EPAC: AMANDA - Post-Tropical

[cycloneye]

Down to 65kts.

EP, 01, 2014052800, , BEST, 0, 145N, 1129W, 65, 989, HU

[Yellow Evan]

No shocking; shear still affecting that system. There is no outflow towards the south and all the convection is to the north of the LLC.

[cycloneye]

TROPICAL STORM AMANDA DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
800 PM PDT TUE MAY 27 2014

Amanda's cloud pattern continues to lose organization. Several
microwave overpasses during the past 6 to 8 hours show that the
center of the cyclone is exposed to the south of the nearest deep
convection and is located farther south than previous estimated.
Late-afternoon visible imagery confirmed these findings, with
geostationary imagery also showing the convection warming and
shrinking in coverage. The degradation in organization has resulted
in a significant decrease of satellite intensity estimates since
this afternoon. The initial intensity is somewhat uncertain since
the Dvorak technique does not work well for rapidly weakening
cyclones but is reduced to 60 kt based on a blend of T- and CI
numbers from TAFB and NESDIS SAB. Additional weakening is likely as
south-southwesterly shear, the entrainment of drier and more stable
air, and a cooler ocean surface take their toll on Amanda. Even
though the shear is forecast to decrease in 24 to 36 hours, it
appears that it will be too late for the cyclone to overcome the
combined effect of these negative factors for intensification.
Remnant low status is now forecast in 72 hours, although it could
occur sooner. The official forecast is lower relative to the
previous one and near but a bit lower than a combination of the
multi-model consensus, Decay-SHIPS, and LGEM.

Center fixes suggest that the motion had been west-northwesterly
throughout the day, and the initial motion estimate is left of
the previous one or 305 degrees at 3 kt. The cyclone remains
embedded in a weak steering environment between a low- to mid-level
ridge to the east-northeast and a mid- to upper-level trough to the
northwest. This synoptic pattern should allow for a generally slow
northward or north-northeastward motion for the next few days before
Amanda degenerates into a remnant low and turns westward or
southwestward. Should Amanda weaken faster than forecast, little
motion is expected, and its remnants could turn eastward in an
anomalous low-level westerly flow. The official forecast is on the
far western side of the guidance envelope, and is much slower than
the previous forecast due primarily to the more southern initial
position.


FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 14.6N 112.9W 60 KT 70 MPH
12H 28/1200Z 15.0N 112.8W 50 KT 60 MPH
24H 29/0000Z 15.8N 112.4W 40 KT 45 MPH
36H 29/1200Z 16.5N 111.9W 35 KT 40 MPH
48H 30/0000Z 17.0N 111.5W 30 KT 35 MPH
72H 31/0000Z 17.1N 111.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0000Z 16.8N 111.5W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 02/0000Z 16.5N 111.8W 15 KT 15 MPH...POST-TROP/REMNT LOW

$$
Forecaster Kimberlain

[Yellow Evan]

Wow, this is weakening fast! But I'd agree with the 60 knt estimate. Maybe looks a little weaker. The shear appears to be ripping apart all convection and displacing to the north.

[Steve820]

Yeah, Amanda's weakening fast now. It was an interesting storm though, especially since it's the strongest EPac hurricane in May on record! Well, let's say goodbye to Amanda as it appears to be weakening for good.

[xtyphooncyclonex]

Amanda was such a fun storm to track, and brought to us an extraordinary start to the 2014 Pacific hurricane season. Oh well, while it is weakening, it does not mean it is over yet. From rapid intensification-slight weakening-reintensification, now to rapid weakening.

[Extratropical94]

Huge convective blowup over the center ocurring right now.

[cycloneye]

TROPICAL STORM AMANDA DISCUSSION NUMBER 23
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
200 AM PDT WED MAY 28 2014

A 0457 UTC AMSU pass confirmed that Amanda is a sheared tropical
storm, with the low-level center displaced to the south of the deep
convection due to about 15 kt of southerly shear. The convection
itself increased beginning around 0100 UTC, and now the center is
located beneath the cirrus canopy. The initial intensity is held
at 60 kt based mainly on SAB's Dvorak classification of T3.5/4.0
using a shear pattern.

Modest south to southwesterly shear is expected to continue
affecting Amanda for the next 24-36 hours. The shear could relax
somewhat after 36 hours, but Amanda will have moved into a less
favorable thermodynamic environment by that time. Therefore,
gradual weakening is expected, and Amanda is likely to degenerate to
a remnant low in about 3 days. The NHC official forecast is
unchanged from the previous advisory and is fairly close to the
intensity consensus IVCN.

Fixes based on microwave data indicate that Amanda's center began
meandering and drifting eastward during the past 12 hours. The
initial motion is 050/2 kt, but that estimate is highly uncertain.
The steering pattern around Amanda is complicated at the moment.
An elongated mid-level ridge extends from the Four Corners region
of the U.S. southeastward along the length of Mexico, while a broad
mid-level trough covers much of the area west of the Baja
California peninsula. These features should push Amanda slowly
northeastward during the next 48 hours while the cyclone still has
some vertical coherency. Once it becomes a remnant low, Amanda
will be located in very weak low-level flow and will likely meander
or drift southwestward on days 3 through 5. The new NHC track
forecast is farther east than the previous forecast due to the
relocated initial position. It is not, however, quite as far east
as the GFS, ECMWF, or multi-model consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0900Z 14.6N 112.4W 60 KT 70 MPH
12H 28/1800Z 15.0N 111.9W 50 KT 60 MPH
24H 29/0600Z 15.8N 110.9W 40 KT 45 MPH
36H 29/1800Z 16.6N 109.9W 35 KT 40 MPH
48H 30/0600Z 17.2N 109.0W 30 KT 35 MPH
72H 31/0600Z 17.5N 109.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 01/0600Z 17.0N 110.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/0600Z 16.0N 110.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Berg

[xtyphooncyclonex]

Amanda just wants to hold on, and does want to keep on bringing up the ACE of the EPac. As for the blowup, it is just impressive for a storm weakening in the EPac.

