Tropical Storm Kirk Discussion Number   8
NWS National Hurricane Center Miami FL       AL122024
1100 AM AST Tue Oct 01 2024

Kirk's structure on satellite is gradually becoming better 
organized, with deep convective bands attempting to wrap around the 
center, though there still remains evidence that dry air could be 
getting into the core on the western side. Some of this less humid 
air could be getting imported due to subtle northerly mid-level 
shear above 20-kt as diagnosed by the ECMWF analysis this morning. 
With that said, we have received some fortuitous surface data from 
a moored PIRATA buoy (13008) that Kirk passed close by this morning 
at around 09 UTC. The buoy reported sustained tropical-storm-force 
winds at 4 meters, and a concurrent minimum pressure down to 990 
mb. Thus the initial intensity has been raised to 60 kt with an 
estimated minimum pressure a little lower at 988 mb. This intensity 
is a little above the subjective Dvorak estimates but closest to 
the latest DPRINT estimate from UW-CIMSS.  

Kirk is still moving west-northwestward, estimated at 300/11 kt. 
This motion with perhaps a slight slowdown should continue over the 
next couple of days as Kirk is primarily steered along the 
southwestern edge of a subtropical ridge positioned to its north. 
The western extent of this ridge will become eroded by a long-wave 
trough offshore of eastern North America towards the 
latter part of this week, allowing Kirk to turn first northwestward 
and then northward by the end of the forecast period. The track 
guidance continues to be in good agreement, and the latest NHC track 
forecast lies near the middle of the guidance envelope, very similar 
to the prior advisory and between the consensus aids HCCA and TVCN. 

While Kirk is stronger this morning, it is feeling some of the 
effects of the aforementioned mid-level shear, preventing 
convection from fully wrapping around the center. However, other 
environmental factors, namely warm 28-30 C sea-surface temperatures 
and plenty of deep-layer moisture, are quite conducive for 
strengthening. For now, the shear is anticipated to prevent a 
faster rate of intensification, but Kirk should become a hurricane 
later today. After 24 h, even the mid-level shear is expected to 
decrease, and a faster period of intensification is likely in the 
24-60 h period. The NHC intensity forecast shows Kirk becoming a 
major hurricane at the end of this period. In addition, Kirk's wind 
field is also forecast to grow in size by the end of the week. 
Thereafter, hard to predict inner-core structural changes will 
likely lead to fluctuations in intensity, though by day 5 shear 
begins to increase again with weakening beginning by that time. 
However, Kirk will likely remain a large and formidable hurricane. 
The NHC intensity forecast is close the middle of the guidance 
envelope early on but is near the higher end of the aids in 72 h.


FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 15.3N  39.2W   60 KT  70 MPH
12H  02/0000Z 16.0N  40.7W   65 KT  75 MPH
24H  02/1200Z 17.0N  42.4W   75 KT  85 MPH
36H  03/0000Z 18.2N  43.9W   85 KT 100 MPH
48H  03/1200Z 19.3N  45.3W   95 KT 110 MPH
60H  04/0000Z 20.5N  46.8W  105 KT 120 MPH
72H  04/1200Z 21.6N  48.3W  110 KT 125 MPH
96H  05/1200Z 25.0N  51.0W  110 KT 125 MPH
120H  06/1200Z 30.0N  51.0W   95 KT 110 MPH

$$
Forecaster Papin