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Hurricane Paulette Discussion Number 26
NWS National Hurricane Center Miami FL AL172020
500 AM AST Sun Sep 13 2020
Over the past 6 hours, conventional and passive microwave satellite
data indicate that very little change to Paulette's overall
convective cloud pattern and inner-core structure has occurred.
A recent GMI pass indciated that the inner-core convection remains
somewhat disheveled due to a narrow but pronounced band of dry air
having penetrated the mid-levels of the cyclone. However, the
low-level eye feature remains intact with a diameter of at least 30
nmi. Given the little change in structure since the previous
reconnaissance mission, the intensity is being maintained at 65
kt. Another Air Force Reserve Hurricane Hunter aircraft will be
investigating Paulette later this morning to provide a better
estimate of the hurricane's intensity.
The initial motion estimate remains west-northwestward or 300/12 kt.
Overall, there is no significant change to the previous track
forecast or reasoning. The global and regional models are in
excellent agreement on Paulette passing over or near Bermuda during
the 24-36 hour period as the cyclone rounds a sharp east-to-west
oriented subtropical ridge located near and due east of Bermuda.
After passing Bermuda and moving north of the ridge in about 36
hours, Paulette is forecast to accelerate northeastward ahead of an
approaching deep-layer trough and associated surface cold front.
There is one important feature to mention -- the official forecast
track is west of the latest 0600 UTC interpolated models due to the
interpolated model tracks taking the center of Paulette at least 30
nmi east of Bermuda. In contrast, the GFS, UKMET, and ECMWF are less
than 6 nmi apart at 12-48 hours, and that consensus brings the
hurricane across or just west of Bermuda in about 30 hours.
Therefore, the new NHC official track forecast is essentially just
an update and extension of the previous advisory track, and lies
just west of the tightly packed NHC guidance envelope.
Environmental conditions appear favorable to Paulette to strengthen
during the next 72 hours or so, with only occasional intrusions of
dry mid-level air briefly interrupting the intensification process.
The ragged inner core structure will likely delay intensification
this morning, but by the this afternoon and continuing into Monday,
the vertical shear is forecast by the global models to decrease to
near zero, which should allow for significant strengthening to
occur. In fact, it highly probable that Paulette will continue to
intensify as the hurricane passes over Bermuda. By 48 hours when the
hurricane is expected to be north of Bermuda, baroclinic
interaction with the aforementioned deep-layer trough is forecast
to aid in the intensification process with Paulette possibly
becoming a major hurricane around 72 hours. Thereafter, increasing
vertical wind shear in excess of 25 kt should gradually weaken the
cyclone. It is possible that by 96 hours or so, Paulette could merge
with a frontal system and become a powerful extratropical low. For
now, however, Paulette is forecast to remain just ahead of the
front within the warm sector of a flat frontal wave. The official
intensity forecast is similar to the previous advisory, and is near
the upper end of intensity guidance throughout the 120-h forecast
1. Paulette is expected to approach Bermuda as a hurricane on Sunday
and will be near the island Sunday night and Monday. A prolonged
period of strong winds, storm surge, and heavy rainfall is expected
on Bermuda beginning Sunday evening, and a hurricane warning is in
effect for the island. Preparations to protect life and property
should be rushed to completion.
2. Swells produced by Paulette are affecting portions of the
Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, and
the east coast of the United States. These swells could cause
life-threatening surf and rip current conditions.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0900Z 29.4N 60.8W 65 KT 75 MPH
12H 13/1800Z 30.2N 62.5W 70 KT 80 MPH
24H 14/0600Z 31.8N 64.4W 80 KT 90 MPH
36H 14/1800Z 34.0N 65.0W 90 KT 105 MPH
48H 15/0600Z 35.9N 62.4W 95 KT 110 MPH
60H 15/1800Z 37.8N 57.9W 95 KT 110 MPH
72H 16/0600Z 39.3N 54.0W 90 KT 105 MPH
96H 17/0600Z 42.0N 46.0W 80 KT 90 MPH
120H 18/0600Z 43.8N 40.0W 65 KT 75 MPH