Anticosti Vortices

In eastern Canada, the large island of Anticosti lies between the mouth of the St. Lawrence River and the main part of St. Lawrence Bay. In both visible and infrared satellite imagery today, two mesoscale cyclonic vortices have been remarkably persistent approximately south of the eastern and western tips of Anticosti Island.

The high-resolution MODIS satellite data provides a beautiful close-up view of the vortices.

The surface analysis from NOAA NCEP Hydrological Prediction Center shows generally weak easterly flow over the region, ahead of a weak warm front.

Looking at the nearby radiosonde sounding from Sept-Iles reveals an inversion layer with northeasterly flow below about 950 hPa (600 m), with shear to northwesterly flow above. Although the highest elevation on Anticosti is around 300 m, it is likely that the island itself is largely responsible for deflecting the flow sufficiently to form these nearly stationary vortices.

Nadine, Norman, and Tropical Plume Impacts

Although we have gone a while now without any direct threat of 'tropical' weather in the mainland United States, there are a couple of interesting cases currently unfolding. Far out in the Atlantic Ocean, Nadine has again strengthened to hurricane strength. This indecisive storm has been wandering around since September 11. Although initially following a reasonable mid-oceanic track, it has behaved more erratically over the last 10 days or so. Not only did it suddenly swerve away from the Azores, but it transitioned briefly to a subtropical storm, then a post-tropical storm, before again becoming a tropical storm. After looping and zigzagging its way back westward, it has just now again become a hurricane.

Looking toward the Pacific basin, Miriam dissipated to a remnant low last night west of Baja California, while just to the east of Baja a new storm formed, Tropical Storm Norman. Although Miriam swerved west instead of making landfall in Baja California and Norman is doomed to a very short existence by its proximity to land, the two storms may actually have a significant impact . . . on Texas. As occasionally happens with Pacific hurricanes, the tropical moisture that they have transported up into the mid and upper troposphere is being transported northeastward across the plateaus and mountains of northern Mexico into south and west Texas. Such 'tropical plumes' have been responsible for some of the most devastating flash flood events in the Texas Hill Country. Accordingly, the National Weather Service is warning of the possibility of widespread rainfall in South Texas that may be as high as 8 inches locally.

To add to the intrigue, the numerical model guidance gives good reason to expect that some of the mid-level circulation/vorticity from Norman will make it across Mexico over the weekend and then help to intensify the approaching shortwave trough. The resulting cyclogenesis will then produce a distinct surface low in the northwestern Gulf of Mexico. This is one of the relatively rare scenarios to bring significant widespread rain over Mississippi and surrounding states in October. Since this will be forming in conjunction with a mid-latitude shortwave trough and a weak pre-existing surface front, there is very little reason to think that the Gulf low could attain 'tropical' characteristics. (In the extremely rare cases when tropical storms do move from the Pacific into the Atlantic basin while maintaining their tropical character, they receive a new Atlantic name instead of keeping their Pacific one.)

Xynthia

A very strong midlatitude cyclone roars ashore in western Europe. The storm has been nicknamed "Xynthia". Over 50 people are known to have died so far from flooding and hurricane-force winds.

Slow Recovery from Ice Storm

The ice storm on January 26-27 that crippled much of the middle part of the country is still not over for many residents. Two weeks later there are still more than 50,000 people without electricity. In the Bootheel of southern Missouri, it may still be another two weeks before power is fully restored.

Snowstorm in England

Southern England (in particular London) is recovering from a rare heavy snow yesterday that largely shut down transportation. Because of the rarity of significant winter weather, preparations were of course not what would have been done in a colder place. The approximately 10 inches accumulation is the greatest since 1991.

Hurricane Season Wrap-Up

Finally, a news story to remind us about the huge clean-up problems still remaining from hurricanes Dolly, Gustav, and Ike. Lots of questions, no easy answers. Certainly it was another rough year for Texas (not to mention Cuba).

A High Tide in a Low City

Residents of Venice, Italy dealt with widespread flooding from the sea yesterday. Strong winds helped to raise the sea to its highest level since 1986. Although parts of the city are perennially submerged and served by water buses and gondolas, the rise of waters to about 5 feet above normal exceeded the limits of the city's transportation system and put almost all of the city's streets under water. As the normal astronomical low tide set in later in the day, conditions rapidly returned to normal and clean-up began.

The Storms After the Election

After a period of mostly moderate weather across the country, today we have a late-season hurricane (not expected to impact the United States) and a strong mid-latitude cyclone.

In the wake of the occluded low in Minnesota, much of the northern Plains has had to deal with blizzard conditions. In western South Dakota, snow accumulation has exceeded 4 feet and up to 20 foot drifts have been reported. At one point, peak winds exceeded 70 mph.


