cieldumort
(Moderator)
Thu May 24 2018 03:17 AM
Invest 90L Becomes Subtropical Storm Alberto

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.
-Ciel



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.


Original Update


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).

Invest 90L Model Discussions and Speculations 90L Lounge

{{NortheastGulfRadar}}

{{FloridaPowerOutage}}

{{EastFloridaRadar}}

{{MSMedia}}

{{StormLinks|Alberto|01|1|2018|01|Alberto}}

** Please note the floater satellite images linked above are old, nothing new using the new GOES-16 exists yet that matches *


MikeCAdministrator
(Admin)
Thu May 24 2018 01:48 PM
Re: Expansive Hybrid Invest 90L a Flood Threat and Could Get Named

Recon has been scheduled for 90L, chances up to 90% now.

MikeCAdministrator
(Admin)
Thu May 24 2018 11:37 PM
Re: Expansive Hybrid Invest 90L a Flood Threat and Could Get Named

Tropical Cyclone Formation Alert issued:

Wtnt21 Kngu 242330
Subj/Tropical Cyclone Formation Alert//
Rmks/
1. Formation of a Significant Tropical Cyclone Is Possible
Within 160 Nm Either Side of a Line From 17.7n 88.2w to 25.1n 87.0w
Within the Next 24 Hours. Available Data Does Not Justify Issuance
Of Numbered Tropical Cyclone Warnings at This Time. Winds in The
Area Are Estimated to Be 30 Knots. Metsat Imagery at 242000z
Indicates That a Circulation Center Is Located Near 19.3n 88.2w. The
System Is Drifting North-northeastward at 02 Knots.

2. Remarks: A Low Pressure System Located Inland Over the Eastern
Portion of the Yucatan Peninsula Is Gradually Becoming Better
Defined.

The System Is Producing a Disorganized Area of Showers And
Thunderstorms Over the Northwestern Caribbean and Yucatan Channel
With Winds of 30 Kts. Environmental Conditions Are Expected To
Become More Favorable for Developement Friday and Saturday and A
Subtropical or Tropical Cyclone Is Likely to Form While the Low
Moves Into the Southern Gulf of Mexico.

3. This Alert Will Be Reissued, Upgraded to Warning or Cancelled By
252330z.//


OrlandoDan
(Storm Tracker)
Fri May 25 2018 11:22 AM
Re: Expansive Hybrid Invest 90L a Flood Threat and Could Get Named

90L has been named subtropical storm Alberto. Breakout the umbrella, Florida. Going to be a wet Memorial Day weekend.

Doombot!
(Weather Guru)
Fri May 25 2018 11:40 AM
Re: Expansive Hybrid Invest 90L a Flood Threat and Could Get Named

It's been a wet week already...

MARK053162
(Registered User)
Fri May 25 2018 02:58 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

It looks on satellite the center continues to move east southeast There also seems like another circulation further northeast nearer to the convection. Will have to watch if this trend continues and if a new center forms further northeast..

Doombot!
(Weather Guru)
Fri May 25 2018 03:18 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

I doubt anyone would be supprised.

The sooner this thing gets and established LLC, the quicker the models can get a handle on it.


craigm
(Storm Tracker)
Fri May 25 2018 06:00 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Quote:

It looks on satellite the center continues to move east southeast There also seems like another circulation further northeast nearer to the convection. Will have to watch if this trend continues and if a new center forms further northeast..



Agree there is definitely an exposed LLC still heading to the east and the whole mess is tilted by shear to the NE.There are multiple vortices at different levels and the models must be picking up on something further to the north. We are seeing model runs that are 6 to 12 hours old with data input earlier than that. Will have to see if initialization starts to move east. Either way looks like just a rain event on already saturated ground for Florida and possibly more of an impact in the panhandle. BTW didn't last year start off like this?

http://rammb-slider.cira.colostate.edu/?...;s=rammb-slider


MikeCAdministrator
(Admin)
Sat May 26 2018 12:56 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

The latest recon report with 997 is off the Northwest Tip of cuba, it also suggests Alberto is beinging to transition into a fully tropical storm.

Prospero
(Weather Guru)
Sat May 26 2018 01:23 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

It appears GOES-East is not updating its images. The latest images seem to hint at some circulation, but then they stopped...

Prospero
(Weather Guru)
Sat May 26 2018 01:42 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

I found this link, I like it better than what I had been looking at:

http://weather.cod.edu/satrad/exper/?par...;colorbars=data


kapSt.Cloud
(Weather Watcher)
Sat May 26 2018 01:54 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Barometric Pressure took a nosedive from this morning which was 1005mb. Now 999mb! My migraines are reacting!

MikeCAdministrator
(Admin)
Sat May 26 2018 10:13 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Watching the satellite closely right now, still looks like a slight east of due north movement, still trying to transition to tropical, getting close.

EMS
(Weather Watcher)
Sun May 27 2018 09:57 AM
Re: Invest 90L Becomes Subtropical Storm Alberto

The center of circulation seemed to be getting better defined/more tropical in nature. But dry air now seems to have wrapped itself into the core and really diminished rain coverage.

MikeCAdministrator
(Admin)
Sun May 27 2018 10:13 AM
Re: Invest 90L Becomes Subtropical Storm Alberto

Yeah dry air from the south and west is affecting it, and making it appear to be moving northwest on radar (recon is finding it more N to NNW) The left bend/slowdown is supposed to occur sometime later today.

