EPAC: KARINA - Post-Tropical

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 24
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
200 PM PDT MON AUG 18 2014

Karina has made a little bit of comeback this afternoon. Visible
satellite images indicate that the center is embedded within
the deep convection and there is a hint of a intermittent eye
feature. In addition, there is a cyclonically curved convective
band to the the south of the center. The outflow has also become
better defined. The latest intensity estimate from TAFB was T3.0,
and given the improvement in the cloud pattern, the initial
intensity has been increased to 50 knots. As mentioned in earlier
forecasts, Karina has the opportunity to strengthen a little more as
the circulation moves over warmer waters and into weaker shear
during the next day or so. This is still the case, and it is
indicated in the NHC forecast. By the end of the forecast period,
the outflow from larger Tropical Depression 12-E located to the
northeast should induce stronger shear and prevent Karina from
additional strengthening.

Best estimate of the initial motion is 245 degrees at 6 kt.
There has been no changes in the steering flow around Karina. The
cyclone continues to be trapped south of a subtropical ridge, and
this pattern will keep the cyclone moving slowly south of due west
or to the west for the next 2 to 3 days. The confidence in this
portion of the forecast is high with good guidance agreement.
After that time, Karina's motion will be dominated by the
larger-than-normal TD 12-E, which is forecast to pass to the
northeast. This should result in a collapse of the steering flow
near Karina and very little motion of the cyclone. By the end of the
period, Karina should begin to turn slowly to the northeast steered
by the southwesterly flow on the south side of TD 12-E. This latter
portion of the forecast is much less certain due to the large
guidance spread.

FORECAST POSITIONS AND MAX WINDS

INIT 18/2100Z 16.1N 133.0W 50 KT 60 MPH
12H 19/0600Z 16.1N 134.0W 60 KT 70 MPH
24H 19/1800Z 16.1N 135.0W 60 KT 70 MPH
36H 20/0600Z 16.1N 136.0W 50 KT 60 MPH
48H 20/1800Z 16.2N 136.4W 45 KT 50 MPH
72H 21/1800Z 16.3N 136.5W 45 KT 50 MPH
96H 22/1800Z 16.3N 136.5W 45 KT 50 MPH
120H 23/1800Z 16.8N 136.0W 45 KT 50 MPH

$$
Forecaster Avila

[Kingarabian]

TropicalAnalystwx13, looks like the HWRF continues to do better and better.

It called Karina to weaken to a weak TS quicker than the NHC and it indeed verified.

Yesterday, it called for Karina to strengthen back to a decent hurricane but the NHC resisted. That forecast actually appears to be verifying as well.

[Steve820]

Karina's strengthening and looking good. We could see it re-strengthen to a hurricane by tomorrow.

[xtyphooncyclonex]

Wah! After days of waiting, it has reorganized, and has a few annular features. Not surprised to see this get to category 1 later.

[Kingarabian]

Nice comeback. Excited to see a decent microwave pass to see what is really going on.

[Yellow Evan]

I'd go with 55 knts atm.

[Kingarabian]

I think these microwave passes show a hurricane.

[Yellow Evan]

I think a hurricane for now is pushing it a little. Maybe tomorrow though.

[Yellow Evan]

EP, 11, 2014081900, , BEST, 0, 160N, 1332W, 50, 996, TS, 34, NEQ, 70, 30, 30, 70, 1008, 150, 30, 0, 0, E, 0, , 0, 0, KARINA, M,
EP, 11, 2014081900, , BEST, 0, 160N, 1332W, 50, 996, TS, 50, NEQ, 30, 0, 0, 30, 1008, 150, 30, 0, 0, E, 0, , 0, 0, KARINA, M,

Same intensity but pressure down 4 mbar's.

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 25
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
800 PM PDT MON AUG 18 2014

Karina has continued to become better organized over the past few
hours. A convective cloud band wraps about 80 percent around the
circulation, and the Dvorak data T-number from TAFB is now 3.5 which
corresponds to an intensity estimate of 55 kt. The vertical shear
over the storm has decreased and is forecast to stay low for another
24-36 hours. Upper-level outflow has also increased over the
tropical cyclone. Therefore, Karina has an opportunity to intensify
some more and it could become a hurricane tomorrow as indicated by
the official forecast. Later in the forecast period, east-
northeasterly shear is predicted to increase, which should cause
gradual weakening. The official intensity forecast is close to the
SHIPS model guidance through 36 hours, and close to the intensity
model consensus thereafter.

