cieldumort
(Moderator)
Tue Aug 18 2020 04:01 PM
Hurricane Laura Lounge


Visible image of 98L at 1745z on August 18, 2020

Invest 98L is a large, sprawling, monsoon-like depression, and as such, may be slow to get named, but then far more able to fend off attacks of any dry air, shear and land interaction down the road.

Initial model forecasts strongly suggest Florida may be in a direct threat, and this looks reasonable, but there is still a lot of time between now and when the system, possibly then a strong tropical storm if not a formidable hurricane, would be at that longitude.


As of 11PM ET August 19, Invest 98L is now a Tropical Depression, the thirteenth of the very active 2020 Atlantic Hurricane Season, and the title has been updated accordingly.

THIRTEEN is producing winds to tropical storm force and the title has been updated accordingly.


craigm
(Storm Tracker)
Tue Aug 18 2020 04:48 PM
Re: Invest 98L Forecast Lounge

Looks like Laura is clearing her throat this afternoon -not quite there yet at the mid levels.

MikeCAdministrator
(Admin)
Tue Aug 18 2020 08:56 PM
Re: Invest 98L Forecast Lounge

Not quite ready to do model run downs on this one yet, but very mixed signals, Euro and GFS not liking this, although the GFS changed its tune at 18z. 18z HWRF bombs this thing out to major status in the Bahamas at the end of its run. I think the bigger models are having issues with the double center nature of the 98L blob right now, but I suspect tomorrow will iron this out.

MikeCAdministrator
(Admin)
Tue Aug 18 2020 10:10 PM
Re: Invest 98L Forecast Lounge

0z early models shifted a bit right, TVCN, and intensity models now showing a hurricane in the future, so I'd suspect some changes tomorrow.

MikeCAdministrator
(Admin)
Wed Aug 19 2020 07:54 AM
Re: Invest 98L Forecast Lounge

TVCN moved back over land (PR, DR, Haiti and Cuba), GFS and Euro still don't have a good handle on it, and 6z HWRF moves it over Puerto Rico. 98L is still too disorganized to really make the model runs worth it, particularly since land interaction issues make it a bit scrambled.

doug
(Weather Analyst)
Wed Aug 19 2020 10:06 AM
Re: Invest 98L Forecast Lounge

Models will not get this one until it develops a dominant LLC.

MikeCAdministrator
(Admin)
Wed Aug 19 2020 12:15 PM
Re: Invest 98L Forecast Lounge

I'd expect advisories to begin at 5PM for 98L, not sure if it'll be a depression or a "PTC", but either way there should be advisories.

cieldumort
(Moderator)
Wed Aug 19 2020 03:38 PM
Re: Invest 98L Forecast Lounge

98L has continued its consolidation process that began slowly overnight and has picked up throughout the day, and a depression appears to be forming. Advisories on a numbered TC or PTC by 5 or 11 seems almost certain.

Prospero
(Storm Tracker)
Wed Aug 19 2020 06:45 PM
Re: Invest 98L Forecast Lounge

I wonder if the major models will amp up once called. Seems strange 98L does not appear to be in their focus at all.

cieldumort
(Moderator)
Wed Aug 19 2020 08:21 PM
Re: Invest 98L Forecast Lounge

There are reliable globals that do develop either or both 98L and 97L, unlike the ECMWF and GFS. Given that the preponderance of the models sans EURO - GFS - and their member ensembles - do cook eitiher or both 97L and 98L up this week, it's even harder to deny what our own eyes see, and strongly lean to tossing out the two top-tier globals (ECMWF and GFS) and most of their individusal members members until they latch on to reality.

Prospero
(Storm Tracker)
Wed Aug 19 2020 08:36 PM
Re: Invest 98L Forecast Lounge

It's worth paying attention to here in Florida. It's already Wednesday evening and usually the cones are up before five days. If this becomes a Monday event, a lot of people will be taken by surprise.



NewWatcher
(Storm Tracker)
Wed Aug 19 2020 08:42 PM
Re: Invest 98L Forecast Lounge

The models are not getting all the pertinent information this year because ships and airplanes are not traversing the areas to give reports, this in turn makes the models less reliable.Once Recon goes in, they should get better, especially if and when we get the upper air data.

MikeCAdministrator
(Admin)
Wed Aug 19 2020 10:34 PM
Re: Invest 98L Forecast Lounge

TD#13 at 11PM, watches probably for some of the islands.

MikeCAdministrator
(Admin)
Thu Aug 20 2020 12:37 AM
Re: Invest 98L Forecast Lounge

Ok some 0z models:

euro not out yet

0z GFS rides along the caribbean islands, landfalls in Central Louisiana on a week from thursday, cat 2

0z Canadian stays north of the Caribbean islands goes over southern Bahamas, as a cat 1, cat 2 landfall near Boca Raton late Monday night, then stays inland up through Florida.

0z Icon rides along islands, cat 2 landfall near Morgan City, LA a week from Thursday.


