Heavy rain, some wind for Jacksonville from Alberto - Talking the Tropics With Mike

May 27, 2018 — Tropical storm WARNING west coast & Big Bend of Florida... Fl. Panhandle & coastal Alabama......

"Alberto" will transition to fully tropical by Sunday night/Monday as the storm moves some semblance of northward over the Gulf of Mexico. Some semblance of north because the center has - & will likely continue to - "jump around" from time to time. Rain & a few t'storms will increase Sunday followed by heavy & potentially strong t'storms Monday.......

The "Buresh Bottom Line": Always be prepared!..... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.

The first named storm in May to form over/near the Gulf of Mexico since 1976 -- & only 5th since 1851 -- "Alberto" is near the Yucatan Channel & will slowly move northward over the Gulf of Mexico through the weekend. The storm is being called - & appears on satellite imagery to be - subtropical which means the system does not yet have a full warm core. There's some cool air & frontal structure involved in other words. But this is simply semantics & does not change the overall forecast. In fact, Alberto is showing solid indications of becoming fully tropical. Alberto's center has had a tendency to reform & jump around or again due to bursts of convection. But convection is showing signs of becoming more symmetrical so ultimately the center may jump north or northwest then should become more steady state. Therefore, the trend has been for a more eastward track overall which is one reason why we (meteorologists) don't want to simply rely on a single forecast model when forecasting tropical systems (European model has been too far west... GFS model was initially too far east). The most probable landfall is the Fl. Panhandle centered on Panama City to Pensacola or so during the day Monday. The exact timing & location of landfall will vary because of the center's continued tendency to reform but leaning toward late Sunday night/Mon. morning.

Given this track... the impacts for Jacksonville / NE Fl. / SE Ga. are mainly fringe - in order of magnitude:

* heavy rain - rainfall will average 2-4" through Mon. night but locally more causing some localized flooding. Most of this total will fall Sunday/Memorial Day.

* rip currents at area beaches. A broad & persistent onshore flow out of the southeast will cause a moderate to high rip current risk through the holiday weekend. Never swim & surf alone & always as close to a lifeguard as possible.

* somewhat breezy winds of 10-20 mph on avg. but with locally much higher brief gusts - 40-50 mph - with any strong rain bands or with any stronger thunderstorms

* isolated waterspouts or tornadoes - greatest threat appears to be Sunday night - Monday.

If traveling west along the I-10 corridor through the Panhandle to Mobile & Biloxi, flooding rain will be likely along with rip currents at beach locations... strong winds... at least some storm surge... & a few tornadoes.

May tropical cyclones have occurred 4 times in the last 5 years but developed over the Atlantic:

2016 (1 - Bonnie)... 2015 (1 - Ana)... 2012 (2 - Alberto & Beryl).

The list of names repeats every 6 years, & - interestingly - Alberto was also a May storm in 2012.

On an historical note - only 4 tropical or subtropical cyclones have developed over the Gulf of Mexico since 1851 during the month of May. Just 1 of those storms has been during the satellite era of the early 1960s - on May 22nd, 1976.

Despite increased convection overall... Alberto remains within a highly sheared environment juxtaposed with some very dry mid & upper level air. The system will gradually pick up some speed over the Central/Eastern Gulf while moving north/northeast then turning more north before curving northwest with time.

The combination of strong shear out of the west... dry air immediately to the west & south of the system.... & marginal sea surface temps. should all add up to a system that remains heavily weighted on the east side which is typical of early season tropical disturbances. Shear will lessen over the far Northern Gulf & several forecast models respond by showing an intensifying system - this is something to consider though still likely at tropical storm strength upon landfall Monday.

The screaming message with this disturbance will be heavy rain potential for Jacksonville & especially west along the I-10 corridor all the way to Mississippi. The more west you go from Jacksonville, the greater the impacts: gusty winds, rough seas/surf, rip currents, some storm surge, heavy rain & tornadoes.

Water vapor imagery shows a lot of dry air - an obstacle for development as Alberto moves north over the Gulf. Some of that dry air is trying to fully wrap around the center which may cause two distinct bands/areas of heavier rain - (1) near the Fl. east coast & offshore to the Bahamas..... (2) Big Bend/Fl. Panhandle close to the center's landfall.

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear. An upper level trough is "capturing" Alberto thereby weakening shear near & over the storm.