ATL: GRACE - Remnants - Discussion

[AubreyStorm]

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 9.0
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 14 AUG 2021 Time : 145020 UTC
Lat : 16:11:20 N Lon : 57:51:04 W


CI# /Pressure/ Vmax
3.6 / 996.9mb/ 57.0kt


Final T# Adj T# Raw T#
3.6 3.8 4.1

[Woofde]

Approaching Guadalupe radar now.

http://www.meteo.fr/temps/domtom/antill ... f_com.html

[NotSparta]

The mid-level easterly shear is likely to continue to displace the MLC to the west of the LLC and also prevent the LLC from assuming a WNW component.

Perhaps, however if Grace manages to continue to strengthen over the next 24-36 hours there is a better chance that it does in fact take a more WNW path... wait and see.

Personally, I don’t think that Grace is actually intensifying much, if at all. Structurally it is stagnant, and structure is more important than convection, at least in this case. Currently Grace has very little outflow, and the convection is clearly to the west of the LLC, as is the MLC. As Grace interacts with Puerto Rico and the eastern Dominican Republic, orographic lift associated with mountainous terrain will combine with easterly shear to prevent the LLC from assuming a WNW component. Instead, the MLC and the convection will remain to the west and south of the LLC and instead “drag” the LLC farther west and even south of due west, similarly to Fred. Unfortunately, I think the very high PWATs may work to offset Grace’s fast motion and still result in locally prolific rainfall over Puerto Rico and Hispaniola. This would also affect areas recently impacted by the latest earthquake.

Little outflow? What do you call all that cirrus coming from Grace then?

[Jr0d]

Poor Haiti can't catch a break

Unfortunately, the latest news does not seem auspicious. Given Grace’s rapid movement it is likely to continue generally westward toward Hispaniola.

Steering currents are not directly westward... there is enough of a northward component that Grace could just scrape Hispanola or miss entirely

Bad for Hispaniola, good for Florida. Upper level winds may weaken Grace without the help of high terrain as it approaches the Bahamas and Florida. However those forecasts are notoriously inaccurate, especially 5 days out.

[BobHarlem]

Wide satellite with Grace shows how fast its moving to the west, I'm interested in that blob in the caribbean because it may give a hint at what happens to Grace, note its shifting north. But between that and the other areas I'm thinking the NHC's track is solid.

[Shell Mound]

 https://twitter.com/AndyHazelton/status/1426540310994341893



 https://twitter.com/DerekOrtt/status/1426542475737550857



 https://twitter.com/AndyHazelton/status/1426550892740976640

[AutoPenalti]

If it’s not stacked yet, it will continue at pace until it does so, until then, full steam ahead towards Hispanola...

Shear is now SW.

[Hypercane_Kyle]

Well, if the center is on the northern envelope of the convection, that increases the chances that Grace will be able to avoid PR and Hispaniola.

[Category5Kaiju]

Unfortunately, the latest news does not seem auspicious. Given Grace’s rapid movement it is likely to continue generally westward toward Hispaniola.

Steering currents are not directly westward... there is enough of a northward component that Grace could just scrape Hispanola or miss entirely

Bad for Hispaniola, good for Florida. Upper level winds may weaken Grace without the help of high terrain as it approaches the Bahamas and Florida. However those forecasts are notoriously inaccurate, especially 5 days out.

Also this is something that we saw with TS Dorian and has happened in the past, but if a storm is well-built and pretty robust in size and structure, it could actually push away any nearby TUTT (and with Fred weaker and more to the west, any induced shear or what not from that system may be mitigated). This allows the storm to "cocoon" itself in a bubble of favorable conditions.

[Kohlecane]

Oh boy here comes the GFS in the Gulf at 150h, Prepare!!!!

[skyline385]

Oh boy here comes the GFS in the Gulf at 150h, Prepare!!!!

12Z ICON had the same route as well

[Category5Kaiju]

A certain "R" storm from 16 years ago comes into my mind with this new GFS run.

[SFLcane]

Here we go!

 https://twitter.com/derekortt/status/1426579910009761797

[Woofde]

Either this is just visual noise that looks like a well structured core, or it is a well structured core. It seems to line up pretty well with the center of the convection as well. We will know better once it gets closer shortly.

[Shell Mound]

High-resolution visible imagery indicates outflow boundaries in the eastern semicircle, so Grace is almost certainly less organised than it appears to be.

[Yellow Evan]

High-resolution visible imagery indicates outflow boundaries in the eastern semicircle, so Grace is almost certainly less organised than it appears to be.

What?

[SFLcane]

High-resolution visible imagery indicates outflow boundaries in the eastern semicircle, so Grace is almost certainly less organised than it appears to be.

Please stop. Nothing suggests this

[Category5Kaiju]

High-resolution visible imagery indicates outflow boundaries in the eastern semicircle, so Grace is almost certainly less organised than it appears to be.

What image are you looking at?

[tolakram]

There's not a lot of mid-level rotation, but convection is vigorous at the moment.

[Jr0d]

Haiti just had a 7.1 earthquake, with likely significant loss of lives.

I pray Grace misses Haiti, the landslides and wind a few days after a major earthquake would be even more horrible.