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Tropical Storm Melissa Discussion Number 6
NWS National Hurricane Center Miami FL AL132025
500 PM EDT Wed Oct 22 2025
Like yesterday, Melissa's structure has come unglued this
afternoon, with the low-level circulation becoming exposed to
the west of the bursting deep convection. While that convection
continues to have very cold cloud tops, it lacks much organization,
remaining parked down-shear of the storm with 20-30 kt of
west-northwesterly shear undercutting the outflow layer. This
disjointed structure is nicely exhibited on an 1825 UTC AMSR2 pass.
While the objective intensity estimates in general are a little
higher than this morning, the subjective Dvorak estimates are lower,
and given the disjointed structure of Melissa, it favors holding the
intensity at 45 kt this advisory. Another Air Force Reserve and the
first NOAA Hurricane Hunter mission will be in the storm this
evening to provide more structural information.
Melissa has taken a short-term jog westward as it became exposed,
but now appears to be resuming a very slow west-northwestward motion
at 290/2 kt. The track reasoning remains similar to the previous
forecast over the next 2-3 days, with the forecast storm structure
likely to have a significant role in the future track. Dynamical
models that show the storm becoming more vertically aligned and deep
(GFS, HWRF) show Melissa turning north or northeastward due to
westerly deep-layer steering into a weakness induced by a broad
upper-level trough located over the Bahamas. However, models that
show Melissa remaining more shallow and misaligned (ECMWF, HAFS-A/B)
maintain a northwestward or north-northwestward component of
motion. Compared to this morning, the track guidance has shifted
slower and farther west, possibly due to the farther west initial
position. The NHC track has been shifted westward and is also a
little southward after 60 h, but remains farther north and east of
the ECMWF and HAFS models this cycle, and is roughly in between the
HFIP consensus approach (HCCA) and Google DeepMind ensemble mean
(GDMI). This track forecast favors the models that keep Melissa weak
and less prone to the deep-layer steering over the next 24-48 hours.
However, this remains a low confidence track forecast other than
Melissa maintaining a slow motion for the majority of the period.
The current vortex misalignment of Melissa is a significant
impediment to short-term intensification, and the vertical wind
shear is expected to maintain this tilted structure over the next
24-36 hours, although I can't preclude any center reformations
down-shear, like what occurred last night. After this period, the
ECWMF-SHIPS guidance now indicates the ongoing westerly shear will
decrease to 10-15 knots, and the storm remains over very warm
sea-surface temperatures and high oceanic heat content. The
hurricane-regional models have all responded by showing significant
intensification after the vortex becomes vertically aligned,
sometime in the 60-96 h period, though timing when this may occur is
challenging. The intensity guidance is once again higher than the
previous cycle, and the NHC intensity forecast was raised once
again, showing Melissa becoming a hurricane in 72 h, rapidly
intensifying into a major hurricane by 96 h, with additional
intensification likely thereafter. This forecast is in the best
agreement with the HCCA intensity aid, but it is worth noting it's
under the latest HAFS-A/B and HMON forecasts. Unfortunately, it is
becoming increasingly likely that Melissa will become a large and
dangerous hurricane by the end of the forecast period.
Key Messages:
1.
Melissa is forecast to meander over the central Caribbean Sea and
could potentially become a major hurricane by early next week.
Interests in Jamaica, Haiti, Cuba, and the Dominican Republic are
urged to continue monitoring the latest forecasts.
2. Due to Melissa’s slow motion, the risk of a prolonged period of
strong winds, possibly lasting for a day or more, is increasing for
Jamaica and the Tiburon peninsula of Haiti. Preparations to protect
life and property should be rushed to completion, since strong
winds could begin in these areas as early as late Thursday or
Friday and continue increasing over the weekend.
3. Melissa is expected to produce heavy rainfall across portions of
the Dominican Republic, Haiti, and Jamaica through this weekend,
bringing a risk of significant, life-threatening flash flooding and
numerous landslides.
(snip)
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