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Tropical Depression Norbert Discussion Number 24
NWS National Hurricane Center Miami FL EP192020
300 PM MDT Wed Oct 14 2020
Vertical wind shear and dry mid-level air are clearly taking a toll
on Norbert. Infrared cloud top temperatures have rapidly warmed as
Norbert has lost most, if not all, of its deep convection. Water
vapor imagery shows a tongue of dry air drawn into the cyclone's
circulation by a mid-level low pressure system centered to the west
of Norbert. If current trends continue, Norbert could degenerate
into a remnant low tonight or early Thursday. The advisory
intensity is lowered to 30 kt based on a 1750Z ASCAT-B overpass
that showed 25-30 kt winds in the northern semicircle of Norbert.
This is consistent with T2.0 subjective Dvorak classifications from
SAB and TAFB.
Norbert has moved a bit faster than was previously forecast, and
its initial motion is estimated at 330/15 kt. The track guidance
consensus depicts a northwestward motion with a decrease in forward
speed through tonight as the depression moves between a mid-level
ridge over northern Mexico and the aforementioned mid-level low. A
slow northward turn is expected on Thursday. The NHC track forecast
was adjusted slightly to the right of the previous forecast based
on 12Z global model trends.
Norbert will continue weakening during the next day or so in an
environment characterized by 20-25 kt of deep-layer shear, dry
mid-level air, and low oceanic heat content. The official intensity
forecast shows remnant low status at 24 h and dissipation at 36 h,
which is consistent with the consensus of reliable global models.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 24.7N 114.9W 30 KT 35 MPH
12H 15/0600Z 25.9N 115.7W 25 KT 30 MPH
24H 15/1800Z 26.9N 115.8W 20 KT 25 MPH...POST-TROP/REMNT LOW