ATL: JOAQUIN - Post-Tropical - Discussion

[ozonepete]

HAMMY standing ground to the professional MET....LOVE IT!! Though I agree this is likely going to be a named stormed and possibly a strong one and is at least a threat from NC north

I love it too. Hammy and I go toe to toe a lot each season. I won't say anything more...

[Hammy]

Does anybody know of an alternate site to access SSMI/GMI microwave data?

[ozonepete]

Does anybody know of an alternate site to access SSMI/GMI microwave data?

The COLO STATE RAMMB site has some. Other than that I don't know who does.

http://rammb.cira.colostate.edu/products/tc_realtime/

[Kingarabian]

Hammy, FNMOC.

[NDG]

Probably this is as good as 98L will look, northerly shear may start affecting it more little by little. Hard to see if it has a defined LLC, might be just an elongated COC at the moment.

[Hammy]

Probably this is as good as 98L will look, northerly shear may start affecting it more little by little. Hard to see if it has a defined LLC, might be just an elongated COC at the moment.

Shear already starting to blow the convection south, much of it that was near the circulation has weakened over the last several hours.

[ozonepete]

It is sitting in a very small area of light shear but, if the CIMSS analysis is correct, it is surrounded by increasing shear on all quadrants. Can't see how it can survive now unless it drifts southward or southeastward. BUT, it sure is a tropical depression right now. If half of this season's depressions are any example, then this surely is one right now.

[LarryWx]

It is sitting in a very small area of light shear but, if the CIMSS analysis is correct, it is surrounded by increasing shear on all quadrants. Can't see how it can survive now unless it drifts southward or southeastward. BUT, it sure is a tropical depression right now. If half of this season's depressions are any example, then this surely is one right now.

I was thinking similarly. As long as this doesn't start drifting south with the 500 mb and higher level winds, there shouldn't be much to worry about. If it were to somehow do that (I have seen ZERO model runs to that), it would become an entirely different ballgame in terms of its future. It moving south would be quite odd, however, being that it is weak, meaning lower steering levels which don't have northerly winds to push it southward. The satellite animation shows a lot of high clouds being blown to the south all around this and to the west toward FL. One might think the LLC may also do that but not if one would assume that 98L's mean steering level is too low to move with those higher level northerly winds. Instead, that should act as northerly shear and not northerly steering. The overwhelming model consensus has it moving slowly WNW.
This was near 27N, 69W a few hours ago. Let's see where is the next position to get an idea of its movement.

[ozonepete]

Yeah Larry, any south to southwest motion would ensure an entirely different ballgame. Since it's in very weak steering winds right now it's reasonably possible it could drift south or southeast and then it might get cast adrift for a while in favorable conditions. Definitely worth watching.

Btw, the latest satellite images seem to show it is not really getting sheared off the way many were saying but is instead consolidating to the southeast; i.e. it's moving away from the shear, not towards it. This is far from over right now.

[gatorcane]

Any chance of a center reformation further south?

[rickybobby]

Fox 35 said Florida should monitor this storm.

[cycloneye]

TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015
1100 PM AST SUN SEP 27 2015

Late-afternoon visible satellite imagery indicates that the
circulation of the low pressure area located midway between the
Bahamas and Bermuda has become well defined. Since the low has
already had persistent and organized deep convection, the system is
being declared a tropical depression. A 2312 UTC SSMI/S overpass
indicated that the center of the depression has become at least
partially exposed to the northwest of a large convective mass due to
moderate northwesterly shear. The initial wind speed is set to 30
kt, based on a T2.0/30 kt classification from TAFB. The depression
is expected to be blasted by strong north-northwesterly or northerly
winds associated with the tail of an upper-level trough over the
central Atlantic beginning on Monday. In fact, global models show
the shear being sufficiently strong enough to result in the cyclone
either becoming a remnant low or dissipating within a few days. The
intensity forecast is below the multi-model consensus through the
forecast period, closest to the HWRF solution.

A low- to mid- level ridge north and northeast of the cyclone is
steering the lower half of the depression's circulation
northwestward while increasing northwesterly winds aloft are
opposing this motion. The net deep-layer mean flow is therefore
providing for only a slow northwestward motion of 315/02 kt, a
rather uncertain estimate considering the scatter of recent fixes.
This synoptic pattern is expected to persist for the next couple of
days, resulting in a the cyclone's drifting west-northwestward or
northwestward. The low- to mid-level ridge is forecast to shift
eastward in 2-3 days as a trough reaches the eastern seaboard of the
United States, and the increasingly shallow system should turn
northwestward and north-northwestward at a faster forward speed if
it still exists. The track forecast is close to a blend of the GFS
and ECMWF model solutions.

FORECAST POSITIONS AND MAX WINDS

INIT 28/0300Z 27.5N 68.7W 30 KT 35 MPH
12H 28/1200Z 27.7N 69.4W 30 KT 35 MPH
24H 29/0000Z 27.9N 69.9W 30 KT 35 MPH
36H 29/1200Z 28.2N 70.4W 30 KT 35 MPH
48H 30/0000Z 28.8N 70.8W 30 KT 35 MPH
72H 01/0000Z 31.0N 71.6W 30 KT 35 MPH
96H 02/0000Z...DISSIPATED

$$
Forecaster Kimberlain

[Hammy]

The depression
is expected to be blasted by strong north-northwesterly or northerly
winds associated with the tail of an upper-level trough over the
central Atlantic beginning on Monday.

No intensification forecast, as expected. Seeing how all the forecasts have overdone intensity it's likely peaking at the moment.

[ozonepete]

this is what I was saying about shear forecasts before: they are often ridiculous. The CIMSS shear tendency from 1800 UTC had wicked shear to the northwest and increasing. Now at 0000 UTC it has shear dropping by at least 5 knots to the north and west with readings already as low as 10-15 knots which is not that bad at all. This is not a reflection on CIMSS - they just use model consensus and all of the other shear products are also often pretty poor. But it does show you how difficult it is to use shear forecasts with any accuracy unless all products have a consensus and the track of the TC is pretty certain. In this case there is no consensus on shear and the track is not very certain now that blocking high pressure is building north of it.

[bamajammer4eva]

Why did they show Tropical Storm Warnings in the graphic but not in the advisory?

[ozonepete]

The depression
is expected to be blasted by strong north-northwesterly or northerly
winds associated with the tail of an upper-level trough over the
central Atlantic beginning on Monday.

No intensification forecast, as expected. Seeing how all the forecasts have overdone intensity it's likely peaking at the moment.

Not if the shear forecasts for that area are as bad as they've been the last 24 hours...

This one is extremely difficult to forecast given the rapidly changing environment.

[ozonepete]

And moving northwest at 2 knots? Don't take that to the bank.

[Hammy]

Why did they show Tropical Storm Warnings in the graphic but not in the advisory?

Stranger yet, I think those are hurricane warnings. I know the warning/track maps are automated, could be a computer glitch and using Arthur's warning map from last year.

[gatorcane]

The nhc has had its fair share of forecast graphic issues this year.

[LarryWx]

The advisory has the current latitude at 27.5 N. If that is accurate, that would mean there has been a northerly component of motion over the last few hours.