ATL: JOAQUIN - Post-Tropical - Discussion

[Alyono]

Convection is being pushed further south over the last few hours. I still think the shear will increase and this may be a sign of this happening.

There are no indications at all that the shear will increase. Not this time

[xironman]

Pressure does seem to be going in one direction

[cycloneye]

TROPICAL STORM JOAQUIN DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015
500 AM EDT TUE SEP 29 2015

The low-level center of Joaquin remains exposed on the northwestern
edge of the deep convection due to about 20 kt of shear. A pair of
ASCAT passes around 01-02Z showed peak winds of around 35 kt, and
that remains the intensity for this advisory, in agreement with the
latest TAFB and SAB Dvorak estimates. The ASCAT data were also used
to adjust the initial 34-kt wind radii.

After moving quickly southwestward earlier, the center of Joaquin
appears to be moving more slowly westward at about 4 kt. The track
forecast remains highly uncertain, and if anything, the spread in
the track model guidance is larger now beyond 48 hours due to
uncertainty in the evolution of the synoptic-scale flow and the
structure of Joaquin. In particular, the global models are having
trouble with the evolution of a deep layer trough over the
southeastern U.S. late in the forecast period, with added
uncertainty about the structure of Joaquin and how it might interact
with the trough. The latest runs of the UKMET and ECMWF bring
Joaquin farther southwest early in the period and then show a
northward and northeastward motion, respectively, ahead of the
trough at days 4 and 5. The GFS shows a weaker Joaquin being
absorbed into a frontal zone off the U.S. east coast in 3 to 4 days,
while the HWRF and GFDL continue to show a faster northward and
then northwestward track. In the first 48 hours, the new NHC track
is a little to the south of the previous one accounting for the
initial position and motion and a trend toward the multi-model
consensus. At days 3 through 5, the official forecast is a little to
the right of and slower than the previous one given the large
spread in the track guidance. Needless to say, confidence in the
details of the track forecast, especially beyond 48 hours, is
extremely low.

The SHIPS model output shows moderate to strong northerly shear
continuing over the cyclone for the next 24 to 36 hours, which
should only allow for slow strengthening. After that time, the shear
decreases a bit and the cyclone could strengthen a little more while
over warm waters. However, there is a lot of spread in the intensity
guidance as well. As noted above, the latest run of the GFS
dissipates Joaquin in 3 to 4 days. On the other hand, the ECMWF and
UKMET show the cyclone deepening considerably in the short term,
while the HWRF and GFDL show more strengthening later in the period.
Given the uncertainty in Joaquin's structure and track, the new NHC
forecast remains conservative, and is closest to the SHIPS model and
below the intensity consensus.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0900Z 26.6N 70.6W 35 KT 40 MPH
12H 29/1800Z 26.6N 71.3W 40 KT 45 MPH
24H 30/0600Z 26.7N 72.2W 40 KT 45 MPH
36H 30/1800Z 26.8N 72.8W 45 KT 50 MPH
48H 01/0600Z 27.1N 73.2W 50 KT 60 MPH
72H 02/0600Z 28.5N 73.5W 55 KT 65 MPH
96H 03/0600Z 32.0N 73.0W 55 KT 65 MPH
120H 04/0600Z 36.5N 73.0W 55 KT 65 MPH

$$
Forecaster Brennan

[NDG]

Northerly shear is still affecting it.

[cycloneye]

They will go this afternoon.

Code: Select all

ATLANTIC REQUIREMENTS....ADDED
    1. TROPICAL STORM JOAQUIN
       FLIGHT ONE -- TEAL 72           
       A. 29/1730Z
       B. AFXXX 0211A JOAQUIN         
       C. 29/1315Z                     
       D. 26.6N 71.2W
       E. 29/1700Z TO 29/2100Z         
       F. SFC TO 10,000FT             

    2. OUTLOOK FOR SUCCEEDING DAY.....FURTHER TASKING ON JOAQUIN.

[cycloneye]

I'd like to know why recon was cancelled for tomorrow

A early morning TCPOD was released and a mission will go this afternoon (See Recon thread)

[TheProfessor]

Looking at the 10z HRRR it has a quite a bit of rain for the Northeast falling in the next 13 hours and forward, grounds might be saturated if Joaquin makes landfall and moves into these areas.

