Edouard

Update, September 18, 2014, 1:29 p.m. Edouard is still a Category 1 hurricane, but it’s weakening. Per the NHC currently:

Given that the cyclone will be moving over cooler
waters and experiencing increased vertical wind shear, steady
weakening is expected during the next 24 hours. Edouard should lose
its deep convection in 36 to 48 hours and become post-tropical by
that time. Global model fields show the circulation of Edouard
dissipating by the end of the period, and that is reflected in the
official forecast. The new NHC intensity forecast is an update of
the previous one and is close to the IVCN multi-model consensus.

The initial motion estimate is now eastward, or 085/22, as Edouard
is currently located north of a mid-level ridge over the central
Atlantic. The cyclone will move eastward and then southeastward
around this ridge during the next 72 hours, and then turn southward
by day 4. Most of the track model guidance remains in good agreement
on this scenario, with the continued exception of the GFDL and
UKMET which show a more northeastward and southward motion,
respectively. The new NHC track forecast is close to a consensus of
the GFS and ECMWF models, and is similar to the previous advisory.

The initial wind radii were modified based on data from the
above-mentioned ASCAT pass.

FORECAST POSITIONS AND MAX WINDS

INIT 18/1500Z 39.9N 42.7W 70 KT 80 MPH
12H 19/0000Z 40.1N 39.9W 60 KT 70 MPH
24H 19/1200Z 39.9N 37.8W 45 KT 50 MPH
36H 20/0000Z 40.0N 36.2W 35 KT 40 MPH
48H 20/1200Z 40.0N 34.3W 35 KT 40 MPH…POST-TROPICAL
72H 21/1200Z 37.5N 30.0W 30 KT 35 MPH…POST-TROP/REMNT LOW
96H 22/1200Z 33.0N 30.0W 30 KT 35 MPH…POST-TROP/REMNT LOW
120H 23/1200Z…DISSIPATED

$$
Forecaster Brennan

Thanks, Edouard for a dramatic, and more importantly, nonthreatening show during this quiet Atlantic hurricane season!

Update, September 17, 2014, 10:47 a.m. Pacific: In the last update, an eyewall replacement cycle that typically weakens hurricanes was mentioned. Apparently Edouard, now a Category 1 hurricane, didn’t read that – it went on to develop two eyewalls, per the NHC! Their current forecast discussion is underneath the following animated microwave image of Edouard forming its two rings:
 


 
Wow!

000
WTNT41 KNHC 171457
TCDAT1

HURRICANE EDOUARD DISCUSSION NUMBER 25
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062014
1100 AM AST WED SEP 17 2014

Edouard is maintaining two concentric rings as indicated in the
latest visible satellite images and recent NOAA Hurricane Hunter
aircraft wind data. Even though the central pressure is rather low,
958 mb, the pressure gradient is spread out over the large area
comprising the two rings, leading to a lower peak wind than a
typical cyclone would have. Flight-level and SFMR winds still
support an intensity of about 80 kt, which is unchanged from the
previous estimate.

Edouard is accelerating northeastward with a motion of 045/20 kt.
The hurricane is being steered by mid-latitude flow between the
subtropical ridge and a broad trough over the western Atlantic
Ocean. This pattern should force Edouard to move faster toward the
east-northeast by late tonight, and eastward by late tomorrow. In
a couple of days, Edouard (or its remnants) should turn southward
to the west of the Azores around a large trough over the eastern
Atlantic Ocean. The track guidance remains tightly clustered for
the first 48 hours but continues to show some divergence during
the post-tropical phase. The ECMWF has remained consistent on a
sharper southward turn, while the GFS is showing a more gradual
equatorward motion. Because of the consistency of the ECMWF during
the past few runs, the latest NHC track is staying on the southwest
side of the model envelope at long range, roughly halfway between
the model consensus and the ECMWF.

Edouard is moving quickly toward the northeast and should pass over
waters cooler than 26C in less than 12 hours. Only a gradual
weakening is shown during the first 24 hours due to cooler waters
and moderate shear. All of the global models show a sharp increase
in shear after that time while the cyclone is moving over much
colder water. Thus a more rapid weakening is shown beginning late
tomorrow, which is similar to a blend of the previous NHC forecast,
the Florida State Superensemble, and the intensity consensus. The
cyclone is expected to become post-tropical in 2 or 3 days, which
is in good agreement with the global models. Although Edouard is
expected to traverse warmer waters by the end of the forecast
period, strong northwesterly shear is anticipated to hinder any
redevelopment potential.