MikeCAdministrator
(Admin)
Thu Aug 20 2020 06:59 AM
Re: Invest 98L Forecast Lounge

Morning model runs,

6z GFS, keeps it JUST north of the Caribbean islands, moves it into the Turks and Caicos on Sunday morning, starting to get stronger, just south of Andros Island Monday morning, Cat 1/2 hurricane, landfall late Tuesday night near Largo or Homestead, strong Cat 2. Exits into the Gulf over Naples tuesday morning, then cat 3 landfall near alligator point in the Florida Panhandle midday Wednesday.

6z Icon keeps it north of the islands and south of the Bahamas, landfall middle keys as a tropical Storm Monday night, then enters the gulf where the run ends for the 6z Icon.

0z Hwrf (6z not finished yet) goes over the Virgin Islands as a depression or storm, but stays north of Puerto Rico. Manages to avoid Hispaniola to the north, over Inagua island as a hurricane on midday Sunday, passes just south of Key west on Monday evening as a major hurricane, then enters the gulf, still strengthening, run ends here.

0z hmon stays off the Caribbean islands, but moves over Crooked Island in the Bahamas Sunday afternoon as a hurricane, crosses the southernmost tip of Andros island on Monday morning as a major hurricane, then landfall in Key Largo as a cat 3/4 hurricane Monday afternoon, exits into the Gulf near Everglades City, then restrengthens in the Gulf, where the run ends.

0z Euro keeps it north of the islands, weak


MikeCAdministrator
(Admin)
Thu Aug 20 2020 07:44 AM
Re: Invest 98L Forecast Lounge

6z HMON avoids Caribbean islands to the north, over andros as a Cat 2/3 midday Monday, landfall Cat 3 downtown Miami, Late Monday night, crosses Florida, and ends the run directly over Tampa Bay as a Cat 2.

6Z HWRF slides through the Bahamas, and landfalls near Melbourne,FL Monday night as a cat 3.

GFS Ensembles:




JMII
(Weather Master)
Thu Aug 20 2020 09:07 AM
Re: Invest 98L Forecast Lounge

Quote:

Models will not get this one until it develops a dominant LLC.




Yeah I don't put much stock in these early model runs. Of course I'll watch it but current guidance is all over the place, from a complete miss of FL to a Cat 3 on my doorstep.


MikeCAdministrator
(Admin)
Thu Aug 20 2020 12:23 PM
Re: Invest 98L Forecast Lounge

12z Gfs, keeps the system very weak (but strengthens TD#14). Landfall near Largo Late Monday as a weak wave or TD.

12z Icon shoots the Florida straits and then landfalls near Alligator Point in the Big Bend as a cat 2/3 Wednesday night.

12z Canadian cat 1/2 landfall near Homestead Monday Afternoon, then Mexico beach landfall on Early Wednesday as a cat 1/2.

12z HWRF, over turks Caicos, cat 2 on Sunday midday, cat 2/3 over Crooked Island Sunday afternoon, over Great Exuma Saturday night, cat 2/3, over Andros Island early Monday, cat 3. Landfall, downtown Miami Cat 4 Midday Monday. Cat 1/2 over Tampa Tuesday Morning, ends run back in the Gulf as a cat 2.

12z HMON Avoid direct landfall will all but the northern Tip of Andros, on Monday morning, as a cat 2. Landfall Cat 3 Midday Monday near Boca Raton, Just north of Tampa, Cat 1, By Tuesday morning, then exits briefly in the Gulf by Cedar Key, before another landfall in the Big Bend.

12z Euro doesn't do much with TD13, wave crosses the keys Monday morning, not strong. Then landfall near Pensacola sill very week Wednesday. It does send TD14 toward Galveston as a Tropical storm, however.

GFS Ensembles:






scottsvb
(Weather Master)
Thu Aug 20 2020 06:02 PM
Re: Invest 98L Forecast Lounge

as of 6pm... LLC is around 17.4N and 54.7W moving WNW..

Looking at the 18Z GFS... it has it moving almost due west for next 18hours.. and is already SW of the actual low. NHC did mention the swirl but I believe is the LLC. GFS might adjust at 0Z or forsure by 12Z tomorrow but we will see where exactly this is by morning..probably be already around 18.5N and 58W my guess by Friday 11am.


MichaelA
(Weather Analyst)
Thu Aug 20 2020 08:53 PM
Re: Invest 98L Forecast Lounge

Looking at floater imagery, 13 is a hot mess. I’m seeing what may be multiple, short lived, low level mesoscale vortices. Development is going to be slower than forecast. That may affect the long term intensity and track guidance. I don’t expect much change to the 11 PM package. The 5 AM package tomorrow morning may be more telling.

MikeCAdministrator
(Admin)
Thu Aug 20 2020 10:02 PM
Re: Invest 98L Forecast Lounge

I don't see anything much changing with this until around Saturday night.