Between that and the cooler water in that part of the Gulf, chances of it becoming a hurricane are thankfully extremely low.


MikeCAdministrator
(Admin)
Sun May 27 2018 10:17 AM
Re: Invest 90L Becomes Subtropical Storm Alberto

Recon has been finding pressures dropping this morning, though, (994 mb) so when it does move over a bit warmer water it will still get a chance to become a bit stronger, probably not hurricane force, though.

MikeCAdministrator
(Admin)
Sun May 27 2018 11:48 AM
Re: Invest 90L Becomes Subtropical Storm Alberto

12Z GFS showing a landfall near ft walton beach tomorrow around noon at 985mb (Strong TS/borderline hurricane) This system seems to be out of the strong easterly shear now and is beginning to wrap around to the west, pulling dry air in the south side, which hopefully will be enough to keep it away from hurricane strength. Model track is a bit iffy, so prefer the NHC track. There's a big tail of rain east of Florida that will probably get pulled into the peninsula later today. Smaller, but stronger bands are coming up along the west coast (one near Naples right now) and another big band over N. Florida.


MikeCAdministrator
(Admin)
Sun May 27 2018 03:54 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

System has veered quite a bit west of the official track, I've noticed. See the Florida Radar. (Similar to the UKMet track)

Tropical Conversion is nearly complete also.


MikeCAdministrator
(Admin)
Sun May 27 2018 04:47 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Still mainting 994/50mph probably until another recon flight arrives. Watching the motion of the storm closely tonight also.

The water vapor imagery does show the dry air being injected into the center of the storm from the s/sw .









MikeCAdministrator
(Admin)
Sun May 27 2018 09:19 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

There was a special advisory issued tonight because recon found lower pressure and stronger winds. I figured they may have added a hurricane watch or warning because of how close it was getting, however the dry air intrusion is probably too much to make it get over, so I can't disagree with the call. The upper level WV shows dry air, lower level WV images show even more dry air coming in, it may be starved for moisture tomorrow morning.

MikeCAdministrator
(Admin)
Sun May 27 2018 09:33 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Latest recon in the last few minutes supports 70mph in the northeast part of the system. This is an odd hybrid subtropical storm and very dry, relative to others. I can't really recall anything like it I've seen recently.


Prospero
(Weather Guru)
Sun May 27 2018 09:52 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Is there such a thing as a "dry" hurricane??

Almost what it looks like...



MikeCAdministrator
(Admin)
Sun May 27 2018 09:55 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Recon's found a little lower pressure with 991mb, and the storm actually moved a bit southwest (doing a cyclonic loop?) 28.2N 85.85W

cieldumort
(Moderator)
Sun May 27 2018 09:58 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

Not sure if flight-level winds are efficiently mixing down to the surface, except in what could be more or less microbursts due to dry air, in which case I would expect surface winds in the mean to be running closer to 40-50, but gusting much higher (70, perhaps even higher). Alberto sure looks like what we typically see of a tropical cyclone undergoing extratropical transition, more so than the other way around. But I think a compelling case could be made to start calling him more tropical, than not.

Very latest pass through now showing a SW jog, and further lowering of central pressure.
Quote:

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 28th day of the month at 1:40Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5306
Storm Number & Year: 01 in 2018
Storm Name: Alberto (flight in the North Atlantic basin)
Mission Number: 5
Observation Number: 14

A. Time of Center Fix: 28th day of the month at 1:30:40Z
B. Center Fix Coordinates: 28°10'N 85°51'W (28.1667N 85.8500W)
B. Center Fix Location: 139 statute miles (224 km) to the S (185°) from Panama City, FL, USA.
C. Minimum Height at Standard Level: 1,340m (4,396ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 46kts (52.9mph)
E. Location of the Estimated Maximum Surface Wind Inbound: 33 nautical miles (38 statute miles) to the NE (35°) of center fix
F. Maximum Flight Level Wind Inbound: From 128° at 64kts (From the SE at 73.6mph)
G. Location of the Maximum Flight Level Wind Inbound: 40 nautical miles (46 statute miles) to the NE (37°) of center fix
H. Minimum Sea Level Pressure: 991mb (29.27 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,525m (5,003ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 1,523m (4,997ft)
K. Dewpoint Temp & Sea Surface Temp: Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Levels (surface & flight level centers within 5nm of each other): Surface and 850mb
O. Navigational Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 4 nautical miles

Remarks Section:

Maximum Flight Level Wind: 64kts (~ 73.6mph) which was observed 40 nautical miles (46 statute miles) to the NE (37°) from the flight level center at 1:18:00Z
Dropsonde Surface Wind at Center: From 95° at 2kts (From the E at 2mph)




cieldumort
(Moderator)
Sun May 27 2018 11:07 PM
Re: Invest 90L Becomes Subtropical Storm Alberto



Doombot!
(Weather Guru)
Mon May 28 2018 01:58 AM
Re: Invest 90L Becomes Subtropical Storm Alberto

Agreed that this is an odd one. Just a little breeze and mostly dry near Legoland.

I'm starting to think that the beginning of and end of seasons are going to becoming the frontiers of hurricane research.


OrlandoDan
(Storm Tracker)
Mon May 28 2018 01:05 PM
Re: Invest 90L Becomes Subtropical Storm Alberto

What in the world is that convection over Cuba?

cieldumort
(Moderator)
Thu May 31 2018 02:43 AM
Re: Invest 90L Becomes Subtropical Storm Alberto




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