Down in the Caribbean, Hurricane Paloma has reached Category 2 strength and is moving northeast towards Cuba. The immediate threat however is for the Cayman Islands. After passing over Cuba during the weekend, the weakened storm is expected to proceed through the islands of the Bahamas, with little chance of a significant impact on South Florida.

National Weather Association Meeting

Just got back from the annual meeting of the National Weather Association (NWA) in Louisville, KY. Unlike the American Meteorological Service, the NWA emphasizes operational meteorology, particularly for National Weather Service forecasters. So it's a different crowd and the conference presentations are much more commonly dealing with recent and historical case studies rather than purely theoretical studies.

One complete session this year was focused on the tornado and severe storm outbreak that occurred on February 5-6 of this year, during the Super Tuesday primary election. Some noteworthy talks on tools for operational meteorology included: "High Resolution, Lower Tropospheric Radar Networks: The CASA Program" by Brenda Phillips et al.; "Using Google Earth as a Situational Awareness Tool: An NWS Central Region Headquarters Example" by Brian Walawender; and "GR Level 2 Analyst" by Mike Gibson. Some other talks that I especially enjoyed were: "The Columbus Day Windstorm of 1962" (Wikipedia) by Brad Coleman; "Wintertime Mesoscale Vortices over Lake Michigan" by Sam Lashley; and "Forecasting Cold Air Damming and the Position of the Wedge Front over Northern Georgia" by Patricia Atwell et al.

Interesting poster presentations included: "Analysis of an Undular Bore over the Gulf of Mexico on March 15, 2008" by Roger Erickson; "West Texas Mesonet Proximity Observations for Wind-Driven Wildfire Starts" by Jeffrey Vitale and T. Todd Lindley; "Point Verification of Acceptable Temperature Forecasts Across the NWS Southern Region" by Bernard Meisner and Mark Fox; and "Case Study of the 3 February 2008 Valdez Bora Wind Event" by Louise Fode and James Nelson.

Omar Va Por El Mar

After its rapid intensification over the last couple days, Hurricane Omar has skirted Puerto Rico and the Virgin Islands. Now it will continue to accelerate northeastward into the middle of the Atlantic Ocean. Winds have already decreased from a peak of 125 mph to only 70 mph.

Speaking of hurricanes, recent preoccupation with the economic crisis and presidential election has taken hurricane recovery in Texas and Louisiana out of the spotlight even faster than usual. Nevertheless, challenges still remain for many whose homes were damaged by Gustav and Ike.

East Coast Storms

A low pressure area that developed along a weakening cold front has intensified substantially over the warm waters of the Gulf Stream. Although surface winds are strong enough to be a tropical storm, the system does not really appear to be "tropical", at least not at this point. Current satellite imagery reveals a structure more similar to a "subtropical storm". There is a tight circulation of cloud bands, but not continuous convection in all quadrants or concentrated near the center. It also has some characteristics of an early fall "nor'easter".



Tropical storms are primarily driven by latent heat release from an inner core of thunderstorms with a broad area of outflow above the low. This deep warm core of rising motion is related to the relatively small area of intense low pressure at the surface. In contrast to most extratropical (i.e. not tropical) cyclones, thermal wind arguments imply that the strongest winds in a tropical cyclone will be near the surface rather than near the tropopause. With the current system, the center does not appear to be very convectively unstable and it looks like it will take on a more extratropical character over the next couple days. In any case, it will bring some messy conditions along much of the Eastern Seaboard, but probably no reason for hysteria. There is also a good discussion on Jeff Masters' Wunder Blog.

Another area of interest, to the east of the Bahamas, is definitely tropical and may have some potential for development. But it's relatively unlikely to impact the United States.

First Day of Fall . . . or Spring?

It was a nice first day of fall across most of the United States today. But in the Southern Hemisphere it's the first day of spring. In some of the higher elevations of South Africa that meant a surprise snow storm that has caused problems for traffic in the KwaZulu-Natal and Eastern Cape areas.

Monsoon Flooding in West Texas?

The extensive rains across northern Mexico and West Texas from the retreating North American monsoon are bringing historic flooding to the Rio Conchos and Rio Grande. As reservoirs on the Rio Conchos overflow, the downstream cities of Ojinaga (in Chihuahua, Mexico) and Presidio (in Texas) have watched flood waters breach their levees. The deaths of the U.S. and Mexican directors of the International Boundary Waters Commission and Rio Grande Council of Governments in a plane crash while surveying the flood have added to the tragedy.

