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Norbert threatens Baja; midget Marco a record-breaker

By: Dr. Jeff Masters, 2:10 PM GMT on October 08, 2008

The tropics are quiet in the Atlantic, and no reliable computer models forecast tropical cyclone development over the next four days. The UKMET model continues to predict a tropical depression could spin up in the middle Atlantic between Africa and the Lesser Antilles Islands about five days from now, but the GFS model has stopped predicting this. Climatology does not favor development in this region in October. A better chance for development will be over the Caribbean a week from now, and most of the models indicate the possibility of a Caribbean storm developing a 6-8 days from now.

Midget Marco sets a new record for the Atlantic
The hurricane season of 2008 has a new record--the kind of record we don't mind seeing! Tropical Storm Marco was the smallest tropical storm on record in the Atlantic. Records of tropical storm size only go back to 1988, so it is likely there have been other tropical storms as small as Marco in the past, though. If one looks at the maximum area covered by tropical storm force winds (in nautical miles squared, nm^2), given the radius of these winds for all four quadrants of each storm, the winners of the meekest of the meek award in the Atlantic are:

1) Marco, 2008, 1158 nm^2
2) Henri, 2001, 2238 nm^2
3) Bertha, 2002, 2827 nm^2
3) Bret, 2005, 2827 nm^2
3) Unnamed, 2006, 2827 nm^2

At Marco's peak size, tropical storm-force winds extended out 25, 15, 0, and 25 nm in its four quadrants. This means Marco covered an area of about 1,158 square nautical miles, which is slightly smaller than Rhode Island's area of 1,162 nm^2. Marco was about 1/75 as large as Ike at its peak, and 1/500 as big as the record holder, Tropical Storm Olga of 2001 (591000 nm^2, three times the size of Texas).

No casualties or damage were reported from Marco's landfall. The storm dumped up to six inches of rain along a 30-mile stretch of coast, according to satellite estimates.

Figure 1. Microwave image of Tropical Storm Marco superimposed on an infrared satellite image, shortly before landfall. Image credit: Navy Research Lab, Monterey.

Hurricane Norbert takes aim at Baja
Hurricane Norbert put on an impressive burst of rapid intensification last night, strengthening into the season's second major hurricane in the Eastern Pacific. Infrared satellite loops show a well-formed eye with a large area of heavy thunderstorms with cold cloud tops. There is excellent upper-level outflow in all quadrants. The satellite appearance has not changed significantly in the past six hours, and Norbert may have peaked in intensity. The first Hurricane Hunter mission into Norbert is scheduled for Thursday afternoon.

The NOGAPS, GFDL, HWRF, and UKMET models are tightly clustered around a landfall in southwestern Baja near San Carlos, 150 miles north of the southern tip of Baja, on Friday night or Saturday morning. However, the ECMWF and GFS predict Norbert will stall just offshore of Baja on Friday, and we cannot rule this possibility out yet. Wind shear is about 5 knots over Norbert, and the waters are a warm 28.5°C. As Norbert approaches Baja on Friday, wind shear is expected to increase to 15 knots and sea surface temperatures will cool to 27°C. These conditions can still support a major hurricane, and it is possible that Norbert will make landfall as a Category 3 hurricane. However, most of the intensity guidance predicts weakening of Norbert before landfall. The latest 2 am EDT run of the GFDL model predicts landfall Saturday morning as a Category 1 hurricane with 95 mph winds, as does the latest SHIPS model. The HWRF model, though, predicts a Category 3 hurricane with 125 mph winds at landfall. The official NHC forecast of a Category 2 hurricane at landfall looks like a reasonable compromise. Tropical storm force winds should extend outwards about 130 miles at landfall, so the southern tip of Baja (San Lucas) will probably see sustained winds of 35-40 mph, should Norbert hit near San Carlos. One can look at the forecast radius of tropical storm force winds by clicking on the wundermap for Norbert, then selecting "wind radius" in the check boxes at the bottom of the page.

Figure 2. Latest satellite image of Norbert.

Hurricane Ike relief efforts
Here's the latest update on the Hurricane Ike relief effort started by wunderground members Patrap, Presslord, and Stormjunkie:

The push to continue to keep supplies rolling to the Gulf Coast continues. This morning we shipped out three sets of packages with medical supplies and some cleaning supplies. The first set of two boxes went to the Bridge City Fire Department. It contained burn kits, bandages, first aid kits, Neosoprin, an air splint and more. The second set of boxes went to Eagle Heights Fellowship in Baytown. This is a shelter being run by a local pastor and seems to be one of the few shelters in this area that will remain open for the next four to six weeks. The supplies in these three boxes included CPR kits, first aid kits, disinfectant wipes, gloves, and more. The third set of three boxes were shipped to EmmyRose which she will personally deliver to the San Leon/Baycliff area. They included many of the same items listed above. We have estimated the value of these seven boxes to be between $4000 and $5000 which we shipped for just under $350.

Contributions to this highly worthy portlight.org charity fund are fully tax-deductible, and will go to provide relief supplies for those smaller communities typically bypassed by the traditional relief efforts. More details can be found at StormJunkie's blog.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.