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Tropical Storm Gert Discussion Number 8
NWS National Hurricane Center Miami FL AL082017
500 PM EDT Mon Aug 14 2017
The satellite presentation of Gert has continued to improve today.
Convective banding has increased around the center, and a large
banded eye has appeared in recent visible satellite pictures.
Satellite intensity estimates from TAFB, SAB, and UW-CIMSS supported
an intensity of around 55 kt at 18z, but due to the continued
increase in organization, the initial wind speed is set at 60 kt
for this advisory. Although there is some light northerly shear
over the system, it should not prevent additional strengthening
during the next day or so while Gert remains over SSTs of 28 to
29 deg C. Gert is expected to become a hurricane within 12 hours,
and the updated NHC intensity forecast calls for a bit higher peak
intensity than before. The NHC forecast is a little above the
statistical guidance and calls for peak intensity a little sooner
than most of the guidance. The HWRF continues to be very bullish
in bringing the system to major hurricane status, but since it
shows peak intensity well after the system is expected to encounter
westerly shear and cooler SSTs, less weight has been placed on that
scenario. Gert is expected to complete extratropical transition
within 72 hours, then gradually weaken over the North Atlantic
before it merges with a larger extratropical cyclone in 4 to 5 days.
Gert has been moving more slowly than expected today while it has
been rounding the western portion of the ridge. The storm is
expected to turn north-northeastward and begin to accelerate
Tuesday ahead of a shortwave trough approaching the northeastern
United States. The track guidance continues to be in excellent
agreement, but is generally slower than before. As a result, little
cross-track change was required in the NHC track through 72 h, but
the new forecast is slower than the previous one to account for the
latest trend in the latest guidance.
Swells from Gert are expected to spread northward along the
mid-Atlantic coast of the United States during the next few days.
These swells are likely to produce dangerous surf and rip current
conditions. Please consult products from your local National
Weather Service office.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 30.6N 72.3W 60 KT 70 MPH
12H 15/0600Z 31.6N 72.3W 70 KT 80 MPH
24H 15/1800Z 33.3N 71.6W 75 KT 85 MPH
36H 16/0600Z 35.6N 69.0W 80 KT 90 MPH
48H 16/1800Z 38.0N 64.0W 80 KT 90 MPH
72H 17/1800Z 44.5N 48.0W 70 KT 80 MPH...POST-TROP/EXTRATROP
96H 18/1800Z 52.0N 39.0W 50 KT 60 MPH...POST-TROP/EXTRATROP
120H 19/1800Z...ABSORBED BY LARGER EXTRATROPICAL LOW