ATL: JOAQUIN - Post-Tropical - Discussion

[Weatherwatcher98]

Good news on the forecast could have been a BIG problem for the NE

[Ntxw]

I'm impressed how this system worked its way to the surface over the days. Good following by some of our seasoned posters on it.

On the other hand...another naked swirl..or half naked..the obscene season continues

[cycloneye]

TROPICAL DEPRESSION ELEVEN DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015
1100 AM AST MON SEP 28 2015

Satellite imagery indicates that the depression's overall cloud
pattern has become better organized since yesterday despite
persistent north- northwesterly shear of about 20 kt. The exposed
low-level center is located near the northwestern tip of a curved
band over the southeastern quadrant of the circulation. However,
satellite data indicate that the low- to mid-level centers have
recently become more separated. Dvorak intensity estimates are a
consensus T2.0/30 kt from TAFB and SAB, so the initial intensity is
held at 30 kt.

Smoothing fixes over the last 12 hours yields an initial motion of
300/04, a little faster than before. The depression is embedded in
low- to mid-level southeasterly flow around a ridge to its
northeast, with northwesterly flow aloft. This synoptic pattern
should only favor a slow northwestward motion for the next couple of
days. After 48 hours, the cyclone should reach the western end of
the low- to mid-level subtropical ridge and begin to respond to the
southerly and southwesterly flow ahead of a baroclinic trough
nearing the U.S. east coast. This change to the steering should
result in a gradual northward turn with increasing forward speed.
The new track forecast is a little left of the previous one at 48
hours and a little faster, close to a blend of the GFS and ECWMF
model solutions.

GFS- and ECMWF-based SHIPS model output indicates a continuation of
moderately strong north-northwesterly shear over the cyclone for the
next day or so. Even though other large-scale factors are generally
conducive for intensification during this time, shear of this
magnitude suggests that only slow intensification is possible. While
the shear should decrease some by 36 hours, other environmental
factors are not forecast to be as conducive and little further
strengthening is indicated. Large-scale models depict the cyclone
merging with a frontal zone offshore of the Mid-Atlantic or New
England coasts by 96 hours, and the system is therefore shown to be
post-tropical at that time. An alternate lower probability scenario
is that the cyclone could race ahead of the frontal boundary and
retain its tropical characteristics for a bit longer. The new
intensity forecast is above the previous one through 24 hours and
near the multi-model consensus but below the statistical-dynamical
guidance after that time due to more reliance on the global models
which show little further intensification.





FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 27.8N 69.6W 30 KT 35 MPH
12H 29/0000Z 28.1N 70.0W 40 KT 45 MPH
24H 29/1200Z 28.5N 70.6W 40 KT 45 MPH
36H 30/0000Z 29.1N 71.4W 40 KT 45 MPH
48H 30/1200Z 29.6N 72.0W 40 KT 45 MPH
72H 01/1200Z 32.0N 72.9W 35 KT 40 MPH
96H 02/1200Z 37.7N 72.9W 35 KT 40 MPH...POST-TROPICAL
120H 03/1200Z...DISSIPATED

$$
Forecaster Kimberlain

[LarryWx]

The LLC of TD 11 is becoming exposed this morning due to the light to moderate NW shear, story of this season, lol.

http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... umframes=9

My provider's 6Z GFS shows shear dropping substantially from the current 20 knots down to a favorable less than 10 knots already by sometime this afternoon and remaining that way until late tonight. If this occurs, I'd expect it to strengthen into a TS tonight. Any other opinions about the 6Z GFS' projected shear and the implications if accurate?

Meanwhile, it is moving just north of due west fairly steadily now and looks even more naked.

[LarryWx]

I just looked at the incoming 12Z GFS vs the 6Z. Two things are quite noteable as of hour 60 vs the 6Z:
- it is stronger by two mb's (1003 vs 1005)
- it is some 150 miles SSE as model catches up with reality of not being as far NW as previous runs showed

[Alyono]

UKMET LOVES this

[LarryWx]

Looking at the close-up view of the vis 9:30 AM-noon EDT, the net movement of the center looks like it was actually just south of due west rather than the earlier net just north of due west for an earlier similarly lengthed period. Model consensus has been suggesting WNW. Let's see how long this south of due west movement lasts.

[Alyono]

URNT15 KNHC 281647
AF307 0111A CYCLONE HDOB 16 20150928
163800 3010N 07557W 3759 08086 0466 -185 -252 248010 010 017 000 00
163830 3009N 07554W 3759 08084 0464 -185 -259 246010 010 017 000 00
163900 3008N 07551W 3758 08086 0465 -186 -270 242009 010 018 000 00
163930 3008N 07547W 3759 08084 0465 -186 -293 238008 009 017 000 00
164000 3007N 07544W 3759 08085 0464 -185 -315 246009 009 017 000 00
164030 3006N 07541W 3759 08085 0465 -185 -324 240008 009 017 000 00
164100 3006N 07538W 3759 08084 0465 -188 -328 234009 010 019 000 00
164130 3005N 07535W 3759 08086 0465 -188 -323 238010 010 019 000 00
164200 3004N 07532W 3758 08087 0466 -186 -326 238010 010 019 000 00
164230 3004N 07529W 3759 08085 0466 -187 -323 240009 010 018 000 00
164300 3003N 07526W 3759 08085 0466 -186 -284 239009 009 019 000 00
164330 3002N 07522W 3758 08087 0465 -188 -255 241008 009 018 000 00
164400 3002N 07519W 3759 08084 0465 -189 -263 246008 009 019 000 00
164430 3001N 07516W 3761 08084 0465 -190 -277 249008 008 020 000 00
164500 3000N 07513W 3758 08087 0466 -188 -276 254008 008 020 000 00
164530 3000N 07510W 3758 08090 0467 -186 -261 253008 008 019 000 00
164600 2959N 07507W 3759 08086 0467 -187 -263 250008 008 019 000 00
164630 2958N 07504W 3759 08086 0467 -187 -277 257008 008 019 000 03
164700 2957N 07501W 3759 08086 0467 -185 -289 258008 009 019 000 00
164730 2957N 07458W 3758 08088 0468 -188 -301 255008 008 019 000 00

