Ed Dunham
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(Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017))
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Wed Sep 05 2012 12:20 PM
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Invest 90L Forecast Lounge
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Invest 90L located along the Alabama/Western Florida Gulf coast is moving south at about 15 knots. Early model runs suggest a continued south to south southwest movement. The system currently has a low chance for additional development on Wednesday and Thursday. SSTs of 29-30C. This is the place for your long range guesstimates on what this system will become (if anything) and where it might eventually go.
ED
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MichaelA
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(Weather Analyst)
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Wed Sep 05 2012 01:12 PM
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Re: Invest 90L Forecast Lounge
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The 00Z NGP model shows a weak system developing and, eventually, moving into the Tampa Bay area of Florida. I'm not holding my breath on that, though. It's simply too early to tell. If anything, it could be another rain maker for Florida if that scenario does play out.
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Joeyfl
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(Weather Guru)
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Wed Sep 05 2012 07:37 PM
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Re: Invest 90L Forecast Lounge
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Need to keep an eye on 90L at least FL. Not really concerned about a monster storm a TD/TS looks to be most likely with this system. It looks to be a higher confidence forecast with it being picked up and moved E/NE as a strong cold front for early September drops all the way through at least central FL. Looks to be mainly a rain maker for FL. But nonetheless will keep an eye on it.
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OrlandoDan
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(Weather Master)
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Wed Sep 05 2012 10:10 PM
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Re: Invest 90L Forecast Lounge
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I see most models have 90L heading east, over Central Florida. Not intensifying much, but bringing more rain to Central Florida. We can still use more rain here. The Lake Harris lake system in Lake County is still low, even after the rains from Isaac.
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OrlandoDan
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(Weather Master)
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Wed Sep 05 2012 10:16 PM
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Re: Invest 90L Forecast Lounge
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CMC model as of 09/05/2012 at 1816 EDT has it generating into something noticeable, for what that is worth.
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OrlandoDan
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(Weather Master)
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Wed Sep 05 2012 10:44 PM
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Re: Invest 90L Forecast Lounge
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Interesting radar signature from Mobile long range loop. Some degree of some spin there?
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MichaelA
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(Weather Analyst)
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Wed Sep 05 2012 10:51 PM
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Re: Invest 90L Forecast Lounge
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It has some significant northerly shear over it right now with the convection displaced to the apparent LLC's south, so any intensification is going to be slow.
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Joeyfl
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(Weather Guru)
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Thu Sep 06 2012 01:08 AM
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Re: Invest 90L Forecast Lounge
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90L is going to be a rather slow developer if it does at all. I would say 50/50 right now. I feel confident that this gets maybe as strong as moderate TS at its highest. Cimss analysis wind shear shows 20-40 knot wind shear over the eastern Gulf/FL to east of the system, however it is dropping into an area of low shear 10 knots or less. So shear will not be as big of an issue I think as the dry air around the system will be. However as front/trough drop into the north Gulf this weekend shear will increase moving into the weekend when it will get picked up and shoved E and NE across FL.
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TXEB
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(Weather Watcher)
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Thu Sep 06 2012 01:41 AM
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Re: Invest 90L Forecast Lounge
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Don't take your eyes off of 90L until it is well dead. I am having nightmarish memories of TS Allison (June 2001). I was on an airplane that tried twice to land at IAH just as Allison was hitting Houston. It was an interesting night (and next day too).
While not commonplace, tropical cyclones can form amazingly fast in the northern GoM. Quoting from the NHC's Report on Allison, " No meaningful track and wind forecast statistics are available due to the limited period for which the National Hurricane Center (NHC) issued forecasts. Since the system reached storm strength quickly, there was little warning lead time. A tropical storm warning was issued at 1900 UTC 05 June from Sargent, Texas eastward along the Gulf of Mexico coast to Morgan City, Louisiana. This was less than 3 hours before tropical storm force winds were reported along the upper Texas coast. "
FWIW - Allison left 41 dead in her wake (23 in TX), and a damage estimate of $4.8 billion for Houston alone.
(While this is good info, it would be better suited to the Hurricane History Forum.)
