10AM CT Update 25 May 2018
Advisories for Subtropical Storm Alberto will begin at 11AM this morning.
5AM CT Update 25 May 2018
An organized LLC appears to be developing just off the eastern Yucatan this predawn, with pressures falling at a good clip. Maximum sustained winds as indicated by scatterometer, buoy and ship data support going directly to Alberto upon becoming a numbered cyclone. Should NHC confirm current trends, Advisories on Alberto may begin as soon as today.
Quick 5PM Update 24 May 2018
90L has improved its appearance a great deal this afternoon, wtih a 90% chance for development now, it may develop as early as sometime tomorrow.
Current model trends show a potential impact to the north and northeaster Gulf, with rainfall extending east to Florida peninsula as well this weekend. There is a bit of concern the slow forward motion toward the end of the run may provide some time for strengthening, possibly to hurricane strength, so it is important to keep watch on this system for those in the MS/AL and Florida Panhandle areas.
Quick 9AM Update 24 May 2018
Development chances for Alberto (Tropical or Subtropical) are up to 80%, bringing a good bit of rain. Landfall will likely be somewhere between the MS/LA state line and Panama City Beach, FL. However most of the rain will be on the east side (and sometimes very east) of the center.
On/Off Bands of rain will likely start on Saturday for most of Florida, then moving up to include the Northeast Gulf as the weekend progresses, probably through Monday/Tuesday.
There may be some short lived Tornadoes in a few areas east of the center, so look out for watches if they do come.
There may be some minor storm surge along the north gulf points east of landfall as well.
Those from MS to the Big Bend will want to watch this system very closely for changes, there is a small window for intensification Sunday.
A Central American Gyre (CAG) interacting with a stubborn mid-upper level trof over the southern states and Gulf is producing an area of disturbed weather that is gradually organizing in the northwest Caribbean. This expansive hybrid system is being tracked as Invest 90L - not to be confused with the similar, but less coherent, hybrid feature we were watching in the GOM just ten days ago.
What is truly remarkable, is how stubborn this pattern continues to be, already having flipped the Florida dry season on its head in next to no time, and now with even greater chances of a named system, one possibly lingering for several days to come.
With nearly all subtropical and tropical cyclones in general, and certainly the slower moving ones in particular, inland flooding is by far the greatest threat to life and property, and that would be no surprise here, especially given how saturated much of the area already is, and how long this system - and its parents, the Upper Trof and/or the Central American Gyre, may stick around.
According to Dr. Klotzbach, since 1950 only 8 named storms have formed during the last week of May in the Atlantic. In fact, no named storms on record have formed in the GOM at all during this time, so should 90L become Alberto here (very possible), it would indeed be something for the books.
Tropical or subtropical cyclogenesis could happen as soon as later today, with odds forecast to be increasing heading into the weekend. Recent ship and buoy reports suggest that maximum sustained winds associated with 90L may already be on the rise, and based on satellite imagery, so is deep convection. Thus, it would not be inconceivable to see NHC begin advisories on this "Potential Tropical Cyclone" prior to formation given how close it is to land. (In fact, at the time of this entry, 90L's "center" appears to be inland or just barely offshore of the Yucatan).
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** Please note the floater satellite images linked above are old, nothing new using the new GOES-16 exists yet that matches *