Lamar-Plant City
(Storm Tracker)
Thu Aug 20 2020 10:40 PM
Re: Invest 98L Forecast Lounge

I am a bit worried about a possible fast ramp-up starting Saturday when it gets into more favorable conditions...if it retains most of its forward speed, that would really shorten prep time here in Central Florida! People are pretty distracted by the beginning of schools right now, too!

MikeCAdministrator
(Admin)
Fri Aug 21 2020 05:30 AM
Re: Invest 98L Forecast Lounge

0z model summary:

0zGFS 13 Goes through the NE Islands, clips by Puerto Rico on the Northeast side tomorrow around noon, critical time is Saturday evening, weak over Key West midday Monday, then weak into Panama City Tuesday afternoon/evening. (TD#14 moves into Western Louisiana weak, but stronger than TD13)

0z Canadian keeps it north of the Caribbean islands, starts to strengthen northwest of Puerto Rico, Cat 1 landfall near the middle Keys Midday Monday, cat 2 landfall near Panama City, FL on Wednesday morning. While it does nothing with TD14, and it falls apart.

0z Icon, lots of land interaction, keeping it weak all the way into the Gulf. TD14 remains weak into Louisiana also, falling apart as it approaches.

0z HWRF keeps the northern part of TD13 the most active, firing it up northwest of Puerto Rico tomorrow night. Landfall Key West Midday Monday as a cat 3 or 4, then ends the run as a cat 4 on approach to Mobile, AL.

0z HMON keeps it disorganized and moves over the greater Antilles, eventually goes into Southeast Louisiana as a weak wave.

0z UKMET rides along the Antilles and Cuba, keeping it generally weak.

0z Euro is a little stronger than prior runs, but not by much, still opens it up into the Gulf with an eventual wave into Mobile,AL Tuesday night. TD14 goes into Texas near freeport Tuesday afternoon/evening, as a weaker system/TS.

For 13 there seems to be more open possibilities, so it'll unfortunately mean we probably won't know too much until Saturday night or even Sunday. The Gulf of Mexico and Bahamas area range from generally favorable to very good for development. In the shorter term a lot rides on where the center settles and if it is over the land in the islands or comfortably north of them. In the Gulf depends on if TD13 gets too close to 14. But yeah, it's pretty wide, the possibilities range from the system degenerating to an open wave as seen in the GFS and ECMWF to a major hurricane as seen in the HWRF.


cieldumort
(Moderator)
Fri Aug 21 2020 07:44 AM
Re: TD13 Forecast Lounge

THIRTEEN has been skirting the line between open wave and tropical cyclone for the better part of 12 hours now. Recon is presently back in trying to confirm a closed circulation still exists. If it finds one, and indications are that one has possibly reformed, it might necessitate naming as winds to the north of the apparent 'center' are already blowing at tropical storm force. However, one important caveat being that these storm-force winds are likely more the result of the pressure gradient that exists with higher pressure to its north, as well as the forward speed of 13, within a fairly stout easterly jet.

Provided the low/wave/low/wave can come together at enough latitude to reduce or avoid interaction with mountainous islands, the upper bound of intensity forecasts look within the realm of possibility. Barring that, and especially if it is an island runner, the system may even struggle to become a hurricane ever, at all.

By this time tomorrow we should have a much better idea as to which of whether the weaker or stronger scenario is more likely. As of this morning, just too many variables and questions remain.


cieldumort
(Moderator)
Fri Aug 21 2020 08:31 AM
Re: TD13 Forecast Lounge

Recon has found a new center of circulation quite a bit south of the naked swirl being tracked last night (and used to extrapolate the current official location) in the southeastern portion of the deeper convection. A second circulation center may also exist to the south of that. Further center reformations are possible unless and until THIRTEEN pulls together, and until then, model runs will remain somewhat dubious.

JMII
(Weather Master)
Fri Aug 21 2020 08:43 AM
Re: TD13 Forecast Lounge

13 is a real mess. The longer is stays disorganized the further west it will track so the threat to S FL gets lower. At this rate it could possible run smack into one of several land masses and dissipate. I'm taking the under bet on this one.

doug
(Weather Analyst)
Fri Aug 21 2020 09:04 AM
Re: TD13 Forecast Lounge

that is not a good sign ...Consolidation of the system around the midlevel increases the possibility of the system creating a stacked vortex as it moves up the islands and leads to a stronger system.
Early data this morning suggests the system remains very disorganized..as long as it remains in its current configuration it may never consolidate. The next 24 hours should clarify the siruation


MichaelA
(Weather Analyst)
Fri Aug 21 2020 10:43 AM
Re: TD13 Forecast Lounge

The overnight and morning satellite indicate a more robust system than what appeared yesterday. Now that it has achieved TS status with a better fix on a center, things should begin to gell into more consistent model runs. Waiting for the 11 AM advisory package, but the 5 PM package may be more telling.

