A historic drought at the peak of hurricane season ended yesterday when Tropical Storm Francine formed. After Ernesto formed on August 12th, a new tropical system did not form in the Atlantic Basin until Francine became a tropical storm yesterday, on September 9th. This 27 day stretch marks the longest such stretch in August and September in over 50 years. This lull has come to an end as Francine bears down in the Gulf of Mexico. On top of that, two other tropical waves are being monitored.
FRANCINE
Francine is poised to become a hurricane later today as it parallels the Texas coastline. Models are in excellent agreement on the storm's motion through Thursday. The storm will remain offshore of Texas as it moves in a northeast direction. The storm will very likely make landfall across Louisiana as a hurricane. Hurricane warnings are in effect from the Texas-Louisiana border through the central Louisiana coast. Tropical storm watches and warnings are in effect for all of the Texas and Louisiana coastlines.
The storm will continue to gradually gain strength as it approaches the Gulf Coast. Francine is forecast to reach category one hurricane strength later today. A gradual strengthening is likely to continue through landfall. Currently, the hurricane is forecast to make landfall as a high end category one or low end category 2 storm. Heightening levels of shear will likely prevent rapid strengthening. This will bring the usual hurricane conditions of high winds, heavy rain and storm surge flooding. 3-6 inches of rain is likely across much of southern Louisiana and Alabama.
Model forecasts for Francine's strength. Models are in good agreement on the storm gradually strengthening before landfall:
As with most hurricanes, storm surge will be a paramount threat. A surge of 5-10 feet is possible across much of the central Louisiana coast. A surge of at least three feet is possible from High Island, Texas through the Mississippi-Alabama border.
After Francine makes landfall, the storm will move inland across the center of the United States. Exactly where Francine goes and the overall evolution of the storm remains up in the air. The storm will likely slow down or stall late this week. This is thanks to an expansive area of high pressure over the northeast, which will prevent the remnants storm from taking a standard path through the northeast. The storm will likely rain itself out across the Mississippi River valley as it dissolves with no place to go.
Weather Prediction Center 5 day rainfall forecast:
OTHER TROPICAL WAVES
Two other disturbances are currently being watched by the National Hurricane Center. Both of these are in the eastern Atlantic and don't pose an immediate threat to the United States or outlying islands. These disturbances have a modest chance of developing over the next week.
1 (orange). Conditions are marginally favorable for gradual development of this system. A tropical depression could form within the next couple days. Very gradual strengthening is possible thereafter. The National Hurricane Center currently gives this storm a 40% chance of development. Steering patterns favor this storm taking a standard turn to the north at some point as it crosses the Atlantic.
Spaghetti models:
2 (red). An area of low pressure is expected to merge with a tropical wave near the Cape Verde islands in the coming days. This will likely spawn a tropical depression at some point late this week. The storm will likely traverse the open Atlantic Ocean in a west-northwest direction, typical of Cape Verde systems. The National Hurricane Center gives this storm a 70% chance of development. The storm will pose no immediate threat, but will need to be watched heading into next week.
LOOKING BACK
Last week's tropical update showed three areas of interest for development. Two of them ran into high levels of shear and faded away. The third area of interest from last week has developed into Francine. In last week's update, we did mention the possibility of this system impacting the western Gulf Coast this week.
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