Weekly Summary: Early in the period, low pressure tracked from the northeastern Gulf up the Atlantic Seaboard, producing showers and thunderstorms, some severe (tornadoes in Virginia), and moderate to heavy rains (more than 2 inches) from southern Georgia northward into New England. Meanwhile a slow-moving cold front in the Nation’s midsection brought some rain to the Midwest and parts of the central and southern Plains. A Pacific system dropped light to moderate precipitation on the Northwest. As the week progressed, an upper-air low north of the Great Lakes generated windy and wet weather in the region, while weak Pacific systems tracked eastward across the northern Rockies with light precipitation. By Monday, a northward-moving disturbance in the east-central Gulf of Mexico west of Cuba was dumping heavy rain on southern Florida. Farther west, a stationary front was draped from the eastern Great Basin to the mid-Atlantic. As the period ended, additional rains were falling on parts of the Midwest, Southeast, and Northeast, while dry weather encompassed the U.S. west of the Mississippi River. Weekly temperatures generally averaged above-normal except in parts of the Northwest, central Plains, and Southeast. Moderate to heavy precipitation fell on south-central and southeastern Alaska while the interior was mostly dry, Hawaii saw light showers on the windward sides, and Puerto Rico recorded light to moderate showers throughout the island.
Northeast and Mid-Atlantic: Widespread showers and thunderstorms soaked much of the mid-Atlantic and New England with 2 or more inches of rain last week, effectively eliminating the three small areas of D0(S) in western New York and southeastern West Virginia. None of the drought products or indices depicted any areas of dryness, and nearly all of the short and medium-term AHPS precipitation anomalies were either surpluses or close to normal. The few remaining minor deficit areas were too small to be depicted on the map. Farther south, heavy rains in south-central Virginia improved conditions by a category, effectively removing D0 and D1 out of the state.
Southeast: Heavy tropical showers and thunderstorms from a disturbance in the east-central Gulf of Mexico and a stationary front focused heavy rains on southern Florida, removing the lingering D0(L) there. Key West received a 3-day total (October 15-17) of 10.35 inches, including an 18-hour amount of 7.24 inches. D0(L) was kept around Lake Okeechobee as it remained below the Water Shortage Management level, although it has steadily risen (a foot this past week) due to the heavy rains in the Kissimmee River basin ten days ago. Farther north, light to moderate rains (0.5 to 2 inches) fell on much of northern Georgia, the western Carolinas, southern Appalachians, and eastern Tennessee, with some embedded heavier bands of thunderstorms (2 to 5 inches) in southeastern and east-central Georgia, and from central North Carolina into Virginia. Accordingly, a 1-category trimming of the D0 and D1 areas along the western and northern drought boundary was made where the rains exceeded 1.5 inches, in the larger bands of heavy thunderstorms, and D0(S) was erased in southeastern Tennessee. Even with the rain, USGS 7-day averaged stream flows (as of Oct. 18) still remained in the lower tenth percentile across many areas of the northern Florida Panhandle, Georgia, South Carolina, and central North Carolina.
In contrast, much of Alabama and the Florida Panhandle missed this week’s rain, and also missed out on Tropical Storm Lee’s soaking rains. As a result, short and medium-term deficits have accumulated (4 to 7 inches at 90-days, and 7 to 11 inches in parts of the Florida Panhandle). As a result, a general westward creep of D0-D3 was made into southeastern Alabama. Farther north, a serious short-term dry spell (past 30 days) has enveloped northwestern Alabama (under an inch of rain, or less than 25 percent of normal), and D0(S) was introduced. Similarly in Louisiana and southern Arkansas, little or no precipitation and above-normal temperatures continued the slow eastward crawl of drought in the states. As deficits continued to accumulate, a general 1-category degradation of the D0-D4 areas were made in Louisiana and southern Arkansas at about the size of a county or parish. In contrast, 1.5 to 2.5 inches of rain fell on northern Arkansas, providing some relief to former D0 and D1 areas.
Northern Plains and Midwest: A widespread area of 1 to 2 inches of rain fell on much of the Midwest, stretching from southern Missouri northward into the upper Great Lakes region. The heaviest rains fell on the southern and eastern sections of the drought areas, while the western sections saw much lower amounts (less than 0.5 inches). Since the drought areas were mostly short-term deficiencies (past 90-days or less), these rains were beneficial in easing the accumulated deficits. Accordingly, where more than 1.5 inches fell, a 1-category improvement was made, and included most of northeastern Missouri, Illinois, eastern Iowa, southern and northern Wisconsin, northern Indiana, the Upper Peninsula (UP) and northern lower Michigan, and northeastern Minnesota. In central Illinois, D2 remained in Macon County because of water restrictions at Decatur. In southern Missouri, a band of heavy rain (2 to 4 inches) improved conditions by a category, but in southwestern Missouri (1 to 2 inches), the rains were not enough to compensate for impacts made by this summer’s extreme heat and dryness, and D2 remained. The Impact Types were modified in the UP of Michigan (L) and northern Minnesota (SL) based upon the blends and various AHPS and SPI periods. Farther west, the D0 area in southwestern North Dakota was expanded to account for short topsoil moisture due to subnormal precipitation the past 60-days, above-normal temperatures, and windy conditions. Fortunately, these conditions are beneficial for farmers to harvest their crops.