scottsvb
(Weather Master)
Fri Aug 21 2020 12:29 PM
Re: TD13 Forecast Lounge

Pressures are not falling much so center reformations are still possible further north again tonight. With pressures around the same.. a new LLC can reform anywhere as a new vortex as this has a few still. IDT the models have a good idea on what is happening until the system gets down to at least 1005mbs... stronger system will go more WNW.. I agree with GFS out to 48hours within 50 miles and expect another jump WNW of the current or reformation to around St Thomas by morning.

scottsvb
(Weather Master)
Fri Aug 21 2020 12:29 PM
Re: TD13 Forecast Lounge

Btw .. Mike can you post the Radar for the Islands with timelapse.. . TY

EMS
(Weather Hobbyist)
Fri Aug 21 2020 12:57 PM
Re: TD13 Forecast Lounge

Important to note while the NHC position is far better for Florida now, there seems to be continued poor organization and multiple swirls, reminiscent of Isaias when it was in a similar spot. If you recall when Isaias got to Puerto Rico/Hispaniola the center reformed around a more northern mid level swirl and shifted the track north. Tomorrow night seems like the critical time in determining whether Florida falls back into the cone or not as the center should be around Hispaniola by then.

scottsvb
(Weather Master)
Fri Aug 21 2020 01:11 PM
Re: TD13 Forecast Lounge

I think S Florida will... depends on how well organized it gets Saturday into Saturday night. A more organized system 1005mb or stronger will go more WNW... but usually these systems turn more NW earlier than at first forecasted.. it's expected to turn more NW once it gets close the the keys... a more organized system will turn NW just before and might go from just south of Miami-Key Largo NW along SW florida and out west of Ft Myers.. but again.. that's speculation in 3-4 days.
A honest upfront forecast is just go out 24 hours.. lets see how strong this is or really organized by Saturday morning once it gets to the US and British Virgin islands as it races near or north of PR Saturday.


scottsvb
(Weather Master)
Fri Aug 21 2020 02:23 PM
Re: TD13 Forecast Lounge

Looks like Euro has a very strong ridge, so Laura moves into Hispaniola or at least N Cuba before exiting just south of the strats and into the open GOM via 72-96 hours... everything will depend by 12Z Saturday after we see how far N it gets in the next day or so and how organized Laura gets

doug
(Weather Analyst)
Fri Aug 21 2020 02:44 PM
Re: TD13 Forecast Lounge

Totally agree. The 11 advisory tomorrow should reveal a lot. If the storm comes together better between now and then and intensification is occurring a more easterly track becomes more plausible.

JMII
(Weather Master)
Fri Aug 21 2020 05:23 PM
Re: TD13 Forecast Lounge

Given Laura's poor organization and the revised track (further S and W) it will be sputtering over pretty much every large land mass in the Caribbean, thus I don't see how it can survive. Heck I have trouble believing its a TS now.

MikeCAdministrator
(Admin)
Fri Aug 21 2020 06:49 PM
Re: Tropical Storm Laura Lounge

With how in flux the center is, the models are still kinda useless other than general patterns, this goes for TD#14 also. I'm still waiting for tomorrow night.

MichaelA
(Weather Analyst)
Sat Aug 22 2020 08:03 AM
Re: Tropical Storm Laura Lounge

Neither system is well organized this morning. With that in mind, Laura’s future is pretty iffy. Will the interaction with the Greater Antilles cause it to dissipate (like the one a few years ago that dissipated near the Florida Straights) or will it do something similar to Isaias with a reformed center north of the islands? As usual, it’s a wait and see situation.

Lamar-Plant City
(Storm Tracker)
Sat Aug 22 2020 10:23 AM
Re: Tropical Storm Laura Lounge

Tropical Tidbits also presented a scenario on yesterday's post where interaction with the land drags the low level circulation back to the mid level, allowing the system to better stack vertically and strengthening it a bit. This will be in interesting trip for Laura to take. A lot of data to be acquired for the models.

scottsvb
(Weather Master)
Sat Aug 22 2020 11:02 AM
Re: Tropical Storm Laura Lounge

IDK what they are seeing at the NHC but Laura is NOT at 17.8N and 66.8W 20 miles SW of Ponce... it's clearly at 18.7N and 65.5W or about 50 miles NW of San Juan heading WNW... you can clearly see on radar the low level bands and flow on the north side of PR moving slightly from the west while just NE of there moving from the SE and just west of the LLC moving NE. Also surface obs have SW winds west of San Juan but light..IDS what they are seeing near ponce and we all see the midlevel low further south. Models show nothing on the midlevel coming to the surface but it might once it crashes into Hispaniola tonight.. it might then get to the surface and ride thru Cuba or the LLC of Laura (if she is where I think the HWRF thinks will stay near or just north of Cuba.. but 90% of the energy is with the MLC. Hard to win and get pressure drops when your energy is 150 Miles SE of you.

