Monday, August 26, 2019

Tropical Depression Number Six forms, is a Potential Threat to the Region


248
WTNT41 KNHC 262038
TCDAT1

Tropical Depression Six Discussion Number   1
NWS National Hurricane Center Miami FL       AL062019
500 PM EDT Mon Aug 26 2019

The circulation associated with the area of low pressure that has
been tracked across the western Atlantic the past several days has
become better defined during the past 24 hours.  The associated
convection, which is located well to the southeast of the low-level
center due to shear, has also become more persistent and organized
into a band today.  As a result, advisories are being initiated on a
tropical depression.  The initial wind speed has been set at 30 kt,
based on earlier ASCAT data.  There were a few 35-kt vectors in the
ASCAT-A overpass but those data appeared to be rain-inflated.

The depression is currently located over warm water but within an
environment of moderate westerly shear, which is likely to continue
during the next day or so.  Although some slight strengthening is
forecast, the shear is likely to prohibit significant deepening
during that time.  After 36 h, the shear is forecast to decrease
while the system moves northeastward and some modest strengthening
is anticipated.  Later in the period, an approaching mid-latitude
trough may also help to strengthen the cyclone due to baroclinic
processes, and the system is forecast to become extratropical in
3 to 4 days, and should be absorbed by a larger extratropical
cyclone by day 5.

The initial motion estimate is a somewhat uncertain 080/2 kt.  The
depression is forecast to drift eastward or northeastward during
the next day or so as it remains in an area of weak steering flow
between a couple of mid-level anticyclones. As the aforementioned
mid-latitude trough approaches the northeastern United States on
Wednesday, it should cause the cyclone to accelerate northeastward
well east of the east coast of the United States.  The track
guidance is in relatively good agreement, but there are some
differences in how fast it will be ejected northeastward.  The NHC
track forecast leans toward the slower ECMWF solution during the
first day or so, then closer to the consensus aids later in the
period.


FORECAST POSITIONS AND MAX WINDS

INIT  26/2100Z 31.7N  72.5W   30 KT  35 MPH
 12H  27/0600Z 31.8N  72.0W   35 KT  40 MPH
 24H  27/1800Z 32.1N  71.9W   35 KT  40 MPH
 36H  28/0600Z 32.9N  71.9W   35 KT  40 MPH
 48H  28/1800Z 34.6N  71.5W   40 KT  45 MPH
 72H  29/1800Z 40.3N  66.8W   45 KT  50 MPH
 96H  30/1800Z 47.0N  60.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  31/1800Z...DISSIPATED

$$
Forecaster Brown

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