Tracking the Tropics:

[srainhoutx]

The 18Z HWRF suggests potential Hermine finally organizes well S and W of what we've been seeing becoming a Tropical Storm NW of Havana and WSW of the Dry Tortugas.

Meanwhile the National Hurricane Center decreased the changes for development, but does acknowledged that conditions may become more favorable for Tropical Development early next week over the SE Gulf of Mexico.

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT THU AUG 25 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical
Storm Gaston, located about 1100 miles east-northeast of the
Leeward Islands.

1. A broad area of low pressure associated with a tropical wave is
moving westward at 15 to 20 mph through the southeastern Bahamas.
This system has become less organized since yesterday, with only
minimal associated shower activity, and the chances for development
during the next 2 days have decreased. Overall, environmental
conditions are not expected to be as conducive for development of
this system as anticipated earlier this week. However, upper-level
winds could become a little more favorable over the weekend or early
next week when the system is expected to be near the Florida Keys or
over the southeastern Gulf of Mexico.

Regardless of development, heavy rains, with the potential to
cause flash floods and mudslides, are likely over Hispaniola and
eastern Cuba through tomorrow. This system could produce gusty
winds and locally heavy rainfall over portions of the Bahamas during
the next day or two. Interests in South Florida and the Florida Keys
should monitor the progress of this disturbance since it is possible
that some impacts, such as heavy rains and gusty winds, will occur
beginning this weekend.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...60 percent

Forecaster Blake

[Scott747]

Still would like to see the 0z runs with full data, but....

Bad news is that 99l looks like it will make it much further into the Gulf.

Good news is that it's on life support right now and the environment as modeled isn't the most conducive.

Still PLENTY of time to track, conditions to change and models to flip flop.

[Skyguy]

From my good buddy:meterologist in Houston area

Good afternoon everyone,

I hope your Thursday is going well. We are just a couple of days from the weekend. So this email will not be quite as lengthy as yesterday's as many of you are thinking "thank goodness." HA! Anyway, here are the trends we have seen today along with my thoughts over the next couple of days as well.

The tropical disturbance out there is very poorly defined as you can see on visible satellite imagery. Now keep in mind, if you look at this link later tonight when it is dark, you will not see what I am seeing now, however if you do view it by 6-7 PM central time, you will see what I am talking about below.

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

Do not pay any attention to the cloud cover along the Dominican Republic and Hispaniola. This is associated with the disturbance but due to the 40-50 knots of shear (inhibiting development) affecting this system, the activity is being displaced from the center. Notice the little swirl north of the islands in the image above.

The other factor not allowing it to develop is the dry air. The water vapor which is the link below shows dry air (orange color) just west of the disturbance which also inhibits development. There is still quite a bit of shear and dry air ahead of this thing and it will need to rally big time for it to develop before making the Bahamas.

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

Many of the model runs have shifted further west during the day and this goes with my thinking from yesterday as the ridge of high pressure (what steers the system) sits across the southeast United States. This will be strong enough to push it west into the eastern and eventually the central Gulf of Mexico.

The strength of this thing could vary from a strong tropical storm to a major hurricane. Like I mentioned yesterday, predicting the magnitude of a tropical system is nearly impossible. The conditions will be ripe for prime strengthening across the Gulf of Mexico but what matters is how long is stays over the waters.

So my thoughts and where I still feel will strike are below...

The disturbance will remain an open wave until it reaches the Bahamas, it will strengthen into either a depression of Tropical Storm where it would become Hemine. It will either clip the southern tip of Florida or make it through the Florida Straits. It will continue on a west to northwestward track into the southeast Gulf of Mexico. This ridge will still hold strong. After that, is really up in the air to whether it continues west towards the Texas/Louisiana coastline, the central coast or the Florida panhandle. As for the strength of this storm, it is really hard to say at this time.

Here are my thoughts for the FINAL LANDFALL:

Brownsville to Matagorda Bay, TX - Less than 5%
(Late week to Labor Day weekend)

Matagorda Bay to Sabine Pass, TX - 20-30%
(Late week to Labor Day weekend)

Sabine Pass, TX to New Orleans, LA - 20-30%
(Late week)

New Orleans, LA to Panama City, FL - 30-40%
(Mid week)

Panama City to Tampa, FL - 10-20%
(Early to mid week)

On many of the TV stations you will see the spaghetti plots that have really become popular over the past few years. I will not show them for a couple of reasons; first, when a "storm" hasn't formed yet, it is hard for weather models to focus on an actual center, and secondly when a person sees one plot heading their way, they instantly think it is going to affect them. When and if something does form, I am fine (for the most part) with showing those plots. Ok, I am off my soap box...sorry...

There are three things I look at when looking at the track of a tropical system: historical tracks, upper pattern and my gut. Sounds crazy but these are the factors I look at and they have helped me become a better forecaster because of it.

