DC Held Heat Hostage: Day 51 of 90°+ Temperatures

1 AM Update: The temperature is still 85°; the new record high minimum goes into the books.

Midnight Update: The midnight (EDT) temperature is down to only 85°, so the record high minimum will most likely hold.

Original post:
Today's preliminary high/low temperatures of 97°/80° at Washington raise the summer average to date another notch to 81.9°. The August average is now 82.0°, 3.2° above average and the second hottest August in history. There have now been 51 days of 90°+ temperatures this year, 46 of them this summer. The summer total is now within 2 of the amount in 2002 and more than double last year's. The record for a calendar year is 67 in 1980.

The high missed the daily record by 3°, but the low, if it holds through midnight (1 am EDT), will break the old record high minimum of 78°. If it occurs, this will be the 4th daily low of 80° or higher this summer, the first time there have been more than 3 80°+ lows in the same year. In all, there have been only 28 such lows since records began at or near the current location of National Airport in 1930. The highest was 84° on July 16, 1983. If no rain showers lower the temperature, as seems likely from the current regional radar, the record will undoubtedly hold. Interestingly, however, on July 20, 1981, an impressive 0.76" fell within the 2 hours of 7 to 9 pm (EDT), but the low temperature for the day was still 80°.

The high of 97° at Washington Dulles was enough to beat the old record of 96° in 1980. Records at Dulles extend back to 1962. Wallops Island, VA, which also has a relatively shorter record (since 1963), beat the old record of 92° in 1977 with a high of 97°.

Summer of Simmer: 67-Year Record Tied; 50th Day of 90°+

Evening Update: The monthly and seasonal cooling degree days for Washington continue to run significantly above average, driving up area utility bills:

Today    22 +57%
August  166 +14%
Summer 1205 +33%
2010   1446 +39% 

Original post:
Today's preliminary high temperature of 98° at Washington ties the record for August 10 set in 1943. Along with the low so far of 76°, this brings the August monthly average to 81.4°, which is 2.5° above the long-term average. The summer average to date is 81.8°.

The high of 97° at Baltimore was 3° short of the record, and the high of 95° at Washington Dulles was 2° below the record there. The downtown Baltimore high was also 97°.

The high of 97° at Salisbury, MD tied a record set in 1977 in a temperature history dating back to 1900. The high of 99° at Georgetown, DE broke the record of 98° set in 1949. Georgetown records began in 1948.

This is the 45th summer day with a temperature of 90° or higher and the 50th of 2010 including the 5 in April and May. The record is 67 days of 90°+ in 1980.

Summer of Simmer: August Week 1 Update

See here for more Washington, DC weather records

Following a slight break on Saturday (high 87°, low 68°), Washington, DC's summer was back on simmer by yesterday with a high temperature of 91°. After readings of 92° for 4 consecutive hours, it was likely that today's high would be warmer than that, and in fact the maximum so far is 93°. Meanwhile, the low so far of 75° is 5° above the forecast, and that is likely to hold through midnight.

The cumulative average temperature so far this summer is now a toasty 81.7° for the 70 days of meteorological summer since June 1. This is 4.6° above the 30-year climatological average and an incredible 2° or more above each of the 3 previous hottest summers to date. There has never been a summer in Washington with an average temperature above 80°, but with August so far averaging 80.7°, all 3 months this summer are above 80°.

Using the National Weather Service forecast temperatures for the next 7 days and climatological averages for the rest of the month, the summer of 2010 would average 80.9°, nearly a whole degree above the old record in 1980. However, the extended outlook from the Climate Prediction Center calls for over a 60% chance of above-normal temperatures for August 15-19 and a 50-60% chance of above-normal for August 17-23. If this pans out, the final average could very well be higher.

Images (click to enlarge): Washington, DC average summer temperatures to date for 2010 and previous record years 1980, 1991, 2002, and climatological period 1971-2000; Daily high temperatures, summer 2010 (portion above 90° in dark red); CapitalClimate charts from National Weather Service data, background photo from Kevin Ambrose; 6-10 day and 8-14 day temperature outlooks from Climate Prediction Center/NWS

Bonnie Lies Over the Ocean, Colin Lies Over the Sea; Revised 2010 Hurricane Forecast Still Shows Strong Season

Evening Update: Reconnaissance has determined that Colin has strengthened back to a tropical storm with peak winds of 60 mph. The official National Hurricane Center forecast track indicates a possible threat to Bermuda and then later to the Canadian maritimes, although the path of the center is currently expected to pass west of Bermuda and southeast of Newfoundland.