Central and Southern Plains: As we hit the third week of October, precipitation normally begins to decrease in the High Plains (e.g. eastern New Mexico, western parts of Texas, Oklahoma, and Kansas), and continues into the winter months. As a result, it is uncommon that widespread, precipitation-drenching storms would occur and alleviate any drought conditions. With that said, however, any precipitation deficits that would accumulate during dry periods would be small, and temperatures and evaporation would typically be much lower than the summer. This week saw mostly dry weather in the southern and central High Plains and near to above-normal temperatures. Farther east, showers and thunderstorms developed and dropped some light to moderate amounts (1 to 2 inches) on north-central Kansas, extreme eastern Oklahoma, and northeastern Texas. Based upon the Texas SPI blends, October rainfall was enough to make a 1-category improvement in portions of the northeastern Texas counties of Tarrant, Parker, Denton, and Wise. The rains that fell farther to the southeast were not enough to overcome this summer’s record heat and long-term drought, and status-quo prevailed. In northwestern Kansas, a re-evaluation of various high-resolution precipitation products depicted a surplus at several time scales (30-, 90-, 180-days), resulting in improvement and removal of drought and dryness there.
Farther north, a 1-category deterioration was made in east-central and southeastern Kansas and northeastern Oklahoma where little or no rain fell this week and where mid-September and early October rains had missed. Similar to Texas, the record heat in Oklahoma and southern Kansas also exacerbated the effects and impacts of the drought. In Oklahoma, changes to the major reservoirs over the past month were: Grand Lake 0 percent change, 10 percent since March 18; Eufaula 2 percent decline, 3 percent since March 18; Texoma 5 percent decline, 30 percent since March 18. Since Grand was in flood control back in March, it currently sits at 100 percent of capacity, but Texoma and Eufaula were not and are now at 66 and 74 percent, respectively.
Southern Rockies and Southwest: A lull in precipitation usually occurs in the Southwest during the fall months between the end of the southwestern summer monsoon and the start of the winter rainy season. Not surprisingly, little or no precipitation fell, and temperatures averaged above normal throughout the area. But since most of this area saw a wet week during early October, no changes were made to the depiction. An exception was made in southwestern Colorado and northwestern New Mexico where new and updated information for September and early October depicted much improved conditions (surpluses at 30-, 60-, and 90-days and longer, SPIs positive). Accordingly, D0 was removed from southwestern Colorado (La Plata County), and a 1-category improvement was made in northwestern New Mexico where nearly all Navajo Nation stations reported a wet September.
Hawaii: Light to moderate (0.25 to 1 inches, a few 1 to 3 inch totals) daily showers were mostly limited to the windward sides of Kauai, Oahu, Maui, and the Big Island, occurring mainly during the weekend. Little or no rain fell on the leeward locations. Dryness during September has basically continued into October, with additional impacts developing. In eastern Oahu, D1(L) was added due to mandatory restrictions (10 percent cutback) on irrigation water use at Waimanalo Reservoir as of October 17. Water levels have fallen from 60 feet early in the year to 28 feet this week. In western Molokai where D2(L) was introduced, users of irrigated water at Kualapuu Reservoir are on a mandatory 30 percent cutback and the water levels have slowly but steadily declined over the past several months. On the Big Island, growing short-term deficits called for a D1(S) expansion eastward into the central third of the island.
Looking Ahead: During the next 5 days (October 20-24), relatively tranquil weather will envelop most of the lower 48 States once the current storm systems in the Midwest and Northeast move out by early Friday. Expect the largest totals (1 to 3 inches) in the northeastern quarter of the U.S., especially Michigan and coastal New England. 5-day temperatures should be above-normal in the western half of the Nation and in northern New England, while subnormal readings cover the Midwest, mid-Atlantic, and Southeast.
The CPC 6-10 day outlook (October 25-29) calls for an amplified ridge over the West Coast with a trough over the East. This translates to favorable odds of above-normal precipitation in the Northeast, southern Florida, and the central Rockies, with subnormal precipitation in the West, the Great Plains, and across the southern tier of States. Above-normal temperatures are forecast for the Far West, with subnormal readings predicted for much of the Nation east of the Rockies, especially in the South.
Author: David Miskus, NOAA/NWS/NCEP/CPC
D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.
Drought Intensity Categories
D1 ... Moderate Drought
D2 ... Severe Drought
D3 ... Extreme Drought
D4 ... Exceptional Drought
Drought or Dryness Types
S ... Short-Term, typically <6 months (e.g. agricultural, grasslands)
L ... Long-Term, typically >6 months (e.g. hydrology, ecology)