HURRICANE FLORENCE

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Hurricane Florence Discussion Number 56
NWS National Hurricane Center Miami FL AL062018
500 AM EDT Thu Sep 13 2018

The satellite presentation of Florence has changed little overnight
with the eye waxing and waning in infrared imagery. The eye has
moved into NWS radar range and can be seen in radar data from
Morehead City and Wilmington NWS 88-D imagery. An 0616 UTC
AMSR2 microwave overpass indicated that the convection over the
southern and southeastern portions of the storm is still disrupted,
and that the eyewall was open to the southeast. An Air Force
Hurricane Hunter aircraft also reported that the eyewall was not
fully intact on its last pass through the storm just after that
time. The Air Force plane measured a peak 700-mb flight level wind
of 102 kt and peak SFMR winds of 85 kt during the mission. These
data suggest that the intensity may be slightly lower, but the
initial intensity has been maintained at 95 kt, since the plane
may not have sampled the strongest winds. Another Air Force
plane will be in Florence shortly, and should provide a better
assessment of the intensity of the hurricane. As mentioned in
the previous discussion, it appears that some southern shear has
caused the degradation of the inner core. The global models suggest
that this shear will relax today while Florence moves over warm
waters, however, given the current storm structure, little overall
change in strength is anticipated as Florence approaches the coast.
Gradual weakening should occur as the hurricane interacts with land
in 24-36 h, with a faster rate of weakening predicted once Florence
moves farther inland.

Florence is moving northwestward or 315 degrees at 13 kt. A
developing mid-level ridge over the north-central United States
should cause the forward speed of the hurricane to decrease today.
As the steering currents collapse tonight and Friday, Florence is
forecast to drift westward or west-southwestward and continue that
slow motion into the weekend. The global models predict that the
ridge will slide eastward over the weekend, which should allow
Florence to turn northwestward and northward by the end of the
forecast period. Although there is still some spread in the
guidance by 48 hours, with the GFS along the northern side of the
guidance envelope, and the ECWMF along the southern edge, the
various consensus aids have moved little. As a result, the new NHC
forecast track is very similar to the previous advisory.

Aircraft and satellite wind data show that Florence is a large
hurricane. Life-threatening storm surge, heavy rainfall, and
damaging wind will cover a large area regardless of exactly where
the center of Florence moves.

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[Squirrelmonkey]

(09-13-2018 05:38 AM)jess Wrote:  Satellite imagery shows the eye wall is not as distinct, and the storm is increasing in size.

If I had to make a guess, I'd say Florence will lose much of its punch by slowing down. The interaction with dryer air, movement away from the warmer water of the Gulf Stream, and cooler surface temperatures will decrease the intensity more. By the time the eye makes landfall, it might only be a strong category 1, with lots of rain, and an unusually high surge for the intensity.

Like Ike

Weakening at landfall, but big, formerly powerful, and will push a bunch of water.....

[jess]

(09-13-2018 07:38 AM)Squirrelmonkey Wrote:  

(09-13-2018 05:38 AM)jess Wrote:  Satellite imagery shows the eye wall is not as distinct, and the storm is increasing in size.

If I had to make a guess, I'd say Florence will lose much of its punch by slowing down. The interaction with dryer air, movement away from the warmer water of the Gulf Stream, and cooler surface temperatures will decrease the intensity more. By the time the eye makes landfall, it might only be a strong category 1, with lots of rain, and an unusually high surge for the intensity.

Like Ike

Weakening at landfall, but big, formerly powerful, and will push a bunch of water.....

I rode out Ike about 50 miles from the center at landfall. The sustained winds (according to a NOAA wind gauge 2 miles away) was 80 mph. The wind damage was minimal compared to Rita, but the surge filled ditches near my home, which is over twenty miles inland, and 23 feet above sea level. If we'd had that type of surge, with Harvey's rain, the damage would have been substantially worse.

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Marky Mark is live and begging for donations

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BULLETIN
Hurricane Florence Advisory Number 57
NWS National Hurricane Center Miami FL AL062018
1100 AM EDT Thu Sep 13 2018

...HEAVY RAINBANDS WITH TROPICAL-STORM-FORCE WINDS SPREADING ACROSS
THE OUTER BANKS AND COASTAL SOUTHEASTERN NORTH CAROLINA...
...LIFE-THREATENING STORM SURGE AND RAINFALL EXPECTED...


SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...33.4N 75.5W
ABOUT 145 MI...230 KM ESE OF WILMINGTON NORTH CAROLINA
ABOUT 195 MI...315 KM E OF MYRTLE BEACH SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NW OR 315 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...955 MB...28.20 INCHES

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WTNT41 KNHC 131456
TCDAT1

Hurricane Florence Discussion Number 57
NWS National Hurricane Center Miami FL AL062018
1100 AM EDT Thu Sep 13 2018

The satellite and radar presentations of Florence have improved
somewhat this morning, with a 20-25 nmi wide eye closing off in the
radar data from the Morehead City and Wilmington WSR-88D Doppler
weather radars. However, an Air Force Reserve reconnaissance
aircraft investigating the hurricane this morning has not yet found
any flight-level or SFMR winds to support more than about 80 kt at
the surface thus far, even though the pressure has decreased to 955
mb. The initial intensity has only been lowered to 90 kt, given
that there are peak Doppler velocity values up to 110 kt with
average values of 95-97 kt at 15,000 ft in the northern eyewall
region, an area of the hurricane that the reconnaissance aircraft
has not yet sampled. The upper-level outflow pattern remains quite
impressive.

Florence has been gradually slowing down this morning, and the
initial motion estimate is now 315/09 kt. The subtropical ridge to
the northeast and east of Florence is now well-established between
Bermuda and the U.S. mid-Atlantic region and extends westward into
Virginia and the central Appalachians. This large-scale feature is
expected to keep the hurricane moving northwestward today, followed
by a turn toward the west at a much slower speed on Friday as the
ridge to the north of Florence weakens due to a weak shortwave
trough dropping slowly southward from the Ohio Valley. On days 3-5,
Florence is forecast turn toward the northwest and north around the
western periphery of the subtropical ridge, and move across western
South Carolina on Sunday, across western North Carolina and eastern
Tennessee on Monday, and then move up the spine of the Appalachians
as an extratropical low after the cyclone merges or interacts with a
frontal system. The new NHC forecast track is similar to the
previous one, and lies close to a blend of the consensus models
TVCA, HCCA, and FSSE.

Florence is currently approaching the Gulfstream current, and the
hurricane is forecast to move over warmer and deeper waters in 6-12
hours, which could allow for some slight strengthening. Just prior
to landfall in about 24 hours, Florence is expected to weaken some
due to upwelling of the shallow coastal waters. After landfall
occurs, rapid weaning of the stronger inner-core wind field is
expected to due land interaction and Florence's slow forward speed
of 5 kt or less. However, intense rainbands are expected to develop
over the Atlantic waters and keep moving along the coast and inland,
likely producing strong wind gusts through Saturday night.

Aircraft and satellite wind data show that Florence remains a large
hurricane. Life-threatening storm surge, heavy rainfall, and
damaging wind will cover a large area regardless of exactly where
the center of Florence moves.

Key Messages:

1. A life-threatening storm surge is now highly likely along
portions of the coastlines of South Carolina and North Carolina, and
a Storm Surge Warning is in effect for a portion of this area. The
greatest storm surge inundation is expected between Cape Fear and
Cape Hatteras, including the Neuse and Pamlico Rivers and western
Pamlico Sound.

2. Life-threatening, catastrophic flash flooding and prolonged
significant river flooding are likely over portions of the Carolinas
and the southern and central Appalachians through early next week,
as Florence is expected to slow down as it approaches the coast and
moves inland.

3. Damaging hurricane-force winds are likely along portions of the
coasts of South Carolina and North Carolina as soon as this evening,
and a Hurricane Warning is in effect. Strong winds could also spread
inland into portions of the Carolinas.

4. Large swells affecting Bermuda, portions of the U.S. East
Coast, and the northwestern and central Bahamas will continue this
week, resulting in life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT 13/1500Z 33.4N 75.5W 90 KT 105 MPH
12H 14/0000Z 33.9N 76.6W 95 KT 110 MPH
24H 14/1200Z 34.2N 77.8W 85 KT 100 MPH...NEAR THE COAST
36H 15/0000Z 34.1N 78.7W 65 KT 75 MPH...INLAND
48H 15/1200Z 34.0N 79.6W 45 KT 50 MPH...INLAND
72H 16/1200Z 34.3N 81.8W 25 KT 30 MPH...INLAND
96H 17/1200Z 36.9N 83.0W 25 KT 30 MPH...INLAND
120H 18/1200Z 40.3N 79.2W 20 KT 25 MPH...POST-TROP/EXTRATROP

$$
Forecaster Stewart

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ULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Newport/Morehead City NC
1100 AM EDT THU SEP 13 2018

The National Weather Service in Newport has issued a

* Tornado Warning for...
Central Hyde County in eastern North Carolina...

* Until 1115 AM EDT.

* At 1100 AM EDT, a severe thunderstorm capable of producing a
tornado was located near Swindell Fork, or 27 miles north of Cedar
Island, moving west at 45 mph.

HAZARD...Tornado.

SOURCE...Radar indicated rotation.

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