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

I will continue to provide updates each evening through the rest of the week and into the weekend. If many of you want this sent to your personal emails versus work emails during the weekend because you don't check them, please let me know. Also, if there is anyone else who wants to receive these emails, also shoot me a quick message and I will add them to the list.

As always, you can follow me on Twitter @Nathan_Weather where I also provide updates, retweets, other pertinent information as well.

I hope everyone has a great Thursday and Friday. I will try to have an update out to you all tomorrow afternoon before leaving for work for the weekend. Enjoy!

Nathan

Are you saying that New Orleans, LA to Panama City stands the best chance of getting hit at 30-40%?

[Skyguy]

1. I don't know what bearing this has on Houston's chances of getting hit, but I'll post it anyway:

National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.
Given this agreement, have opted to stick with a drier forecast as
strong mid and upper level ridging develops across the Lower
Mississippi Valley. The strong ridging aloft should warm and dry
out the mid and upper levels of the atmosphere resulting in lower
instability and lower atmospheric moisture content. At this time,
have went with POP of 20 to 30 percent for each day next week.
Temperatures should also climb due to the sinking air aloft and
increase in solar insolation with highs easily climbing into the
middle 90s each day. Fortunately, with dewpoints somewhat lower
heat index values should remain below advisory levels.


2. Is this thing drawing a bead on SE Texas?

[jasons2k]

1. I don't know what bearing this has on Houston's chances of getting hit, but I'll post it anyway:

National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.
Given this agreement, have opted to stick with a drier forecast as
strong mid and upper level ridging develops across the Lower
Mississippi Valley. The strong ridging aloft should warm and dry
out the mid and upper levels of the atmosphere resulting in lower
instability and lower atmospheric moisture content. At this time,
have went with POP of 20 to 30 percent for each day next week.
Temperatures should also climb due to the sinking air aloft and
increase in solar insolation with highs easily climbing into the
middle 90s each day. Fortunately, with dewpoints somewhat lower
heat index values should remain below advisory levels.

2. Is this thing drawing a bead on SE Texas?

It's just too early to tell. If it continues to clip along and ends-up in the Gulf, anything could happen. Question is, can anything hold together and make it that far? The shear has been pretty tough but conditions gradually improve going forward.

My opinion - if anything happens, I don't expect it until it gets to about the FL Straits. Sometimes the land effect between FL and Cuba can help tighten up a slowly strengthening system, and it's like bath water. Then it all depends on the ridge. A lot will change between now and then, but at least for now we have some time to watch it.

[Skyguy]

1. I don't know what bearing this has on Houston's chances of getting hit, but I'll post it anyway:

National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.
Given this agreement, have opted to stick with a drier forecast as
strong mid and upper level ridging develops across the Lower
Mississippi Valley. The strong ridging aloft should warm and dry
out the mid and upper levels of the atmosphere resulting in lower
instability and lower atmospheric moisture content. At this time,
have went with POP of 20 to 30 percent for each day next week.
Temperatures should also climb due to the sinking air aloft and
increase in solar insolation with highs easily climbing into the
middle 90s each day. Fortunately, with dewpoints somewhat lower
heat index values should remain below advisory levels.

2. Is this thing drawing a bead on SE Texas?

It's just too early to tell. If it continues to clip along and ends-up in the Gulf, anything could happen. Question is, can anything hold together and make it that far? The shear has been pretty tough but conditions gradually improve going forward.

My opinion - if anything happens, I don't expect it until it gets to about the FL Straits. Sometimes the land effect between FL and Cuba can help tighten up a slowly strengthening system, and it's like bath water. Then it all depends on the ridge. A lot will change between now and then, but at least for now we have some time to watch it.

I'll trust the WPC.

[houstonia]

1. I don't know what bearing this has on Houston's chances of getting hit, but I'll post it anyway:

National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.

It seems a little presumptuous of the NoLA weather service, doesn't it? Do the models actually loop it back to the NE after it enters the Gulf? That seems like a pretty big switch after talking about the strong ridge, doesn't it? Is there something that I am not understanding, I wonder?

[Ptarmigan]

1. I don't know what bearing this has on Houston's chances of getting hit, but I'll post it anyway:

National Weather Service New Orleans LA
355 PM CDT THU AUG 25 2016

Heading into next week, both the ECMWF and the GFS indicate that
any potential tropical system should remain east of the region.

It seems a little presumptuous of the NoLA weather service, doesn't it? Do the models actually loop it back to the NE after it enters the Gulf? That seems like a pretty big switch after talking about the strong ridge, doesn't it? Is there something that I am not understanding, I wonder?

Probably not to scare people. Lot of uncertainty.

[Andrew]

GFS is back on development slightly.

[Skyguy]

GFS is back on development slightly.

Emphasis on slightly.

