[Aug 27] Update: Tropical Storm Idalia (AL10) is predicted to be a Cat 2 hurricane
Idalia's maximum intensity forecast has been raised slightly to a Cat 2 with predicted sustained winds of 100 mph (85 kts). The forecaster noted that the intensity forecast is somewhat challenging for this storm. See "Discussion Number 5" in the comments for details.
Current predictions from the National Hurricane Center have Tropical Storm Idalia (previously Tropical Depression 10) developing into
a Cat 1 hurricane by Tuesday (the next 48 to 72 hours).
It's expected to make landfall in Florida by Wednesday.
The official forecast line has it hitting somewhere between Panama City (panhandle) and Tampa Bay (peninsula).
The GFS and ECMWF models are mostly predicting landfall around Apalachee bay.
These predictions, both the storm track and intensity, may change as the storm develops.
When the storm enters the Gulf of Mexico on early Tuesday there will be very warm waters conducive to development, but it will also be under heavy windshear.
Tropical Storm Idalia Discussion Number 5
NWS National Hurricane Center Miami FL AL102023
400 PM CDT Sun Aug 27 2023
Idalia's cloud pattern is gradually becoming a little better
organized, with a curved convective band forming over the southern
semicircle of the circulation. Upper-level outflow is currently
restricted over the northern portion of the system, however.
The advisory intensity is held at 35 kt based on a subjective
Dvorak estimate from TAFB. Another aircraft reconnaissance mission
into the storm is scheduled for tonight.
The tropical cyclone continues to move rather slowly, and the
initial motion estimate is 040/3 kt. Idalia should remain in a weak
steering pattern through tonight so slow and possibly erratic
motion is likely for the next 12 hours. On Monday, a mid-level
ridge begins to build to the northeast of the tropical cyclone.
This should result in a slightly east of northward motion during
the next day or two. When the system moves into the northeast Gulf
of Mexico, a mid-level trough developing over the eastern United
states will likely cause Idalia to turn northeastward with an
increase in forward speed. The new official forecast is again
shifted slightly eastward, and is somewhat faster than the previous
one. This is a blend of the latest ECMWF and GFS solutions and is
also between the simple and corrected dynamical consensus tracks.
The intensity forecast is somewhat challenging. Idalia will be
traversing eastern Gulf of Mexico waters of high oceanic heat
content, and the environmental air mass should remain fairly moist.
The flow to the east of an upper-level trough could impart some
vertical wind shear over the system, but this shear could also be
compensated by the conducive effect of upper-level diffluence.
There is considerable spread in the model intensity guidance,
ranging from minimal to major hurricane status before landfall on
the northeast Gulf coast. The official intensity forecast is a
little higher than the previous one, and remains near the higher
end of the guidance. Given the uncertainties, users should monitor
future NHC forecasts for possible changes in the predicted strength
of Idalia, and prepare for possible significant impacts within the
hurricane and storm surge watch areas.
KEY MESSAGES:
Idalia is forecast to become a hurricane over the eastern Gulf of
Mexico, and there is an increasing risk of life-threatening storm
surge and hurricane-force winds along portions of the west coast of
Florida and the Florida Panhandle beginning as early as Tuesday.
Although it is too soon to specify the exact location and magnitude
of these impacts, residents in these areas should monitor updates to
the forecast and follow any advice given by local officials. Storm
surge and hurricane watches have been issued for portions of the
west coast of Florida and the coast of the Florida Panhandle, and
residents in these areas should monitor updates to the forecast and
follow any advice given by local officials.
Scattered flash and urban flooding can be expected across
portions of the west coast of Florida, the Florida Panhandle and
portions of the Southeast U.S. by Tuesday into Thursday. Flooding
from heavy rainfall is likely over portions of the southeast U.S. by
mid to late week.
Heavy rainfall from Tropical Storm Idalia is expected across
portions of the eastern Yucatan and western Cuba and may produce
areas of flash and urban flooding as well as landslides across
western Cuba.
Tropical storm conditions are expected over portions of the
Yucatan Peninsula and extreme western Cuba with tropical storm
conditions possible on the Isle of Youth.
Tropical Storm Idalia Tropical Cyclone Update
NWS National Hurricane Center Miami FL AL102023
1015 AM CDT Sun Aug 27 2023
...DEPRESSION STRENGTHENS TO A TROPICAL STORM...
