633
WTNT43 KNHC 221455
TCDAT3

Tropical Storm Melissa Discussion Number 5
NWS National Hurricane Center Miami FL AL132025
1100 AM EDT Wed Oct 22 2025

While Melissa continues to produce bursting convection on satellite
imagery, with very cold cloud tops down to -95C, there is little
evidence these convective bands are wrapping around the center. West-northwesterly shear of 20 to 25 kt is currently preventing the
low-level and mid-level circulation centers from aligning. This
downshear tilt with height has also been observed by the latest Air
Force Reconnaissance mission, which reported significant winds at
the surface in their most recent 850 mb center drop. The initial
intensity for this advisory is held at 45 kt, taking a blend of
recon observations which had a peak wind of 52 kt at 850 mb, and
satellite intensity estimates from TAFB, ADT, and D-MINT. The wind
field of Melissa also remains very asymmetric, as evidence of a
recent 1040z RCM-1 Synthetic Aperture Radar pass showing the bulk of tropical-storm-force winds east of the center.

The tropical storm has slowed down to a crawl this morning, with the
estimated motion at 300/2 kt. The track forecast remains challenging
today, and strongly related to the storm's structure in the
short-term. For the next 12-24 hours, Melissa is forecast to move
very slowly to the northwest as it attempts to move into a weakness
produced by an broad upper-level trough centered over the Bahamas.
Whether or not it turns more rightward into this weakness is related
to the vertical depth the various model guidance is depicting. The
06z GFS run, which is the model that has been on the right side of
the guidance envelope for days, shows a more vertically coherent
system over the next 24-48 hours, and causes Melissa to abruptly
turn northeastward over the next 48 hours. While this appears to be
an outlier solution, the Google DeepMind ensemble mean (GDMI) also
shows this northeastward motion, and a significant fraction of its
ensemble members show the Melissa making landfall on the Island of
Hispaniola. However, the remainder of the track guidance, including
the ECMWF and its ensemble mean, suggest that Melissa will remain
misaligned and move more slowly north-northwest over the next couple
of days. The NHC track solution slightly favors the latter
scenarios, lying just east of the ECMWF mean, out of respect of the
reliable GDMI aid. After about 60 h, mid-level ridging begins to
build back in to the north, and most of the guidance responds by
showing a sharp turn westward, albeit still at a snail's pace. The
overall track guidance, GFS and GDMI excluded, has shifted left this
cycle beyond 72 h, and the NHC track was shifted in that direction,
but not as far south and west as the HAFS-A/B regional models. It
goes without saying, this is a very challenging track forecast.

The intensity forecast has its own share of challenges. At least in
the short-term, vertical wind shear is expected to persist between
20 to 30 kt, and will likely prevent Melissa from becoming fully
aligned and taking advantage over the very warm 30-31C sea surface temperatures. After about 48 hours, the GFS and ECMWF-based SHIPS
guidance shows the shear decreasing gradually, but the timing on
when the system becomes more vertically coherent varies among both
the global and hurricane-regional model guidance. Most of the
guidance shows significant or even rapid intensification in days
3-5, and the NHC intensity forecast was raised once again during
this time frame, but not as high as the HCCA or hurricane-regional
models due to continuity constraints to the previous forecast. The
day 5 forecast now shows Melissa becoming a major hurricane, and
further upward adjustments may be necessary in subsequent cycles.
The intensity forecast is also more uncertain than usual, in large
part related to the track uncertainty.

Key Messages:

1. Melissa is expected to produce heavy rainfall across portions of
the Dominican Republic, Haiti, and Jamaica through this weekend,
bringing a risk of significant flash flooding and landslides.

2. Hurricane conditions are possible in the southwestern peninsula
of Haiti where a Hurricane Watch is in effect. A Tropical Storm
Watch is in effect for Jamaica. Preparations to protect life and
property should be completed by Thursday.

3. There is significant uncertainty in the track and intensity
forecast of Melissa. Interests elsewhere in Hispaniola and Cuba
should continue to monitor the latest forecasts.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 14.4N 73.6W 45 KT 50 MPH
12H 23/0000Z 14.8N 73.9W 45 KT 50 MPH
24H 23/1200Z 15.2N 74.3W 50 KT 60 MPH
36H 24/0000Z 15.6N 74.4W 55 KT 65 MPH
48H 24/1200Z 16.0N 74.4W 55 KT 65 MPH
60H 25/0000Z 16.3N 74.6W 60 KT 70 MPH
72H 25/1200Z 16.5N 74.9W 70 KT 80 MPH
96H 26/1200Z 16.6N 75.8W 90 KT 105 MPH
120H 27/1200Z 16.4N 77.4W 105 KT 120 MPH

$$
Forecaster Papin


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