Uh, wouldn't a system like that be less trouble for Houston than a mature TC?

[unome]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT FRI AUG 26 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical Storm Gaston, located about 1200 miles east-southeast of Bermuda.

1. A weak area of low pressure extending from eastern Cuba northward to the central Bahamas is producing disorganized shower and thunderstorm activity. Upper-level winds are expected to remain unfavorable for significant development during the next couple of days while the system moves west-northwestward at about 10 mph. Environmental conditions could become a little more conducive for development early next week when the system moves into the eastern Gulf of Mexico. The Air Force Reserve Hurricane Hunter aircraft scheduled to investigate this system this morning has been canceled.

Regardless of development, heavy rains, with the potential to cause flash floods and mud slides, are likely over Hispaniola today and over eastern and central Cuba through the weekend. Gusty winds and locally heavy rainfall are likely over portions of the Bahamas, and will likely spread into parts of South Florida and the Florida Keys over the weekend. Interests elsewhere in Florida and the eastern Gulf of Mexico should continue to monitor the progress of this disturbance.
* Formation chance through 48 hours...low...20 percent
* Formation chance through 5 days...medium...60 percent

2. A weak area of disturbed weather is located over the north-central Gulf of Mexico. Surface pressures in this area are currently high, and little to no development of this system is expected before it reaches the coast of Texas over the weekend.
* Formation chance through 48 hours...low...10 percent
* Formation chance through 5 days...low...10 percent

Forecaster Brennan/Brown

[houstonia]

Morning briefing from Jeff regarding our area of disturbed weather as well as 99L:

Increasing heavy rainfall threat this weekend generally along and SE of US 59.

An upper level low over the NW Gulf will move inland over S TX today and will gradually result in the formation of a mid level and possibly surface low pressure system over the NW Gulf of Mexico this weekend. Forecast models are in some agreement on a surface low forming roughly 150 miles SE of Galveston starting late tonight and into Saturday and drifting toward the WNW this weekend and inland over the upper TX coast. Upper level winds out of the SSW and S on the eastern flank of the upper level low are currently unfavorable for development, but there could be a window on Saturday for some modest organization of this feature and NHC currently gives the system a 10% chance of formation over the next 48 hours.

Main impact of this system will be heavy to excessive rainfall as the envelop of tropical moisture associated the feature across the northern Gulf moves ashore over TX. A low level trough axis of actual surface low formation will only help to organize and concentrate excessive rainfall around a central core which would increase the flooding threat especially across the coastal counties Saturday night into Sunday. Overall system and individual storm motions will be very slow and this combined with the very moist air mass points to the potential for several inches of rainfall along and SE of the US 59 corridor over the weekend.

Grounds across the region are wet to saturated from all the recent rainfall and additional heavy rainfall over the weekend is expected to generate run-off.

99L:

Much talked about tropical wave has become extremely disorganized overnight due to strong upper level winds shear of 20-30kts over the system and dry mid level air (RH around 45%). The result of these two negative factors along with the disruption of southerly moist inflow by the higher terrain of the mountainous Caribbean Islands has resulted in an overall degradation of the feature. In fact the USAF mission for today has been cancelled and the NHC currently only gives the system a 20% chance of development over the next 48 hours as it moves generally W to WNW toward Cuba and the Florida Straits.

Development chances increase to 60% after 48 hours as the feature moves into the SE Gulf of Mexico, but is very possible that there will not be enough organization of the wave by that time for anything to develop. Interestingly, global and hurricane forecast models continue to have varying degrees of development over the eastern Gulf of Mexico along with continued various tracks. Given the overall disorganization of the feature this morning and lack of any defined low level center or “vortex” support of any of the model guidance is of very low confidence. There is some consensus that if anything does form over the SE Gulf of Mexico that it would tend to track toward the central or eastern Gulf coast.

[sau27]

Although still displaced from what appears to be the center, convection looks better this morning than it has in past 24 hours or so.

[sambucol]

Are there signs it's starting to develop?

[srainhoutx]

It appears that it is developing now. Wind shear has collapsed and a Reconnaissance Mission is due to arrive later this afternoon to verify if we indeed have a Tropical Cyclone.

[tireman4]

This might be the ramping up period that Srain, Andrew and Wxman 57 have talked about since the beginning. Be aware folks. Meanwhile, we have to deal with rain this weekend.

[ticka1]

can someone point where the LLC might be developing? thank you

[tireman4]

I think it is the blue Ascat pass...but Srain can tell you more..

https://postimg.org/image/coloyp1el/

[ticka1]

I think it is the blue Ascat pass...but Srain can tell you more..

https://postimg.org/image/coloyp1el/

thank you that helps

[Andrew]

LLC still looks a little displaced to the west but convection is increasing around it. During D-MAX tonight we may see more thunderstorms increase around in and as a result see some genesis over the next 24-48 hours.