The forward motion continues to slow and is now around 255/7 kt. A
mid-level ridge to the north of Karina should push the tropical
cyclone a little farther west over the next day or two. However the
westward steering is likely to end in a couple of days as Karina
becomes more influenced by the large circulation of Tropical
Storm Lowell passing to its northeast. By late in the forecast
period, a broad area of southwesterly low-level flow associated with
Lowell should start drawing Karina toward the northeast. The
official forecast takes the storm farther northeast late in the
period than the previous one, but not as much as some of our better
track guidance. The new NHC track forecast is in good agreement
with latest Florida State University Superensemble prediction.


FORECAST POSITIONS AND MAX WINDS

INIT 19/0300Z 15.9N 133.6W 55 KT 65 MPH
12H 19/1200Z 15.9N 134.3W 60 KT 70 MPH
24H 20/0000Z 15.9N 135.3W 65 KT 75 MPH
36H 20/1200Z 15.9N 136.0W 65 KT 75 MPH
48H 21/0000Z 16.0N 136.5W 60 KT 70 MPH
72H 22/0000Z 16.0N 136.5W 50 KT 60 MPH
96H 23/0000Z 16.6N 135.8W 45 KT 50 MPH
120H 24/0000Z 17.5N 134.5W 45 KT 50 MPH

$$
Forecaster Pasch

[Yellow Evan]

Looks torn apart by shear again. So much for a hurricane.

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
200 AM PDT TUE AUG 19 2014

Karina continues to be a difficult puzzle to solve. The
strengthening trend observed on Monday has ceased, and the cyclone
appears to have weakened a bit during the past few hours. Water
vapor imagery suggests that the outflow from Tropical Storm Lowell
may be helping to produce southeasterly shear over Karina, and the
low-level center is now exposed to the east of a small area of deep
convection. The initial intensity is lowered to 50 kt based on a
blend of CI numbers from TAFB and SAB, although this could be a
generous estimate.

Karina's sudden weakening has resulted in a significant change to
the intensity forecast. The cyclone is expected to remain over
warm water for much of the forecast period, but the SHIPS
diagnostics indicate that easterly shear is likely to remain steady
or increase through the next 5 days. In addition, Karina will
likely start to ingest drier, more stable air in a couple of days.
The intensity models no longer show strengthening, and in fact, the
Florida State Superensemble and HWRF models weaken Karina to a
tropical depression in about 72 hours. The official forecast holds
Karina steady at 50 kt for 36 hours while the thermodynamics remain
favorable, followed by steady weakening through the end of the
forecast period. This solution is very close to the SHIPS and LGEM
models, as well as the intensity consensus, but weakening could
definitely occur sooner than indicated.

Recent microwave fixes indicate that the initial motion is 255/6 kt.
Karina is forecast to move westward and slow down during the next
36-48 hours when it begins to feel the tug of larger Tropical Storm
Lowell to its east. After 48 hours, Karina should begin moving
east-northeastward and pick up speed within the southern part of
Lowell's circulation. The official forecast is essentially
unchanged during the first 48 hours. However, the track guidance
has sped up after 48 hours, and the updated NHC forecast is faster
on days 3-5 to be closer in line with the multi-model consensus
TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 19/0900Z 15.7N 134.0W 50 KT 60 MPH
12H 19/1800Z 15.7N 134.7W 50 KT 60 MPH
24H 20/0600Z 15.7N 135.6W 50 KT 60 MPH
36H 20/1800Z 15.7N 136.2W 50 KT 60 MPH
48H 21/0600Z 15.6N 136.3W 45 KT 50 MPH
72H 22/0600Z 16.0N 135.0W 40 KT 45 MPH
96H 23/0600Z 17.0N 133.0W 35 KT 40 MPH
120H 24/0600Z 19.0N 130.5W 35 KT 40 MPH

$$
Forecaster Berg

[Yellow Evan]

EP, 11, 2014081912, , BEST, 0, 157N, 1342W, 45, 1000, TS, 34, NEQ, 70, 30, 30, 70, 1010, 180, 30, 0, 0, E, 0, , 0, 0, KARINA, M,

Also 45 knts

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 27
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
800 AM PDT TUE AUG 19 2014

The cloud pattern associated with Karina has changed very little
during the past few hours. There is a well-defined convective
band wrapping around the center, but there is some dry air
entraining into the cyclone. The convection is not very deep, and
Dvorak T-numbers are on a weakening trend supporting an initial
intensity of 45 knots. The outflow of large Tropical Storm Lowell
located to the east will likely induce some moderate shear over
Karina, but should not be strong enough to weaken the cyclone
significantly. Karina most likely will experience some fluctuations
in intensity during the next 2 to 3 days. After that time, as
Karina gradually becomes pulled northeastward by the flow around
Lowell, it will encounter cooler waters and the cyclone will likely
begin to weaken.

