ATL: HARVEY - Post-Tropical - Discussion

[TheStormExpert]

For those living in Texas

KNOW WHAT YOU WOULD DO IF THIS COMES OUR WAY. DO NO WAIT UNTIL THE LAST MINUTE

Couldn't of said it better enough! This could be a significant storm at landfall in Texas especially if the GFS pans out.

[GCANE]

Current Yucatan Obs showing lowest surface pressures in Belize at 29.84mb.

[GCANE]

Currently, closed vorts at 850mb and 700mb.
500mb open.
Boundary layer (1000mb to surface): very weak low.

[GCANE]

Air column over the Yucatan is essentially super saturated.
From the top of the boundary layer to the tropopause.
Very likey, will see massive convection fire up over the Yucatan this afternoon.
With the well structured 850mb to 700mb vort, I expect to see Harvey hit the BoC water running hard this evening.
Also, given the more northerly track, secondary Coriolis effects will likely enchance spin up.

[GCANE]

Lots of fuel to work with here.
Once Harvey deepens in the BoC, he will draw TPW out of the East Pac where there is nearly an endless supply.

[Nimbus]

The winds in Cancun shifted south of east briefly earlier but the surface low appears quite far south over the Yucatan. When the convection starts to burst off the coast over the BOC later today we should know if the center is going to reform further north. GFS appears to be based off Wxman57's forecast for a fastball pitch.

[Digital-TC-Chaser]

There some dry-air about in SE BOC.

[GCANE]

Very high Theta-E in the GOM waiting for Harvey to jump in.
Large areas of 3000+ CAPE forecast to develop this afternoon.
More fuel for the fire.
Any convection / area of LL convergence that runs into a area of high instability such as this essentially explodes.

[GCANE]

Looks like a VHT is currently firing off the coast of Cancun.

[cycloneye]

@EdValleeWx
Plentiful energy for #Harvey to regenerate on its approach to #Texas. Big time rains likely, intensifying tropical system possible this wknd

 https://twitter.com/EdValleeWx/status/899943137996656640

[GCANE]

That is a very vigorous and persistent Vortical Hot Tower just NE of Cancun.

[NDG]

The Euro shows the building UL anticyclone over the GOM by tomorrow through Friday night, incredible favorable UL conditions for Harvey over the GOM through that time, its outflow will be incredible!

[Digital-TC-Chaser]

http://rammb-slider.cira.colostate.edu/ ... mmb-slider


Dry-air about is likey sinking down from the ULL,Atm with the sar's sounding and the airmass,
sat-pic little doubt i thinks there will be some dry air intrusion in the BOC.

[GCANE]

The Euro shows the building UL anticyclone over the GOM by tomorrow through Friday night, incredible favorable UL conditions for Harvey over the GOM through that time, its outflow will be incredible!

GFS is also showing a massive equatorward outflow channel.
A rare and deadly one for the Atlantic.

[NDG]

I keep seeing people post that the disturbance over the NW GOM is an upper level low but it is also in the mid levels, this is what is causing the weakness in the ridge across the southern US in the western GOM. I mentioned this a few days ago. If it wasn't for this mid and upper level low ridging to the north across the GOM would had been stronger, Harry's remnants would had kept going towards the BOC and lower MX coast, just like the models were showing a few days ago.

[GCANE]

Latest Sat estimate at 900Z, almost 3 hrs ago.

[SoupBone]

I keep seeing people post that the disturbance over the NW GOM is an upper level low but it is also in the mid levels, this is what is causing the weakness in the ridge across the southern US in the western GOM. I mentioned this a few days ago. If it wasn't for this mid and upper level low ridging to the north across the GOM would had been stronger, Harry's remnants would had kept going towards the BOC and lower MX coast, just like the models were showing a few days ago.

Is that still within the realm of possibilities, that the ridge doesn't weaken as much, allowing for more western movement? I know anything is possible, but realistically speaking.

[NDG]

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.

[cycloneye]

8 AM TWO:


Disorganized showers and thunderstorms over the Yucatan Peninsula
and adjacent water areas are associated with the remnants of Harvey.
Environmental conditions are expected to be conducive for
development when the system moves over the Bay of Campeche tonight,
and a tropical depression is expected to form over the southwestern
Gulf of Mexico on Wednesday or Thursday. Regardless of development,
locally heavy rainfall and gusty winds are expected to spread
westward across Belize and the Yucatan Peninsula during the next day
or so. Interests in northeastern Mexico and along the Texas coast
should monitor the progress of this system.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

[NDG]

I keep seeing people post that the disturbance over the NW GOM is an upper level low but it is also in the mid levels, this is what is causing the weakness in the ridge across the southern US in the western GOM. I mentioned this a few days ago. If it wasn't for this mid and upper level low ridging to the north across the GOM would had been stronger, Harry's remnants would had kept going towards the BOC and lower MX coast, just like the models were showing a few days ago.

Is that still within the realm of possibilities, that the ridge doesn't weaken as much, allowing for more western movement? I know anything is possible, but realistically speaking.

The trend has been the other way around during the past few days that the ridge has been weaker in the western GOM than forecasted because of this mid and upper level low. We are now within 96 hrs so at this point models do a fairly good job with sypnotics.