Observations from a NOAA Hurricane Hunter aircraft indicate that
Tropical Depression Ten has strengthened into Tropical Storm Idalia.
The maximum winds are estimated to be 40 mph (65 km/h) with higher
gusts.
SUMMARY OF 1015 AM CDT...1515 UTC...INFORMATION
LOCATION...19.9N 85.8W
ABOUT 80 MI...135 KM ESE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...E OR 90 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES
$$
Forecaster Pasch
000
WTNT45 KNHC 271500
TCDAT5
Tropical Depression Ten Discussion Number 4
NWS National Hurricane Center Miami FL AL102023
1000 AM CDT Sun Aug 27 2023
So far this morning, the overall cloud pattern of the tropical
cyclone has not become significantly better organized. The small
center is partially exposed on GOES-16 visible imagery, and
convective banding features are still not very well defined. The
current intensity is held at 30 kt for this advisory which is in
line with the latest Dvorak Satellite estimates. A NOAA Hurricane
Hunter aircraft, flying at around 12000 ft, is near the center of
the system taking Doppler radar wind velocity measurements. These
data should provide valuable information on the structure of the
cyclone for initializing the numerical weather prediction models.
The center of the cyclone appears to have been moving in a small
clockwise loop overnight and into this morning, and it will
probably complete this loop today. The initial motion estimate is
now around 090/2 kt. Steering currents should remain weak through
today and tonight. Beginning on Monday, a mid-level ridge starts to
build near southern Florida and eastward. This evolution should
cause a generally northward motion during the next couple of days.
In 48 to 72 hours, a mid-level trough dropping into the eastern U.S.
will likely induce a turn toward the north-northeast and take the
system across the northeast Gulf of Mexico coast on Wednesday. The
official forecast track has been nudged to the right of the
previous one, but is not quite as far east as the latest corrected
consensus, HCCA, prediction. Users are reminded not to focus on
the exact forecast track, since strong winds, heavy rains and
dangerous storm surges extend well away from the center.
The cyclone will be moving over waters of high oceanic heat content
over the eastern Gulf of Mexico and within a moist mid- to
low-level air mass for the next few days. An upper-tropospheric
trough is predicted to develop over the western Gulf of Mexico in 48
to 72 hours. Although this feature could produce some moderate
southwesterly vertical wind shear over the system, positive
vorticity advection and diffluent upper-level flow to the east of
the trough will likely be conducive for strengthening. The
official forecast, like the previous one, calls for the cyclone to
reach hurricane status over the eastern Gulf of Mexico in 48 to 72
hours. This is at the high end of the latest intensity model
guidance.
KEY MESSAGES:
The depression is forecast to become a hurricane over the eastern
Gulf of Mexico, and there is an increasing risk of life-threatening
storm surge, flooding from heavy rainfall, and hurricane-force winds
along portions of the west coast of Florida and the Florida
Panhandle beginning as early as Tuesday. Although it is too soon
to specify the exact location and magnitude of these impacts,
residents in these areas should monitor updates to the forecast,
have their hurricane plan in place, and follow any advice given by
local officials. Storm surge and hurricane watches may be required
for portions of the Gulf coast of Florida later today.
Heavy rainfall is expected across the eastern Yucatan Peninsula
and western Cuba and may produce areas of flash and urban flooding
and landslides across western Cuba. The depression is forecast to
become a tropical storm later today, and tropical storm conditions
are expected over portions of the Yucatan Peninsula and extreme
western Cuba with tropical storm conditions possible on the Isle of
Youth.
Scattered flooding from heavy rainfall is likely over in
portions of the southeast U.S. by mid to late week.
Tropical Depression Ten Discussion Number 3
NWS National Hurricane Center Miami FL AL102023
400 AM CDT Sun Aug 27 2023
The small circulation of Tropical Depression Ten continues to be
well-defined in Cancun radar, with the center moving across Cozumel
during the past few hours. Data from a Weatherflow sensor on the
island indicated that the pressure dropped to about 1001 mb, with
sustained winds of about 30 kt. A small burst of convection has
formed just south of the center recently, with scattered banding
features in the eastern semicircle. Most of the satellite
estimates are just shy of tropical storm strength, so the initial
winds speed will stay 30 kt. Both Air Force Reserve and NOAA
Hurricane Hunter aircraft will be in the system later this morning
to get a better look at the structure and winds.
