ATL: HARVEY - Post-Tropical - Discussion

[N2FSU]

If we keep seeing those storms re-firing on the northern side of the Yucatan P low pressure could form closer to those storms making the models to shift more to the right, IMO.

Will be interesting to see if any more significant eastward track shifts occur, or is that about as far east as we can expect?

[GCANE]

If we keep seeing those storms re-firing on the northern side of the Yucatan P low pressure could form closer to those storms making the models to shift more to the right, IMO.

Agreed. The VHT is heating a core at the mid-levels around 500mb to 400mb.
That should close off the 500mb vort.
So, the 850mb-to-700mb vort will be coming off the coast SW of the 500mb vort this evening.
The way I see it, the LL vort should shift a bit NE as it attempts to stack with the 500mb vort in the BoC.
Houston may get more in the cross hairs.

[Thetxhurricanemaster]

If we keep seeing those storms re-firing on the northern side of the Yucatan P low pressure could form closer to those storms making the models to shift more to the right, IMO.

Will be interesting to see if any more significant eastward track shifts occur, or is that about as far east as we can expect?

I think it's shifted as far East as it's gonna go most models been aiming at north padre island or Matagorda Bay the furthest east this will probably shift is Galveston island and I'm thinking a south padre island kinda hit I don't want a hurricane I'm in corpus christi and I hope it doesn't become a hurricane we can take a tropical storm because of our drought

[TexasStorm]

Now that there is a chance of a cane in the GOM, gas prices are going to shoot up the next few days. Fill up now!

[SouthDadeFish]

If you live in northeast Mexico or near the Texas coast, you should definitely pay close attention to the remains of Harvey. If genesis does occur in the Gulf, which looks likely at this time, the models are indicating the potential TC will be in a favorable environment for intensification. There is no reason to freak out, but it is mid-August and you should definitely have your hurricane plans in place.

[stormlover2013]

kinda of hard not to freaking out when its tuesday lol,.. the window is closing!!!

[Digital-TC-Chaser]

That dry air will mix in with the shear.



Divergence aloft below 25-30 is not suggestive for a storm to explode in the lower BOC.
A large depression or TS is more likely in the BOC. Not thinking HARVEY Remnants will
organise very quickly. Further N is likely a cane tho.

[TeamPlayersBlue]

Based on the Upper level high and where its developing, my guess is Matagorda, north of Palacios. We will know more after they sample the GOM today. Im in Sugar Land and currently the models send the buzz saw right through me, so we will see.

Intensity? I dont want to answer that question.

[Bhuggs]

Watching the coverage of this is very interesting. No one (other than on here) is talking about it. Waiting for something to form I guess. Problem is, when it forms there won't be much time. If it was one model I would understand, but every model is showing it now. Hope people aren't caught too off guard

[Alyono]

favorable conditions may not occur until late Thursday. However, once they do appear, rapid or explosive intensification is what the models are saying

[srainhoutx]

favorable conditions may not occur until late Thursday. However, once they do appear, rapid or explosive intensification is what the models are saying

Our biggest fear is a Humberto like Storm, except slower forward motion and a possible stall before being picked up by the frontal boundary. NOAA G-IV mission hopefully will resolve some of the guidance issues.

[NDG]

This is where I am seeing the vorticity this morning, IMO.

[Digital-TC-Chaser]

favorable conditions may not occur until late Thursday. However, once they do appear, rapid or explosive intensification is what the models are saying

Hear, hear
Agree nothing atm suggests this will take off out off the blocks.Condition don't look that great in the lower BOC.

[CYCLONE MIKE]

Agree, see no possible outcome that this is going to bomb once it enters the gulf. Even the NAM, navgem, and other models that like to blow things up quickly don't have this really getting organized quickly until Thursday.

[Tireman4]

favorable conditions may not occur until late Thursday. However, once they do appear, rapid or explosive intensification is what the models are saying

Our biggest fear is a Humberto like Storm, except slower forward motion and a possible stall before being picked up by the frontal boundary. NOAA G-IV mission hopefully will resolve some of the guidance issues.

My worry too....It might catch folks off guard....

[cycloneye]

NDG,close to your position.

12z Best Track:

Location: 19.4°N 89.2°W
Maximum Winds: 25 kt Gusts: N/A
Minimum Central Pressure: 1010 mb
Environmental Pressure: 1013 mb
Radius of Circulation: 120 NM
Radius of Maximum Wind: 90 NM

[vbhoutex]

This is Jeff Lindner's take on the possibilities of Harvey regenerating as of last night.