[Yellow Evan]

Convection refiring north of the LLC. Stil,, this is typical of many EPAC majors that after they fall to around 55 knts or so, they re-fire convection. DMAX may be a factor as well.

[cycloneye]

TROPICAL STORM AMANDA DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
800 AM PDT WED MAY 28 2014

Although Amanda is producing a considerable amount of deep
convection, with cloud tops as cold as -85 C, the cloud pattern
lacks organization. Microwave images show that the
low-level center is located near the southern edge of the
convective area, indicative of the continued influence of
southerly shear. The latest Dvorak classifications have decreased
slightly, and support lowering the initial wind speed to 55 kt.

Vertical cross sections from the GFS model show a pronounced south
to north tilt of the vortex due to the shear. Since the
environmental winds are not expected to change much during the next
24 hours, additional weakening is anticipated. Even though the
shear is forecast to lessen on Thursday, Amanda is expected to
continue to lose strength due to dry air entrainment and lower sea
surface temperatures along the forecast track. The NHC intensity
forecast follows the trend in the guidance and calls for Amanda to
become a remnant low in a few days.

The tropical storm is moving slowly northeastward in the flow
between a trough to its west and a ridge to its east over Mexico.
This continued motion, with some increase in forward speed, is
expected during the next day or two. After that time, however,
Amanda is forecast to reverse its course and move slowly
southwestward when a low- to mid-level ridge builds to the north of
the weakening system. The NHC track forecast is close to the
multi-model consensus, and not too far from the previous
official track forecast.

FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 15.0N 112.0W 55 KT 65 MPH
12H 29/0000Z 15.5N 111.4W 45 KT 50 MPH
24H 29/1200Z 16.3N 110.2W 40 KT 45 MPH
36H 30/0000Z 17.1N 109.2W 35 KT 40 MPH
48H 30/1200Z 17.5N 108.7W 30 KT 35 MPH
72H 31/1200Z 17.7N 109.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 01/1200Z 17.0N 110.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 02/1200Z 16.0N 111.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi

[tolakram]

Odd cloud pattern this afternoon.

16:30Z

[hurricanes1234]

It just doesn't want to quit. I've never seen a storm like this. Now it appears to be getting back the banding and the Best Track kept it at 55 knots. Amazing little cyclone.

01E AMANDA 140528 1800 15.6N 111.7W EPAC 55 996

[cycloneye]

TROPICAL STORM AMANDA DISCUSSION NUMBER 25
NWS NATIONAL HURRICANE CENTER MIAMI FL EP012014
200 PM PDT WED MAY 28 2014

Amanda continues to gradually lose strength. Deep convection has
decreased in coverage during the last several hours, and the
cloud tops are not as cold as they were this morning. Dvorak
Final T-numbers were 3.0/45 kt and 3.5/55 kt from SAB and TAFB,
respectively. In addition, an ASCAT-B overpass at 1642 UTC showed
maximum reliable winds in the 45-50 kt range. Based on these data,
the initial intensity is lowered slightly to 50 kt.

The low-level center of Amanda, which appeared somewhat elongated
in the scatterometer pass, remains near the southern edge of the
main area of thunderstorms. This asymmetric cloud pattern is due to
about 15 to 20 kt of south-southwesterly shear. Slow weakening is
expected to remain the theme during the next few days due to the
combination of shear, dry air, and cooler water along the forecast
track. The NHC intensity forecast is very similar to the previous
one and in line with most of the guidance.

The storm is moving a little faster to the northeast, with the
latest initial motion estimate being 035/7. A mid- to upper-level
trough to the west of Amanda is expected to keep the cyclone moving
northeastward or north-northeastward during the next day or two.
After that time, the weakening system is expected to reverse its
course and turn southwestward when a low- to mid-level ridge builds
to its north. Only slight changes were made to the previous
official track forecast and it lies fairly close to the multi-model
consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 28/2100Z 15.8N 111.6W 50 KT 60 MPH
12H 29/0600Z 16.3N 110.8W 45 KT 50 MPH
24H 29/1800Z 16.9N 109.7W 40 KT 45 MPH
36H 30/0600Z 17.4N 108.7W 35 KT 40 MPH
48H 30/1800Z 17.7N 108.3W 30 KT 35 MPH
72H 31/1800Z 17.6N 109.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 01/1800Z 16.7N 110.7W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 02/1800Z 16.0N 112.0W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
Forecaster Cangialosi

[Yellow Evan]

Amanda does not look a whole lot worse than it did yesterday IMO. I'd say 50 knts is about right.

[Steve820]

Amanda is holding on. The current NHC advisory has Amanda at 50 knots (60 mph). It should gradually weaken before dissipating on Friday or Saturday. Well, it was a fun storm to track!

[Yellow Evan]

Cloud tops warming, and the LLC may be separating from the MLC. Could squash any hope of re-development.

[TropicalAnalystwx13]

It looks like the proverbial curtain is closing on a historic and exciting cyclone.

[TropicalAnalystwx13]

45kt.

EP, 01, 2014052900, , BEST, 0, 161N, 1116W, 45, 1002, TS, 34, NEQ, 80, 0, 0, 80, 1010, 200, 30, 0, 0, E, 0, , 0, 0, AMANDA, M,

[hurricanes1234]

Based on the current look, I have a feeling they will downgrade it to 40 knots at the time of the update.