Not So Doggy Day

After finishing July with 13 90-degree days (season total so far: 20), temperatures at mid afternoon were mainly in the upper 80s in the Washington metro area with sunny skies and light and variable winds. Even Leesburg was in line with other locations at 88. Humidities were marginally comfortable with readings from the mid 60s to a bit over 70. The only showers on radar within a couple of hundred miles were tiny isolated spots in the mountains of West Virginia.

Outlook

Low temperatures tonight under mostly clear skies should be near 70. Tomorrow will be a little warmer and more humid, highs in the low 90s.

Tropical Topics

Here is something we haven't seen much lately from the National Hurricane Center: "There are no tropical cyclones in the Atlantic at this time." There are a couple of tropical waves each in the Caribbean and Atlantic, but none of them are showing signs of development in the near future.

Meanwhile, in the Indian Ocean region, heavy monsoon rains are continuing. The death toll is near 1000 in the Mumbai (Bombay) region, and more heavy rain is expected. The Indian Meteorological Department publishes a daily monsoon report along with rainfall data.

Hurricanes and Global Warming

Meteorology Professor Kerry Emanuel of MIT published an interesting study of hurricane intensity in the online edition of the journal Nature yesterday. The article, titled "Increasing destructiveness of tropical cyclones over the past 30 years", defines an "index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone." The study finds that the index has "increased markedly since the mid-1970s." The increase results from both increased storm lifetimes and greater storm intensities. As measured by the index, the total destructiveness has roughly doubled over the 30-year period. The author concludes that "net hurricane power dissipation is highly correlated with tropical sea surface temperature." In other words, the observed increases in sea-surface temperatures appear to be related to increased total power of tropical storms.

These results are particularly significant because Prof. Emanuel, who is an expert in modeling hurricane intensity, has long been skeptical of alleged relationships between global warming and hurricanes. He is listed as the third author of a joint article titled "Hurricanes and Global Warming" which was accepted in June for publication in the Bulletin of the AMS. This article concludes that "claims of linkages between global warming and hurricanes are
misguided." Prof. Emanuel also wrote a favorable review in the May 2005 BAMS of Michael Crichton's scientifically dubious "State of Fear".

On the other hand, there are some serious caveats to the latest results. Improvements in airplane reconnaissance and satellite technology mean that recent storm data are more likely to be accurate than older data. This means that there is a relatively short time span available for comparison, even after making corrections for changes in methods of data analysis. A graph from the paper which is available online shows the wide scatter in the data points for the relationship between minimum air pressure and maximum winds. Hurricane-frequency forecaster Prof. William Gray of Colorado State University is quoted as saying, ''It's a terrible paper, one of the worst I've ever looked at." (C'mon, Dr. Gray, tell us what you really think!)

The full text of the article is only available by subscription, but it is being widely covered in the press:

• Boston Globe: "Hurricanes more powerful, study says"
  
• Seattle Times (Knight Ridder): "Scientist links global warming to rising ferocity of hurricanes"
  
• Seattle Post-Intelligencer (Scripps Howard): "Increasing fury of tropical storms linked to warming sea"
  
• Los Angeles Times: "Storms' Fury Linked to Warming"

Reflecting its continuing neglect of science and environmental issues, the Paper of Watergate and Don't Ever Forget It has the Associated Press article online and a 187-word blurb buried under "Ornithologists have discovered a male bird in South America that attracts mates by rubbing its wings together to generate 'songs.'" in the "Science Notebook" of the dead-tree edition.

Prof. Emanuel has published widely on the subjects of hurricanes and convection. He has a new book called Divine Wind on the history and science of hurricanes which is about to be published by Oxford University Press.

Prof. Gray is scheduled to release his updated hurricane season forecast on Friday.

Near Miss

Currently

It's the 31st, and the Washington DC metro area is on the verge of just missing a tie with 2003 for the coolest May since 1967. Temperatures in mid afternoon are in the upper 70s throughout the area, just below the long-term average high of 80 for the date. Frederick was the warm spot at 4pm with 81 degrees. At the beach, an easterly breeze is keeping Ocean City at 70 under sunny skies. Regional radar is totally clear in all directions. As a high pressure area centered over the Great Lakes spreads over the entire East Coast except for Florida, the nearest precipitation extends from near Atlanta to southern South Carolina.

Outlook

After maxing out around 80, temperatures tonight will drop to lows in the upper 50s. Partly cloudy skies tomorrow will be accompanied by highs again from the upper 70s to 80.

