Friday, October 28, 2005

Taking a Beta-ing


Rain from a weak low pressure area off the North Carolina coast is remaining well offshore, and the Washington DC metro area is enjoying a mostly sunny late October afternoon, with temperatures in the mid 50s.

Tonight and Tomorrow

Clear skies and low winds tonight will allow temperatures to drop into the 30s in many locations, and there is a frost advisory in effect for the entire area, including the District itself. Tomorrow will feature sunny skies and highs around 56. The weekend, especially Sunday afternoon, looks like a fine time to get in that one last lawn mowing of the season.

Tropical Beat

Tropical Storm Beta continues to move slowly off the Nicaragua coast. The Miami Herald and Washington Post (Reuters) reported that the Colombian-owned islands of San Andrés and Providencia were being lashed by the storm. Its 65 mph winds at 5pm are expected to intensify to hurricane strength, possibly by tomorrow. If it does become the 13th hurricane of the season, it will beat the old record of 12. The forecast track along the Nicaragua/Honduras border puts it close to the region which was devastated by the flooding from infamous Hurricane Mitch in late October 1998. The toll from Mitch was the deadliest in the Atlantic Basin since 1780. Some unofficial rainfall reports from that storm were over 48 inches at the higher elevations.

A tropical wave in the central Caribbean is showing no signs of development, and its area of showers may be absorbed into Beta.

Climate Clues

An article about Arctic warming which was published online September 22 has appeared in the issue of Science magazine published today. The article, entitled "Role of Land-Surface Changes in Arctic Summer Warming", analyzes feedback effects from atmospheric warming. It finds that local warming caused by decreased albedo (reflectivity) from earlier snow melting is on the order of 3 watts per square meter per decade, which is comparable to the heating from a doubling of atmospheric CO2 alone. An accompanying analysis, "Tipping Points in the Tundra", says, "Environmental changes in the Arctic may be an early warning system for global climate change, and recent reports from the region are alarming."

Weather Man Movie

I agree with Jason that the "Weather Man" movie sounds like a mixed bag. I'm waiting to hear from Ebert and Roper (set your TiVo for 1:05am Sunday) to form my final opinion on whether it's worth seeing. If you do decide to go, showtimes and online ticket ordering are available at Moviefone.

Wednesday, October 26, 2005

Becoming Better and Beta


Today's weather map shows a large high pressure area centered over Ontario and a deep low pressure area (yesterday's nor'easter) centered over the Maritime provinces of Canada. The pressure gradient force between these two features, modified by the Coriolis force, is producing a geostrophic wind in the form of strong northwesterly breezes over the Northeast and Mid Atlantic states. Here in the Washington metro area, winds have been gusting as high as 26 mph, keeping temperatures in the mid 50s despite abundant October sunshine. Overall, it's a much better day than yesterday.

Chart by from NWS dataimage
Yesterday's 0.59" of rain in the Official Bucket puts the new record for October precipitation at 9.41", vs. the previous record of 8.81" in 1937. This month is now tied for 22nd wettest overall in 135 years of record in Washington.

Tonight and Tomorrow

Tonight, diminishing winds and clear skies will help temperatures dip to the coldest levels so far this season: near 41 inside the Beltway, as low as the mid 30s in the outer suburbs. There is a frost advisory in effect for the western and northern suburbs. Temperatures will have a hard time rebounding tomorrow as clouds increase and highs remain in the mid 50s.

Beta on Deck

That low pressure area in the southwest Caribbean is showing more signs of becoming Beta. The afternoon tropical weather discussion from NHC points out the "hallmarks of development": dropping pressure, curved convection bands on satellite becoming better defined. It's most likely an artifact, but the latest image I'm viewing as I write this shows an eye-like feature; it's just northwest of the label for longitude 80W.

Media Mutters

Once again, the WaPo trashes science for the sake of generating "news". It took 2 "Staff Writers" to find enough morons to produce a story on how some Florida residents were "surprised" by the strength of Wilma, particularly on the east coast. Even the mayor of Fort Lauderdale is quoted as saying he expected a Category 1 storm. Excuse me, but what part of Category 2 don't you understand? Even if there were any reputable forecasts of Category 1, which I most seriously doubt, the fundamental rule of preparedness is to anticipate one category higher than forecast. In any case, a number of people (I believe 6) died as a result of ignoring the risk of Katrina when it was a Category 1 in the Miami-Dade area. Rather than pointing out the outstanding accuracy of the forecast track even before the turn away from Yucatan, the article digs up a bureaucrat from Silver Spring HQ to mumble about the difficulty of forecasting intensity.

Broadcast News

The dcrtv blog reports the latest chapter in the misadventures of former Channel 9 weatherman and now inmate Bill Kamal. When Kamal's former station in Miami was knocked off the air by Wilma, someone put on an old hurricane preparedness tape by Kamal. The tape ran for about 10 minutes before the mistake was noticed and it was taken off.