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 02:00 AM
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Re: Invest 90L Forecast Lounge
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A couple of the 18Z model runs (GFS and HWRF) are showing it merging with a frontal trough and tracking across north FL Sunday - Tuesday. That is also reflected in the surface forecasts from the NWS over the same period. Looking at the latest sat loops and long range radar loops along the northern Gulf coast, there is no longer any hint of a low level circulation this evening.
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TXEB
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(Weather Watcher)
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Thu Sep 06 2012 02:17 AM
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Re: Invest 90L Forecast Lounge
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Saw the same things in those models. CMC diverges a bit - develops the trough further north and seems to trap what would be 90L on the SE side of a ridge forecast to build from the NW US, allowing it to move across FL and possibly strengthen off the SE Atlantic coast.
Looking across those and the ECMWF, the bigger worry may become a wave that is forecast to come off Africa and turn into something starting ~Saturday morning.
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Re: Invest 90L Forecast Lounge
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Could the circulation be hiding under that blow up of convection? It seems odd to say it, but all of the sudden we need rain again here in Central Florida. Not a drop since Isaac until today and it missed me (by THAT much!).
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OrlandoDan
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(Weather Master)
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Thu Sep 06 2012 10:28 AM
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Re: Invest 90L Forecast Lounge
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It looks like 90L is in and up for quite a different environnment than Allison in 2001. But we could use some serious rain here in Central Florida. This dry air that has been hanging over us for the last few days is unusual for this time of the year. We did have some rain here in Longwood, FL late yesterday evening however.
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TXEB
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(Weather Watcher)
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Thu Sep 06 2012 11:16 AM
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Re: Invest 90L Forecast Lounge
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Certainly 90L shouldn't be compared to Allison. The point I was trying to make, but did so poorly, is that along the northern Gulf coast, very serious storms can develop in very short order and with little forecast warning. It's a good idea to keep an eye on it.
By all the model forecasts I have seen, 90L isn't expected to do much of anything for the next couple of days if it sticks around that long, which appears unlikely.
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Re: Invest 90L Forecast Lounge
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90L has lost all of its tropical look since last night. It looks like a harmless thunderstorm no more threatening than the ones over land. There doesn't look like there is a center of circulation either unless its is tucked under the convection. I guess time will tell since it is supposed to slowly move toward Florida according to the weatherman out of Tampa Bay last night.
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doug
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(Weather Analyst)
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Thu Sep 06 2012 01:19 PM
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Re: Invest 90L Forecast Lounge
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Actually there is a broad circulation to the NE of all the convection and there is some convection developing around this broad circulation. There is no doubt that this thing has the same DNA as Isaac because of its disorganized and displaced presentation. However, there is a circulation and associated convection in the GOM and it bears watching...especially if convection can develop and be sustained around the periphery of the actual circulaiton center...that's what to watch for...
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 01:36 PM
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Re: Invest 90L Forecast Lounge
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Yes, I'm beginning to see a rather broad and elongated low level circulation in the later frames of the Gulf RGB satellite loop this morning. The more robust convection is still displaced to the S and SW for now, but it looks like the shear is beginning to relax a bit. The system does bear watching as any system in the Gulf should be watched this time of year. Looking at the Central US water vapor loop, the upper level low NE of the Bahamas is beginning to lift out to the NE and the trough down the eastern seaboard is moving away from 90L leaving it between that trough and the frontal system that is well to its NW, so a continued southward drift seems plausible for the immediate future until that frontal system begins to approach the Gulf coast and begins to have its affect on 90L.
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 04:24 PM
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Re: Invest 90L Forecast Lounge
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Shear is continuing to keep 90L from developing. There was a short period this AM that it looked like maybe it would acquire some minimal organization, but now it's looking not so likely.
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OrlandoDan
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(Weather Master)
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Thu Sep 06 2012 04:43 PM
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Re: Invest 90L Forecast Lounge
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In the latest RGB loop, is the LLC appearing closer to the NE quadrant of the convection?
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 04:54 PM
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Re: Invest 90L Forecast Lounge
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What was an apparent LLC seems to have been disrupted - located about 27.5N; 93.0W. It may be reforming just on the NE side of the convection near 27.4N; 93.5W, but the system is still very sheared.
EDIT: Subtract 5º W from the above coordinates. 
