ATL: HARVEY - Post-Tropical - Discussion

[Alyono]

still have moderate wind shear over this, likely mid level shear. However, the shear is dropping off. In addition, spiral banding is starting to form

[ROCK]

still have moderate wind shear over this, likely mid level shear. However, the shear is dropping off. In addition, spiral banding is starting to form

oh I agree...probably a stacking issue attm...and wasn't even forecasted to strengthen right away. Just looks really good to be 1003MB

[Digital-TC-Chaser]

Upstream pineye core cane maybe.

[TeamPlayersBlue]

Im still not sure aboiut this GFS shift. Strengthened the HP quite a bit more than before. We shall see, i still think it has Matagorda in its sites as a strong Cat 1. Now, intensity wise, i could be wrong, it could be alot stronger, but im hoping the shear can choke it off a bit

[hd44]

has to be a TS now...geez...best TD I have ever seen..

I expect ts by 11pm and potentially strong ts by 8am.

[RL3AO]

has to be a TS now...geez...best TD I have ever seen..

I expect ts by 11pm and potentially strong ts by 8am.

I still don't see the internal structure yet. These depressions take time before they can go nuts.

[Alyono]

has to be a TS now...geez...best TD I have ever seen..

I expect ts by 11pm and potentially strong ts by 8am.

I still don't see the internal structure yet. These depressions take time before they can go nuts.

actually getting a blast of mid level shear. all convection on the west side is dying. That said, banding is improving on the eastern side.

This structure can take a day or two where they do nothing, but when they consolidate, they can intensify 60 mb in 24 hours.

[RL3AO]

I expect ts by 11pm and potentially strong ts by 8am.

I still don't see the internal structure yet. These depressions take time before they can go nuts.

actually getting a blast of mid level shear. all convection on the west side is dying. That said, banding is improving on the eastern side.

This structure can take a day or two where they do nothing, but when they consolidate, they can intensify 60 mb in 24 hours.

Yeah. By tomorrow evening we should be watching for signs of RI.

[hd44]

I am not seeing a lot of quick organization too however the coc does appear to be over the new exploding tstms. This should continue to lower pressure overnight and increase winds. This is because the ull is weakening on water vapor imagery (decreasing shear).
http://tropic.ssec.wisc.edu/real-time/atlantic/winds/wg8vor.GIF
Cimss 850 00z analysis shows increase of spin, and this has the hallmarks of a storm that could surprise us as we wake up. Hopefully it doesn't become a strong tropical storm and I am wrong. This will need another 24 hours before we talk hurricane though.

[tolakram]

 https://twitter.com/BigJoeBastardi/status/900502615074758656

[davidiowx]

I'm kinda wondering if this ends up being a lopsided type system where all the moisture ends up on the east side of the storm. Looking at WV there is still a lot of dry air on the western side all the way down the TX/MX coast line.

That would shove a lot of rain into central and SE Texas as well as La. Which explains a lot of the ridiculous rain totals.

Then you see the NW quadrant cirrus really clearing that ULL out today. It kinda looks like it just ate it and the cirrus are just driving the dry air westward. Granted the tops are warming but it's trying to get going.

I'd say that may explains the models inconsistencies. As well as the disparity in tracks with the lack of steering currents in the upper levels the models continue to depict.

What a time to be alive. This looks like it's anybodies guess as to where this ends up. It's one of those wait and see storms, that could come in stronger or weaker once it's near land.

In a way, maybe the stall helped as people have started to take notice and prepare. At least I hope they have. I know I've talked to coworkers and clients and the like and they have all mentioned getting water, batteries, canned foods etc. It's always better safe than sorry!

[ROCK]

I don't get Jeff Linder's email...anyone have it here locally? Jasons?

[davidiowx]

Wednesday evening briefing from Jeff:


Weak Hurricane or strong tropical storm heading for the TX coast

Preparations to protect life and property should be underway in the hurricane and tropical storm watch areas

Potentially dangerous and life threatening flood and flash flood event for a large portion of coastal, SC, and SE TX

Discussion:

Harvey has moved little today based on USAF mission fixes and has shown very little increase in organization. While the surface circulation appears to be becoming better defined, the convective pattern has been sporadic and disorganized and there are few banding features. Some of the “slowness” on the organization is likely the NNE extending trough axis that is elongating the circulation some and spreading out the deeper convection reducing the organization near the center. Additionally, dry air is lurking just west of the center and some of this may be intruding into the circulation helping to cut down on organization.

Track:

Forecast track models continue to move Harvey toward the NW and NNW with a landfall along the lower to middle TX coast between Corpus and Matagorda Bay Friday evening. There is a general decent consensus on this track reasoning although there has been some development of model spread today compared to yesterday. Near and after landfall the steering flow collapses and Harvey is left to meander near/just inland of the coast around the coastal bend region. Harvey will find itself in a region trapped by building high pressure to the NW of TX and over the central Gulf of Mexico and a weak trough extending into E TX from the NE US. Models have shown more of a gradual loop today with the system moving W on Saturday and then S and then E by Sunday/Monday and nearly back to where it makes landfall on Friday night. For now will not go with as of dramatic of westward loop and instead slow the system and meander it slowly E to ESE near/around the Matagorda Bay/coastal bend Saturday, Sunday and Monday before a slightly faster E/ENE motion may develop by next Tuesday.

