A tranquil and record-warm Thanksgiving for much of the U.S.

Celebrations of the Thanksgiving holiday in the United States in 2012 were aided by some of the most tranquil travel weather ever seen on what is America's busiest travel week. Unusually warm and precipitation-free conditions prevailed over almost the entire nation on Wednesday and Thursday, with many locations in the Midwest reporting their warmest Thanksgiving Day on record. At least three cities set records for their warmest temperature ever recorded so late in the year: Valentine, Nebraska (76° on Wednesday); Rochester, Minnesota (70° on Wednesday); and Sault Ste. Marie, Michigan (65° on Thursday.) While the quiet weather was a boon for travelers, the lack of rain in the Midwest allowed the nation's worst drought since 1954 to expand; the U.S. Drought Monitor reported that the area of the contiguous U.S. covered by moderate or greater drought expanded by 1% to 60% this week. This reversed a seven-week trend of slowly decreasing drought that began on September 25 and extended until November 13, when the area covered by drought declined from 65% to 59%. The latest ten-day forecasts from the GFS and ECMWF models show much below average chances of precipitation across more 90% of the U.S., including the drought regions. These dry conditions will allow the drought to expand over the next two weeks, and potentially cover 65% of the contiguous U.S. again by mid-December. The next chance for significant rains in excess of one inch in the Midwest will not occur until December 2, at the earliest. The lack of rain will potentially cause serious trouble for barge traffic on the Mississippi River by December 10, when the river may fall below the level of -5 feet at St. Louis needed to allow barges to not scrape bottom.


Figure 1. This week's U.S. Drought Monitor shows 60% of the contiguous U.S. was in moderate or greater drought.


Figure 2. Predicted 8-day precipitation amounts from the 06Z (1 am EST) November 23, 2012 run of the GFS model. For the 8-day period ending on Saturday, December 1, only the Northwest Coast, Central Gulf Coast, and portions of the Tennessee Valley are predicted to receive rains in excess of one inch. Image credit: NOAA.

Quiet in the Atlantic
There are no threat areas in the Atlantic to discuss today, and none of the reliable models is forecasting tropical cyclone development between now and the Friday, November 30 official end of hurricane season. I wouldn't dismiss the possibility of one more named storm forming in December in the middle Atlantic between Bermuda and Puerto Rico, but late-season storms forming in that location rarely affect land.

Have a great holiday weekend, everyone!

Jeff Masters