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Joeyfl
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(Weather Guru)
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Thu Sep 06 2012 05:38 PM
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Re: Invest 90L Forecast Lounge
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90L to me looks better than it did yesterday even though it is still feeling some slight shear from the north northeast. of where a possible LLC is forming or is located (northeast of the convection). Still have not heard if recon is going out or is cancelled. No changes really to overall thinking with 90L hanging out in central Gulf for next 48hrs before making a bee line across FL late this weekend. I still say 50/50 right now with respect to it becoming tropical storm/depression in any event it looks to mainly enhance rainfall across FL as front drops into central FL possibly stalling out which seems reasonable as it is still early for cool frontal passage here. But if 90L is able to get its act together and ride front across FL it would help to push whatever is left of the front through the state. If this forms and thats a big IF I still see maybe moderate TS at best. Time will tell...
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Joeyfl
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(Weather Guru)
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Thu Sep 06 2012 05:41 PM
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Re: Invest 90L Forecast Lounge *Killed -- Sent to Graveyard*
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This post was sent to the Hurricane Graveyard
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 06:08 PM
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Re: Invest 90L Forecast Lounge
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Very sheared system (even more than yesterday). Apparent weak LLC is near 28.2N; 88.3W with the convection removed well to the SW. If this system doesn't form independently from the approaching front, it will simply merge with that frontal trough and not become tropical at all. If anything forms here, it will be very weak.
Watch the Floater Loop for a better idea of what's going on.
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WeatherNut
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(Weather Master)
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Thu Sep 06 2012 06:17 PM
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Re: Invest 90L Forecast Lounge
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There is a vigorous LLC to the NE of the main convection. It shows up nicely on the visible SAT. It is also getting closer to the convection. If the shear subsides a bit it could become something, but not anything more than a weak TS. Will be interesting to see what happens at the D.Max later
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doug
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(Weather Analyst)
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Thu Sep 06 2012 07:30 PM
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Re: Invest 90L Forecast Lounge
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It does not look healthy at all. The vortex is ragged and the shear has blown convection a considerable distance from that point. It may not survive, IMO.
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MichaelA
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(Weather Analyst)
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Thu Sep 06 2012 09:21 PM
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Re: Invest 90L Forecast Lounge
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The convection is even farther removed from the weak LLC this afternoon. The shear is tearing it apart, so I don't believe that there will be any tropical development of this at all now (unless there is a miraculous convective burst over the LLC  ). Even the 12Z model runs aren't developing it now instead, showing a very weak low on the front that is approaching the Gulf coast and Florida this weekend.
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OrlandoDan
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(Weather Master)
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Thu Sep 06 2012 09:58 PM
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Re: Invest 90L Forecast Lounge
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Agreed. What I did observe earlier today was correct. The LLC was close to the NE quadrant of the convection but the convection has since been completley sheared off to the SW.
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OrlandoDan
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(Weather Master)
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Fri Sep 07 2012 09:30 AM
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Re: Invest 90L Forecast Lounge
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Looks like convection just tried to flare up directly to the south or SSE of the LLC but then got quickly sheared right off.
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Re: Invest 90L Forecast Lounge
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The blob is looking less and less like a storm. Is the center of circulation still intact or has it disappeared too? This little blob made the national news last night and our local met says that we will see rainfall from it this weekend. It looks very weak . I wonder if the 40 per cent chance of development still stands.
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berrywr
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(Weather Analyst)
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Fri Sep 07 2012 04:23 PM
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Re: Invest 90L Forecast Lounge
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Two scenarios; one, the system moves south and southwest out ahead of a narrow upper ridge axis that will be in place throughout the forecast period but I'm leaning on the second scenario and that's the arrival of major shortwave that will deepen the long wave trough along the eastern side of the United States dragging a cold front with it and bringing in some wonderful, wonderful dry weather for the a good part of the Southeastern US this upcoming weekend and whatever there is of this system being absorbed by this system. Leslie and Michael will be steered in due time by the approaching trough in the next couple of days.
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Re: Invest 90L Forecast Lounge
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90l is a little streak in the Gulf this morning. We are supposed to get the cold front with the system attached to it. The 2:00am advisory does not expect it to become viable giving it a 10 per cent chance. I guess this is the last of Isaac.
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