The depression has turned southward tonight, moving at about 4 kt,
apparently rotating around the western periphery of its larger
parent circulation to the east. Little net motion is expected for
about a day as steering currents remain weak. After that time, a
developing trough over the Gulf of Mexico and stronger ridging over
the western Atlantic is expected to lift the system toward the north
and north-northeast over the eastern Gulf of Mexico. This track
takes the system toward Florida, and then near the southeastern
coast of the U.S. The overnight model guidance is a bit farther
west and slower than the last cycle, probably due to the depression
being further south than anticipated. Thus, the NHC forecast is
nudged westward, and lies on the east side of the guidance envelope.
These are small changes overall, and the track should be considered
lower confidence until it starts moving in a more consistent manner.
The NOAA G-IV aircraft should be in the area this afternoon to
help smooth out the model differences along with special upper-air
soundings scheduled across many areas of the southeastern United
States.
The very warm and deep waters of the northwestern Caribbean Sea and
Gulf of Mexico should support at least gradual strengthening during
the next few days, tempered by moderate shear from a flat upper-
level trough. However, this trough is forecast to amplify over the
western Gulf of Mexico around Tuesday, which causes the shear to
decrease near the cyclone in that time frame. There's a notable
risk of rapid intensification while the system moves across the
record warm eastern and northeastern Gulf of Mexico, which is
highlighted by the recent HAFS and HWRF guidance. The new NHC
forecast is raised from the previous one, near or above the model
consensus, and could be too low. I'm reluctant to make any big
changes to the forecast until we get more in-situ data, but the
upward overnight model trend certainly bears watching. Users are
reminded to continue monitoring forecasts for any changes to the
system's expected intensity as it approaches Florida.
KEY MESSAGES:
Heavy rainfall from Tropical Depression Ten is expected across
the eastern Yucatan Peninsula and western Cuba. The heavy rainfall
may produce areas of flash and urban flooding, as well as
landslides, across western Cuba. The depression is forecast to
become a tropical storm later today, and tropical storm conditions
are expected over portions of the Yucatan Peninsula and extreme
western Cuba where a Tropical Storm Warning is in effect. Tropical
storm conditions are possible on the Isle of Youth, where a Tropical
Storm Watch is in effect.
The depression is forecast to strengthen during the next few days
and could become a hurricane over the eastern Gulf of Mexico,
bringing a potential of dangerous storm surge, heavy rainfall, and
strong winds to portions of the west coast of Florida and the
Florida Panhandle by the middle of this week. Heavy rainfall is
also likely to spread into portions of the Southeast U.S. by mid to
late week. Although it is too soon to specify the exact location
and magnitude of these impacts, residents in these areas should
monitor updates to the forecast of this system and ensure that they
have their hurricane plan in place.
BULLETIN
Tropical Depression Ten Advisory Number 4
NWS National Hurricane Center Miami FL AL102023
1000 AM CDT Sun Aug 27 2023
...DEPRESSION COULD BECOME A TROPICAL STORM AT ANY TIME...
...EXPECTED TO STRENGTHEN INTO A HURRICANE OVER THE EASTERN GULF OF
MEXICO...
SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
LOCATION...19.9N 85.8W
ABOUT 80 MI...135 KM ESE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...E OR 90 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
None.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
Yucatan Peninsula from Tulum to Rio Lagartos, including Cozumel
Pinar del Rio Cuba
A Tropical Storm Watch is in effect for...
Isle of Youth Cuba
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area.
Interests in Florida should monitor the progress of this system.
Storm surge and wind watches for portions of the Florida west coast
will likely be required later today.
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 Depression Ten was
located near latitude 19.9 North, longitude 85.8 West. The
depression is moving toward the east near 2 mph (4 km/h), and
it is likely to meander near the Yucatan Channel through tonight.
A faster motion toward the north is expected on Monday, bringing the
system over the eastern Gulf of Mexico.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
The depression is expected to become a tropical storm today, and
strengthen into a hurricane by Tuesday.