Karina is already slowing down and is moving westward at 4 knots.
An additional decrease in forward speed is anticipated as the
steering currents collapse further, and Karina is expected to drift
westward or even meander for the next 2 to 3 days. Then, as
Lowell passes to the north, the cyclone should turn northeastward
with increased forward speed around the southwesterly flow
associated with the large circulation of Lowell. The NHC forecast is
very close to the consensus of the GFS and the ECMWF models, which
has been performing quite well with Karina so far. It is also
similar to the previous NHC forecast.


FORECAST POSITIONS AND MAX WINDS

INIT 19/1500Z 15.7N 134.4W 45 KT 50 MPH
12H 20/0000Z 15.7N 135.0W 45 KT 50 MPH
24H 20/1200Z 15.8N 135.7W 45 KT 50 MPH
36H 21/0000Z 16.0N 136.2W 45 KT 50 MPH
48H 21/1200Z 16.0N 136.5W 40 KT 45 MPH
72H 22/1200Z 16.0N 136.5W 40 KT 45 MPH
96H 23/1200Z 17.7N 132.3W 35 KT 40 MPH
120H 24/1200Z 21.0N 129.0W 35 KT 40 MPH

$$
Forecaster Avila

[Yellow Evan]

Looking better, but still 45 knts

EP, 11, 2014081918, , BEST, 0, 157N, 1346W, 45, 1000, TS, 34, NEQ, 70, 30, 30, 70, 1010, 180, 30, 0, 0, E, 0, , 0, 0, KARINA, M,

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 28
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
200 PM PDT TUE AUG 19 2014

Although Dvorak T-numbers no longer directly support 45 knots,
visible satellite images show that Karina still has a vigorous
circulation. An 1807 UTC ASCAT-B overpass missed the low-level
center and the western half of the circulation where stronger
winds could exist, but one 38-kt surface wind vector was indicated
southeast of the center. Assuming that stronger winds could exist
west of the center, the initial intensity is being kept at 45 knots
until we have more solid evidence of weakening.

The outflow of large Tropical Storm Lowell located to the east will
likely induce some moderate shear over Karina, but it should not be
strong enough to weaken the cyclone significantly. Karina most
likely will experience some fluctuations in intensity during the
next 2 to 3 days because of the marginal environment. After that
time, as Karina gradually becomes pulled northeastward and northward
by the flow around Lowell, it will encounter cooler waters and the
cyclone will likely weaken.

Karina is moving westward at 4 knots. The steering currents are
forecast to collapse, and Karina is expected to drift westward or
even meander for the next 2 to 3 days. Then, as Lowell passes to
the north, the cyclone should turn northeastward with increased
forward speed within the southwesterly flow associated with the
large circulation of Lowell. The NHC forecast follows the trend
of the dynamical guidance, which unanimously brings Karina
northeastward toward Lowell.


FORECAST POSITIONS AND MAX WINDS

INIT 19/2100Z 15.7N 134.8W 45 KT 50 MPH
12H 20/0600Z 15.7N 135.4W 45 KT 50 MPH
24H 20/1800Z 15.7N 136.0W 45 KT 50 MPH
36H 21/0600Z 15.8N 136.3W 45 KT 50 MPH
48H 21/1800Z 15.8N 136.3W 40 KT 45 MPH
72H 22/1800Z 16.5N 135.5W 40 KT 45 MPH
96H 23/1800Z 18.5N 132.0W 30 KT 35 MPH
120H 24/1800Z 23.5N 129.5W 25 KT 30 MPH

$$
Forecaster Avila

[Steve820]

I guess Karina won't re-strengthen to hurricane intensity, but it might stick around for quite a while before dissipating.

[Yellow Evan]

EP, 11, 2014082000, , BEST, 0, 158N, 1351W, 45, 1000, TS, 34, NEQ, 60, 50, 40, 70, 1010, 150, 20, 0, 0, E, 0, , 0, 0, KARINA, D,

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 29
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
800 PM PDT TUE AUG 19 2014

Deep convection with cloud tops colder than -80C has redeveloped
near Karina's center, and convective banding features have improved
during the past 6 hours now that the cyclone is moving over a ridge
of warmer sea surface temperatures. The result is that intensity
estimates from both TAFB and SAB have increased to a consensus
T3.0/45 kt, so the initial intensity is being held at 45 kt.

