000
WTNT43 KNHC 140233
TCDAT3

Tropical Storm Gert Discussion Number   5
NWS National Hurricane Center Miami FL       AL082017
1100 PM EDT Sun Aug 13 2017

Gert continues to gradually become better organized on satellite
imagery.  A large curved band feature has formed in the eastern
semicircle, with very deep convection.  It still appears the center
is on the northwest side of the convection, somewhat displaced to
the north of the mid-level center.  Intensity estimates are a little
higher than the last advisory, so the wind speed is raised to 40 kt.
Gert should remain in a light-to-moderate northerly wind shear
environment for the next couple of days, with anomalously warm SSTs
and increasing mid-level moisture in the forecast path.  Almost all
of the historically reliable guidance now show Gert becoming a
hurricane in a couple of days under these moderately favorable
conditions, and so does the official forecast. The latest NHC
prediction is raised from the previous one but remains below the
model consensus, closest to the LGEM model.  Gert should rapidly
weaken as it undergoes extratropical transition in 3-4 days over the
cold north Atlantic waters.

Gert is moving north-northwestward at 8 kt on the southwestern
periphery of a subtropical ridge.  A northward turn is expected
on Monday while the system rounds the western side of the ridge, and
Gert is expected to be about midway between Bermuda and North
Carolina on Tuesday.  After that time, a progressively faster motion
to the northeast and east-northeast is forecast as the system
becomes embedded in the mid-latitude westerlies until it dissipates
in about 5 days.  The guidance has shifted a little bit to the west
after recurvature, so the official forecast is moved in that
direction.

FORECAST POSITIONS AND MAX WINDS

INIT  14/0300Z 28.8N  71.9W   40 KT  45 MPH
 12H  14/1200Z 30.0N  72.1W   50 KT  60 MPH
 24H  15/0000Z 31.6N  72.1W   55 KT  65 MPH
 36H  15/1200Z 33.6N  71.2W   60 KT  70 MPH
 48H  16/0000Z 36.0N  68.5W   65 KT  75 MPH
 72H  17/0000Z 41.0N  55.5W   65 KT  75 MPH
 96H  18/0000Z 48.0N  41.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  19/0000Z...DISSIPATED

$$
Forecaster Blake

NHC Atlantic Ops‏Cuenta verificada @NHC_Atlantic  26 minHace 26 minutos
 #Gert is now forecast to become a #hurricane while it recurves away from the United States in a couple of days. http://hurricanes.gov

Michael Ventrice‏Cuenta verificada @MJVentrice  30 minHace 30 minutos
 Possible rapid intensification of #Gert taking place; Now has a robust eye with two vortical hot towers cyclonically rotating around the eye

000
WTNT43 KNHC 150833
TCDAT3

Hurricane Gert Discussion Number  10
NWS National Hurricane Center Miami FL       AL082017
500 AM EDT Tue Aug 15 2017

After a period of intensification several hours ago, recent
satellite images show that the cloud pattern has deteriorated a
little bit. The eye is no longer discernible, and the center is now
located to the west of an area of very deep convection. Dvorak
numbers still support an initial intensity of 65 kt.  Gert has an
opportunity to gather some strength in the next day or so after
recurvature. The new NHC forecast is not as aggressive as the
previous one, and it follows very closely the intensity consensus.
Only the HWRF model significantly strengthens the cyclone. After two
days, Gert will be completely embedded within the mid-latitude
westerlies and should become a post-tropical cyclone.

The best estimate of the initial motion is toward the north or 360
degrees at 10 kt. Gert is being steered northward by the flow around
the western edge of the subtropical ridge. The cyclone should then
turn to the northeast with an increase in forward speed later today
as it becomes embedded within the mid-latitude flow. The NHC track
forecast is similar to the previous one, and is in the middle of the
tight guidance envelope.

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  15/0900Z 31.8N  72.5W   65 KT  75 MPH
 12H  15/1800Z 33.3N  71.5W   70 KT  80 MPH
 24H  16/0600Z 35.5N  68.9W   75 KT  85 MPH
 36H  16/1800Z 37.8N  64.0W   75 KT  85 MPH
 48H  17/0600Z 40.0N  57.0W   70 KT  80 MPH
 72H  18/0600Z 46.5N  41.0W   65 KT  75 MPH...POST-TROP/EXTRATROP
 96H  19/0600Z 52.0N  36.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  20/0600Z...DISSIPATED

$$
Forecaster Avila