Tuesday, June 20, 2017

New National Hurricane Center Advisory Policy in Play this Week

For days meteorologists have been watching a disturbance in the Gulf of Mexico. Today that disturbance became Tropical Storm Cindy, the third storm of this young season and concurrent with T.S. Brett in the Caribbean. This year the National Hurricane Center has the option of issuing the full range of advisories, watches, and warnings for disturbances that not yet a tropical cyclone but which  pose the threat of bringing tropical storm or hurricane conditions to land areas within 48 hours. Under previous longstanding NWS policy, it was not been permitted to issue a hurricane or tropical storm watch or warning until after a tropical cyclone had formed. The purpose of these potential tropical cyclone advisories, watches, and warnings is to provide more lead time to those that will be impacted, hopefully minimizing injuries and saving lives.

Monday at 4:00 p.m. CDT the first advisory was issued for Potential Tropical Cyclone Three, now Tropical Storm Cindy. That advisory, which included a tropical storm warning and watch, was issued 18 hours earlier than would have been allowed in previous years.

Here is the forecast track of the storm as of 10:00 p.m. CDT. As the graphic states, hazardous conditions can occur outside the probable path of the storm. Typically with systems like this one, heavy rainfall and flooding is the biggest threat. 

To give you an idea of the extent of the storm, here is the Quantitative Precipitation Forecast for the next five days. Note that the heavy rain and likely most of the impacts, including some storm surge, will be well east of the storm track.

Over the next 72 hours the heaviest rain is expected over the Mississippi and southwest Alabama coast.

A complicating factor for the southeast is a frontal system which will likely slow to a crawl or stall out as it moves into the Tennessee Valley late in the week providing additional lift in the moisture-laden atmosphere associated with the remnants of Cindy. CoCoRaHS observers from eastern Texas to West Virginia will be busy measuring rain the rest of this week.

Forecast surface weather map for 7:00 a.m. CDT Saturday, June 24, 2017.

Only three previous Atlantic hurricane seasons on record have had two concurrent named storms in June prior to this year: 1909, 1959, 1968, and now 2017. In addition, T.S. Bret and T.S. Cindy became named storms only 21 hours apart, the shortest time between two June named storm formations in Atlantic on record. Late this afternoon Brett was downgraded to a tropical depression.

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