The estimated minimum central pressure is 1001 mb (29.56 inches).
HAZARDS AFFECTING LAND
Key messages for this system can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT5 and WMO header WTNT45 KNHC.
RAINFALL: The system is expected to produce the following rainfall
amounts:
Portions of the eastern Yucatan: 2 to 4 inches, with isolated higher
totals of 6 inches.
Western Cuba: 3 to 6 inches, with isolated higher totals of 10
inches.
Portions of the west coast of Florida, the Florida Panhandle, and
southern Georgia: From Tuesday into Wednesday, 3 to 6 inches, with
isolated higher totals of 10 inches.
Heavy rainfall is also likely to spread into portions of the
Carolinas by Wednesday into Thursday.
This rainfall may lead to flash and urban flooding, and landslides
across western Cuba. Scattered flash and urban flooding can also be
expected across portions of the west coast of Florida, the Florida
Panhandle and portions of the Southeast U.S. by Tuesday into
Thursday.
WIND: Tropical storm conditions are expected over portions of the
warning area over the Yucatan Peninsula today and western Cuba
tonight or Monday. Tropical storm conditions are possible within
the watch area on the Isle of Youth tonight or Monday.
STORM SURGE: Minor coastal flooding is expected within the Tropical
Storm Warning area over the Yucatan Peninsula in areas of onshore
winds.
NEXT ADVISORY
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT. \
$$
Forecaster Pasch
000
WTNT35 KNHC 271155
TCPAT5
BULLETIN
Tropical Depression Ten Intermediate Advisory Number 3A
NWS National Hurricane Center Miami FL AL102023
700 AM CDT Sun Aug 27 2023
...DEPRESSION NEARING TROPICAL STORM INTENSITY...
...EXPECTED TO STRENGTHEN INTO A HURRICANE OVER THE EASTERN GULF OF
MEXICO IN A COUPLE OF DAYS...
SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
LOCATION...19.7N 86.3W
ABOUT 70 MI...110 KM SE OF COZUMEL MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...SE OR 135 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
None.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for...
Yucatan Peninsula from Tulum to Rio Lagartos, including Cozumel
Pinar del Rio Cuba
A Tropical Storm Watch is in effect for...
Isle of Youth Cuba
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area.
Interests in Florida should monitor the progress of this system.
For storm information specific to your area, please monitor
products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
At 700 AM CDT (1200 UTC), the center of Tropical Depression Ten was
located near latitude 19.7 North, longitude 86.3 West. The
depression is moving toward the southeast near 5 mph (7 km/h), and
it is likely to meander near the Yucatan Channel through early
Monday. A faster motion toward the north or north-northeast is
expected later on Monday, bringing the system over the eastern Gulf
of Mexico.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
The depression is expected to become a tropical storm later today
and a hurricane by Tuesday.
The estimated minimum central pressure is 1001 mb (29.56 inches).
HAZARDS AFFECTING LAND
Key messages for Tropical Depression Ten can be found in the
Tropical Cyclone Discussion under AWIPS header MIATCDAT5 and WMO
header WTNT45 KNHC.
RAINFALL: Tropical Depression Ten is expected to produce the
following rainfall amounts:
Portions of the eastern Yucatan: 2 to 4 inches, with isolated higher
totals of 6 inches.
Western Cuba: 3 to 6 inches, with isolated higher totals of 10
inches.
Portions of the west coast of Florida, the Florida Panhandle, and
southern Georgia: From Tuesday into Wednesday, 3 to 6 inches, with
isolated higher totals of 10 inches.
Heavy rainfall is also likely to spread into portions of the
Carolinas by Wednesday into Thursday.
This rainfall may lead to flash and urban flooding, and landslides
across western Cuba. Scattered flash and urban flooding can also be
expected across portions of the west coast of Florida, the Florida
Panhandle and portions of the Southeast U.S. by Tuesday into
Thursday.
WIND: Tropical storm conditions are expected over portions of the
warning area over the Yucatan Peninsula today and western Cuba
tonight or Monday. Tropical storm conditions are possible within
the watch area on the Isle of Youth tonight or Monday.
STORM SURGE: Minor coastal flooding is expected within the Tropical
Storm Warning area over the Yucatan Peninsula in areas of onshore
winds.