Karina is moving slowly westward or 275/04 kt. There remains no
significant change to the previous reasoning. Karina is forecast to
stall and/or make a small loop in 24 to 48 hours when steering
currents are forecast to weaken considerably. By 72 hours and
beyond, the cyclone is expected to come under the influence of
southwesterly steering flow generated by the very large circulation
of Tropical Storm Lowell, which is currently located well to the
east of Karina. The NHC model guidance is actually in very good
agreement on the development of this rather complex synoptic flow
pattern and eventual interaction between the two tropical cyclones.
The only significant difference since the previous advisory is that
the model guidance envelope has shifted well to the east. The
official forecast track follows suit and has been shifted slightly
to the east, but not nearly as far east as the consensus model TVCE
due to the uncertainty in which direction Karina will move after the
cyclone stalls and/or completes a looping motion.

The outflow from Tropical Storm Lowell is expected to affect
Karina within the next 12 hours, producing modest easterly to
southeasterly vertical wind shear across the cyclone through 72
hours. The result is that little change in intensity is forecast,
although there will likely be some small fluctuations in the
intensity during that time. By 72 hours and beyond, the shear is
expected to steadily increase as Karina moves closer to Tropical
Storm Lowell, which should induce steady weakening. By Day 5,
Karina will be moving over 22C SSTs, causing the system to
degenerate into a post-tropical remnant low pressure system. The NHC
intensity forecast is just an update of the previous advisory and
closely follows the consensus intensity model ICON.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0300Z 15.9N 135.3W 45 KT 50 MPH
12H 20/1200Z 15.9N 135.8W 45 KT 50 MPH
24H 21/0000Z 16.0N 136.2W 45 KT 50 MPH
36H 21/1200Z 15.8N 136.2W 45 KT 50 MPH
48H 22/0000Z 15.6N 135.7W 45 KT 50 MPH
72H 23/0000Z 16.7N 134.0W 40 KT 45 MPH
96H 24/0000Z 19.5N 130.5W 30 KT 35 MPH
120H 25/0000Z 24.0N 128.3W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart

[cycloneye]

TROPICAL STORM KARINA DISCUSSION NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112014
200 AM PDT WED AUG 20 2014

Although Karina's low-level center is embedded beneath the cold
cirrus canopy, microwave imagery indicates that it is located on
the northeastern edge of the deep convection. TAFB and SAB Dvorak
estimates have not changed from six hours ago, and a 0602 UTC
ASCAT pass confirmed that maximum winds are about 45 kt. Moderate
east-northeasterly to easterly shear is expected to continue
affecting Karina during the next several days, and thermodynamic
conditions will gradually become less favorable once the cyclone
begins gaining some latitude beyond day 3. The official NHC
intensity forecast is largely unchanged from the previous forecast,
holding Karina steady at 45 kt for the next 48 hours and then
showing weakening to a remnant low by day 5 over significantly
colder water. This scenario is very close to the SHIPS and LGEM
models, as well as the ICON intensity consensus.

Karina continues to move slowly westward with an initial motion of
270/4 kt. All of the track models now indicate that Karina will
slow down and turn southward, making a small counterclockwise loop
during the next 48 hours as it comes under the influence of Tropical
Storm Lowell's larger circulation. Karina will then backtrack on
its past track, accelerating northeastward and northward between
days 3 and 5 while it swings around the south and east sides of
Lowell. As mentioned in the previous forecast, the track guidance
had been shifting eastward in recent cycles, and that trend has
continued. Therefore, the NHC track forecast is again pushed
eastward, although it still lies along the left side of the guidance
envelope near the ECMWF and the multi-model consensus TVCE.

FORECAST POSITIONS AND MAX WINDS

INIT 20/0900Z 15.9N 135.9W 45 KT 50 MPH
12H 20/1800Z 15.9N 136.3W 45 KT 50 MPH
24H 21/0600Z 15.5N 136.3W 45 KT 50 MPH
36H 21/1800Z 15.2N 135.9W 45 KT 50 MPH
48H 22/0600Z 15.3N 135.0W 45 KT 50 MPH
72H 23/0600Z 17.0N 132.5W 40 KT 45 MPH
96H 24/0600Z 20.5N 129.5W 35 KT 40 MPH
120H 25/0600Z 25.5N 129.5W 25 KT 30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Berg