Lamar-Plant City
(Storm Tracker)
Sat Aug 22 2020 11:33 AM
Re: Tropical Storm Laura Lounge

Thanks for the observations....those problems are the main reason I do NOT trust the NHC track right now. But the local Mets are acting like it isn't a threat to central Florida anymore. Until it clears Haiti and/or forms a defined COC, I don't think the models have a solid grasp on this thing. With the very warm water ahead of it, now is far too soon for the locals to say things that would encourage people to drop their guard....
Am I way off base here??


scottsvb
(Weather Master)
Sat Aug 22 2020 11:59 AM
Re: Tropical Storm Laura Lounge

12Z GFS handles LAURA better after 12 hours.. first 12 though I feel is displaced SW where the NHC has her.. but I think it's more NE of there.. we will see as the afternoon and evening come along with the next recon.. wish it was in there earlier. GFS thus takes Laura near Key West and Dry Tortugas as a stronger Tropical Storm.. but if it does stay more offshore Cuba.. Laura has the potential to get a hurricane...but again.. any deviation to the south will keep this weak thru Cuba. 12Z Euro and HWRF will be interesting.

MikeCAdministrator
(Admin)
Sat Aug 22 2020 12:01 PM
Re: Tropical Storm Laura Lounge

I think an east coast hit is much much less likely, but a gulf surprise isn't. This thing is going to change daily with the two systems.

scottsvb
(Weather Master)
Sat Aug 22 2020 12:24 PM
Re: Tropical Storm Laura Lounge

Pasch has it still 17.8 and 67.2 now.. sat has 45mph... was updated at noon.. still I think they are using 1 of many vortexs.. main 1 is closer to now 19N 67W but broad lacking TStorms

JMII
(Weather Master)
Sat Aug 22 2020 12:29 PM
Re: Tropical Storm Laura Lounge

Laura is getting some convection and outflow going but I'll be darned if I can't find the center. I think its even further south the NHC has it. With each cone update the NHC has moved it further south. For example the Thurs 5PM advisory had it forecast to be nearly 110 miles N of its current position. Its got the same problem Isaias had with multiple spins none of which are stacked over the surface low. The weather stations I've checked in PR indicate a weak storm, the strongest winds are well displaced to the east. Once again on its current track (if even remotely accurate) it will be over land for the next 48 hours. This seems like an impossible to survive scenario.

cieldumort
(Moderator)
Sat Aug 22 2020 01:23 PM
Re: Tropical Storm Laura Lounge


Tropical Storm Laura base map from Wunderground.com (IBM)

At 1200 PM AST Sat Aug 22 2020 NHC has Laura's center located at 17.8N 67.2W or about 40 miles to the WSW of Ponce, PR (denoted by the red "L" on the map above). However, the most recent surface and ship obs strongly suggest that the surface center is becoming much better aligned with the very healthy mid-level center. This mid-level circulation center has become obvious on radar. Based on surface obs I've drawn in a possible new surface center location "Unofficial LLC."

It is increasingly possible that Laura has reformed just south enough to bypass at least some direct island interaction, and is availing itself of the very warm waters of the Caribbean. Should this trend continue, Laura may indeed yet become a hurricane, albeit a good distance southwest of where it was originally forecast to do so.

Interests in the central to western Gulf of Mexico may want to begin paying much more attention to Laura, as the odds of not one, but possibly two landfalling significant tropical cyclones is going up.

This does not yet clear Florida. Tropical models seem to be struggling this year. They are lacking lots of flight data, and this is an especially unusual setup with two tropical cyclones in the western Atlantic so close to each other at the same time. As always, best to pay close attention to the NHC and local NWS for the most relevant, local and official weather information.


cieldumort
(Moderator)
Sat Aug 22 2020 02:49 PM
Re: Tropical Storm Laura Lounge

Radar - including velocity data - plus surface and ship obs, strongly suggest that a surface circulation center exists and is co-located with the vigorous mid-level circulation center (complete with an eye-like feature), and has just made landfall east of Ponce, PR.

Velocity data near the time of landfall were showing winds of about 60-70 mph at 1,500'



cieldumort
(Moderator)
Sat Aug 22 2020 03:12 PM
Re: Tropical Storm Laura Lounge

As a follow-up, it remains to be seen if this substantial mesolow pointed out in the two entries above takes over the entire system and becomes the dominant center. The last few frames of conventional satellite indicate a trend towards this outcome, but does not yet appear conclusive.

A center reformation to the northeast - and as of now right on top of Puerto Rico - tosses future track and intensity back into more complexity, as it could drive Laura over Hispaniola.

Time will tell. Exceptionally difficult track and intensity forecast here.


scottsvb
(Weather Master)
Sat Aug 22 2020 03:13 PM
Re: Tropical Storm Laura Lounge

I still have it around 19.4N and 68.3W moving just north of west around 280dg.. but the MLC does have a reflection at the surface but I think it always has. .that is moving NW at a good clip now.. If that does come down to the surface.. it will be 6 hours behind model schedule and might end up being slightly further north unless it starts bending more W-WNW in the next few hours

Owlguin
(Weather Hobbyist)
Sat Aug 22 2020 03:48 PM
Re: Tropical Storm Laura Lounge

Well, my totally untrained self will rely what I am seeing on radar, and that is that I agree with the posts above, the center of circulation is now over Western PR. I appears to me it will ride the northern coast of the DR.