FORECAST POSITIONS AND MAX WINDS

INIT 17/1500Z 36.4N 53.3W 80 KT 90 MPH
12H 18/0000Z 38.3N 49.9W 75 KT 85 MPH
24H 18/1200Z 39.8N 44.7W 70 KT 80 MPH
36H 19/0000Z 40.1N 40.7W 55 KT 65 MPH
48H 19/1200Z 39.7N 38.7W 40 KT 45 MPH
72H 20/1200Z 39.4N 35.8W 35 KT 40 MPH…POST-TROPICAL
96H 21/1200Z 37.5N 33.5W 30 KT 35 MPH…POST-TROPICAL
120H 22/1200Z 34.5N 33.0W 30 KT 35 MPH…POST-TROPICAL

Edouard has passed Bermuda at a very safe distance. At 5 p.m. Eastern, the NHC noted that the hurricane had begun to recycle its eyewall (as strong tropical cyclones will do). This will weaken Edouard and then the storm will move over cooler waters, weakening it even more. Still, it has been terrific to see a major hurricane and one that didn’t threaten anybody – wish it was that way with all of them.

Update, September 15, 2014, 11:14 a.m. Pacific: Category 2 Hurricane Edouard rules the Atlantic today.
 
Edouard in NA

It is still forecast to become a low-end Category 3, and it will miss Bermuda completely. It’s too early to say whether it will still be a hurricane next weekend, when it may reach the Azores.

Update, September 14, 2014, 3:38 p.m. Pacific: The NHC made Edouard a hurricane this morning. Currently there is a lot of dry air nearby, but water vapor imagery shows that the cyclone’s center is well protected:
&nbsp:
Edouard

The NHC is now expecting the hurricane to intensity to a low-end Category 3 over the next two days:

000
WTNT41 KNHC 142032
TCDAT1

HURRICANE EDOUARD DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062014
500 PM AST SUN SEP 14 2014

Edouard has become better organized this afternoon. The eye of the
hurricane has again made an appearance in satellite images, and
deep convection surrounding the center has increased in intensity
and coverage during the past few hours. NOAA hurricane hunters
investigated the system this afternoon and found maximum flight-
level winds of 90 kt and SFMR winds of 68 kt. These data and
the consensus Dvorak classifications of 4.5/77 kt at 1800 UTC,
support raising the initial wind speed to 75 kt. Additional
strengthening seems likely during the next couple of days while the
hurricane remains over warm water and the shear lessens somewhat.
The only potential inhibiting factor is the influence of dry air
that is seen wrapping into the eastern side of the circulation.
Steady weakening is expected beyond a couple of days when the
cyclone moves over much cooler water and into a stable air mass,
which will eventually cause extratropical transition to occur in
about 5 days. Little change was made to the previous intensity
forecast, with the current forecast showing a peak intensity in
about two days followed by a steady decline after that.

The hurricane is moving west-northwestward or 300/13 kt, steered by
a subtropical ridge centered to its north. This ridge is expected
to weaken and shift eastward, and that should cause Edouard to
gradually turn toward the north during the next couple of days. By
mid-week, Edouard is expected to become embedded in the mid-latitude
zonal flow that will cause the cyclone to turn toward the east. The
NHC track forecast is nudged a little to the west for the next few
days, toward the latest guidance, and is similar to the previous
advisory at 96 and 120 h.

The NASA Global Hawk is currently dropping numerous dropsondes into
and around the circulation of Edouard. These data will be useful in
analyzing the intensity and structure of the hurricane, and should
help the models better initialize the cyclone and its environment.

FORECAST POSITIONS AND MAX WINDS

INIT 14/2100Z 25.4N 52.1W 75 KT 85 MPH
12H 15/0600Z 26.4N 53.9W 85 KT 100 MPH
24H 15/1800Z 27.8N 55.7W 90 KT 105 MPH
36H 16/0600Z 29.3N 56.8W 100 KT 115 MPH
48H 16/1800Z 31.2N 56.9W 100 KT 115 MPH
72H 17/1800Z 35.9N 53.3W 90 KT 105 MPH
96H 18/1800Z 40.1N 45.0W 70 KT 80 MPH
120H 19/1800Z 41.0N 37.5W 55 KT 65 MPH…POST-TROP/EXTRATROP

$$
Forecaster Cangialosi

Luckily for Bermuda, it is still expected to turn north and then northeast, passing the island Tuesday afternoon far to the east.

