Click here to go to the US Drought Monitor website. Here’s an excerpt:
Summary
This USDM week began with an upper-level ridge bringing above-normal temperatures to much of the central third of the CONUS. Short-wave troughs moving through the ridge brought surface lows and cold fronts as they moved across the country. By the end of the week, a large upper-level trough and its associated surface low and front were bringing cooler temperatures and much-needed precipitation to many drought areas. Drought contracted in parts of the Ohio to Lower Mississippi Valleys and Southern Plains. Drought expanded in parts of the Central to Southern Plains which missed out on the frontal precipitation. The early week fronts fell apart before reaching the Southeast drought area, and the late week front did not reach most of the Southeast before the cutoff date for this week’s USDM. As a result, drought expanded in southern Alabama to southeast Georgia, and in eastern Kentucky, and did not improve in the Southeast much from the frontal passages…
The Great Plains
Precipitation from the low pressure systems that moved across the middle of the country fell as snow in the northern Plains with rain in parts of the central and southern Plains. Precipitation amounts ranged from 0.5 to 1.5 inches from parts of Nebraska to North Dakota, as well as parts of Texas and southeast Oklahoma, while northeast Texas to the southeast tip of Oklahoma received over 2 inches and locally over 4 inches. But little to no precipitation fell from northwest Texas to much of Kansas. D0-D3 were pulled back in eastern and southern Texas, D2-D3 contracted in southeast Oklahoma, and the central Nebraska D1 blob was trimmed. But D0-D1 expanded in western Nebraska to central Oklahoma and the Texas panhandle, and an oval of D2 was added to southwest Kansas into the Oklahoma panhandle. As of November 27, the USDA reported that 41% of the topsoil was rated short to very short in Nebraska and Texas, and subsoil moisture was short to very short in 42% of Nebraska and 39% of Texas. Topsoil moisture short to very short increased in Kansas from 41% last week to 45% this week, while 35% of the subsoil moisture was rated short to very short. In Oklahoma, topsoil moisture short to very short increased from 50% last week to 55% this week, with 44% of the subsoil short to very short of moisture…
The Rockies and Far West
The upper-level troughs brought locally heavy precipitation to the coastal Northwest, with locally 10 inches or more measured in favored upslope areas of Washington and northwest Oregon. Two or more inches of precipitation fell from the northern California coast to the Cascades of Washington, and along upslope areas of the Sierra Nevada in California. Much of the Rockies and higher elevations elsewhere in the West received half an inch or more of precipitation, but parts of Montana and the Southwest had less than a tenth of an inch. The precipitation increased high elevation SNOTEL station snow depth almost everywhere across the West, but SWE (snow water content) values continued to be lower than average across the Pacific Northwest and most of the Rockies. The weekly precipitation totals were below normal for Montana, the interior Northwest, and parts of the Great Basin and Southwest. This was still early in the snow season, so no change to the USDM depiction was made across most of the West, except for a few locations. An oval of D0 was added in eastern Montana based on short-term drought indicators, and D0 expanded along the Rocky Front Range in the vicinity of Great Falls based on 30-day precipitation departures and low SNOTEL SWE values. In Montana, 34% of the subsoil moisture and 28% of the topsoil moisture were rated short or very short by the USDA. D0 was pulled back in north central New Mexico where short-term indicators showed wetness, especially NASA’s SPoRT LIS soil moisture tool and the USGS streamflow percentiles. Reservoirs in this area continued below 30+ year average levels, but this is due to long-term conditions mostly upstream in the basin out of state; in arid regions like New Mexico, it may take many years for some of these reservoirs to refill to these long-term average levels. November 27 USDA reports still indicated 67% of New Mexico’s topsoil, and 47% of the subsoil, were rated short to very short of moisture. As noted by the National Weather Service, November 28 SNOTEL data reflected a good start to the snow season for northern California mountain snowpack, with some basins 130-140% of median. But this is early in the snow season, so median values are easy to exceed. And basins to the south, including the San Joaquin, are still lagging, below 70% of median in more southerly locations. In California, 65% of the topsoil was rated short to very short, an increase of 5% from last week, and 65% of the subsoil was short to very short, according to the USDA. In Colorado, 60% of the topsoil and 59% of the subsoil were rated short to very short of moisture, while the statistics were 50%/60% in Nevada, 19%/32% in Oregon, 27%/30% in Utah, and 50%/50% in Wyoming…
Looking Ahead
In the day since the Tuesday morning cutoff time of this week’s USDM, the cold frontal passage dropped an inch to locally over 3 inches of rain from parts of Louisiana northeastward to western Virginia, and over parts of the Northeast. For November 30-December 5, a series of fronts and low pressure systems are forecast to drop an additional 1-2 inches of precipitation across the South from Texas to Virginia, and parts of the Northeast, with locally 3+ inches from Texas to Mississippi. One to 3 inches is progged for parts of the coastal Northwest and Northern Rockies. A tenth to half of an inch is expected across the Midwest, extreme northern Plains, and much of the central and northern portions of the West. No precipitation is forecast for southern California or much of the Southwest to central Plains. Temperatures should average warmer than normal in the East and cooler than normal in the West. For December 6-14, odds favor wetter-than-normal conditions for the northern tier States and drier than normal for the Southwest to southern Plains, with the Southeast transitioning from wet to dry. Temperatures are expected to be colder than normal in the West to Plains. The East Coast will transition from warmer than normal to cooler than normal as an upper-level trough migrates east through the period. Odds favor cooler- and drier-than-normal weather over Alaska.