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Tropical Storm BERYL


Tropical Storm Beryl Discussion Number   3
NWS National Hurricane Center Miami FL       AL022018
1100 PM AST Thu Jul 05 2018

Tiny Beryl has maintained a small ball of convection near the center
except for a brief period around 2300 UTC when a tight curved band
was exposed, revealing 10- to 11-tenths banding. Passive microwave
satellite data during the past 6 hours have also indicated
5-nmi-diameter eye exists underneath the CDO feature.  Given the
small size of the cyclone, which can quickly adjust to convective
changes, and a Dvorak satellite estimate of T3.5/55 kt from SAB, the
advisory intensity has been increased to 55 kt.

The initial motion estimate is 275/12 kt. Most of the latest model
guidance has made a pronounced southward shift, which is significant
since all of the models have displayed a distinct right-of-track,
poleward bias over the past 48 hours. The ECMWF has had the greatest
poleward bias, and is now the northernmost solution in the model
suite. The GFS, HWRF, and UKMET are now clustered along the southern
edge of the guidance envelope, with the consensus models somewhere
in between those latter models and the ECMWF. Given the very small
size of Beryl, I am having difficulty envisioning the cyclone moving
into the strong subtropical ridge situated to its north and gaining
as much latitude as the ECMWF has been and is still indicating. As a
result, the new NHC forecast track has been shifted south of the
previous advisory track, but not as far south as the GFS-HRWF-UKMET
consensus, and lies a tad south of the HCCA and FSSE solutions.

Water vapor and model moisture analyses indicate that Beryl has been
able to maintain a buffer between it and the very dry, stable air
just to its north, due in large part to the deep, southerly moisture
fetch coming up from the equatorial region. This pattern is forecast
by most of the global models to continue for at least the next 48
hours. That favorable environment, coupled with forecast low
vertical wind shear conditions of near 5 kt for the next 24 hours,
should allow Beryl to achieve hurricane status by late Friday. By 72
hours when Beryl will be approaching the Lesser Antilles, the shear
is forecast to increase from the west and northwest at 20-25 kt,
which is expected to induce rapid weakening. All of the global
models continue to show the cyclone opening up into a tropical wave
shortly after 72 hours, which is what the current forecast continues
to depict in order to maintain continuity with the previous advisory
track. However, only a slight delay in the onset of the strong shear
conditions could result in Beryl maintaining tropical cyclone status
when it moves across the Lesser Antilles on Sunday.

Even though Beryl is expected to dissipate just east of the Lesser
Antilles early next week, the remnant tropical wave will continue
moving quickly westward and will likely bring locally heavy rains
and strong gusty winds to portions of the Leeward Islands on Sunday
and Monday.

Key Messages:

1. Due to its very small size, there is greater-than-usual
uncertainty in the analysis of Beryl's current intensity. Confidence
in the official intensity forecast is also much lower than normal.
Rapid changes in intensity, both up and down, that are difficult to
predict are possible during the next couple of days.

2. While Beryl is still expected to dissipate as a tropical cyclone
by Monday before reaching the Lesser Antilles, there will likely be
some rain and wind impacts on those islands early next week.
Residents there should monitor products from their local weather
office for more information.


INIT  06/0300Z 10.4N  44.0W   55 KT  65 MPH
 12H  06/1200Z 10.7N  45.5W   60 KT  70 MPH
 24H  07/0000Z 11.2N  47.4W   65 KT  75 MPH
 36H  07/1200Z 11.9N  49.7W   65 KT  75 MPH
 48H  08/0000Z 12.7N  52.5W   60 KT  70 MPH
 72H  09/0000Z 14.4N  59.7W   50 KT  60 MPH
 96H  10/0000Z...DISSIPATED

Forecaster Stewart