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Hurricane Grace Discussion Number 23
NWS National Hurricane Center Miami FL AL072021
1000 PM CDT Wed Aug 18 2021
Grace has become a bit better organized during the past several
hours. Cuban radar data indicates that the eye and eyewall have
become better defined, and reports from Air Force Reserve and NOAA
Hurricane Hunter aircraft show that the inner core circulation has
become better defined. There are also occasional attempts at eye
formation in satellite imagery. However, these changes have not
yet resulted in significant intensification, with the maximum winds
remaining near 70 kt and the central pressure hovering near 988 mb.
One possible restraint on development is a dry slot that is seen
wrapping around the central core in both satellite imagery and
Cuban radar data.
The center has jogged a little to the left during the past few
hours, and the initial motion is now 280/16. The hurricane should
continue to move generally westward to west-northwestward for the
next 24-36 h, followed by a westward to west-southwestward motion
from 36-48 h. This motion should bring the center over the
Yucatan Peninsula of Mexico during the next 12 h, followed by
passage across the southwestern Gulf of Mexico or the Bay of
Campeche to a second landfall in mainland Mexico between 48-60 h.
After that, the cyclone should continue moving into the mountains
of Mexico until it dissipates. The new forecast track is nudged a
little south of the previous forecast, and it lies near the various
Except for the aforementioned dry slot, conditions appear
favorable for intensification before landfall on the Yucatan
peninsula. While not explicitly show in the intensity forecast,
Grace could reach an intensity of 75-80 kt before it reaches
Yucatan. The cyclone should weaken some as it crosses the
peninsula, then re-intensify over the Gulf of Mexico until it
reaches mainland Mexico. After final landfall in Mexico, Grace is
expected to quickly weaken and dissipate over the mountains of
Mexico just after 72 h. The remnants of Grace are likely to emerge
in the Pacific and possibly re-develop there, but the uncertainty
of whether this will be the original center or a new center
precludes forecast points over the Pacific at this time.
A Hurricane Watch and a Tropical Storm Watch have been issued for
portions of mainland Mexico.
1. Hurricane conditions and a dangerous storm surge are expected
in portions of the Hurricane Warning area in the eastern Yucatan
Peninsula of Mexico beginning during the next several hours.
Preparations to protect life and property should be rushed to
2. There is an increasing risk of hurricane conditions and dangerous
storm surge in portions of eastern mainland Mexico beginning late
Friday, and a Hurricane Watch has been issued for part of this area.
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 19/0300Z 19.8N 85.6W 70 KT 80 MPH
12H 19/1200Z 20.3N 88.1W 70 KT 80 MPH...INLAND
24H 20/0000Z 20.6N 91.4W 60 KT 70 MPH...OVER WATER
36H 20/1200Z 20.7N 94.0W 65 KT 75 MPH
48H 21/0000Z 20.5N 96.1W 75 KT 85 MPH
60H 21/1200Z 20.0N 98.8W 35 KT 40 MPH...INLAND
72H 22/0000Z 19.7N 101.6W 20 KT 25 MPH...POST-TROP/INLAND