[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT45 KNHC 252051
TCDAT5

Hurricane Tammy Discussion Number  30
NWS National Hurricane Center Miami FL       AL202023
500 PM AST Wed Oct 25 2023

Tammy is beginning to interact with a front to its north. The eye
has lost some of its definition as the northern eyewall slowly
erodes. Outflow is now limited to the southern and eastern portions
of the circulation. Subjective and objective satellite intensity
estimates have fallen since the last advisory. Final T-numbers from
SAB and TAFB are both T4.5 and ADT is down to T4.2. Given the recent
degradation in satellite appearance, the initial intensity has been
lowered to 85 kt.

It appears that Tammy has moved out of the region with favorable
upper-level dynamics. Strong upper-level winds and surrounding dry
air are expected to steadily weaken the system through the forecast
period. Model guidance shows that the hurricane should become
entangled with the frontal feature to its north and transition into
an extratropical cyclone within the next 24 hours. By 48 hours, the
global models depict Tammy occluding and shedding its front.
Therefore, the most recent NHC forecast shows the system as a
post-tropical cyclone instead of extratropical beginning at day 2.
There is a possibility that Tammy could regain tropical or
subtropical status as the vortex meanders over sufficiently warm
ocean waters during days 2 and 3.

Tammy is still moving northeastward, but model guidance insists that
the hurricane will make a turn to the north shortly. This is
followed by a northwestward turn with a slower forward speed by
Thursday. By Friday, Tammy is expected to meander over the
northwestern Atlantic in the light steering currents between two
building ridges over the eastern Atlantic and southeastern United
States. The official NHC track forecast shows Tammy slowly turning
back to the east by the weekend. However, more model guidance is
showing a faster turn to the east resulting in a large spread in the
track guidance envelope. The current forecast is on the western edge
of the track solutions and is closest to the GFS. Further
adjustments may be needed if these trends continue.


FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 28.0N  57.9W   85 KT 100 MPH
 12H  26/0600Z 29.5N  58.4W   80 KT  90 MPH
 24H  26/1800Z 30.5N  59.4W   70 KT  80 MPH...POST-TROP/EXTRATROP
 36H  27/0600Z 31.1N  60.4W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  27/1800Z 31.5N  61.1W   55 KT  65 MPH...POST-TROPICAL
 60H  28/0600Z 31.8N  61.5W   50 KT  60 MPH...POST-TROPICAL
 72H  28/1800Z 32.1N  61.7W   50 KT  60 MPH...POST-TROPICAL
 96H  29/1800Z 32.5N  61.5W   45 KT  50 MPH...POST-TROPICAL
120H  30/1800Z 32.8N  61.0W   40 KT  45 MPH...POST-TROPICAL

$$
Forecaster Bucci/R. Zelinsky
This weather bulletin was brought to you by:
www.nashvilleweather.net