacent areas. Outside the contiguous U.S., near normal temperatures are forecast for southeast Alaska, with nominally elevated chances for warmer than normal conditions across most of Hawaii.