Hurricane Vance

000
WTPZ42 KNHC 242040
TCDEP2
 
Hurricane Vance Discussion Number  14
NWS National Hurricane Center Miami FL       EP222026
300 PM CST Sat Oct 24 2026

Vance has become significantly less organized since the last 
advisory due to a combination of cold water near the center and 
increasing southwesterly shear. Microwave data indicates that the 
eyewall has broken open, with the remaining convection limited to 
north of the center. In addition, visible imagery shows the 
low-level center to be near or a little south of the southern edge 
of the convective mass. The various satellite intensity estimates 
have dropped, and based on them the initial intensity is lowered to 
80 kt.  This could be quite generous, as the current structure does 
not look much like a hurricane.
 
The intensity forecast is still problematic, but perhaps a little 
less so than earlier. Vance is likely to weaken during the next 
12-18 h as it crosses a pool of colder water with temperatures near 
27C that has been upwelled by several previous tropical cyclones, 
while at the same time it experiences at least moderate 
southwesterly shear.  Beyond that time, the center is expected to 
move over sea surface temperatures near 29C closer to the coast of 
Mexico. This could allow intensification if the shear is light 
enough and the storm structure is still good enough to allow it. The 
GFS and ECMWF continue show a period of reduced, but still marginal, 
shear that could allow some intensification, and based on this and 
trends in the guidance slight re-intensification is shown at 48 h. 
By the end of the forecast period, increasing shear is likely to 
cause Vance to steadily weaken. It is still possible that Vance 
could weaken more than forecast before reaching warmer water and 
that the shear may be too strong to allow re-intensification after 
36 h. The new intensity forecast has major downward adjustments from 
the previous forecast.

The initial motion remains north-northwestward or 340/5 kt.  Vance 
is being steered by a weak low- to mid-level ridge over eastern 
Mexico, and it is approaching a large mid-latitude trough over the 
western United States and northwestern Mexico. While neither of 
these features will change much during the next few days, Vance is 
likely to move into an area of lighter steering currents near the 
base of the trough and slow its forward motion during the next 
24 or so.  The track forecast beyond that time is dependent on the 
cyclone's strength and vertical structure. A weaker system that 
shears apart like shown in the UKMET and Canadian is likely to move 
west-northwestward to northwestward before resuming a more northerly 
motion, while a stronger and vertically deeper system is likely to 
continue slowly northward or north-northwestward.  The track 
guidance envelope has shifted westward since the previous advisory, 
and the new forecast track has been nudged westward as well. 
Additional westward adjustments to the track may be necessary if 
Vance continues to lose organization.


Key Messages:
 
1. Due to the uncertainties in both the track and intensity
forecasts, it is too early to say what wind and storm surge
impacts Vance may cause along the coast of Mexico. Interests in
southwestern Mexico should continue to monitor the progress of the
hurricane.
 
2. Heavy rainfall associated with slow-moving Hurricane Vance will 
impact the western coast of Mexico from Michoacán to Jalisco during 
much of next week. This rainfall may produce life-threatening 
flooding and mudslides across Colima and western portions of 
Michoacán and Jalisco, especially in areas along steep terrain.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  24/2100Z 13.3N 103.3W   80 KT  90 MPH
 12H  25/0600Z 14.0N 103.6W   75 KT  85 MPH
 24H  25/1800Z 14.9N 104.0W   70 KT  80 MPH
 36H  26/0600Z 15.6N 104.4W   70 KT  80 MPH
 48H  26/1800Z 16.0N 104.6W   75 KT  85 MPH
 60H  27/0600Z 16.4N 104.8W   70 KT  80 MPH
 72H  27/1800Z 17.0N 104.9W   65 KT  75 MPH
 96H  28/1800Z 18.1N 105.2W   50 KT  60 MPH
120H  29/1800Z 19.3N 105.6W   40 KT  45 MPH
 
$$
Forecaster Beven