PM Update: As of 2 pm, the remnants of Colin are now getting a 70% chance of regenerating, and an Air Force reconnaissance flight has been sent to investigate.

Original post:
Following a strong early showing by Hurricane Alex, Tropical Storm Bonnie fizzled in the Gulf of Mexico after crossing southern Florida. The remnants of Tropical Storm Colin are now about 300 miles north of the Virgin Islands, where they are given a 50% chance of regaining tropical storm status.

As the usual peak of the hurricane season approaches, the NOAA Climate Prediction Center has lowered the high end of its forecast. The current prediction sets a 70% probability of:

• 14-20 Named Storms
• 8-12 Hurricanes
• 4-6 Major Hurricanes

A Major Hurricane is defined as Category 3 or higher.

Yesterday, the Tropical Meteorology Project at Colorado State University released its revised hurricane season forecast:

• 18 Named Storms
• 10 Hurricanes
• 5 Major Hurricanes

Earlier, WSI, a division of The Weather Channel, also lowered its forecast to a similar range:

• 19 Named Storms
• 11 Hurricanes
• 5 Major Hurricanes

Although slightly lower than earlier forecasts, these all indicate a more active season than average. Overall, NOAA is forecasting a 90% chance of an above-average hurricane season. In addition to record warm Atlantic sea surface temperatures, this is also a reflection of the development of La Niña conditions in the tropical Pacific. La Niña is associated with a reduction in the wind shear in the Atlantic Basin which weakened Bonnie and Colin. There is also a long-term trend for more active hurricane seasons which began in 1995.

Images (click to enlarge): NOAA revised 2010 hurricane season forecast and associated climatic factors from Climate Prediction Center

Climate Consequences: Heat 'N' Wheat Russian Roasting Propels Prices

Aug. 5 Update: The Russian government announced today that it would implement a total ban on grain exports starting August 15. As wheat prices continued rising to a 22-month high, CNBC had a discussion this morning of the implications for the commodity markets. Here's a piece of good news for consumers: Packaging and advertising account for so much of the cost of cereal production that the prices of the finished product won't go up nearly as much as the raw materials. Here's a piece of good news for investors: The food companies will use the increase in ingredient prices to raise prices anyway.



Original post:
Climate has consequences. The unprecedented heat wave and accompanying drought and wildfires in Russia have seriously impacted agriculture; the world's largest supplier of wheat has seen its crop reduced by 15-20%. Russian exports are expected to be slashed by 30% or more. Meanwhile, heavy rain in Canada's wheat-producing areas has also impacted that country's crop. The shortage in production is driving up wheat prices at the highest rate since the 1950s, rising 40% in the past month. In an interview with CNBC, hedge fund founder and commodities investor Jim Rogers predicts that food prices will be rising "much higher" in the near future.

Other commodities are also affected. Excessive heat in the northeastern U.S. has reduced milk production, leading to higher prices for liquid milk and cheese. Milk Class III (hard cheese) has risen in price by 50% in the past year.

CNBC this morning reviewed the current situation and future prospects with a wheat trader and milk trader:

Featured Question

"Featured Question" is an irregular feature in which we highlight interesting questions asked by blog visitors. If your question is interesting enough, you might get a T-shirt. Or not. Other questions have previously been highlighted here.

The Goog is a wonderful resource; it's used almost continuously here at the CapitalClimate Capitol. However, contrary to popular belief, it can't read your mind. Sometimes, you don't get what you're looking for, even though the information is out there somewhere. From looking at our traffic statistics, it seems that some users are getting to CapitalClimate with what we would call "drive-by Googling". If they don't find the exact phrase they wanted staring them directly in the face, they go away. There are a multitude of carefully vetted links on this site, along with over 5 years of archives. If you don't immediately get your question answered, look around a little or even pose the question directly as a comment; we'll do our best to respond promptly.

Today's featured question comes from Rocky Ford, Colorado, where a user was searching for "average aug 28 temp in wash d.c.". For some reason known only to the gnomes of Googleland, the link which came up was to a recap of January 2010 monthly temperatures. The phrase "average aug 28 temp in wash d.c." is what is technically known as a Googlenope. In all the vast reaches of the Galactic Internet, this particular phrase doesn't exist. (Or at least it didn't until this blog post.)

The data, however, are readily available. Here's how. (Follow along in a separate browser tab or window so you don't get lost.)