Tropical storm or hurricane threat to the TX coast late this week

The strong tropical wave formerly known as Harvey have continued to show increased signs of organization today, but there is no evidence of a defined low level circulation and convection has been decreasing this evening. Surface observations suggest that a broad circulation is found generally ESE of where the deep convection has been found today moving generally toward the WNW or in the direction of the southern Yucatan.

Expect the tropical wave axis to reach the eastern coast of the Yucatan on Tuesday and then emerge into the southern Gulf of Mexico early Wednesday. The well defined upper level low pressure system over the central Gulf of Mexico continues to move westward and will reach the NW Gulf late Tuesday into Wednesday and begin to weaken into a large weakness or shear axis. In other words this feature will break down the remaining ridging over TX and the NW Gulf allowing a trough across the central US by late week to push a frontal boundary deep into the state. This weakness in the ridge appears enough now to turn “Harvey” NW over the Gulf of Mexico with landfall potential from near Tampico, MX to Matagorda Bay, TX. The GFS has become the northern outlier today with a track toward Port Aransas while the CMC is the southern outlier with a track toward Tampico, MX and the ECMWF showing a landfall between BRO and CRP. At this point it is not overly important to focus on individual operational model runs, but instead the trends and the model ensembles. The trends today have been a general more northward track from an early morning consensus in NE MX to a late afternoon consensus over S TX. The CMC, GFS, and ECWMF ensembles are generally aimed at NE MX/S TX.

Much will depend on where a “new” center forms once the wave reaches the Gulf of Mexico early Wednesday. Should the surface center form northward along the wave axis a track toward the middle or upper TX coast would be possible, while a center formation toward the northern Bay of Campeche would likely result in a track toward NE MX/ S TX. It is impossible to determine at this time where any center may form which leads to a low amount of confidence.

One aspect noted in the model trends today is that even with a NE MX landfall the remains of the system get brought northward into SC TX this weekend and collide with the stalled frontal slop over the region. Both the GFS and ECMWF show the outbreak of a fairly significant rainfall event as the remains linger over coastal TX for 3-4 days post landfall and interact with the stalled frontal boundary. This trend can be noted in the “EPS” tracks below showing varying directions and looping motions over TX later in the forecast period indicating a system that is trapped in weak steering flow aloft.

Conditions appear generally favorable for intensification over the Gulf of Mexico with most models showing the formation of a 200mb high pressure cell over the system by the middle of the week helping to vent the surface center and preventing any sort of wind shear. Water temperatures are certainly warm enough to support intensification. The only drawback to intensification will be the 48-60 hours over the Gulf waters, but if conditions are ripe we have certainly seen storms in the past increase 40-60mph in that amount of time. For now will cap the intensity near a strong tropical storm, but a hurricane is certainly possible especially if the system develops quickly after leaving the Yucatan.

Note: NHC has tasked a high altitude mission tomorrow evening across the Gulf of Mexico to sample upper air steering patterns and have 3 USAF missions planned for Wednesday

Tropical Storm or Hurricane watches and warnings may be required for portions of the MX/TX coast as early as Wednesday.

Impacts:

For now will only raise rain chances starting Thursday and hold them high into the weekend and likely will need to closely monitor trends in amounts over the next few days. Will likely have to start pushing up tides starting Thursday, but not sure how high they may go at this point. Seas will almost certainly need to be raised from the flat-2ft currently over the coastal waters. Likely will see 6 ft by Thursday and could likely double that for Friday and Saturday for portions of the TX waters especially south of Matagorda Bay.

Residents along the TX coast should review hurricane preparation plans and be prepared to enact those plans this week

[Christiana]

This is potentially catastrophic in terms of flooding. The quick right turn in the models tells me that a lot will go into timing. This thing will need to be shunted out of there, a slow moving coastal rider, awful. ....and the only place probably worse to try to evac from than NOLA, is Houston. Time for our Texas friends to get their ducks in a row. Looking forward to recon.

[srainhoutx]

Tuesday morning briefing from Jeff:

***Tropical storm or hurricane threat to TX late this week/weekend***

Residents along the entire TX coast should review hurricane preparation plans today and be fully ready to enact these plans.

