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Tropical Storm Grace Discussion Number  26
NWS National Hurricane Center Miami FL       AL072021
400 PM CDT Thu Aug 19 2021

Grace has now been inland for almost 12 hours and the inner core 
structure has been gradually decaying. In fact, the low-level center 
is now partially exposed to the north of the mid-level vortex which 
still has the majority of the deep convection. The initial intensity 
has been lowered to 45 kt this advisory, assuming a bit more 
weakening of the low-level center has occurred since 1800 UTC. 

Environmental conditions appear favorable for Grace to restrengthen 
after the storm moves offshore this evening. However, it will take a 
bit of time for the inner-core to reorganize before a faster rate of 
intensification can occur. After that process occurs, significant 
intensification is possible, and the latest intensity forecast makes 
Grace a hurricane again by 24 hours and is near the upper end of the 
intensity guidance by 36 hours when Grace will be just inland over 
Mexico. However, it remains possible that the storm could intensify 
more than indicated between the 24 and 36 hour points, when both the 
global and regional high-res hurricane model guidance suggests Grace 
will be near peak intensity.

Grace is still moving a bit north of due west at 280/13 kt. A 
continued westward to west-northwestward motion is expected for the 
next 6-12 hours and Grace should be emerging offshore of the western 
Yucatan Peninsula later this evening. Thereafter, a strong mid-level 
ridge oriented southwest-to-northeast ahead of Grace is likely to 
steer the cyclone towards the west, and then west-southwest as it 
nears mainland Mexico. The track guidance remains in good agreement, 
and the latest track forecast is quite similar to the previous one, 
staying close to the multi-model consensus aids. Although Grace is 
likely to dissipate by 60 hours over the high terrain of Central 
Mexico, the mid-level circulation should survive and emerge into the 
East Pacific. This feature could contribute to the formation of a 
new tropical cyclone in that basin.
 
Key Messages:
 
1. Tropical storm conditions will continue this afternoon and 
evening across the northern Yucatan Peninsula but should subside 
later tonight.
 
2. Hurricane conditions and dangerous storm surge are likely along
portions of eastern mainland Mexico beginning late Friday. A
Hurricane Warning is in effect from Puerto Veracruz northward to
Cabo Rojo.
 
3. Through the weekend, heavy rainfall across central and northern
portions of the Yucatan Peninsula and Veracruz State should lead to
flash and urban flooding. In addition, the heavy rainfall from Grace
will be capable of producing mudslides in Veracruz.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/2100Z 20.6N  90.2W   45 KT  50 MPH...INLAND
 12H  20/0600Z 20.8N  92.5W   55 KT  65 MPH...OVER WATER
 24H  20/1800Z 20.7N  94.9W   70 KT  80 MPH
 36H  21/0600Z 20.4N  97.0W   75 KT  85 MPH...INLAND
 48H  21/1800Z 19.6N  99.4W   35 KT  40 MPH...INLAND
 60H  22/0600Z...DISSIPATED
 
$$
Forecaster Papin/Cangialosi
 
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