A seemingly slow start to the Atlantic Hurricane Season in and around the Gulf of Mexico, but models are now homing in on development very close to home within the next seven days.

The view from 50,000'
A moisture surge is set to approach and cross Florida over the weekend and multiple models spin this feature up. Additionally, a CAG (Central American Gyre) or something at least close enough to meeting a more formal definition, is likely to develop over the next several days, and help promote the production of one or more tropical cyclones in the western Atlantic. These will also benefit from the development of a belt of low-level westerly anomalies creating cyclonic background vorticity across the tropical Atlantic, very uncharacteristic of El NiÃ±os. The ECMWF ensemble has also shown an overlap of anticyclonic wave breaking over this forecast enhanced vorticity in the western Atlantic and Gulf of Mexico, which can further encourage "home grown" genesis.

ECMWF currently suggests around a 40-50% chance of development close to Florida over this weekend into early next week, increasing to 65% by the time the forecast area of interest is in the central to western Gulf by the middle of next week (Aug 23-24 or so). The GFS also develops this region.

While a disturbance for an Invest tag to be assigned has yet to appear, this now looks probable, and as such we are starting this lounge. An Invest number will be assigned and added to the title should these forecasts verify.

We are now in the climo peak of the Atlantic basin, and climatology shows us that systems in this part of the basin around this time of year can go from zero to a real threat quickly. NHC opening odds of development are set at 20%, and this could be conservative.

The forecast Gulf disturbance has become defined enough to be assigned an Invest tag, 91L, and the title has been updated accordingly.
PTC-NINE on 8/21/10CT -Ciel