The Long Reach of Ike

While news coverage of the devastation from Hurricane Ike has somewhat been in competition with election and financial news, and the problems are less dramatized than with Katrina, it's important to consider how broad a swath of the country has been impacted by this storm. While Hurricane Katrina effectively wiped out infrastructure from southern Louisiana to central Mississippi, the rapid movement of Ike brought major problems all the way up to the Canadian border. This is shown dramatically by the 24 hour radar-estimated precipitation through Sunday morning.



The combination of flooding and high winds have left millions of people homeless or without power as far away as western Pennsylvania! On the other side of Ike's (fourth!) landfall, the rebuilding process is challenging the residents of Grand Turk, Inagua, Haiti, eastern Cuba, and western Cuba. The wipeout of Galveston should be compared to the destruction that Grand Turk has sustained from when the hurricane was still a Category 4 on the Saffir-Simpson scale, or the misery of Gonaives, Haiti after being inundated by four tropical cyclones in a row.

A Tropical Plume

The big news story lately has of course been Hurricane Ike. However there was also an interesting situation further to the west, before the landfall of Ike. From northern Mexico up into West Texas and Oklahoma, there was a persistent swath of cloud cover and rain. In spite of some analyses, this was not primarily due to interaction with a frontal zone. Instead, it was due to a plume of mid-level tropical moisture being blown northeastwards from Tropical Storm Lowell in the Pacific. In terms of winds or direct impacts, Lowell was never much of a storm. But its remote impacts through this plume of moisture were fairly significant. To some extent this pattern simply extended the influence of the North American Monsoon System further east into the Plains than usual. Because of the relatively wet ground in northern Mexico, it was feared that there could have been particularly bad flash flooding if Ike had tracked to the west over the region. The area of East Texas that was traversed by Ike was actually somewhat in need of rain, although they obviously could have done without the high winds.

Between Storms?

A preliminary description of impacts of Gustav on the Ark-La-Miss region is now available. Many homes in Louisiana and Mississippi remain without power. Now all eyes are on Hurricane Ike, with its 135 mph winds and a forecast that takes it over the Turks & Caicos Islands, the southern Bahamas, Cuba, and then into the Gulf of Mexico.



In central Mississippi, Saturday turned out remarkably cool and fall-like. In spite of official forecasts for a high in the low 90s that were revised to 86, the mercury actually struggled to even reach 80 under a light north breeze.

More on the Way and Some Change in the Air

As people return to south Louisiana and Mississippi, they're finding a mess and a long wait for power restoration, and have been largely forgotten by the media. Meanwhile the tropics continue to cook up more storms. Tropical Storm Hannah may have struggled and appear relatively wimpy, but it's unwelcome excursion southward brought another onslaught of misery to northern Haiti. While it was stuck in an area of with no significant upper-level steering currents, it made an unusual cyclonic loop.


Further out, we have Ike and Josephine. In all probability, Josephine will be a "fish" storm that just spins around in the open ocean, and is not expected to intensify significantly anyway. Ike is another matter. After a dramatic period of intensification yesterday, it is expected to enter the less favorable environment that Hannah has struggled in. It will probably approach the Florida as a significant hurricane, but hopefully no longer as a Category 4 storm.

Meanwhile, central Mississippi had a bit of a change today. Not only did the sun finally come out for a while, but the first weak cold front of the fall pushed through. It's always nice to have dewpoints drop from the mid-70s to the mid-60s. Of course, the reality is that it won't last very long.

Hurricane Party or Gas War?

On the third anniversary of Hurricane Katrina, Mississippi and Louisiana are trying to figure out an eerily familiar scenario. Although Fay pretty well fizzled before it could have much of an impact on central Mississippi, Gustav seems poised to provide a more credible threat to the region, especially for Louisiana. Even though Gustav is currently only forecast to become a Category 2 hurricane, many people are not wanting to take chances. Though the forecast landfall is still five days away and Jackson is three hours from the coast, it's amazing to see the social transformation of hurricane preparedness. People are saying that many stores are already out of bottled water and other common preparedness items. Long, long lines at gas pumps this morning have diminished now that prices have shot up by 20 or 30 cents per gallon and several gas stations have run out of supply.

From a scientific standpoint, it looks like we'll end up with three storms (Fay, Gustav, and Hannah) in a row exhibiting unusual (for the region) tracks with southerly wobbles.
And, at this rate, it looks like pretty much every stretch of coastline from Puerto Rico to Houston is liable to be impacted by a tropical cyclone this year!

A Statehouse Scramble

Even politicians have to duck for cover from tornadoes this spring up in Illinois.

Annual Congress of CMOS

Throughout this week the Canadian Meteorological and Oceanographic Society (CMOS) is meeting for its annual scientific Congress at Kelowna, British Columbia. This year's theme is "Water, Weather, Climate: Science Informing Decisions".