Tropical Depression Fifteen Forecast Discussion Number 5

By | October 15, 2019

Issued at 500 PM AST Tue Oct 15 2019

WTNT45 KNHC 152051

Tropical Depression Fifteen Discussion Number   5
NWS National Hurricane Center Miami FL       AL152019
500 PM AST Tue Oct 15 2019

The multiple circulations mentioned in the previous advisory
discussion now appear to have consolidated into a tight low-level
center that has recently passed over or near Sal island in the
northeastern Cabo Verde archipelago. Deep convection has increased
slightly and now consists of an elongated band confined to the
eastern semicircle due to modest southwesterly vertical wind shear,
leaving the low-level center exposed to the west. A late-arriving
1128Z ASCAT-C scatterometer pass indicated several 28-29 kt surface
wind vectors within the band of convection, which supports
maintaining an intensity of 30 kt.

The initial motion remains northwestward, or 315/09 kt. There is no
significant change to the previous forecast track or rationale. The
latest NHC model guidance remains in very good agreement that the
large cyclone will move generally northwestward during the next 48
hours or so, followed by a turn to the west-northwest when the
expected shallow system will become embedded in the brisk low-level
easterly trade wind flow. The new official track forecast is similar
to the previous advisory track, and lies just to the left of the
HCCA and TVCN consensus models.

The environmental conditions are expected to only be marginal, so
little, if any, strengthening is anticipated during the next 12
hours. By 24 hours and beyond, the combination of strong
southwesterly vertical wind shear, drier and more stable air, and
SSTs less than 26C should cause steady to rapid weakening, resulting
in the cyclone degenerating into a remnant low by 36 hours and
dissipating shortly after 72 hours, if not sooner.

Regardless of whether or not the depression becomes a tropical storm
as it passes near the Cabo Verde Islands, the primary threat from
this system is the potential for locally heavy rainfall and flash
flooding in those islands.


INIT  15/2100Z 16.8N  22.9W   30 KT  35 MPH
 12H  16/0600Z 17.8N  23.7W   30 KT  35 MPH
 24H  16/1800Z 19.0N  24.8W   25 KT  30 MPH
 36H  17/0600Z 19.9N  26.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  17/1800Z 21.2N  28.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  18/1800Z 23.0N  32.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  19/1800Z...DISSIPATED

Forecaster Stewart

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