Tropical Storm Gordon Advisory Number   9
NWS National Hurricane Center Miami FL       AL072018
1000 AM CDT Tue Sep 04 2018

...OUTER RAINBANDS PRODUCING SQUALLY WEATHER ALONG THE COAST OF THE
WESTERN FLORIDA PANHANDLE...
...GORDON EXPECTED TO MAKE LANDFALL TONIGHT AS A HURRICANE...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...28.5N 86.8W
ABOUT 145 MI...235 KM ESE OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES



WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

The Tropical Storm Warning has been discontinued west of Grand
Isle, Louisiana.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Shell Beach to Dauphin Island

A Storm Surge Watch is in effect for...
* West of Shell Beach to the Mouth of the Mississippi River
* East of Dauphin Island to Navarre



A Hurricane Warning is in effect for...
* Mouth of the Pearl River to the Alabama-Florida Border

A Tropical Storm Warning is in effect for...
* West of the Mouth of the Pearl River to Grand Isle, including Lake
Pontchartrain and Lake Maurepas
* Alabama-Florida Border to Okaloosa-Walton County Line



A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline,
in the indicated locations. For a depiction of areas at risk, please
see the National Weather Service Storm Surge Watch/Warning Graphic,
available at hurricanes.gov. This is a life-threatening situation.
Persons located within these areas should take all necessary actions
to protect life and property from rising water and the potential for
other dangerous conditions. Promptly follow evacuation and other
instructions from local officials.

A Storm Surge Watch means there is a possibility of life-
threatening inundation, from rising water moving inland from the
coastline, in the indicated locations.

A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life
and property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning areas.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Gordon was
located near latitude 28.5 North, longitude 86.8 West. Gordon is
moving toward the northwest near 15 mph (24 km/h), and this general
motion is expected to continue until landfall occurs tonight along
the north-central Gulf coast. A northwestward motion with some
decrease in forward speed is expected after landfall, with a gradual
turn toward the north-northwest and north forecast to occur on
Friday. On the forecast track, the center of Gordon will move across
the northern Gulf of Mexico today, and will approach the north-
central Gulf Coast within the hurricane warning area late this
afternoon or evening, and move inland over the lower Mississippi
Valley tonight and early Wednesday.

Reports from NOAA and Air Force Reserve Unit reconnaissance
aircraft indicate that maximum sustained winds remain near 65 mph
(100 km/h) with higher gusts.  Some strengthening is expected today,
and Gordon is forecast to be a hurricane when it makes landfall
along the north-central Gulf Coast.  Rapid weakening is forecast
after Gordon moves inland.

Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center.  NOAA Buoy 42039, located north of Gordon's center,
recently reported a sustained wind of 43 mph (69 km/h) and a gust
to 49 mph (80 km/h).

The minimum central pressure recently reported by a NOAA
reconnaissance aircraft was 1001 mb (29.56 inches).


HAZARDS AFFECTING LAND
----------------------
STORM SURGE:  The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline. The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...

Shell Beach to Dauphin Island...3 to 5 ft.
Navarre Florida to Dauphin Island, including Mobile Bay...2 to 4 ft.
Shell Beach to the Mouth of Mississippi River...2 to 4 ft.
Mouth of the Mississippi River to the Louisiana-Texas border...1 to
2 ft.

The deepest water will occur along the immediate coast near and to
the east of the landfall location, where the surge will be
accompanied by large waves. Surge-related flooding depends on the
relative timing of the surge and the tidal cycle, and can vary
greatly over short distances. For information specific to your area,
please see products issued by your local National Weather Service
forecast office.

RAINFALL:  Gordon is expected to produce total rain accumulations of
4 to 8 inches over the western Florida Panhandle, southwest Alabama,
southern and central Mississippi, southeastern and northeastern
Louisiana, and southern Arkansas, with isolated maximum amounts of
12 inches through late Thursday. This rainfall will cause flash
flooding across portions of these areas.