Widespread excessive rainfall/flood event increasingly likely Friday-Sunday

Forecast trends overnight continue to suggest that the tropical wave currently crossing the Yucatan will emerge into the southern Gulf of Mexico early Wednesday. The well defined, yet weakening, upper level low now S of Lake Charles will continue to move westward and weaken allowing the continued break down of sub-tropical ridging across TX. This will allow the developing tropical system over the southern Gulf of Mexico to turn NW and NNW toward the TX coast. Nearly all global model guidance is now N of the TX/MX border with landfalls anywhere from Freeport, TX to near Brownsville, TX. The general consensus track is in the region bounded by Corpus Christi on the south and Matagorda Bay on the north. While the model spread is fairly large, the timing is fairly similar and has been for the last 24-36 hours that the system will landfall along the TX coast Friday evening.

The forecast becomes incredibly complex near/after landfall as the upper level steering flow weakens and the system begins to slow down and possibly stall or meander over the region not far inland of the coast. This is the result of the system becoming caught in a “col” region between high pressure to our NW and our NE and a weak frontal zone which will stall Thursday north of I-10. It appears the system will eventually become caught in the frontal trough and slowly creep E/ENE across much of SC/SE TX into SW LA from Friday-Monday. Should this verify as suggested by several forecast models, rainfall and flooding would be “incredible” over the region.

Intensity:
Global models have become aggressive overnight with intensity with both the GFS and hurricane model HWRF showing significant intensification over the NW Gulf Thursday and Friday while the ECWMF, CMC, and UKMET show more modest intensification. It appears nearly everything will align for intensification over the NW Gulf with a 200mb high aloft, very warm SST’s, and possibly the formation of an outflow channel to the south and north of the surface circulation which almost always supports intensification…sometimes rapid. The NW Gulf is certainly no stranger to the formation and rapid intensification of tropical systems and this must be watched very closely once the system enters the Gulf early Wednesday. General consensus of the intensity models bring the system to a minimal category 1 hurricane at landfall along the middle TX coast. Any slowing of the forward motion would only give the system more time to intensify across the NW Gulf….this must be watched very closely.

Impacts:

Impacts appear increasingly likely along the entire TX coast starting as early as Thursday along the lower TX coast and spreading northward on Friday into the middle and upper coast. Following the TVCN track of the major multi model consensus brings tropical storm conditions into the Matagorda Bay region on Friday with hurricane conditions possible over that region Friday night into Saturday morning.

As long as the system does not become more than a category 1 hurricane…the legacy will likely become excessive rainfall and inland flooding. Major models are very aggressive and rightly so with some very impressive rainfall totals given the slow meandering motion near/after landfall. A very large portion of the state generally south of the I-10 corridor could see totals over 2-3 days of 10-15 inches with isolated amounts of 25+ inches. This is a potentially very serious flash flood and river flood threat for a large portion SC/SE TX and the coastal bend. Exact totals will be redefined with time as the track confidence increases

Will not use WW3 guidance on coastal impacts as it is based off the highly aggressive GFS run. Instead will follow the TVCN track which would place at least TS force winds across all of the lower and mid coast waters on Friday and at least the western part of the upper coast waters Friday afternoon and night. Hurricane conditions possible Friday night mid coast into our western waters. Will bump seas to 6 feet Thursday as large long period swells begin to arrive out of the central Gulf which will likely start to push up tides. Will go with 12 feet on Friday with 18 ft over our offshore waters as conditions build to near hurricane force west of Palacios Friday night. Will certainly need to start looking at storm surge threat potential, but without a defined track nor guidance from NHC will just have to wait…certainly could see tides breach the 4.5 ft warning criteria over Matagorda Bay and portions of the upper coast on Friday night into Saturday…but unsure how high they may go as this is very dependent on track and intensity.

Much of these impacts will change over the next 24 hours and this is a very low confidence forecast.

Residents along the TX coast should be closely monitoring weather information at least once a day. Hurricane plans should be in place and ready to be enacted over the next 24 hours.

Tropical Storm or Hurricane watches and storm surge watches will likely be required for portions of the TX coast on Wednesday.

[gatorcane]

Well Western GOMers looks like something of significance here. Think you have to go back to 2008 Ike (9 years) since something significant has threatened the USA in the WGOM. Model trends are not looking good for sure with most now pointing at the middle Texas coastline. Think the GFS is too strong (as usual) and the ECMWF might be handling this a bit better. Something in the middle might make sense. Could be a hurricane at landfall.