A Mid-Atlantic Cold Day in July

July 22 Update: For the record, the National Weather Service report:

A RECORD LOW MAXIMUM TEMPERATURE OF 71 DEGREES WAS SET AT WASHINGTON   
NATIONAL DC YESTERDAY...JULY 21ST. THIS BREAKS THE OLD RECORD OF 74   
DEGREES THAT WAS SET IN 1984...1939 AND 1886.  

The Dulles and Baltimore/BWI records were 69°.

1 AM Update: And the 1 am temperature is again 70°, so the new record low maximum is pretty well set.

Some remedial math for Tom Nelson fans:
Total area of District of Columbia: 68 sq. mi.
Total area of Maryland: 12407 sq. mi.
Total area of U.S.: 3,794,100 sq. mi.
Total number of days in July: 31

Midnight Update: The temperature has held at 70° for 5 out of the last 6 hours, so the final high is likely to remain at 71°, setting a new record for July 21.

Attention Tom Nelson fans: Here is the context he's left out:
Washington on Track for 3rd Top-3 Hottest July in As Many Years

Original Post:
Some sun could still break through and nudge the temperature up a few degrees, but the high temperatures so far today in the Washington/Baltimore area are likely to break records for the coldest maximum on July 21:

Location            High Departure Previous record
Washington National  71   -18      74 /1984
Washington Dulles    68   -20      75 /1984 
Baltimore BWI        69   -18      73 /1984 

Although the 18 to 20 degree departures from average are spectacular, the same low clouds, drizzle, and light rain which depressed the daily highs have also kept the daily lows elevated, so the overall averages are in the -10° to -11° range relative to climatology.

The daily average of 69° at Washington National, if it holds, will be the 3rd coldest July 21 since 1929, when the average was 68°. The average on this date in 1939 was 68.5°. The low in 1929 was accomplished the old-fashioned way, with a daily low of 58°. The record low for July 21 was 56° in 1909.

Drought Update: 42% of U.S. Severe to Exceptional

The percentage of the U.S. affected by abnormally dry/drought conditions increased slightly in the past week to 81%, the highest since at least 2000. Meanwhile, the intensity of the drought increased as the severe and above category (D2-D4) jumped 5 percentage points to 42%, also a new 21st century high. The 2 most intense categories (extreme and exceptional), however, are still well below their peaks of 2011.

From the Drought Monitor report:

A strong upper-level ridge of high pressure dominated the nation’s weather this U.S. Drought Monitor (USDM) week, bringing well above-normal temperatures to the central and northern tier states. Clouds with scattered showers and thunderstorms along a stalled cool front kept temperatures below-normal in the southern states. But even then, maximum temperatures were 90 degrees F or warmer across much of the country, with maximums exceeding 100 from South Dakota to Kansas. Philip, South Dakota, reached 109 degrees on July 15. Beneficial rain fell from southern Texas to the southern Appalachians along the front. Excessive rainfall occurred over southeast Texas where amounts totaled 10 inches or more in places, but elsewhere rainfall amounts were generally localized with limited relief. Monsoon showers and thunderstorms brought above-normal rain to parts of the West, but the rain had little impact on deficits which have accumulated over several months. Weak fronts triggered localized showers and thunderstorms along the northern tier states. In between, hot and dry weather dominated from the central Plains to Ohio Valley, Great Lakes, and Northeast.

Another week of hot and dry weather continued the deterioration of crop conditions in America’s breadbasket. U.S. Department of Agriculture (USDA) reports for the week ending July 15 indicated that 38 percent of the nation’s corn crop was in poor to very poor condition, compared to 30 percent a week ago, and 30 percent of soybeans were in poor to very poor condition (compared to 27 percent last week). Fifty-four percent of the nation’s pasture and rangeland was in poor to very poor condition, which is a jump of 4 percent compared to last week and is an all-time high for the 1995-2012 growing season weekly history. About two dozen large wildfires, mostly in the West, were burning on July 17, about half the number compared to a week ago. Streamflows were in the lower tenth percentile of record, or at record low values at several time scales, across much of the Midwest and parts of the central Plains, West, Southeast, and even parts of New England. As a result, the impacts boundaries were shifted to reflect short-term and long-term drought conditions from the west coast to Ohio Valley and Southeast, with short-term conditions indicated in the northern tier states and from eastern Tennessee to New England. Long-term impacts were indicated for parts of the Southwest and central Gulf of Mexico states.

Washington on Track for 3rd Top-3 Hottest July in As Many Years

The high of 101° so far this afternoon at Washington ties July 1930 with the 6th 100°+ temperature for the month. It also puts this month firmly ahead of the pace of last July's all-time hottest month with an average of 86.0°, vs 84.5° in 2011. Even with a 20° cooldown to a forecast high of 81° on Saturday, a projection based on predictions through Tuesday the 24th and climatological averages for the remaining week of the month would put the July average at 83.4°, still ahead of the then record-tying July 2010. That would make the last 3 Julys the hottest on record. The only remaining top-10 hottest July before 1980 will be 1955.

