[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT41 KNHC 221438
TCDAT1

Subtropical Storm Ana Discussion Number   2
NWS National Hurricane Center Miami FL       AL012021
1100 AM AST Sat May 22 2021

Satellite imagery and radar data from Bermuda indicate that the
central convection associated with Ana has changed little in
organization during the past several hours, with a complex of small
bands near the center at this time.  The initial intensity will be
held at 40 kt based on the latest intensity estimate from TAFB,
although recently-received ASCAT data suggests this could be a
little generous.  Although the cyclone has some characteristics of
a tropical cyclone, Ana remains a subtropical storm based on its
position near the center of a large upper-level low pressure system
and the current lack of anticyclonic upper-level outflow.

The initial motion is 270/3.  Ana and the large low it is embedded
in are expected to turn northward later today as a developing
mid-latitude cyclone over eastern Canada and the New England
states erodes the subtropical ridge west of Ana.  After that, the
storm is expected to turn northeastward on the southeast side of
the mid-latitude cyclone.  The track guidance is in good agreement
with this scenario, and the new track forecast is similar to, but a
little slower than, the various consensus models.

Little change in strength is expected for the next 12 h or so.
After Ana recurves, a combination of increasing shear, dry air, and
decreasing SSTs should cause the storm to gradually weaken tonight
and Sunday.  The large-scale models agree upon Ana opening up into
a trough of low pressure in 36-48 h, and the official forecast
shows this happening just after 48 h.  The remnant trough will
likely be absorbed by a cold front associated with the mid-latitude
cyclone shortly thereafter.

The Bermuda Weather Service has discontinued the Tropical Storm
Watch for Bermuda.


FORECAST POSITIONS AND MAX WINDS

INIT  22/1500Z 34.3N  63.0W   40 KT  45 MPH
 12H  23/0000Z 34.8N  62.8W   40 KT  45 MPH
 24H  23/1200Z 35.8N  61.2W   35 KT  40 MPH
 36H  24/0000Z 37.2N  57.9W   35 KT  40 MPH
 48H  24/1200Z 39.7N  52.9W   35 KT  40 MPH
 60H  25/0000Z...DISSIPATED

$$
Forecaster Beven
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