[CrazyC83]

This reminds me of TS Danielle in 1992 (another El Nino year).

[gatorcane]

saved loop showing the naked swirl moving WSW:

[Hammy]

Not sure why NHC is forecasting intensification given it's current state. It's completely decoupled through the morning.

[gatorcane]

I wonder if the swirl is moving SW because another low-level center is trying to establish under the mid-level center (where the rotation is in the mass of clouds SE of the swirl)?

[LarryWx]

Wow, check out the 72 hour 12Z Ukmet to which Alyono aluded: 985 mb hurricane! During the 72 hours from 12Z today, it has the TC actually move SOUTH of due west, which is a couple of hundred miles south and much stronger than the consensus position for 12Z on Thursday 10/1:


http://meteocentre.com/models/get_panel ... =en&hh=000

I assume it will recurve from here pretty sharply from this point on this run but it could look interesting from NC north on it even though it may show it offshore. This may be better reflecting current movement trends, but who knows if it is off of its rocker. The bottom line IMO is that the models as a whole still don't have a good feel for TD 11. Regardless, keep in mind that the Ukmet is one of the most respected models with respect to the tropics unlike the CMC, NAVGEM, and Nam.

[Hammy]

This may be better reflecting current movement trends, but who knows if it is off of its rocker. Keep in mind that the Ukmet is one of the most respected models with respect to the tropics unlike the CMC, NAVGEM, and Nam.

It was also up there with the Euro, both of which were showing a strong hurricane off the EC back in early August which never formed. I think it'll be 2-3 years before we can establish which models are good again given the problems the upgrades caused.

[ozonepete]

Not sure why NHC is forecasting intensification given it's current state. It's completely decoupled through the morning.

Because shear is expected to drop. That's the consensus of most models as well as NHC.

[ozonepete]

I wonder if the swirl is moving SW because another low-level center is trying to establish under the mid-level center (where the rotation is in the mass of clouds SE of the swirl)?

That's a distinct possibility we have to watch for. And if it does happen the forecast would have to be adjusted again.

[Alyono]

URNT15 KNHC 281747
AF307 0111A CYCLONE HDOB 22 20150928
173800 2840N 07129W 8275 01740 //// +166 //// 045015 016 018 000 01
173830 2839N 07128W 8272 01743 0103 +165 +160 047015 017 019 000 01
173900 2837N 07126W 8275 01738 0102 +173 +135 047014 014 017 000 00
173930 2836N 07125W 8272 01743 0101 +174 +123 045014 015 018 000 00
174000 2835N 07124W 8274 01739 0101 +172 +129 042015 016 017 000 00
174030 2834N 07122W 8273 01739 0100 +170 +138 043016 017 017 000 00
174100 2833N 07121W 8273 01740 0099 +171 +140 041017 017 017 000 00
174130 2832N 07120W 8274 01738 0099 +175 +138 040017 017 017 000 00
174200 2830N 07118W 8273 01739 0096 +175 +134 042018 018 017 000 00
174230 2829N 07117W 8272 01740 0095 +175 +134 043018 019 017 000 00
174300 2828N 07116W 8274 01737 0095 +175 +136 045018 019 017 000 00
174330 2827N 07114W 8272 01739 0094 +179 +140 046019 019 017 000 00
174400 2826N 07113W 8273 01738 0093 +179 +143 047019 019 017 000 00
174430 2825N 07112W 8273 01737 0093 +175 +143 045019 020 017 000 00
174500 2823N 07110W 8273 01735 0094 +174 +145 041018 019 018 000 00
174530 2822N 07109W 8273 01734 0094 +170 +153 041017 018 018 000 00
174600 2821N 07108W 8273 01735 0091 +174 +151 042016 017 017 000 00
174630 2820N 07106W 8274 01734 0090 +178 +143 042016 017 017 000 00
174700 2819N 07105W 8272 01737 0090 +176 +143 040017 017 019 000 00
174730 2818N 07104W 8273 01734 0092 +174 +143 036017 017 018 000 00

[LarryWx]

The 12Z Cartoon model (CMC) takes the remnants of Ida, combines it with what is now TD 11, and then slams E MA and E ME with a 984-7 mb H on 10/4:


http://www.tropicaltidbits.com/analysis ... atl_27.png

[gatorcane]

The naked swirl looks to have turned even more SW. Quite interesting indeed. If that is what the NHC is tracking, it is not following their track so far.

[gatorcane]

BIG shift west with the Euro through 72 hours the run is out so far: