Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sat May 22 2021
For the North Atlantic...Caribbean Sea and the Gulf of Mexico:
1. Satellite images indicate that the well-defined low pressure area
located about 200 miles northeast of Bermuda continues to produce
gale-force winds and appears to have acquired subtropical
characteristics. In addition, thunderstorm activity has been
gradually increasing near the center, and if that trend continues
advisories will be issued later this morning. The low is expected
to move little today, remaining in the vicinity of Bermuda, but it
is forecast to turn northeastward and move into a more hostile
environment on Sunday. Additional information on this low pressure
area can be found in High Seas forecasts issued by the NOAA Ocean
Prediction Center and forecast products, including a tropical storm
watch, issued by the Bermuda Weather Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.
2. A well-defined low pressure area is approaching the Texas coast and
is now about 50 miles east-southeast of Corpus Christi. Surface
observations and satellite wind data indicate that the system
continues to produce winds of about 35 mph near and to the east of
its center, but the associated shower and thunderstorm activity
remains limited. Since the low is expected to move inland during
the next several hours, the chances of it becoming a tropical
depression or storm are decreasing. Regardless of development,
the system could produce heavy rainfall over portions of
southeastern Texas and southwestern Louisiana today. Given the
complete saturation of soils with ongoing river flooding along the
Texas and Louisiana coastal areas, heavy rain could lead to flash,
urban, and additional riverine flooding across this region.
Additional information on the rainfall and flooding potential can be
found in products issued by your local National Weather Service
Forecast Office.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...low...30 percent.
High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
online at ocean.weather.gov/shtml/NFDHSFAT1.php
Subtropical Storm Ana Discussion Number 1
NWS National Hurricane Center Miami FL AL012021
500 AM AST Sat May 22 2021
Satellite images indicate that the low pressure system that is
located a couple of hundred miles northeast of Bermuda has become
better organized overnight. The low now has a well-defined center
of circulation, some central deep convection, and thunderstorms that
are organized in curved bands to the north and northeast of the
center. The system is considered a subtropical cyclone rather than
a tropical cyclone since it is still entangled with an upper-level
low as evident in water vapor satellite images, but it does have
some tropical characteristics as well. The initial intensity is
estimated to be 40 kt, which makes the system Subtropical Storm Ana.
Ana is moving slowly to the west-southwest with the initial motion
estimated to be 240/3 kt. An even slower motion is expected later
this morning, and Ana is forecast to meander through tonight while
it remains embedded within the upper-level low in weak steering
currents. However, a mid- to upper-level trough moving off of
Atlantic Canada should cause Ana to turn northeastward thereafter
and accelerate in that direction on Sunday and Monday. The NHC
track forecast lies close to the HCCA and TVCA consensus models.
Ana will likely change little in strength in the short term, but a
combination of increasing shear, dry air, and decreasing SSTs should
cause the storm to gradually weaken tonight and Sunday. Nearly all
of the models show Ana opening up into a trough of low pressure in
about 48 to 60 hours, and so does the NHC forecast. The remnant
trough will likely be absorbed by a front shortly thereafter.
The Bermuda Weather Service has a Tropical Storm Watch in effect
for the island of Bermuda.
Tropical Storm Ana Discussion Number 5
NWS National Hurricane Center Miami FL AL012021
500 AM AST Sun May 23 2021
Satellite images indicate that Ana has contracted significantly
since yesterday and now has a compact area of moderate convection
around the center. Given the tight low-level circulation, small
radius of maximum wind, and compact central convection, Ana is
now estimated to have transitioned from a subtropical storm to a
tropical storm. The initial intensity remains 40 kt for this
advisory based on the earlier ASCAT data, which indicated that the
tropical-storm-force winds were confined to the south side of the
circulation.
Ana is not expected to be around much longer. The storm is headed
for an environment of lower SSTs, drier air, and increasing wind
shear. All of these factors should cause the compact cyclone to
lose strength and ultimately open into a trough in 24 to 36 hours.
In fact, some of the models suggest that the storm could dissipate
even sooner than that. The remnants of Ana will likely be absorbed
by a cold front on Monday.
The storm continues to increase its forward speed, and the initial
motion is now estimated to be 045/10 kt. A faster motion to the
northeast is expected until the cyclone dissipates.
Tropical Depression Ana Discussion Number 7
NWS National Hurricane Center Miami FL AL012021
500 PM AST Sun May 23 2021
Other than brief puff of convection late this morning, tiny Ana has
been devoid of organized deep convection for several hours. ASCAT
overpass data from this morning indicated that the peak winds had
deceased to 35 kt. Due to the lack of convection since that time,
it is reasonable to assume that the vortex has spun down a bit, and
therefore the initial advisory intensity has been lowered to 30 kt.
Ana is over cool waters and surrounded by very dry air in the
mid-troposphere. The brief convection that did occur today was
quickly stripped away, indicating that the anticipated increase in
shear has begun. Satellite imagery suggests that the circulation of
Ana is approaching a strong subtropical upper-level jet just to its
east, which is expected to produce even stronger shear over the
cyclone. These conditions should prevent further convection, if any,
from surviving, and the cyclone is expected to degenerate into a
remnant low by tonight. What is left of Ana's low-level circulation
should open into a trough on Monday as it is absorbed by a large
baroclinic zone approaching from the northwest.
The depression continues to accelerate northeastward, and the
forward motion is now northeastward at 15 kt. An accelerating
northwestward motion is anticipated until dissipation as Ana
gets caught up in increasing deep-layer southwesterly flow.
