BULLETIN
Tropical Storm Grace Advisory Number 25
NWS National Hurricane Center Miami FL AL072021
1000 AM CDT Thu Aug 19 2021
...GUSTY WINDS AND HEAVY RAIN WILL CONTINUE ACROSS YUCATAN
PENINSULA TODAY...
...HURRICANE WARNING ISSUED FOR MAINLAND MEXICO...
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.2N 88.8W
ABOUT 110 MI...180 KM E OF CAMPECHE MEXICO
ABOUT 85 MI...135 KM W OF TULUM MEXICO
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 18 MPH...30 KM/H
MINIMUM CENTRAL PRESSURE...994 MB...29.36 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
The government of Cuba has discontinued all Tropical Storm Watches.
The government of Mexico has discontinued the Tropical Storm
Warning from Puerto Costa Maya to Punta Herrero and the Hurricane
Warning from Punta Herrero to Tulum. The Hurricane Warning from
Tulum to Cancun has been changed to a Tropical Storm Warning.
The government of Mexico has also issued a Hurricane Warning from
Puerto Veracruz northward to Cabo Rojo, and a Tropical Storm
Warning from north of Cabo Rojo to Barra del Tordo.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Hurricane Warning is in effect for...
* The coast of mainland Mexico from Puerto Veracruz to Cabo Rojo
A Tropical Storm Warning is in effect for...
* Yucatan Peninsula of Mexico from Tulum to Campeche
* The coast of mainland Mexico from north of Cabo Rojo to Barra del
Tordo.
A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. A warning is typically issued
36 hours before the anticipated first occurrence of tropical-storm-
force winds, conditions that make outside preparations difficult or
dangerous. Preparations to protect life and property should be
rushed to completion.
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Grace was
located near latitude 20.2 North, longitude 88.8 West. Grace is
moving toward the west near 18 mph (30 km/h). A general westward to
west-northwestward motion is expected today, followed by a general
westward to west-southwestward motion at a slower speed over the
weekend. On the forecast track, Grace is expected to continue to
move across the Yucatan Peninsula today, and move over the southwest
Gulf of Mexico late tonight through Friday. Grace will
likely make a second landfall on the mainland coast of Mexico late
Friday or early Saturday.
Maximum sustained winds have decreased to near 65 mph (100 km/h)
with higher. Additional weakening is possible while Grace moves
across land today. Re-intensification is likely after the center
reaches the Gulf of Mexico. Grace is forecast to be a hurricane when
it makes its second landfall on the mainland coast of Mexico late
Friday or early Saturday. Rapid weakening is expected after Grace
moves inland over central Mexico.
Tropical-storm-force winds extend outward up to 140 miles (220 km)
from the center.
The estimated minimum central pressure is 994 mb (29.36 inches).
HAZARDS AFFECTING LAND
----------------------
Key messages for Grace can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT2, WMO header WTNT42 KNHC
and on the web at
www.hurricanes.gov/graphics_at2.shtml?key_messages.
WIND: Tropical storm conditions will continue to spread
westward today across the northern Yucatan peninsula within the
tropical storm warning area. Hurricane conditions are expected in
the hurricane warning area in mainland Mexico by late Friday or
early Saturday. Tropical storm conditions are expected within the
tropical storm warning area in mainland Mexico by late Friday.
RAINFALL:
Grace is expected to produce the following rainfall amounts:
Over north-central portions of the Yucatan Peninsula...4 to 8
inches of rain with isolated maximum totals of 12 inches are
expected through Friday. Heavy rainfall from Grace will likely
result in areas of flash and urban flooding.
Over central to northern Veracruz, northern Puebla and into
Hidalgo...6 to 12 inches of rain with isolated maximum totals of 18
inches are expected from Friday through Sunday. Heavy rainfall from
Grace will likely result in areas of flash and urban flooding, and
will also be capable of producing mudslides.
STORM SURGE: A dangerous storm surge will raise water levels by as
much as 3 to 5 ft above normal tide levels along the immediate coast
near and to the north of where the center makes landfall along the
eastern mainland coast of Mexico Friday night or early Saturday.
Near the coast, the surge will be accompanied by large and
destructive waves.
Elevated water levels will gradually recede along the coast of
the Yucatan Peninsula during the next several hours.
SURF: Swells generated by Grace will continue to affect portions of
the western Caribbean today. High surf generated by Grace will begin
to affect the southern Gulf of Mexico coastline over the weekend.
These swells are likely to cause life-threatening surf and rip
current conditions. Please consult products from your local weather
office.
NEXT ADVISORY
-------------
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT.
$$
Forecaster Zelinsky
Tropical Storm Grace Discussion Number 25
NWS National Hurricane Center Miami FL AL072021
1000 AM CDT Thu Aug 19 2021
Grace made landfall as a hurricane near Tulum, Mexico around 0945
UTC (445am CDT). A storm chaser in Tulum reported a minimum
pressure of 983 mb at the time of landfall. Since then, the cyclone
has moved further inland where observations are far more
sparse, and we have no recent in situ observations to assist the
intensity analysis. The intensity is therefore set at 55 kt, based
in part on the inland decay wind model built into the SHIPS model.
The central pressure estimate of 995 mb is likewise uncertain.
Some additional weakening is likely this afternoon while Grace
continues to cross the Yucatan peninsula. The tropical storm should
emerge over the southern Gulf of Mexico this evening, and
re-strengthening is anticipated shortly thereafter. Environmental
conditions are expected to be quite conducive for strengthening,
but it will likely take Grace at least a little time to redevelop
its inner-core after disruption by land. That could act to limit
the rate at which the cyclone will intensify at first. The HWRF and
HMON both suggest that the most significant reintensification could
occur in the last 12 hours before final landfall occurs in mainland
Mexico, and that scenario seems likely. It would not be surprising
if Grace strengthened slightly more between the 36 h forecast point
over water and the 48 h point inland, particularly if the hurricane
moves slightly slower, giving it more time over the warm waters of
the southern Gulf of Mexico. After landfall, Grace should quickly
weaken and dissipate over the mountainous terrain of Mexico.
Overall, the NHC intensify forecast is very similar to the previous
advisory.
Grace continues to move to the west near 16 kt. A westward or
west-northwestward motion is likely for the next 12 hours or so,
after which a strong-deep layer ridge extending well over the
northern Gulf of Mexico and southern U.S. will steer Grace westward
until landfall. Only minor adjustments were made to the official
track forecast, which remains near the multi-model consensus.
Although the tropical cyclone will quickly dissipate after it moves
inland, the ridge will likely steer its remnants further westward
toward the eastern North Pacific, where it could contribute to the
formation of a new tropical cyclone there.
Key Messages:
1. Tropical storm conditions will continue today across the
northern Yucatan Peninsula.
2. Hurricane conditions and dangerous storm surge is 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 19/1500Z 20.2N 88.8W 55 KT 65 MPH
12H 20/0000Z 20.6N 91.2W 55 KT 65 MPH...OVER WATER
24H 20/1200Z 20.6N 94.0W 65 KT 75 MPH
36H 21/0000Z 20.4N 96.3W 75 KT 85 MPH
48H 21/1200Z 20.0N 98.7W 40 KT 45 MPH...INLAND
60H 22/0000Z 19.6N 101.7W 25 KT 30 MPH...POST-TROP/INLAND
72H 22/1200Z...DISSIPATED
$$
Forecaster Zelinsky