For the summer to date, the National Weather Service reports:

INCLUDING TODAY...THE HIGH TEMP HAS REACHED OR EXCEEDED 95F ON 18 DAYS AND 100F ON 7 DAYS SO FAR THIS YEAR...WHICH ARE BOTH THE MOST ON RECORD THROUGH 18 JUL AT DCA. PRIOR TO THIS YEAR...THE MOST 95-DEGREE AND 100-DEGREE DAYS THROUGH 18 JUL WAS 16 IN 1991 AND 5 IN 1988...RESPECTIVELY. THE MOST 95-DEGREE AND 100-DEGREE DAYS ON RECORD THAT OCCURRED IN A CALENDAR YEAR WAS 28 IN 1980 AND 11 IN 1930...RESPECTIVELY.

Weekly Weather Wee View: US National Temperature Warmer Than Average 31st Consecutive Week, 48th Out of Last 52

CapitalClimate analysis of National Weather Service reports from 214 stations across the 48 contiguous states shows that the unadjusted US national average temperature was 2.9° above normal for the week ending yesterday, July 14. This was the 31st consecutive week and the 48th out of the last 52 with warmer than average temperatures. The last time there were 4 consecutive weeks cooler than average was in March 2011.

After several weeks of persistently cool temperatures in the Pacific Northwest, the area of warmest temperatures relative to average shifted westward, while heavy rain produced cool temperatures along the western Gulf Coast. The warmest temperature departure was at Yakima, Washington, with +15°F, and the coolest was Beaumont, Texas, with -6°F. Overall, 82% of reporting locations were warmer than average.

Images (click to enlarge):
- Weekly average U.S. temperature departures from normal, weeks ending June 4, 2011 (20110604) through July 14, 2012 (20120714); CapitalClimate chart from NOAA/NCDC data
- Weekly average NWS station temperature departures from normal, week ending July 14, 2012; stations listed alphabetically by state and 3-character station identifier; CapitalClimate chart from NWS data
- Average U.S. temperature departure from normal for week ending July 14, 2012 from High Plains Regional Climate Center

U.S. Drought Coverage Expands to Decade-Plus High of 80%

Despite increased rainfall, the latest U.S. Drought Monitor report, released this morning, shows that the area covered by some level of drought increased to 80% in the week ending July 10. This is up from 76% last week and is the highest dryness at least since Drought Monitor statistics began in 2000. Although D4 (Exceptional) coverage is still well below the extremes reached last summer, drought area increased for all levels except the lowest, D0 (Abnormally Dry).

CapitalClimate analysis of National Weather Service data from 215 major reporting locations across the 48 contiguous states shows that total precipitation for the week ending July 7 was just 51.5% of normal. Weekly precipitation was less than 0.25" at 125 stations, or 58% of the total locations.

The Drought Monitor national summary:

Rainfall was more abundant than last week. A broken pattern of moderate to locally heavy rains (isolated totals up to 5 inches) covered the central and southern Plains, the northernmost Plains and Great Lakes region, the immediate Ohio Valley, and a good chunk of the Southeast and interior mid-Atlantic. However, the heavier amounts were fairly isolated, and with the hot weather that covered much of the central and eastern United States, only a few scattered areas of dryness and drought experienced significant improvement. In addition, the areas with the greatest temperature anomalies (average daily maxima 10 to 13 degrees above normal) generally coincided with an area of scant rainfall across the Midwest, northwestern Ohio Valley, and southern Great Plains, resulting in another week of widespread deterioration and expansion of dryness and drought in these regions.

Images (click to enlarge): U.S. percentage area of drought, weekly from January 4, 2011 through July 10, 2012, CapitalClimate chart from U.S. Drought Monitor data; U.S. Drought Monitor map for July 10, 2012

Man Bites Dog: Extreme Weather and Climate Change Lead National Newscast

The lead story of last night's PBS NewsHour covered recent extreme weather events in the context of global climate change. The 8-minute segment included an extensive interview with Thomas Karl, Director of the National Climatic Data Center. In a stunning reversal of recent churnalistic practices, the message was not diluted by representation of phony skepticism (except in the spittle-flecked comments online). The real question, of course, is what happens to coverage of the issue when records are not being broken so spectacularly.

The intro:

JUDY WOODRUFF: The past 12 months are the warmest ever recorded in the United States since record-keeping began in 1895. That word comes as a new report from the National Oceanic and Atmospheric Administration says climate change, including human factors, has increased the odds of extreme weather. . .

Watch Extreme Weather Records 'Like a Baseball Player on Steroids' on PBS. See more from PBS NewsHour.

Michael Mann Interview on NewsChannel 8

Dr. Michael Mann was interviewed on Washington's NewsChannel 8 this morning regarding his book, The Hockey Stick and the Climate Wars. The climate scientist received top billing over the tax cut food fight.