[northjaxpro]

Northerly shear about 20 kts will continue over Joaquin for the next 24-36 hours. Thereafter, shear may slacken to allow Joaquin to become better vertically stacked and organize better as he makes the eventual turn north later this week.

[wxman57]

Major shift in latest GFS/EC runs. SW to Bahamas then NE and out to sea. Both are in very good agreement on that. Doesn't make me feel more confident in the track, though...

[xironman]

Not only still shear, but the shear is pushing kinda dry air into it.

[Yellow Evan]

I don't see any indications of shear.

[xironman]

I am thinking mid-level given the look of the clouds

[CalmBeforeStorm]

I don't see any indications of shear.

The center being exposed to the north of the convection is a pretty good sign of shear.

[tolakram]

live visible loop

http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=26&lon=-71&info=vis&zoom=1&width=1000&height=800&quality=90&type=Animation&palette=ir1.pal&numframes=10&mapcolor=gray

[HurrMark]

Major shift in latest GFS/EC runs. SW to Bahamas then NE and out to sea. Both are in very good agreement on that. Doesn't make me feel more confident in the track, though...

Right, but it looks like the GFS gets it sucked in by 99L and the trough whereas the EC keeps it as an entity and strengthens it to a significant hurricane before the turn. Hardly see that as agreement (other than track).

[NDG]

Major shift in latest GFS/EC runs. SW to Bahamas then NE and out to sea. Both are in very good agreement on that. Doesn't make me feel more confident in the track, though...

Right, but it looks like the GFS gets it sucked in by 99L and the trough whereas the EC keeps it as an entity and strengthens it to a significant hurricane before the turn. Hardly see that as agreement (other than track).

We probably have to ignore the Euro's bullish solution at this time, it has not had a good track record this year most times in this part of the Atlantic.

[NDG]

live visible loop

http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=26&lon=-71&info=vis&zoom=1&width=1000&height=800&quality=90&type=Animation&palette=ir1.pal&numframes=10&mapcolor=gray

I was about to post this satellite loop, clearly Joaquin's LLC is almost naked, just some high cirrus clouds on top of it with most of the convection over by the MLC. Something about this year with NW shear displacing the MLC vorticity to the south.

[terstorm1012]

there is northwesterly shear. the blob looked great on infrared but visible shows us this has a tough environment right now.

I think the models that want to spin this up into a major think there will be a brief window where shear will lessen so this thing can get stacked.

[LarryWx]

Major shift in latest GFS/EC runs. SW to Bahamas then NE and out to sea. Both are in very good agreement on that. Doesn't make me feel more confident in the track, though...

Right, but it looks like the GFS gets it sucked in by 99L and the trough whereas the EC keeps it as an entity and strengthens it to a significant hurricane before the turn. Hardly see that as agreement (other than track).

We probably have to ignore the Euro's bullish solution at this time, it has not had a good track record this year most times in this part of the Atlantic.

Agreed. There has seemingly been a major flaw with the Euro since 2010 with these sudden steep strengthening periods, especially north of about 25N. In 2010, there was an upgrade in resolution as I recall. I'll never forget (helped by a file of data I saved) the forecasting disaster that was TS Fiona, which on a number of different runs was forecast to get down to below 925 mb (lowest 907 mb)!! It ended up only a TS!

[LarryWx]

live visible loop

http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=26&lon=-71&info=vis&zoom=1&width=1000&height=800&quality=90&type=Animation&palette=ir1.pal&numframes=10&mapcolor=gray

I was about to post this satellite loop, clearly Joaquin's LLC is almost naked, just some high cirrus clouds on top of it with most of the convection over by the MLC. Something about this year with NW shear displacing the MLC vorticity to the south.

However, wasn't the LLC even more exposed 24 hours ago? It recovered from that with the LLC being pulled south into the convection/mid level circ. Do you think that will happen again? Why wouldn't it do it again? Opinion?