• Look at the top of this page. Right below the title header, there's a header called "Climate Data Links".
• Right below that, there's a large blue header "Local:".
• The very first link is called "Washington, DC climate data." Click on it.
• It takes you to a page where we've conveniently collected up some National Weather Service (NWS) links (Your tax dollars at work!) on Washington, DC climate.
• Look at the header "Daily Means and Extremes". There's a link for each of the 12 months. Click on "August".
• It takes you to a NWS page which handily includes just about everything you might want to ask about August weather for each day in Washington.
• Looking down the rows to the one labeled "28" in the first column, you can see that the average high is 84 (in the next column) and the low is 67.
• What could be easier than that? You're welcome.

If you've made a reasonable effort to look around and still don't find what you need, please leave a comment and the Googling Monkeys of CapitalClimate will do their best to help.

Summer of Simmer: Hottest July (Tie), Hottest June-July, 2nd Hottest of Any 2 Months Hottest Summer on Tap?

July 30, 2011 Update: For new all-time hottest month record, see Washington's Hottest Month Ever, By Wide Margin

Aug. 1, PM Update: Today's minimally rain-cooled (a trace) high temperature of 82° is the coolest since July kicked off with 81°. That has already been factored into the August projection below.

Note on regression (see below): If the regression relationship shown in the July vs. August correlation plot were to hold exactly, the August average would be 78.9°, bringing the summer average to 80.9°.

Aug. 1, AM Update: Although there is no official record report as of yet from the National Weather Service, this morning's preliminary monthly climate report confirms that the Washington July average was indeed 83.1°, tying the record for hottest July (and hottest month of all time, since the hottest August was 82.8°).

Here's how much of a squeaker this record was, however. The monthly average is computed by averaging all of the daily high and low temperatures in a month. Since temperatures are reported in whole degrees Fahrenheit, the average is calculated to the nearest tenth of a degree. To 3 decimal places, however, the July 2010 average was 83.065°, which rounds up to 83.1° (thanks to Mr. Softee's Excel™). If any one of the daily highs or lows had been 1° cooler, the average would have been 83.048°, which rounds down to 83.0°, missing the record and tying for second place.

Now, consider yesterday's morning low of 71°. At midnight local time, the temperature had dropped only to 78°. Since daily records are kept on standard time, the month was not closed out until 1 am EDT, when the temperature was at 76°, still not a problem for the record. Showers were moving into the area, however, and by 2:16 am an updated report showed the temperature had already dropped to 70°. This means that the record held by as little as 1 hour and 16 minutes.

Since June set a monthly record, the June-July average of 81.8° is also a record by a wide margin over the 80.6° in 1994. As the summer seasonal average to date, it's also a huge excess over 1980's record pace. On the other hand, average temperatures decline in August, so it's unlikely that pace can be continued. Notice that despite 1994's record performance for the first 2 months, a cool August by about 2° below average knocked it completely out of the top 10 hottest summers. In 1980, however, a relatively cool June was followed by a very hot July and August.

What con be expected for the remainder of this summer? Even projecting an average August, the final summer average would still break the heat record. The upcoming week, however, is already likely to have temperatures in the 90s. Factoring in the forecast for the next 7 days and the climatological average for the rest of the month, this year's summer average would be 80.5°, a very impressive 0.5° above the current record from 1980.

Is there any clue to August's behavior from the fact that it's been so hot in July? Although there is little month-to-month correlation in Washington temperatures, the July-August correlation is one of the strongest in the year. The correlation coefficient of 0.227 says that about 23% of the variance in August temperature is explained by July's temperature. (The June-July correlation is only 0.133.) If you look at the right hand side of the chart of July vs. August temperatures, you can see that all of the hottest Julys are at or above the trend.

Furthermore, 10 of the top 11 hottest Julys have had August averages above the current August normal of 77.4°. Looking at all 28 of the past Julys with averages above 80°, the average for August was 78.1°, which is above average. In recent years, with the notable exceptions of 2004 and 2008, there has also been a tendency for August temperatures to be near or hotter than July on average, even though the long-term average is reversed.

So, it's hardly a guarantee, but the odds are definitely in favor of a record. Stay tuned.

Original post:
Today's high in Washington of 86°, combined with a higher-than-forecast low of 71°, results in a July average of 83.1°. This unofficially squeaks out a tie by the narrowest of margins with 1993 for the hottest July in 140 years of temperature history.

Following a record for the hottest June, this June-July is by far the hottest such period and is the second hottest of any 2 consecutive months in Washington weather history.

More details and graphics to follow.