Tuesday, October 25, 2005

Record Rainfall; Beta Testing

Temperatures this afternoon in the Washington DC metro area are more typical of an average day in mid or late December. Mid or even low 40s prevail as some scattered showers linger in the area. In the higher elevations, snow has been falling, with as much as 6" reported this morning in western Maryland and West Virginia.

Yesterday's rainfall of 0.57" was enough by 0.01" to set a new record for maximum October monthly rainfall in Washington. This record is especially significant since last month set the record for minimum September precipitation. With additional rainfall around an inch today, this month has achieved the dubious distinction of being 1 of only 25 months overall in 135 years to have exceeded 9", and it is well on the way to reaching 10".

Tonight and Tomorrow

Cloudy skies will continue tonight with lows near 40 and a 30% chance of showers (or snow flurries in the colder locations). Tomorrow will see gradual clearing and highs in the mid 50s. A frost advisory may be needed tomorrow night.

Tropical Beat
The idea of Wilma merging with a non-tropical low to produce a "perfect storm" turned out to be a little simplistic. The image shows the surface weather map early this afternoon (18Z or 2pm EDT) from the National Weather Service HPC. The center of Wilma is shown as the small hurricane symbol in the warm-air sector to the northeast of the large nor'easter pummeling New England. (Providence RI was reporting wind gusts of 41 mph, for example, at 4pm.) Although the non-tropical low is absorbing some of the moisture and energy of the tropical system, Wilma is an intense enough storm to maintain its own identity within the larger circulation. At 5pm, the 105 mph winds of this morning had decreased to 85, the storm was losing its tropical characteristics, and advisories were discontinued.

With Wilma rapidly exiting stage right, the search is on for storm Beta. A suitable candidate has appeared in the form of a low pressure area located in the southwestern Caribbean (11N 78W, for those of you keeping score at home). The National Hurricane Center reports this afternoon that computer models "unanimously" agree this area is stocked with those essential ingredients for Momma Nature's favorite Weather Grill tropical treats: warm salt water and low-fat wind shear.

Stupid Storm Stunts

For more on Al Roker's excellent adventure and other stupid storm reporting tricks, check out the reruns of last night's Daily Show on Comedy Central. Since ridicule doesn't reduce this foolish behavior, it seems that a reporter or crew member will have to be killed or maimed before the various news media reform their storm reporting techniques.

Monday, October 24, 2005

Wilma's Wrath Wanes, Waxes

This afternoon's weather map shows Hurricane Wilma emerging as a rejuvenated Category 3 storm over the Atlantic after crossing southern Florida this morning. As the storm continues to accelerate to the northeast, it will interact with a non-tropical frontal system associated with a low developing near Cape Hatteras.

At mid afternoon, radar showed the northern edge of the rain shield from this system extending from near Richmond northeastward across the mouth of the Potomac, the middle of the Chesapeake Bay, central Delaware, and near Atlantic City, NJ. Further west, rain and showers extended from western Pennsylvania through central West Virginia to the border of Virginia. The mountainous portion of this area appeared to include sleet and snow. In fact, Hot Springs, VA reported snow with visibility less than 1/4 mile at 3 and 4pm. At 5pm, showers were approaching the Beltway from the south.

Temperatures around the Washington metro area were mainly in the upper 50s with a northeast wind gusting as high as 28 mph.

Image of NWS/NCEP 24-hour surface map and 6-hr precipitation forecast valid 18Z (2pm EDT) Tuesday

By early afternoon tomorrow, the remains of Wilma and Tropical Depression Alpha will have merged with the "extratropical" low to "bomb out" just south of Long Island. Note that the light blue areas in the image represent precipitation as high as 1.25" in 6 hours. The area within the dashed blue line including West Virginia, western Maryland, and the mountains of Virginia is cold enough for snow showers.

Tonight and Tomorrow

Tonight, rain will continue to advance from the southeast. Heaviest amounts will be on the Eastern Shore and in southeastern Virginia. Low temperatures will drop to the mid 40s. The chance of rain diminishes to 30% by late afternoon tomorrow with highs around 50.

Tropical Beat

Wilma made landfall this morning on the west coast of Florida south of Naples as a Category 3 storm. This is the first time that more than 3 hurricanes have made landfall in the U.S. at Category 3 or higher in the same year. It was downgraded to Category 2 while over southern Florida, but was upgraded again to Category 3 after crossing the east coast into the Atlantic. By 5pm, it was back up to 120 mph peak winds as it moved northeast at about 37 mph.

After a brief fling as a Tropical Storm over the weekend, Alpha became Tropically Depressed following its crossing of Hispaniola. It had maximum sustained winds of 35 mph this morning, but it is expected to be absorbed into the circulation of Wilma.

There are several tropical waves scattered across the Atlantic from near Africa to Central America.

Faces Behind the Signatures

If you read the advisories and discussions issued by the National Hurricane Center, you may have noticed that each one is signed with the name of the lead forecaster. The Daytona Beach News-Journal last fall published a set of profiles of the faces behind those signatures.

Hurricane Seminar Reminder

The AMS Environmental Science Seminar on hurricanes is tomorrow. Scroll on down to Friday's afternoon update for details.

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.