This week’s drought summary: The pattern has been less active over the CONUS over the past seven days, with high pressure dominating over much of the western CONUS. Storm systems riding up and over the Pacific ridge resulted in some precipitation in the Pacific Northwest, but not enough to alleviate the dryness there, particularly for Oregon. Meanwhile a low-pressure system propagated northeastward along the East Coast and out of the domain early in the period, adding to surpluses in the Tennessee and Ohio Valleys. Drought continued to expand in the West, as dry conditions persisted over much of the region. Parts of Oregon and California saw increases in D0 and D1 coverage, while areas of D0 were expanded slightly in Montana. There was some D1 added to northeastern areas of Colorado (High Plains Region), as the past 60 days have seen drier than normal conditions. Drought intensification and expansion also continues in southern Texas (Southern Region), in association with continued dryness, low humidity, and high winds over the past week. The Midwest and Northeast continue to remain as is for now, as 90-day precipitation surpluses are widespread across many of these areas, with other areas near normal. Some D0 reduction in southern Georgia (Southeast Region) was made due to recent heavy rainfall. However, the Florida Peninsula saw some D0 expansion north and east of Tampa, with year-to-date (YTD) precipitation estimates between 25 and 50 percent of normal.
South: Drought intensification over southern Texas continued, along with expansion into adjacent coastal areas. Stream flows are below normal for many areas, and recent high winds and low humidity have enhanced surface soil moisture loss. YTD percent of normal precipitation was 25 to 50 percent for much of southern Texas, with less than 10 percent along the Rio Grande Valley. This is on top of receiving essentially no precipitation over the past 30 days, and beyond, for many areas south of the I-10 corridor. D0 remains for portions of the immediate Gulf Coast in Louisiana, Mississippi, and Alabama this week, although dryness has crept northward in these areas with the sharp north-south precipitation gradients in recent weeks.
Looking Ahead: During the next 5 days (March 5-9), heavy rain will be exiting the Southeast early in the period, leaving behind an estimated 1.5 to 3 inches of rainfall. Light to moderate precipitation is forecast along coastal areas of California, the Sierra Nevada, and the Four Corners Region later in the period. This energy is expected to transition to the central Great Plains by day 5, with estimates of greater than 0.5 inches centered just west of the Mississippi River.
The 6-10 day (March 10-14) extended range forecast suggests a more transient pattern over the much of the CONUS (indicated by weak height anomalies and zonal flow), favoring above normal precipitation over much of the country. Enhanced probabilities for above normal precipitation are favored during the 6-10 day period over southern California and the Four Corners Region, in association with a potential mean trough propagating eastward underneath a Pacific ridge of high pressure. Meanwhile, an active storm track is favored to remain in place across Alaska, enhancing probabilities for above normal precipitation over much of the state during the extended range.