Drought Retains Western U.S. Strangleholds

June 20, 2013 by   - () Comments Off on Drought Retains Western U.S. Strangleholds

Looking Ahead: The NWS WPC 5-Day (June 19-24) Quantitative Precipitation Forecast (QPF) is showing good prospects for a nice shot of unseasonably cooler weather across the Pacific Northwest, California and Nevada. The opposite holds true, though, for the southern Rockies region, central Plains, Midwest and Northeast, where readings could soar well above normal. The precipitation outlook during this period shows the best bet for significant totals to fall in the Pacific Northwest, northern Plains, upper Midwest, Gulf Coast and up along the southern Atlantic coast into South Carolina.

The 6-10 day (June 25-29) outlooks are calling for a real summertime pattern to emerge, with the odds well tilted toward above-normal temperatures across southern California, the Intermountain West, northern Rockies, central and northern Plains, the Midwest and the Northeast. Alaska looks likely to continue with its recent spate of above-normal temperatures as well. The only areas seeing a greater likelihood of cooler weather are the Pacific Northwest coastal ranges and the western Gulf Coast region. Prospects for rain seem to be best in the Pacific Northwest, upper Midwest, Mid-Atlantic and Northeast. Below-normal precipitation is most likely in the Intermountain West, Wyoming and the central Plains. Alaska also looks likely to couple the heat with dryness during this same period as well.

For a review of the past week’s weather by region, see below.

The Northeast: Cooler temperatures prevailed and spotty beneficial rains continued to fall last week across the region, except for portions of Pennsylvania. On the heels of improvement in the region last week, some minor changes are noted this week with the removal of D0 in northeastern New York State and some minor western expansion of D0 in northeastern Pennsylvania into south central New York (although this same region saw some trimming of D0 on the eastern flank).

Mid-Atlantic: Good rains bring reduction of D0 in West Virginia this week along the southern and eastern fronts as soil moisture and streamflows continue to rebound as a result of above-normal rainfall the past 30-90 days. Cooler temperatures also prevailed across West Virginia, although most of Virginia and the Carolinas were relatively dry. Temperatures were mostly cooler than normal to seasonal for the entire region, helping offset demand so far as we head into summer.

The Southeast: Above-normal temperatures pervaded southern Alabama, southern Georgia and the Florida Panhandle last week. Coupled with the recent dryness, seasonal departures over the past 90 days (50-75% of normal) leads to some slight expansion of D0 across extreme southern Alabama, the Florida Panhandle and extreme southwest Georgia. These same regions have been generally seeing a nice recovery this year from a long multi-year drought, so the recent dryness shows that recovery isn’t complete and all aspects of the hydrological cycle haven’t been fully recharged, leaving the area more vulnerable to a relapse should tropical rains avoid the region.

Midwest: The improvement trend continues this week in both Minnesota and northwestern Iowa where recent rains have led to a general 1-category improvement in both states, including the removal of D2 from south central Minnesota.

The Plains: All but western Texas saw well above normal temperatures last week after a cooler start to the growing season (when compared to the very hot start that plagued the region in 2012). In fact, readings farther north were 5-8 degrees above normal across western Kansas and parts of both the Oklahoma and Texas panhandles, with more heat and dry conditions expected to be coming to the region over the next couple of weeks. Rains were scattered and very good for some while not so good for others across the southern Plains. Oklahoma, in particular, continues to see a slow retreat of drought in those counties located along the eastern edge of drought in central and northern portions of the state, including some slight improvement from D4 to D3 across a small portion of the central Panhandle. However, a very tight gradient remains between eastern (no drought) and western (D0-D4) Oklahoma counties as summer appears on their doorstep.

As for changes in Texas, there were many this week, both for the better and worse. In general, counties in central, south central and southeastern Texas saw degradation after the drying trend of the past several weeks and a ramping up of above-normal temperatures for the better part of the past month. An advancement of D0-D3 is seen toward the southeastern coast as a result. Heavy rains brought 1- to 2-category improvements, drastically reducing D3/D4 along the Big Bend region and points south along the Rio Grande corridor. Western Texas and the Panhandle also got a taste of good rains, leading to some scattered improvement and 1-category improvements there, and the same pattern brought changes for the better across central/north central Texas up into the Red River corridor with Oklahoma.

Farther north, the continuation of cooler and wetter conditions brings some improvement to the D0-D2 areas along the Missouri River corridor between northeast Nebraska and southeastern South Dakota. Good rains also came to a good portion of western and central Kansas last week, bringing a reduction of D2 drought there. The rains, however, weren’t significant enough to bring improvement to the long-lived D3/D4 core that is embedded in the western half of Kansas.

The West: Changes are noted for many areas on this week’s map, starting with Colorado and Wyoming, where D0 has been degraded to D1 across north central Colorado and extreme southeastern Wyoming. Other changes in Colorado include an advance of D2 and D3 in the eastern half of the state, coupled with an expansion of D2 and D3 in south central and southwestern counties that extends into southeastern Utah.

After an underwhelming winter overall, temperatures have really increased across the Four Corners region, escalating fire and range condition concerns as we move into summer. This region is quickly becoming home to the new epicenter of the 2013 drought. D3 has also pushed into more of northwest New Mexico, putting virtually all of the state in extreme (D3) or exceptional (D4) drought, the two worst drought severity classifications. Little change is expected in this severity level across the state until we see what benefits the monsoon season may bring them later this month or early in July. These same concerns are being felt farther west as well with D2 expanding in southwestern Idaho. Eastern Nevada sees an introduction of a much larger area of D2/D3 this week as summer heat and dryness settle in and strengthen their influence on the drought in the Intermountain West after a disappointing winter.

A push of D0 is depicted this week across more of western and northern Oregon and into western Washington State as well. Year-to-date dryness and low streamflows are indicative of conditions across more and more of the Pacific Northwest. A slight expansion of D0/D1 also comes to the Idaho Panhandle given low streamflow levels and lack of rains during the past few weeks coupled with well below normal precipitation on the year (50-70% of normal). Severe drought (D2) has also expanded to cover a larger portion of southeastern Oregon into the Klamath region, along with a push westward of D1 in southern Oregon over to the coast.

California also saw an increase in D2 this week across the northern tier of the state. Extremely low streamflow levels and record, or near-record, dryness on the year have elevated short- and long-term concerns with regard to soil moisture, fire potential and distressed native ecosystems not privy to irrigation. Statewide water supply conditions are in pretty good shape for most of California, which should provide a sufficient buffer for irrigators and municipalities this year, but as those supplies are drawn down, there will be little to fill in behind because of the disappointing winter and woeful year-to-date precipitation. The exception to this is the San Joaquin Valley, where irrigation allocations to farmers will be cut significantly.

Hawaii, Alaska, and Puerto Rico: The Big Island sees a slip backward in conditions for some areas as the dry season sets in. The leeward side along the North Kohala District lacked the necessary April and May rains, so they slide back into severe (D2) drought. In addition, a pocket of D3 has reemerged in the Pohakuloa area, which was left vulnerable after being in D3 up until just a few weeks ago. The dry weather, coupled with strong winds, has led to a relapse of conditions in these areas, noted by deterioration of soil moisture and vegetation conditions. The rest of the Big Island and the state remain unchanged from last week.

Alaska and Puerto Rico remained unchanged this week as well.




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