WIND:  Tropical storm conditions are expected to begin this
afternoon within portions of the warning area, with hurricane
conditions expected by this evening in the hurricane warning
area.

Tropical Storm Gordon Discussion Number   9
NWS National Hurricane Center Miami FL       AL072018
1000 AM CDT Tue Sep 04 2018

After an earlier disruption of the inner-core convection due to some
southerly wind shear, Gordon has since developed a band of deep
convection very near the well-defined center noted in both NOAA
GOES-16 high-resolution satellite imagery and coastal NOAA WSR-88D
Doppler radars.  In addition, there has been a significant increase
in lightning activity during the past couple of hours in the inner
core, and Doppler radar velocities have increased to more than 45 kt
at 25,000 ft in the band of convection near the center. NOAA and Air
Force Reserve reconnaissance aircraft further indicate that Gordon
has maintained a small radius of maximum winds (RMW) of 10-15 nmi,
and that SFMR surface winds of 53-55 kt exist in the northeastern
quadrant. These data support an intensity of 55 kt.

The initial motion estimate is now toward the northwest at a
slightly slower forward, or 305/13 kt. There is basically no change
to the previous NHC forecast track reasoning. Reconnaissance fixes
continue to fall along the previous forecast track, and the latest
model guidance remains tightly packed and on top of the previous
NHC forecast. As a result, there is high confidence that Gordon will
make landfall along the north-central Gulf of Mexico coast in about
18 hours. After landfall, steering currents are forecast to weaken,
resulting in Gordon slowing down considerably, which will enhance
the heavy rainfall potential. By Friday, an approaching cold front
and associated mid-/upper-level trough are expected to break down
the subtropical ridge, allowing Gordon to turn northward and
eventually turn northeastward on Saturday and merge with the cold
front. The new official track forecast is near the model consensus
and essentially on top of the previous NHC track.

The aforementioned inner-core changes that have been occurring could
be a harbinger that Gordon is finally starting to intensify. Intense
lightning activity inside the small RMW is an indication of strong
updrafts, which can enhance the strengthening process. Although the
GFS and ECMWF models continue to forecast northwesterly shear of
10-15 kt, the explicit upper-level wind fields in the GFS, ECMWF,
and UKMET models indicate that the 200-mb flow is forecast to become
southeasterly and diffluent across Gordon in the next 12 h or so,
which would act to enhance the development of inner-core convection.
As result, the official intensity forecast maintains continuity and
shows Gordon becoming a hurricane before landfall, which is above
the guidance through that time. Once Gordon moves inland, the small
circulation should spin down fairly quickly, and that portion of the
forecast closely follows the various consensus-model intensity
guidance. By 120 h, Gordon's circulation is expected to merge with a
cold front over the Mississippi Valley region.

Key Messages:

1. Gordon is expected to bring life-threatening storm surge and
hurricane conditions to portions of the central Gulf Coast where a
Storm Surge Warning and Hurricane Warning are in effect. Residents
in these areas should listen to advice from their local officials.

2. Heavy rainfall from Gordon will affect the western Florida
Panhandle, southwest Alabama, southern and central Mississippi,
much of eastern Louisiana, and southern Arkansas, where totals could
reach as high as 12 inches. This rainfall will cause flash flooding
in portions of these areas.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 28.5N  86.8W   55 KT  65 MPH
 12H  05/0000Z 29.8N  88.5W   65 KT  75 MPH
 24H  05/1200Z 31.5N  90.2W   35 KT  40 MPH...INLAND
 36H  06/0000Z 32.8N  91.6W   25 KT  30 MPH...INLAND
 48H  06/1200Z 33.7N  92.7W   20 KT  25 MPH...INLAND
 72H  07/1200Z 35.4N  94.3W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  08/1200Z 37.7N  93.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  09/1200Z 40.9N  90.7W   20 KT  25 MPH...POST-TROP/EXTRATROP

NEXT ADVISORY
-------------
Next intermediate advisory at 100 PM CDT.
Next complete advisory at 400 PM CDT.