Tropical Update

Tomorrow is the official start of the hurricane season. Dr. William Gray of Colorado State University today updated his hurricane season forecast. He is forecasting a "well above-average hurricane season for the Atlantic basin in 2005" and "an above-average probability of U.S. major hurricane landfall." The new forecast increases the number of named storms (15), hurricanes (8), and intense hurricanes (4) from the earlier prediction made on April 1. The increase in activity is due to increased warming of the Atlantic Ocean and decreased likelihood of an El Nino developing in the summer and fall. The forecast probability for at least one major hurricane (category 3-5) landfall on the U.S. East Coast is 59%, vs. an average for the last century of 31%. The Landfalling Hurricane Probability Webpage, based on Dr. Gray's forecast, shows that the probability of landfall by 1 or more named storms in the mid-Atlantic region (northern Outer Banks through New Jersey) is 14.6%, vs. a long-term average of 8.6%. The next forecast update will be issued on Aug. 5. The update will include monthly predictions for August, September, and October.

And now for something completely different . . .

Currently

Spring is back after a brief taste of summer. A cold front passed through the Washington metro area around 5am this morning, and temperatures continued to drop through the morning hours, generally to the low or mid 60's around noon. Dulles was only 61 at noon, over 20 degrees cooler than yesterday at the same time. An area of showers which moved in from central Maryland in late morning has hung around most of the area, except for the southeast portion. The Nats played the first several innings this afternoon in a light rain. Under persistent cloudiness and northeasterly winds, temperatures will have trouble making it to the historical average high for today's date of 68. Today happens to be the latest date in April which has never reached 90 degrees, although interestingly May 2 has also never exceeded 89.

Outlook

With continuing cloudiness tonight, temperatures will drop to near 50. Highs tomorrow will be in the low 60's at best. As Josh describes below, the reversal of seasons continues as another front moves in with even colder air over the weekend.

Blog Log

RealClimate, "a commentary site on climate science by working climate scientists for the interested public and journalists", has a new post on the relationship between ozone depletion and global warming. This is one of the most common areas of misconception in the public view of climate issues. Apparently, people have gotten the idea that the Earth is warming because more solar radiation is coming through the ozone hole. In fact, these are two distinct issues. Complicating the discussion, however, is the fact that there is some connection between them that affects the possible actions to deal with these two separate problems.

Play Ball!

NatCast
Nationals vs. Arizona Diamondbacks, 7:05pm on April 14, RFK
Winds will be northeasterly from 10 to 15 mph, diminishing during the game. Temperatures will be about 65 when the gates open, but expect them to drop steadily after sunset at 7:44 from the game-time level of 58 down to the lower 50's by the 7th-inning stretch and into the 40's on the way home. Go Nats!

Currently

Today's weather map shows a weak low pressure area moving away from the North Carolina coast and high pressure dominating virtually the entire country east of the Rockies. The only precipitation showing on national radar in the eastern two-thirds of the U.S. is an area of lingering showers in the eastern Carolinas. Under brilliantly sunny skies, temperatures are rising from an official low of 42 through the 50's at mid-day toward highs in the mid 60's. Some of the outlying areas were down into the 30's last night with Frederick at 37, Dulles at 39, Culpeper at 33.

Under clear skies, temperatures should drop to near 40 tonight. Tomorrow should be slightly cooler with highs around 60.

Baseball and the atmosphere

Images (click to enlarge): Magnus force, from American Scientist

The May-June issue of American Scientist has an article on "Predicting a Baseball's Path". It explains how the spin of a baseball pitch interacts with the air through the "Magnus force" to affect the ball's motion. A ball moving through air has a turbulent wake behind it. The direction of spin affects the location of the "separation points" where the air flow becomes turbulent. In the case of topspin (movement of the top of the ball is in the direction of the pitch), the upper separation point is deflected upward, so the air in the wake has upward momentum. By the law of conservation of momentum, the ball must move downward. Conversely, a ball with backspin will move upward. By controlling the axis of rotation of the pitch, the pitcher can determine the direction of deflection of the ball.

Good afternoon, Charlottesville

Currently

Last night's rain showers were widely scattered and mainly confined to the south of the Washington metro area. The official rain bucket collected a minimal 0.01". As a weak low pressure area moves slowly off the Carolina coast, skies have cleared in the area. Temperatures were into the upper 50's by noon and lower 60's at 2pm. Here on the admittedly non-standard CapitalClimate Weather Patio, it's 65. In southern Virginia, where clouds and some light rain prevail, temperatures are only in the upper 40's.

Outlook

Under mainly clear skies, temperatures should be in the low 40's tonight, with highs tomorrow near 60.

NatCast
Nationals vs. Arizona Diamondbacks, 7:05pm on April 14, RFK
Outlook for the Nats' home opener: Light, mainly easterly breeze at game time; temperature 54, falling to about 50 by the 7th inning stretch. No rain!