It is possible that Harvey could also stall very near the coast which would limit the amount of weakening to a degree.

Intensity:

Not expecting much organization of the system over the next 12 hours as conditions aloft gradually become better and Harvey attempt to form a more defined inner core area. On Thursday Harvey should begin to gradually intensify as it moves across 85-88 degree water temperatures and a “deep” warm eddy over the WC Gulf that broke off the Gulf stream. As Harvey nears the coast (within 18-24 hours of landfall or Friday) conditions look to become extremely favorable for intensification. In fact the latest SHIPS intensity guidance shows a 62% chance of rapid intensification, which is why it is vitally important that Harvey moves inland before slowing and stalling.

Current NHC forecast brings Harvey to a minimal hurricane just before landfall, and the intensity trend on Friday will need to be monitored extremely closely as the system nears the coast.

Impacts:

Rainfall:

Rainfall amounts of 10-15 inches over a very large area will be possible with isolated totals of 20 inches or more. Where these significant heavy rains fall potentially extends from SW LA to SC TX and S TX.

Flooding is a very real and great concern with Harvey and preparations should factor this potential

Flash flood watches will be required over the next 24-36 hours.

Storm Surge:

Coastal water level rises of 4-5 feet will be possible in the storm surge watch area. Latest NHC inundation graphic shows little above ground flooding from tides/storm surge except in the tidal marshes around Matagorda and Galveston Bays and in the tidal zones and bay around Corpus north to Seadrift.

See link for interact storm surge inundation mapping

http://www.nhc.noaa.gov/refresh/graphic ... n#contents

Coastal water levels will begin rising Thursday afternoon as larger swells begin to arrive on the TX coast. Expect tides to reach some dune lines late Thursday and then more widespread coastal flooding conditions Friday into Saturday…but still mainly in the marsh areas and the lowest most vulnerable areas.

One aspect to consider is that as Harvey stalls it will keep a strong onshore wind flow in place through the weekend and tides will be very slow to recede

Winds:

Tropical Storm force winds will spread into the coastal bend region early Friday and into the Matagorda Bay area Friday afternoon and then possibly as far NE as Galveston Bay Friday night. Hurricane conditions will move into the coastal bend region from Port Aransas to Matagorda Bay Friday night and continue into Saturday morning and spread inland across the current Hurricane Watch area counties. Think Matagorda County may see gusts to hurricane force and this is less likely in Brazoria County even though they are in the hurricane watch area. With very favorable conditions aloft, Harvey will only slowly spin down once inland and hurricane conditions will be possible 1-2 counties inland over SC TX on Saturday which is why the hurricane watch included those inland areas. Tropical storm conditions will be possible along much of the upper TX coast Saturday and inland across portions of Harris, Austin, Fort Bend, Wharton, and Colorado Counties.

Winds across Calhoun, Aransas, Refugio, and San Patricio counties will be the strongest Friday night (sustained 70-80 with gust to 85)

Actions:

Enact your flood and hurricane plans.

Be prepared for a prolonged multi-day event especially with heavy rainfall and flooding that could last well into next week

Power outages will be possible especially in the Matagorda Bay and coastal bend region where hurricane conditions are most likely

Some damage to roofs, windows, vegetation, and mobile homes will be possible in the coastal bend and Matagorda Bay region where hurricane conditions will be felt.

Be prepared for travel disruption across the entire region from late Friday into early next


Steve posted it on the KHOU forum

[RL3AO]

Storm Surge:

Coastal water level rises of 4-5 feet will be possible in the storm surge watch area. Latest NHC inundation graphic shows little above ground flooding from tides/storm surge except in the tidal marshes around Matagorda and Galveston Bays and in the tidal zones and bay around Corpus north to Seadrift.

See link for interact storm surge inundation mapping

http://www.nhc.noaa.gov/refresh/graphic ... n#contents

Steve posted it on the KHOU forum

It's important to note that the storm surge inundation map will show higher values as we approach landfall. This far out, there is too much spread to make the 10% exceedance (which is mapped) more than a foot or two above ground.

[storm_in_a_teacup]

You can see Harvey feasting on the afternoon convection emerging off the Yucatan. This is a rather large system...big impacts will likely happen well away from the center..

He's a hungry boi.

[storm_in_a_teacup]

Some info on lightning:

http://www.aoml.noaa.gov/hrd/tcfaq/G9.html

It doesn't say anything about dry air though.

[ROCK]

RECON making a run for center fix..I see the 1003...maybe get lower IDK...

[floridasun78]

their issue with sat last frame missing http://www.ssd.noaa.gov/goes/east/tatl/flash-ir4.html

[jabman98]

Here in Houston my neighbor reported that our local Kroger is out of water. Family member went to Home Depot and said they were putting out pallets of water bottles so hopefully plenty is incoming. Spent the evening until it was too dark to see cleaning weeds, leaves and other stuff that could make flooding worse. Will be back out tomorrow afternoon and evening to clean whatever else we can.

This storm looks crazy. I guess we're in wait and see mode now.

[Digital-TC-Chaser]

The uppers are looking some what better now, the defluence is slowly being replaced with cell alignment along that trof.