JMII
(Weather Master)
Sat Aug 22 2020 08:35 PM
Re: Tropical Storm Laura Lounge

Quote:

A center reformation to the northeast - and as of now right on top of Puerto Rico - tosses future track and intensity back into more complexity, as it could drive Laura over Hispaniola.




This is a pretty dynamic situation, there are 2 or maybe 3 centers fighting to become Laura. The one that wins and its location will be critical to its future. The storm has developed a much more defined environment around it and outflow continues to improve. If she can punch down to the surface and find warm water it might survive. Current guidance has it tracking right down the middle of the land mass, which clearly would keep it very much in check, but just getting a few miles further north will allow some ocean heat to be draw in and she live to fight on.

Crazy that she is tracking into brother's Marco predicted landfall area too now. A few days ago this possibility seemed ridiculous.


cieldumort
(Moderator)
Sat Aug 22 2020 09:28 PM
Re: Tropical Storm Laura Lounge

The jumpiness of Laura continues tonight. The very impressive mesolow from earlier today likely could have become the new dominant CoC given enough time, but ran into land.

Tonight, deep convection with very cold cloud tops are firing south of Hispaniola, and this is where the current recon mission is finding a renewed, dominant center, with a Vortex message possibly coming out for a location near 17.3N 69.4W, and roughly within the red circle seen in the image uploaded below.

It would seem that Laura is tracking west, or perhaps west-southwest, while now centered fairly south of the Dominican Republic.



cieldumort
(Moderator)
Sat Aug 22 2020 10:58 PM
Re: Tropical Storm Laura Lounge

Timely ASCAT pass from 0138z confirms surface center to the north of the mid-level center found by recon earlier, but likely not over land, and that is seen in the 11PM update from NHC.

Center jumps are going to remain possible if not likely unless and until Laura really can pull it together - tough to do while tracking along or either side of mountainous islands.


IsoFlame
(Weather Guru)
Sun Aug 23 2020 07:25 AM
Re: Tropical Storm Laura Lounge

NHC 5am discussion: There has been a significant westward shift in the latest NHC model guidance, which appears to be due to most of the global models taking the center of Laura farther south over central or southern Hispaniola rather than emerging it off the north coast of Haiti like the GFS is and has been forecasting. Given that the most intense convection has persisted along the southern coast of Hispaniola, that is where the most likely area that a low-level and/or mid-level circulation is most probable to develop or persist.

JMII
(Weather Master)
Sun Aug 23 2020 09:04 AM
Re: Tropical Storm Laura Lounge

Laura has tracked south of guidance for her entire life so far. She is amazingly intact given the mountains she went by. I keep trying to write her off yet she is still chugging along. For storm originally forecast to reach the upper Keys we now have something that could hug the southern coast of Cuba before ramping up in the gulf. The models have been struggling with these two systems.

Keith B
(Weather Watcher)
Sun Aug 23 2020 01:19 PM
Re: Tropical Storm Laura Lounge

My apologies if it applies on how I posted the below on Twitter. I am learning how to use Twitter and I removed the below question from Twitter.

Curious question. The update on the web page for 8/23 @ 0600, what was thinking in regards to a possible threat to W FL?

Thank you.
**
Quote:

It is now clear that Laura has the potential to be a large and major hurricane in the Gulf of Mexico and possibly make landfall as such. Interests from Texas to western Florida would be wise to pay very close attention to her forecast track, and begin making preparations to protect life and property if within her cone and watch/warning zones.




Hello Keith, and thanks for the question. I'm replying inside your post so that the thread doesn't become ASK/TELL (we have a separate forum for that). Short answer: while Laura is most likely to keep heading west of even far western Florida, it is not yet certain. However, and more probable, as Laura is a decent sized system, dangerous storm surge and rip currents may extend a good distance from her center, outer bands can produce severe thunderstorms with waterspouts/tornadoes, etc. Feel free to send me a direct message for more discussion.
Ciel


IsoFlame
(Weather Guru)
Sun Aug 23 2020 02:08 PM
Re: Tropical Storm Laura Lounge

(1PM CDT advisory on Laura):LOCATION ABOUT 55 MI...90 KM S OF THE EASTERN TIP OF CUBA PRESENT MOVEMENT...WNW OR 285 DEGREES AT 21 MPH...33 KM/H

Yes, it is truly amazing that Laura has been able to strengthen a bit (let alone hold together) considering the center's nearly continuous interaction with significant terrain. The favorable mid/upper-level wind environment has greatly helped Laura and may allow a period of potentially rapid intensification in the southeast and central Gulf once clear of Cuba. Given the favorable parameters, perhaps the fast forward motion (over the islands) has helped limit the unfavorable friction of terrestrial interaction.


