Tracking the Tropics:

[houstonia]

Morning briefing from Jeff (I've taken out non-99L references). No graphics (srainhoutx, if you want to post his discussion with graphics, please feel free to delete mine. I still haven't figured out how to resize down to post graphics):

99L:

Concern is growing that a tropical cyclone will move into the Gulf of Mexico late this weekend

99L this morning is over the northern Leeward Islands and while the system looks impressive on satellite images, surface observations show an ill defined surface low pressure system associated with the feature. The Barbados sounding yesterday evening showed two layers of dry air that are likely impacting the wave and helping to mitigate development in the near term. 99L is moving toward the WNW at 15-20mph and this motion is expected to continue bringing the wave across Puerto Rico Thursday and into the SE Bahamas Friday.

Track:

Much of the future track of this system will hinge on the large scale high pressure ridge over the SE US including how strong this feature is, how expansive, and where it is centered. Once in the south/central Bahamas, 99L will begin to feel the large scale high pressure centered near the Carolinas this weekend and will be forced to turn toward the west or even WSW approaching S FL or the keys. Effectively it appears that the door is closed on chances for the system to turn northward and recurve east of the US coast…this suggests a landfalling tropical system is increasingly likely on the US Gulf coast next week.

The next big question, once in the Gulf of Mexico which seems likely at this point, how far west does the system move before turning toward the NW and N and rounding the western edge of the Carolinas high pressure ridge. Global model ensemble support from the CMC, GFS, and ECMWF have all trended westward in the last 36 hours now showing a clustering well into the central Gulf of Mexico and potentially the central US Gulf coast. Operational model runs of these models have been all over the place with widely varied solutions of both track and intensity…but there is starting to be some growing consensus that the US Gulf coast is at threat.

The biggest aspect of the model guidance at this time is the westward trend and general overall placement and intensity of the large scale ridging over the SE US this weekend into early next week. One should not focus on the individual runs of each model, but their 500mb ridge pattern and their respective ensemble plots. Additionally models will continue to struggle until a define low level center develops and the development of this center could be many miles off of where current guidance is suggesting it will form due to the current poor organization of the wave.

Intensity:

Conditions will gradually become increasingly favorable for development as 99L moves toward the Bahamas this weekend. While there are a few factors in/near the Bahamas that could restrict development, the overall pattern appears favorable including generally light wind shear, high moisture levels within where the vortex should be located and very warm waters. This is where model support increases for development. As the system moves into the Gulf of Mexico conditions look ideal for development of a potentially significant tropical cyclone. An upper level 200mb high pressure cell (anti-cyclone) appears to encompass much of the central and eastern Gulf of Mexico with a westward moving upper level trough over MX/SW TX which could help with the upper level outflow and venting of a developing system. Sea surface temperatures are very warm…running in the mid 80’s and moisture looks plentiful. There appears to be little to stop intensification once in the Gulf of Mexico and the last 3 operational runs of the ECMWF have all shown significant growth over the Gulf.

Residents along the entire US Gulf coast and FL should closely monitor the progress of this system.

Review hurricane preparedness plans and be fully ready to enact these plans by late this weekend.

[Portastorm]

It’s inflammatory and misleading and upsetting to coastal residents, and I humbly propose that we quit it.

I have to disagree with Mr. Norcross on this statement. People are going to access the information one way or another. It can't be 'hidden' from the public. We rely on professional Mets to provide model interpretation and context to the general public; that is their job. Some do it better than others. Posting a model graphic is not "inflammatory and misleading" unless the Met presenting it doesn't provide the proper context.

Mr. Norcross - what's "inflammatory and misleading" (and I have a few other choice words in mind) is hiding information from people because you think they can't handle it. A solid, professional Met with good communication skills shouldn't have a panicked audience.

The problem is that many of these model posts come from amateurs and NOT meteorologists and they seldom are put into context. What happens next is government and private sector mets spend the bulk of their time trying to put those initial tweets into some kind of context. No, you cannot stop information from being shared ... but hopefully persons on social media use some personal responsibility and realize that if they are seeing something from a non-professional, they should take it with a grain of salt.

[tireman4]

Better to be in the loop than not. Smart move for any weather events...snow, floods, frigid temperatures.

[sambucol]

When is the next EURO model run?

[Scott747]

When is the next EURO model run?

Starts rolling out around 1 and takes about an hour.

[Scott747]

So far the 12z euro is just a shade further w through 96 hr. Ridging remains stout.

It's also a little weaker on the approach to S Fla.

[Scott747]

Timing is slower compared to 0z.

[Andrew]

Large shift east. Siding towards the Gfs with track. Still little confidence in any solution.

[jasons2k]

So much for the Euro being rock-solid with that ridge. I can't say I believe it after just one run. I think it's having a hard time with the interaction between Gaston and the ridge. Tonight's run will be interesting.

[Andrew]

After several model runs there are a couple things I think can be taken away. First off, I think a general consensus is growing that a faster storm will progress further west under the SE USA ridge. Furthermore, Gaston will have an influence on speed by how far it progresses west and breaks down ridging. A further west track will result in weaker steering and a further east landfall. Finally, the models are having huge troubles with development and breakdown of ridging over the southeast. Until that stabilizes we will continue to see these 500 mile swings.

