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Hurricane Leslie Discussion Number 59
NWS National Hurricane Center Miami FL AL132018
1100 PM AST Wed Oct 10 2018
The overall cloud pattern of Leslie has become somewhat better
organized over the past several hours with increasing convection
in the central dense overcast and tighter banding features. A blend
of the subjective Dvorak and microwave estimates suggest an initial
wind speed of 70 kt for this advisory.
Satellite fixes indicate that Leslie has turned toward the east-
northeast and is moving faster at about 10 kt. The track forecast
really hinges on whether Leslie gets accelerated in southwesterly
flow ahead of an eastern Atlantic trough or gets dropped by that
trough and turns southwestward around a new subtropical ridge.
Sadly, the forecast agreement from the previous advisory has
disintegrated, with all of the GFS-based guidance now indicating a
track more toward Europe, while the ECMWF/UKMET send Leslie in the
exact opposite direction toward the east-central Atlantic. I
clearly drew the small straw in having to make Leslie's forecast
tonight because this situation is resulting in one of the largest
guidance spreads I have seen, about 1000 miles on day 3 and over
2000 miles at day 5. Furthermore, the corrected-consensus guidance
is closer to the GFS guidance, which is way to the northeast of the
previous forecast. The new forecast will somewhat reflect the
latest guidance, showing an adjustment to the east, but is still
hundreds of miles to the southwest of the latest model consensus.
Obviously this is a zero-confidence forecast tonight.
Marginally warm waters and moderate shear could support additional
strengthening of Leslie during the next day or two, although the
guidance is generally lower than yesterday. By Saturday, colder
ocean waters, higher shear and a drier mid-level atmosphere should
cause Leslie to weaken. No significant changes were made to the
previous intensity forecast. By Monday, Leslie, whether it follows
the forecast track or not, will likely be struggling to produce
convection or have already transitioned into an extratropical low.
Thus the 5 day point shows post-tropical status, perhaps
optimistically, but this seems like the most likely option for now.
FORECAST POSITIONS AND MAX WINDS
INIT 11/0300Z 27.9N 41.1W 70 KT 80 MPH
12H 11/1200Z 28.4N 39.4W 75 KT 85 MPH
24H 12/0000Z 29.9N 35.7W 75 KT 85 MPH
36H 12/1200Z 31.3N 30.5W 75 KT 85 MPH
48H 13/0000Z 32.3N 25.0W 70 KT 80 MPH
72H 14/0000Z 32.0N 20.0W 50 KT 60 MPH
96H 15/0000Z 29.5N 20.5W 35 KT 40 MPH
120H 16/0000Z 27.5N 25.0W 30 KT 35 MPH...POST-TROPICAL