Northeast: Most of the region experienced abnormally warm temperatures and dry weather, leading to no changes on the map this week. Impacts haven’t emerged yet, but the dryness of the past two months is of some concern with spring and the growing season right around the corner. This time serves as the recharge season, and that has been lacking.
South Atlantic and Central Gulf Coast Regions: The South Atlantic didn’t fare as well this past week with unseasonably warm weather and very little in the way of precipitation across the Carolinas up into coastal Virginia, Maryland and Delaware. The exception was in south central and southern Georgia, where some modest rainfall occurred. The best rains fell in the heart of the D4 region, and that led to some slight improvement on the northern edge of the D4 within Georgia. The rest of the state remains in status quo given both the short- and long-term drought within the state. Streamflows are historically low virtually statewide save for the northern basins.
Florida saw both the good and bad with regard to the drought this past week, with most of the southern peninsula (basically east of Tallahassee and down to the Everglades) seeing little if any rain. The western Panhandle, however, saw heavy rains of 3 to 5 inches, leading to a 1-category improvement to locales in and around Tallahassee to the west and north into Alabama. Even after the good rains, the area is still in the grips of long-term drought, with D2-D3 left in place. In southern Florida, another week of dryness leads to a slight expansion of D0-D2 from the west coast to the east coast and points south of Orlando.
Both Mississippi and Alabama saw the same heavy bands of rain across the coastal regions, leading to widespread improvement by one category or more in some places within extreme southern Mississippi. Alabama also saw 1-category improvements but the dryness/drought characteristics have shifted a bit more toward the long-term (L) impact type of drought. Southeast Alabama is still fully entrenched in D3 and D4. Streamflows have not rebounded nearly as well in this quadrant of the state but have showed some promise in other regions along the coastal counties in both Mississippi and Alabama and into the extreme western reaches of the Florida Panhandle.
The Southern Great Plains and Louisiana: Louisiana saw a mixed bag of rains and results. The best rainfall totals were observed in western, central and eastern parishes. The New Orleans area and points south didn’t fare quite as well and so status quo remains. The other areas within Louisiana all saw 1-category improvement on the week.
Texas continued to see very un-La Nina like precipitation during the week, with most of it centered on the eastern half of the state. Short-term (S) drought impacts are falling by the wayside, but longer-term hydrological remnants are still there, most obvious in the western counties and up into the Panhandle. The big news is the reduction of D4 in central Texas this week along with reductions of D1-D3. Lesser amounts of the wet stuff fell across western TX, including the Panhandle, and we will continue to reassess the benefit of these rains in the short-term vs. the long-term duration and severity of the drought moving forward in these parts as more data comes in from the field. Oklahoma and the rest of the southern Plains stand pat this week after very little in the way of precipitation.
The Northern Plains: The only change on the map this week is centered on extreme eastern Montana and northwest North Dakota, where the warm winter continues along with the dryness over the past 90 days or so. As a result, D0 has expanded in both eastern Montana and northwestern North Dakota. The rest of the region remains the same after a relatively quiet week.
West: Cooler temperatures settled in last week and all but the coastal Pacific Northwest was dry as well, bucking the general abnormally warm trend of the past month. Changes this week, all in the form of deterioration, are depicted in Wyoming, Utah, Arizona, Nevada and California. Assessment of Water Year-to-date (WYTD) snow pack and water equivalent estimates within the pack shows some very low readings in the regions listed above. The saving grace for many of these basins was the bounty of last year, but in turning our attention to this year we are painting a different picture as the peak snow accumulation season comes down the final stretch. USDA-SNOTEL observations show snow water equivalent (SWE) ranking percentiles for many of the basins in the 6%-10% or even the driest 5% range based on the long-term record (over the past 20 years at least). This has led to the removal of D0 and replacement with D1 in the Mogollon region of central Arizona. It has also resulted in an expansion of D1 in the Upper Bear basin along the Wyoming/Utah state line, along with a slight D1 push into more of extreme northeastern Utah toward Wyoming and Colorado. Colorado, however, stands pat this week.
Farther west, northwestern Nevada and northeastern California both see an expansion of D2 for the same reasons explained above. WYTD precipitation has been slow in coming to date. The dryness also extends farther southward in California and into the lower elevations as well as to the coast in northern California. Both D0 and D1 have pushed west to the coast and south into the Los Angeles region continuing down to just north of San Diego. After a bumper year last winter, results of a new snow survey in the Sierras over the coming weeks will reveal a lot more about where we stand this winter.
Hawaii: No changes are noted across the islands this week.
Looking Ahead: During the next 5 days (February 23 – 27, 2012), the best bets for precipitation are centered on the Pacific Northwest, Southeast, Atlantic Seaboard and up into New England. Only modest totals are forecast for the drought regions across the Southeast, but anything will help at this point with the spring growing season just around the corner. The wetness in the eastern U.S. will be accompanied by warmer-than-normal temperatures as well. Most locations west of the Missouri River can expect to see below-normal temperatures over this period with the exception being the Four Corners region and California, where near-normal readings are expected.
The Climate Prediction Center (CPC) 6-10 day (February 28-March 3, 2012) outlook shows increased odds of precipitation across the Pacific Northwest, the eastern Great Plains, the Midwest and the Mississippi, Missouri, and Ohio River valleys. Below-normal precipitation is anticipated in southern California, the Southwest and the coastal regions of the Carolinas as well as all of Florida except for the Panhandle. Temperatures look to be below normal across all of Alaska and everywhere west of the Rockies. Above-normal temperatures are likely to occur east of the Mississippi Valley and up into New England with the Southeast and Florida showing the strongest chances for unseasonably warm weather as we welcome March in the door.
Author: Mark Svoboda, National Drought Mitigation Center
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)