[srainhoutx]

The afternoon updated Weather Prediction Center Day 3 to 7 surface charts suggests the surface reflection of potential Hermine will be South of Louisiana next week. I see no reason to dismiss a potential Gulf of Mexico scenario regardless of the daily shifts of the operational guidance. The SE Ridge has been very strong all late Spring into Summer. I see no significant changes via the ensembles that the persistent SE United States/Bermuda Ridge will quickly disappear.

Once we get additional synoptic data from the Global Hawk ingested into the Global computer guidance and actual Tropical Cyclone Genesis occurs, expect swings in the computer models.

[don]

One interesting thing to note is that some of the models (Euro,NAM,UKMET) show what appears to be a possible depression or weak tropical storm in the northwest gulf moving towards the Texas coastline around the same time future Hermine is in the gulf,which could be influencing the track of 99l.

[Texaspirate11]

it’s inflammatory and misleading and upsetting to coastal residents, and I humbly propose that we quit it, especially in scenarios like this one that are wildly uncertain except for the broad strokes

With all due respect to this Mr. Norcross, I can guarantee you he's never evacuated a county.
While the models this far out cant be written in stone, it helps us remind the community, that
we are in hurricane season, anything can happen, and one must be prepared.
We can do this without panic ,but with reassurance that being prepared, is the smartest thing to do.

[Andrew]

LLC is quickly racing off to the northwest while the MLC and convection stay off to the south. It will be interesting to see if convection starts to form on the northwest side or if the MLC takes over and makes its way to the surface.

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

[Scott747]

LLC is quickly racing off to the northwest while the MLC and convection stay off to the south. It will be interesting to see if convection starts to form on the northwest side or if the MLC takes over and makes its way to the surface.

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

I think we're still a few hours away before seeing some consolidation. Either we start seeing some as the evening into the early morning hours progress (Euro) or it remains disorganized.(GFS.)

And Steve, apparently I was wrong about the Global Hawk mision. It appears to be scheduled for Gaston and not 99l unless they changed the mission. Rather surprising to be honest but they may have wanted a mature system.

[Andrew]

LLC is quickly racing off to the northwest while the MLC and convection stay off to the south. It will be interesting to see if convection starts to form on the northwest side or if the MLC takes over and makes its way to the surface.

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

I think we're still a few hours away before seeing some consolidation. Either we start seeing some as the evening into the early morning hours progress (Euro) or it remains disorganized.(GFS.)

And Steve, apparently I was wrong about the Global Hawk mision. It appears to be scheduled for Gaston and not 99l unless they changed the mission. Rather surprising to be honest but they may have wanted a mature system.

I think we are still a day or so out before development can occur. Still have 30-40kt shear just north of the system, but anticyclonic flow is developing above (even though it is further to the west) so that will help development over the next couple days as shear decreases.

[srainhoutx]

I think we're still a few hours away before seeing some consolidation. Either we start seeing some as the evening into the early morning hours progress (Euro) or it remains disorganized.(GFS.)

And Steve, apparently I was wrong about the Global Hawk mision. It appears to be scheduled for Gaston and not 99l unless they changed the mission. Rather surprising to be honest but they may have wanted a mature system.

My understanding is that some of the 86 drops from Wallops Island, VA (Global Hawk) en route to Gaston may well provide some synoptic critical data, but that remains to be seen. I do see the a synoptic P-3 flight has been added for 99L, so hopefully these combined missions will assist the computer models over the next 48 hours or so. I will not be surprised to see additional RAOB balloon launches across the United States added to further assist the upstream synoptic data in the next couple of days depending on future development.

Good job gang in providing reliable and factual information. My days will be hectic until the weekend when I will have a bit of additional time to drop in. Meanwhile, Kudos everyone!

[unome]

99L research missons, per HRD: https://noaahrd.wordpress.com/ & https://twitter.com/HRD_AOML_NOAA

Wednesday, 24 Aug 2016

No flights are scheduled for today.

Thursday, 25 Aug 2016

NOAA43: Is scheduled to fly a Genesis/Rapid Intensification Experiment research mission into AL99 – the tropical disturbance north of the Leeward Islands. Take off is scheduled for 0600 UTC (2AM Eastern) to and from MacDill Air Force Base, Tampa, FL. The goal for this mission is to collect data to understand how the disturbance interacts with the surrounding environment. This will be the first flight of a series of flights every 12 hours. Four HRD scientists will be on this flight.

NOAA43: Is scheduled to fly a Genesis/Rapid Intensification Experiment research mission. Take off is scheduled for 1800 UTC (2PM Eastern) to and from MacDill Air Force Base, Tampa, FL. Four HRD scientists will be on this flight.

more here: http://www.aoml.noaa.gov/hrd/Storm_page ... ssion.html

[unome]

more on NASA's Global Hawk

http://www.nasa.gov/mission_pages/hurri ... 74anqI4p2E

http://www.nasa.gov/feature/nasa-global ... orm-gaston

https://www.nasa.gov/centers/armstrong/ ... egins.html

https://twitter.com/NASAHurricane


and SHOUT

http://uas.noaa.gov/shout/

[Scott747]

And the windshield wiping continues...

18z GFS is further W, faster and disorganized. Still another 4 cycles or so before we may get 'some' confidence in models. Around 0z tomorrow night.