Update, September 13, 2014, 4:34 p.m. Pacific: In 72 hours, per the NHC, Edouard should be a strong Category 2 storm. Then, it’s expected to weaken. Here’s the discussion:

000
WTNT41 KNHC 132040
TCDAT1

TROPICAL STORM EDOUARD DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062014
500 PM AST SAT SEP 13 2014

Convection associated with Edouard has blossomed this afternoon. The
cloud pattern has become more symmetric, and the outflow is fair
toward the northwest. The initial intensity has been increased to 50
kt based on Dvorak estimates from TAFB and SAB. The low shear, in
combination with a pool of anomalously warm waters ahead of Edouard,
should result in strengthening, and the NHC forecast calls for the
cyclone to become a hurricane on Sunday or early on Monday. The
intensity forecast is very close to the consensus ICON.

The best estimate of the initial motion is toward the northwest or
310 degrees at 11 kt. The cyclone’s motion is being controlled by
the subtropical ridge to its north. It appears that this ridge
is a little stronger, and that pattern supports keeping Edouard on
a west-northwestward to northwestward course for the next 2 to 3
days. After that time, the subtropical ridge will weaken and move
eastward, allowing Edouard to turn north and then recurve into the
mid-latitude westerlies. The NHC forecast is close to the multi-
model consensus TVCA, which has been very consistent in turning the
cyclone northward over the central Atlantic for the past several
model cycles.

FORECAST POSITIONS AND MAX WINDS

INIT 13/2100Z 22.5N 47.5W 50 KT 60 MPH
12H 14/0600Z 23.7N 49.0W 55 KT 65 MPH
24H 14/1800Z 25.0N 51.4W 60 KT 70 MPH
36H 15/0600Z 26.4N 53.9W 70 KT 80 MPH
48H 15/1800Z 27.6N 55.9W 80 KT 90 MPH
72H 16/1800Z 31.0N 57.8W 85 KT 100 MPH
96H 17/1800Z 36.0N 54.0W 80 KT 90 MPH
120H 18/1800Z 42.0N 45.0W 70 KT 80 MPH

$$
Forecaster Avila

It’s still expected to pass east of Bermuda:
 
five-day

Update, September 12, 2014, 11:31 a.m. At 11 p.m. last night the NHC upgraded TD6 to Tropical Storm Eduardo Edouard.
 
Edouard

The GFS model is consistent with intensification and staying out in the middle of the ocean – at the moment it appears headed straight for Bermuda, but it is expected to turn northeastward well before reaching that island.

This really is a nice setup for, possibly, one of the greatest shows on Earth if Eduardo eventually turns into a major hurricane. It’s a big “if,” though. The current NHC discussion only shows it going up to high-end Category 1 in 120 hours.

At 11 a.m. Eastern, the National Hurricane Center identified as TD 6 the system we’ve been looking at in another post. The GFS computer model currently shows this system intensifying and, very nicely, staying away from land. I hope it goes up to Category 5!

Per the NHC,

000
WTNT41 KNHC 111439
TCDAT1

TROPICAL DEPRESSION SIX DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062014
1100 AM EDT THU SEP 11 2014

Satellite imagery and a recent ASCAT-B overpass indicate that the
low pressure area over the eastern Atlantic has a well-defined
circulation and organized convective banding near the center. Thus,
advisories are being initiated on Tropical Depression Six. The
initial intensity is set at 30 kt based on the scatterometer data
and the satellite intensity estimate from TAFB.

The initial motion is 310/12. A low-/mid-level ridge north of the
cyclone should steer it generally west-northwestward to
northwestward for the next 3-4 days. After that, the track
guidance forecasts the system to turn generally northward between
the ridge and a large mid-/upper-level low south of Bermuda. There
is a fair amount of spread in the guidance on where this turn should
occur, with the extremes being the Canadian model on the east near
45W and the ECMWF model on the west near 55W. The official forecast
lies close to the model consensus in expecting a more northerly
motion between 51W-53W. The forecast track keeps the cyclone well
away from land for the next 5 days.

The depression is currently in an environment of light vertical
wind shear. The large-scale models forecast some increase
in southerly shear after 24 hours, which should persist through the
end of the forecast period. Despite the shear, the intensity
guidance forecasts slow but steady strengthening. The official
forecast follows this scenario and is a blend of the SHIPS model and
the intensity consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 11/1500Z 16.2N 37.1W 30 KT 35 MPH
12H 12/0000Z 17.1N 38.5W 35 KT 40 MPH
24H 12/1200Z 18.2N 40.7W 40 KT 45 MPH
36H 13/0000Z 19.3N 42.9W 45 KT 50 MPH
48H 13/1200Z 20.5N 44.9W 50 KT 60 MPH
72H 14/1200Z 23.5N 48.5W 55 KT 65 MPH
96H 15/1200Z 26.5N 51.5W 60 KT 70 MPH
120H 16/1200Z 29.0N 53.0W 70 KT 80 MPH

$$
Forecaster Beven



Categories: Weather

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