California and National Drought Summary for August 4, 2015
Hawaii, Alaska, and Puerto Rico
Both Alaska and Hawaii remain unchanged on this week’s map. As for Puerto Rico, drought continues to make its mark, and a westward expansion of D0-D3 is worth noting on this week’s map given the near-record/record low streamflows and dwindling water supplies being reported in some locations.The Northeast and Mid-Atlantic
Spotty rains and temperatures running 3 to 6 degrees above normal for the week have led to a mixed bag on the drought front, with expansion outweighing improvement from Maine to South Carolina. D0 has expanded westward out of Maine across southern New Hampshire and Vermont and into extreme east-central New York. Some pockets of localized, heavier rains last week kept the expansion from being greater. D0 has also expanded over extreme southeast Massachusetts. D1 was reduced in southeastern Rhode Island where heavier rains were recorded. In addition, the impacts label was changed from “L” to “SL” to account for the more recent seasonal dryness/drought expansion.To the south, the situation in the Carolinas is deteriorating quickly as the woeful 30 to 60-day precipitation totals have recently been joined by above-normal temperatures, leading to elevated concerns about wild-fires along with soil moisture and forage shortfalls in the agricultural sector. D0-D1 has expanded across more of western and southern North Carolina as well as southern South Carolina. In addition, a large area of D2 has been introduced from central/west-central North Carolina southward across the border into central and eastern South Carolina.
The Northern and Central Plains and Midwest
The best of the rains fell across the dry/drought regions last week but the real story, particularly in the Midwest, was the heat as temperatures ran 3 to 5 degrees above normal. That fact, on top of the recent 30-45 days of dryness (albeit after a cool and wet start to the growing season) brought a sweeping advance of D0 across central Wisconsin into extreme northeastern Iowa. Given the bounty of the early season, this recent hot and dry spell hasn’t led to many impacts yet, as can be commonly depicted under abnormally dry (D0) conditions on the Drought Monitor map. An additional small expansion of D0 can also be found in extreme northwestern Iowa, which has now pushed up against the Minnesota border. In a bit of good news, the last remnant of D0 was removed this week from the Texas Panhandle. Status quo is the call elsewhere this week across Minnesota, the Dakotas, Nebraska and Kansas.The Southern Plains and Southeast
Above-normal temperatures and a generally dry week means drought is regaining a toe hold on the landscape from eastern Texas all the way to Florida. Building off of the expanding dryness last week, a large expansion of D0 is noted across western and northern Louisiana, eastern Texas, extreme southeastern Oklahoma and southwest Arkansas. Many locales in these states have seen less than half their normal rainfall over the past two months and less than 10% of their normal rains over the past 30 days. The quick-hitting, flashy nature of this developing drought across both regions bears watching given the time of year and the fact that the shorter-term forecasts don’t appear overly promising, particularly in the Southern Plains and lower Mississippi basin. Things can go downhill in a hurry this time of year and El Niño’s chokehold on tropical storm activity to date is only enhancing the dry signal. Of course, that same pesky culprit, El Niño, may well be the one that comes to the rescue this fall and winter given the stronger likelihood of a cooler and wetter winter across the Gulf Coast region…stay tuned. As such, D0-D1 expansion is prevalent on this week’s map throughout eastern Texas, most of Louisiana, eastern Mississippi, Alabama, the Florida Panhandle and a good chunk of Georgia. However, not all places saw expansion in the Southeast this past week as D2 was eliminated in extreme southeastern Georgia and D0-D2 was trimmed in general up and down Florida’s east coast from Jacksonville to Miami. Locally heavy rains (2 to 4 inches) were the reason behind the improvement this past week.The West
As can be expected this time of year, it was a pretty uneventful week on the precipitation front across most of the region, including a quiet monsoon signal across the Desert Southwest. The West remains unchanged this week but the impacts (near-record/record low streamflow, water supply, water temperatures, fire, etc.) are still being felt and are of major concern as we head toward a new water year with September now on the horizon.Looking Ahead
For the period August 6 through August 11, monsoon precipitation will again be relatively scarce across the Desert Southwest and the rest of the West will be seasonally dry as well. Prospects for the southern Plains and lower Mississippi Basin don’t look good either. Better odds for the wet stuff can be seen in the upper Midwest, the Mid-Atlantic (heavy rains are forecasted for Virginia, Delaware and extreme western Carolinas along with northeastern North Carolina), the Southeast (central Alabama and the western half of Georgia) and along the coastal reaches of the Gulf Coast region (from southern Alabama across the Florida Panhandle and into northern Florida) if all goes as forecasted. Temperatures for this same period show cooler weather across the Great Basin with near-normal readings likely in the Pacific Northwest and rest of the West Coast. Cooler weather is also expected across the northern Plains, New England and Mid-Atlantic. The only real projected hot spot over the next 5 days can be found in the central Plains, the southern and central Rockies and front ranges, southern Plains and lower Mississippi Basin where temperatures are expected to run 3 to 9 degrees above normal.The 6-10 day (valid for August 11-14, 2015) and 8-14 day (valid for August 13-19, 2015) outlooks appear pretty similar and the models are in good agreement about the building of a ridge across the west-central U.S. during this timeframe. This will likely bring a late summer heat wave across the Great Plains, upper Midwest, lower Mississippi Basin, the Rockies, the Desert Southwest and along the southern coastal tier areas of Alaska. Cooler weather is expected in the Pacific Northwest, western Great Basin and the Northeast. One significant feature worth noting is that the 8-14 day outlook projects a stronger likelihood of above-normal temperatures across the West and into the Southeast and Carolinas and across a larger portion of southern Alaska, which the 6-10 day outlook does not.
As for precipitation during these time frames, below-normal totals are more likely, and coincide with, the projected hot spot areas depicted across the entire mid-section of the country from the Gulf of Mexico to Canada (Texas to Michigan and most points in between across the Great Plains and Midwest). Better chances of precipitation can be found in eastern Alaska, the Pacific Northwest, east-central Great Basin, the Atlantic Seaboard region from Maine to north Florida and the coastal areas in the Gulf Coast region from Mississippi eastward to Florida. The southern tip of Florida looks to remain dry at least through the middle of the August as well.
Author(s):
Mark Svoboda, National Drought Mitigation Center
Dryness Categories
D0 ... Abnormally Dry ... used for areas showing dryness but not yet in drought, or for areas recovering from drought.Drought Intensity Categories
D1 ... Moderate DroughtD2 ... 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)
Source: The National Drought Mitigation Center
