[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 241455
TCDAT4

Tropical Storm Cindy Discussion Number  10
NWS National Hurricane Center Miami FL       AL042023
1100 AM AST Sat Jun 24 2023

After Cindy exhibited a bursting pattern with deep convection
covering the center overnight, more recently morning visible
satellite images show the low-level center accelerating and becoming
exposed on the northwest end of a small area of colder than -70C
convective cloud tops. It appears that the forecast increase in
northwesterly shear is beginning to transpire. Despite the recent
degradation in structure, a blend of both objective and subjective
intensity aids still support a current intensity of 50 kt for this
advisory, though this might be generous. An Air Force Reserve
reconnaissance aircraft is scheduled to investigate Cindy later
today and should provide a better assessment of the storm's
intensity this afternoon.

Now that Cindy is beginning to feel the effects of increased
northwesterly shear, its likely the system has peaked in intensity
with weakening not far behind. Shear in the EC-SHIPS guidance is
expected to increase to 30 kt and shift southwesterly in a day or
so, and that combined with a fairly dry mid-level airmass should
contribute to continued decay over the next several days. The latest
NHC intensity forecast now shows Cindy weakening as soon as later
today. Beyond 48 h, there remains uncertainty in the guidance as to
if Cindy will dissipate. The GFS shows some sort of center
reformation to the north or northeast in the day 3 period, though
the GFS has a habit of being too aggressive with center
redevelopment under sheared convection (see what recently transpired
with Bret). In contrast, the ECMWF continues to show Cindy opening
up into a trough axis sometime in the day 3-4 period, though it
should be noted that some of the ECMWF ensemble members try to
regenerate the storm later on, though not as strong as the GFS.
Given the small size of Cindy's current circulation, it seems more
likely Cindy will succumb to the increasingly unfavorable
environmental conditions and dissipate before the end of the
forecast period, and the NHC track forecast continues to indicate
that scenario, with post-tropical status in the day 3-4 period and
dissipation thereafter. However, this forecast is of lower than
usual confidence, and its possible the storm could regenerate or
reform as suggested by the GFS and high-resolution HAFS-A/B models.

The storm has accelerated a bit to the northwest this morning, with
the estimated motion at 310/17 kt. This same general motion is
expected to continue, albeit a bit slower over the next
couple of days as the system remains steered by a low- to mid-level
ridge located to its northeast. Beyond the next 24 h, the guidance
spread increases quite a bit, again primarily due to the GFS and
some of the regional hurricane models suggesting the system
attempts reformation to the north or northeast in the day 3-4 time
frame. However, the NHC track favors more of a blend between the
latest ECMWF and TVCA consensus aids, which are further south and
west, assuming a weakening tropical cyclone that continues to follow
the low- to mid-level steering flow. On the current track, Cindy
should pass well the northeast of the northern Leeward Islands
Sunday into Monday.


FORECAST POSITIONS AND MAX WINDS

INIT  24/1500Z 16.4N  53.3W   50 KT  60 MPH
 12H  25/0000Z 17.8N  55.0W   45 KT  50 MPH
 24H  25/1200Z 20.0N  57.4W   45 KT  50 MPH
 36H  26/0000Z 21.9N  59.5W   40 KT  45 MPH
 48H  26/1200Z 23.5N  61.3W   35 KT  40 MPH
 60H  27/0000Z 25.0N  62.6W   35 KT  40 MPH
 72H  27/1200Z 26.0N  63.3W   35 KT  40 MPH...POST-TROPICAL
 96H  28/1200Z 28.5N  64.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  29/1200Z...DISSIPATED

$$
Forecaster Papin
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