U.S. Drought Monitor - Latest Update

National Drought Monitor for October 7, 2014

Looking Ahead

For the period October 9-14, temperatures are expected to remain well above normal (3-6 degrees) across most of the West. Temperatures could prove to be even hotter across the Gulf Coast region and the Mid-Atlantic, with temperatures as high as 9 degrees above the norm. The Central Plains, Midwest and the Great Lakes regions are expecting to see much cooler than normal weather, with readings 3-6 degrees below normal. As for precipitation, one place expecting to see good precipitation is the coastal ranges of Washington. The major rainmaker, however, is expected to come from the remnants of Tropical Storm Simon trekking across the Desert Southwest (southern Arizona and New Mexico), central and southern Plains, Mississippi Valley, the Tennessee and Ohio Valleys and the Northeast. Totals are expected to range anywhere from 2 to 5 inches over widespread areas that are currently under the grip of drought.

Looking out a bit further at the 6-10-day time frame (October 14-18), the models are showing a greater likelihood of above-normal temperatures for virtually all of the contiguous United States, with the exception being the Pacific Northwest. The prospects for this unseasonable warmth are quite strong in the West, western Plains and Atlantic Coast. Southern Alaska is the only place that is expecting below-normal temperatures during this period. All areas except northern Alaska are also expected to be below normal on the precipitation side of things. For the Lower 48, the Pacific Northwest and eastern third of the country are showing better odds of above-normal precipitation. The Four Corners region and the central and southern Plains show a stronger tendency of being below normal with regard to the wet stuff.
 

Summary

Another large weather system moved across the country’s midsection last week, bringing the heaviest rains to those areas outside of dryness/drought. The system brought anywhere from 3 to 5 inches of rain across eastern Nebraska and Kansas and then through Missouri, Iowa and into the Midwest and Great Lakes region, with cooler temperatures following in its wake. The rest of the country saw a much drier week and California, Oregon and Washington recorded well above normal temperatures.

Hawaii, Alaska, and Puerto Rico

Across Hawaii, good rains across the windward locales brought widespread improvement across many of the islands on this week, with a removal of D0 for all of Kauai, Niihau and Lanai. In addition, D0 was reduced along the windward side of Oahu, eastern Molokai, windward West Maui and the southwestern half of the Big Island. The D1 areas remain in place.

The Northeast and Mid-Atlantic

Last week brought a mixed bag of weather, with much of New England experiencing warmer and drier conditions, while the Mid-Atlantic saw a little more in the way of precipitation in parts of the western Carolinas and West Virginia, although most changes to this week’s map were minor. The recent rains have brought some improvement to central West Virginia with the trimming of D0 there. Persistent short-term dryness over the past 30-60 days has brought some slight expansion of D0 in north-central North Carolina this week as soils continue to dry out and the risk of fire is heightened. The worst of the low streamflow readings are contained mostly across New England at this time. Recent rains in eastern South Carolina over the past month or more means a cutback on the D0 there this week, although D0 remains intact across the central and east-central counties over into Georgia.

The Plains and Midwest

A large, slow-moving storm system brought heavy rains (3 to 6 inches) and flooding to eastern Nebraska, eastern Kansas, southwestern Iowa, northern Missouri, central Illinois and extreme western Indiana. One-category improvements are noted in these areas, leaving behind small pockets of D0-D1 as the dryness/drought has been pushed farther south. Streamflow values across much of the Missouri and upper Mississippi basins are running very high for this time of year, emptying swollen streams and rivers into reservoirs along the way as recovery from the 2012-2013 drought continues.

One area that has missed out on the wetness of late is the tri-point region between extreme northeast South Dakota, southeast North Dakota and extreme west-central Minnesota, which sees the introduction of D0 this week. Although the past month was particularly dry, some locales in this region have been experiencing this pattern back to 60 and even 90 days. This isn’t necessarily a bad thing as the harvest season is underway for many.

The South

All but eastern Oklahoma and eastern Texas missed out on any substantial precipitation last week while above-normal temperatures returned for most locales across the region, including most of Arkansas. Rains in eastern Texas led to some slight trimming of the southern D0 flank, but all other changes in Texas and Oklahoma were for the worse across south-central Oklahoma along the Red River and in north-central Texas along with the Panhandle, where the past 60 days have brought less than 50% of normal rains coupled with temperatures running 2-4 degrees above normal.

The Southeast

Another round of rains brought improvement to northern and western Mississippi, northern and western Alabama, and along the Alabama-Florida border in the extreme western Panhandle region where rainfall deficits are running on the order of 2 to 4 inches (~50% of normal or less in places) over the past 90 days. The core of D1-D2 (S) in central Alabama remains undisturbed as the rains missed to the north and these deficits can be traced as far back as 6 months. Although conditions are normally dry this time of year, holdover deficits from late summer have put late-season stress on soils and pastures, which are in need of some good moisture recharge heading into the off-season given yet another relatively quiet tropical storm season (although that could change for some parts of this region in the coming days). This dryness has also been lingering in parts of central Tennessee as well although no changes were made to this week’s map. In Georgia, some reduction of D0 took place in the extreme northwest corner of the state.

The West

Hot temperatures (6-10 degrees above normal) and dry conditions were widespread across coastal California all the way up to Washington. Conditions remain unchanged this week on the map, however, as a critical new Water Year begins to spin up. With the 2014 Water Year in the books now, the National Weather Service in Sacramento issued some preliminary numbers that help put this drought into perspective. The Sacramento Water Supply Index (WSI) came in as the 4th driest water year in terms of runoff in the 109-year period dating back to 1906. In case you’re interested, 1977 was the worst year, followed by 1924 and 1931, respectively. Several of California’s largest reservoirs are running at their second-lowest levels, only running behind 1977. This is of particular importance given that the population has roughly doubled since the drought of 1977. No doubt about it, though, an above-normal Water Year is sorely needed to stave off even further depletion of surface and ground water supplies.

Elsewhere across the region, good rains came to the San Juan Mountains of Colorado, resulting in some minor trimming of the western notch of D0-D1 found there. Good rains over the past 90 days (or more) has also led to some trimming of the D3 in extreme southeast Colorado, northeast New Mexico, southwest Kansas and the extreme western Panhandle of Oklahoma. Conditions are still dire, though, as the region has weathered four years of intense, persistent drought. This is another region that could use a good beneficial winter.


Author(s):
Mark Svoboda, National Drought Mitigation Center