Prospero
(Storm Tracker)
Sun Aug 23 2020 08:09 PM
Re: Tropical Storm Laura Lounge

Hmmm, the Main Page plots are not working for me.

I just posted a question about that and it did not take.

Is there a site issue?

Or am I losing my mind?


JMII
(Weather Master)
Sun Aug 23 2020 08:36 PM
Re: Tropical Storm Laura Lounge

Parts of the site are working. I see the 8PM updates and graphics for both systems. However the links to some of the satellite loops are broken, the direct link is here: https://weather.msfc.nasa.gov/ Same goes for the SFWMD plots, which are here: https://www.sfwmd.gov/weather-radar/hurricane-model-plots

cieldumort
(Moderator)
Mon Aug 24 2020 07:37 AM
Re: Tropical Storm Laura Lounge

Recon is finding once again that Laura has been attempting to recenter over water. This time, Laura may not have had as much of a 'choice,' as the convection has been shunted a good deal south from an impinging ULH/ULL nose from her northeast.

IF this recenter over water finally takes, a noteworthy shift west in the track may be coming, along with a commensurate additional time over water, which would favor additional strengthening.

Several model runs favor major, and a few of the plausible regional runs are even reaching for Cat 4+


MikeCAdministrator
(Admin)
Mon Aug 24 2020 10:25 AM
Re: Tropical Storm Laura Lounge

I normally ignore models when they are being influenced (read made wrong consistently) by land interaction, but the UKMet has shown the southerly/westerly route the most. So Galveston to about Cameron, I'd strongly considering doing preps today or leaving before the mad rush. We won't have a good idea until tomorrow morning when it clears Cuba, but by then you'll only have a little under 36 hours for prep work, which means it could be a zoo in the more urban areas if it winds up that way.

The other part with the slight south fix, is more time over water, which means the higher end intensity seems more likely. Also surge may be dramatic with this storm, especially if it ramps up well before landfall. (The momentum is the key there)


MikeCAdministrator
(Admin)
Mon Aug 24 2020 11:29 AM
Re: Tropical Storm Laura Lounge

11AM they held steady looking for more recon information, which is finding it a bit south. There is still some shear on Tuesday to keep Laura in check, but that slips away by the evening tomorrow. There's a pretty good chance 5PM will have hurricane watches up in the Gulf. Probably from Freeport, TX to about Cameron, LA. (but that is just a lounge guess)

IsoFlame
(Weather Guru)
Mon Aug 24 2020 01:24 PM
Re: Tropical Storm Laura Lounge

After clearing Cuba's western tip, Laura has 36 hours (+/-4) or so to undergo rapid intensification and potentially double current wind speed suggested by GFS, which forecasts landfall late Wednesday evening at 957 mb along the NE Texas coast: https://mag.ncep.noaa.gov/data/gfs/18/namer/precip_p06/gfs_namer_084_precip_p06.gif
Dvorak MSLP (Atlantic) 960 mb: Mean Wind Speed: 102 KTS/117 MPH Saffir/Simpson Category: 3 (97-113 KTS)


cieldumort
(Moderator)
Tue Aug 25 2020 04:31 AM
Re: Tropical Storm Laura Lounge

25 0z EURO and ensembles have come in, once again drastically left of OFCL (NHC center line) and this time even more so. In addition, it is worth noting that UKMET has outperformed so far, and while waiting on today's 0z ensembles, those from yesterday were well into Texas, overall - almost unanimously landfalling between Corpus Christi and the TX/LA border.

As Philippe Papin, Atmospheric Scientist at NWS NCEP Environmental Modeling Center, noted on Twitter earlier this morning, "Every single deterministic model has taken #Laura too far N at lead times +24h-120h. UKMET has performed best w/ track, but even it is slightly N of verification."

25 0z GFS ensemble members are almost entirely Texas landfalls.


The trend for a landfall centered in Texas rather than Louisiana continues, with a lot of ensembles honing in around Galveston/Houston. With the likelihood that Laura becomes a Major, this could be a rather 'worst case' outcome.

Two factors could serve to limit the death and destruction: 1. Forward speed should not be anything like Harvey, and 2. There are indications that at least some of the shear which served to shred Marco may still be present over a portion of the western Gulf, but counting on either or both to save the day seems foolish.

Residents along and many miles inland of the Texas coast from roughly Corpus Christi to the Louisiana border, as well as exposed portions of the entire Louisiana coastline and points inland (dangerous weather conditions will still extend a great distance from the center center, especially to the right of the center), may want to rush preparations to protect life and property as a large and significant hurricane could be making landfall within the next 40-60 hours, with weather rapidly deteriorating many hours before then.

It is also worth mentioning that a few ensemble members have been as far south as northeast Mexico/deep south Texas, but these are outliers.