Founding Father, Monticello Meteorologist

Today is the 262nd anniversary of the birth of Thomas Jefferson. The third President of the United States was a dedicated weather observer, recording the temperature at Monticello every day at dawn and at 4pm. He also recorded wind direction and speed and precipitation. The Washington and Jefferson Snowstorm of January 27-28, 1772, was so-named in recognition of the fact that it was recorded by both future presidents. Jefferson, who had just returned from his honeymoon, reported a snow depth of about 3 feet. According to David Ludlum's "Early American Winters", this was "the greatest snowstorm in the history of the middle and lower Potomac Valley." In 1776, Jefferson began to recruit volunteer weather observers around the state of Virginia. This was the forerunner of today's Cooperative Weather Program. The Thomas Jefferson award is the highest award for volunteer weather observation. No more than 5 of these awards are presented each year for "unusual and outstanding achievements." As President, Jefferson also created the Coast Survey (now the National Geodetic Survey), the country's first civilian scientific agency and the oldest component of what is now NOAA, the National Oceanic and Atmospheric Administration.

Current conditions in Charlottesville:
Clear skies, temperature 58.

Three-bagger

Currently

The Washington metro area enjoyed a three-base hit today, as the picture-perfect spring weather continued for a third day. Despite a northeasterly wind behind a cold front which moved through from the north overnight, a sunny sky pushed temperatures to near 70 or a bit above by mid afternoon. The only cool spots in the region were those with cold-water influences: Ocean City was at 50, and Annapolis was 59 at 3pm. The regional radar is clear. In fact, the only precipitation in the eastern half of the country is in the Gulf States ahead of the low pressure area which brought nearly 2 feet of snow to eastern Colorado and closed 200 miles of I-70 over the weekend.

Outlook

The cooler air which is now moving in over us will be reinforced by the strong "meridional flow" pattern which we are in. As the pattern continues through the week, we can expect cool and damp conditions, as described by Jason below. Expect lows tonight in the low to mid 40's and highs tomorrow in the mid to upper 50's with increasing cloudiness.

Blog log: Vote early and often!

The WeatherBug Storm Chase 2005 blog has narrowed down the field to 3 contestants to go storm chasing with them. Read about the 3 candidates, and then cast a vote for your favorite.

Broadcast news

The radio Weather Talk guys Justin Berk and Tony Pann have launched a web site in connection with their show. The first show was yesterday afternoon. If you listened, tell us your impressions of the show in the comments section (link below). I suspect that for at least some parts of the DC area, reception for the Baltimore station will be weak at best. In west-central Montgomery County, I could tune it in only on the upstairs clock radio at maximum volume.

NatCast
Nationals vs. Arizona Diamondbacks, 7:05pm on April 14, RFK
See Jason's post below for a preview of the conditions for the Nats' home opener Thursday night, and watch this space for updates during the week. The blogger gods willing, we'll have a last-minute update Thursday afternoon, so you'll know what to wear and whether to bring your brolly. (Hopefully, umbrellas won't be banned if they're necessary.) One thing we can be confident of at least: With a 7:05 starting time, you won't need sunscreen.

How warm is it?

Currently

If you're still sitting in the office looking out the window, it's not because we didn't warn you. Forecasts of highs near 80 turned out to be a wee bit conservative, as temperatures rose 30 degrees by mid afternoon from an early morning low of 52. Temperatures in the Washington DC metro area were all above 80 at 3pm, except for Quantico, which stubbornly reported 69. Either the south wind at 16 mph was producing a mean river effect, or the site may need a calibration. A southeast breeze off the Bay was chilling Annapolis to 59. The warm spot was Leesburg VA at 88. Roughly due east of there in Montgomery County, I'm seeing a temperature of 88 as well. With the storm windows and doors still in place, that's about a 20 degree excess above the indoor temperature. Shortly before 4 pm, both Leesburg and Frederick MD reached the magic 32 Celsius (90 Fahrenheit). Let us know in the comments how warm it is where you are. (And ignore the comment count; it's being a little flaky.) Last year, the temperature was above 70 only once in the first half of April, reaching 80 for the first time on the 17th.

Outlook

A storm system now slowly working its way through the Gulf States will bring an increasing threat of showers by late tomorrow through the middle of the day Friday. After lows tonight about 60, highs tomorrow should be in the low 70's. Further cooling is on tap for Friday, with highs in the low 60's.

Mass Market Media Meteorologist Moves

The American Meteorological Society announced on Monday that Jack Williams will be joining the AMS staff as the public outreach coordinator. Williams has been the weather editor of USA Today for over 20 years since it first began publication. He has received the AMS Louis J. Battan Author's Award twice: for the "USA Today Weather Book" in 1994 and with co-author Dr. Bob Sheets in 2004 for "Hurricane Watch: Forecasting the Deadliest Storms on Earth". His first task at the AMS will be to develop a new book on weather and climate aimed at promoting scientific literacy. The Weather Grill gang sends best wishes to Jack on his new assignment; don't forget to bring your snow shovel to Boston.