ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Hurricane Gert Discussion Number 18 NWS National Hurricane Center Miami FL AL082017 500 AM AST Thu Aug 17 2017 The expected weakening trend of Gert appears to have started. The eye of the hurricane is no longer evident in satellite images, and the convective pattern has become less symmetric during the past several hours. The initial wind speed is lowered a little to 85 kt, in agreement with a blend of the Dvorak final T- and CI-numbers from TAFB and SAB. The hurricane is crossing the north wall of the Gulf Stream current, and it will soon be moving over substantially colder water. These colder waters combined with a significant increase in wind shear and drier air should cause rapid weakening during the next day or so. Gert is now forecast to lose its tropical characteristics in about 24 hours, when it will be over very cool sea surface temperatures of about 16 deg C. The NHC intensity forecast is an update of the previous one, and it generally follows the GFS model. Gert is embedded in fast mid-latitude flow and it is racing east-northeastward over the central Atlantic at 34 kt. A decrease in forward speed and a slight turn to the northeast is expected during the next couple of days while Gert interacts with a large extratropical low to the east of Atlantic Canada. The global models show this extratropical system absorbing, or merging with, Gert in about 3 days. The NHC track forecast is adjusted a little to the right of the previous one to come into better agreement with the latest consensus models. The track, intensity, and wind radii forecasts have incorporated guidance from NOAA's Ocean Prediction Center. Swells from Gert should continue to affect the coast of the northeastern U.S. and Atlantic Canada through tonight. These swells are likely to produce dangerous surf and rip current conditions. Please consult products from your local weather forecast office for more information. FORECAST POSITIONS AND MAX WINDS INIT 17/0900Z 41.7N 54.0W 85 KT 100 MPH 12H 17/1800Z 44.2N 47.4W 70 KT 80 MPH 24H 18/0600Z 48.0N 40.2W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 18/1800Z 50.7N 36.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 19/0600Z 52.0N 33.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 20/0600Z...DISSIPATED $$ Forecaster Cangialosi NNNN
Alternate Formats
About Alternates -
E-Mail Advisories -
RSS Feeds
Cyclone Forecasts
Latest Advisory -
Past Advisories -
About Advisories
Marine Forecasts
Latest Products -
About Marine Products
Tools & Data
Satellite Imagery -
US Weather Radar -
Aircraft Recon -
Local Data Archive -
Forecast Verification -
Deadliest/Costliest/Most Intense
Learn About Hurricanes
Storm Names
Wind Scale -
Prepare -
Climatology -
NHC Glossary -
NHC Acronyms -
Frequently Asked Questions -
AOML Hurricane-Research Division
About Us
About NHC -
Mission/Vision -
Other NCEP Centers -
NHC Staff -
Visitor Information -
NHC Library
NOAA/
National Weather Service
National Centers for Environmental Prediction
National Hurricane Center
11691 SW 17th Street
Miami, Florida, 33165-2149 USA
nhcwebmaster@noaa.gov
Disclaimer
Privacy Policy
Credits
About Us
Glossary
Career Opportunities
Page last modified: Sunday, 31-Dec-2017 12:09:13 UTC