JMII
(Weather Master)
Tue Aug 25 2020 09:18 AM
Re: Tropical Storm Laura Lounge

Quote:

As Philippe Papin, Atmospheric Scientist at NWS NCEP Environmental Modeling Center, noted on Twitter earlier this morning, "Every single deterministic model has taken #Laura too far N at lead times +24h-120h. UKMET has performed best w/ track, but even it is slightly N of verification."




The error in track guidance has been pretty large with Laura, even the 3 day cone which is normally trustworthy has been too far north especially if you go by the center line (which you shouldn't). However as a hurricane with clearly defined center (with an eye at some point) and what I assume will be more recon and upper air flights the forecast should improve as they focus on a TX landfall.


IsoFlame
(Weather Guru)
Tue Aug 25 2020 10:16 AM
Re: Tropical Storm Laura Lounge

Quote:

Two factors could serve to limit the death and destruction: 1. Forward speed should not be anything like Harvey, and 2. There are indications that at least some of the shear which served to shred Marco may still be present over a portion of the western Gulf, but counting on either or both to save the day seems foolish.

Residents along and many miles inland of the Texas coast from roughly Corpus Christi to the Louisiana border, as well as exposed portions of the entire Louisiana coastline and points inland (dangerous weather conditions will still extend a great distance from the center center, especially to the right of the center), may want to rush preparations to protect life and property as a large and significant hurricane could be making landfall within the next 40-60 hours, with weather rapidly deteriorating many hours before then.




Intensity guidance trending upward, some suggesting a strengthening major hurricane at landfall.


cieldumort
(Moderator)
Tue Aug 25 2020 02:08 PM
Re: Tropical Storm Laura Lounge

Laura is now a latitude that almost entirely removes northeast Mexico/extreme south Texas from landfall. Still in play is Corpus Christi to New Orleans, an admittedly large spread, but also an admittedly unusually difficult tropical cyclone to forecast. This would be for where the eye of Laura makes landfall, not where the worst of the weather would necessarily occur.

Laura could begin turning to the north earlier than forecast if she ramps up quicker than forecast, but unless and until then track is locking in on a landfall center most likely between as far west as Freeport, Tx. to as far east as about Holly Beach, La.


IsoFlame
(Weather Guru)
Tue Aug 25 2020 04:04 PM
Re: Tropical Storm Laura Lounge

FROM THE 2PM ADVISORY:
STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide.
Sea Rim State Park TX to Intracoastal City LA including Sabine Lake
and Calcasieu Lake...9-13 ft
Intracoastal City to Morgan City including Vermilion Bay...7-11 ft
Port Bolivar TX to Sea Rim State Park...6-9 ft
Morgan City LA to Mouth of the Mississippi River...4-6 ft

The forward momentum and perpendicular approach to the Texas coast of the strengthening (and likely major at landfall) hurricane will make the impact of storm surge a great threat. Add to that a night time landfall~, coastal residents in and well to the east of where the eye eventually targets should conclude property preserving and life-saving plans for Laura's impending arrival..


cieldumort
(Moderator)
Tue Aug 25 2020 08:54 PM
Re: Hurricane Laura Lounge


Potential Storm Surge Flooding Map (Inundation)

NHC Potential Storm Surge Flooding Map
From 04 PM CDT Tuesday August 25 to 07 PM CDT Saturday August 29


Laura is not only strengthening tonight, but organizing in a very meaningful way, and may already be feeling the tug to the north that a stronger, deeper, more coherent and symmetric hurricane could.

It is too early to know, but it appears increasingly possible that Laura's eye now tracks into Louisiana rather than extreme SE TX. That said, weather is going to be brutal within many, many tens of miles either side of the eye, regardless, and regions in southern Louisiana are incredibly susceptible to deadly storm surge inundation, surge that will push inland for miles and miles in some places.


IsoFlame
(Weather Guru)
Wed Aug 26 2020 03:15 PM
Re: Hurricane Laura Lounge

Pressure still dropping... down 4 mb from 1pm (CDT) advisory to 948 mb. Eye clearing out, concentric and well-defined.

IsoFlame
(Weather Guru)
Wed Aug 26 2020 03:51 PM
Re: Hurricane Laura Lounge

Not sure of the veracity (may be outdated) of the following information:

"Of the forty major hurricanes to cross the Gulf coast since 1900 - half made landfall with a pressure below 28.00 inches."


Psyber
(Storm Tracker)
Wed Aug 26 2020 08:09 PM
Re: Hurricane Laura Lounge

4 ft of storm surge already being reported.

Fringe reports that if it drops much more that aspects of Louisiana might take up to 20 feet. They're trying to get people to GTFO because it's unsurvivable and juuuust like Katrina people are trying to hunker down.

Fifteen years since Katrina, huge swaths of New Orleans that are STILL uninhabited because nobody wants to live there and STILL people think they can wait a storm out versus hopping in a car, driving west until they can find the cheapest Hotel-6 with rooms and maybe save their lives.

Unbelievable.



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