ATL: IRMA - Post-Tropical - Discussion

[txwatcher91]

Something I've noticed that is consistent on ALL the models.. As this near the Bahamas or north of them, the pressure gradient will increase due to the strong HP to the north and east of the system.. and it appears the storm may really grow in size as well by then. The storm surge and wind field is MASSIVE on all the models, check out this link and see what I mean.

https://www.tropicaltidbits.com/analysi ... eus_41.png

This is a good point. We could end up with a system that is more "Floyd-esque" in size, if not in track (too soon to say, for instance, if this will be a FL threat, NC threat, or no U.S. threat)

Exactly, an a close call to Florida would bring hurricane force winds to coastal areas even if it doesn't make landfall. This looks like it will grow into a monster of a storm that will have strong winds well away from the center.

[Weatherboy1]

FWIW, this is the latest extended range discussion from the WPC. They aren't sold yet on either an EC trough or a cut-off low setting up. Will definitely take another couple days of modeling to lock that down ...

THE MOST SIGNIFICANT DIFFERENCE WITHIN THE EASTERN TROUGH ARISES
BY DAYS 6-7 THU-FRI WITH INDIVIDUAL MODELS/ENSEMBLE MEMBERS EITHER
MAINTAINING AN OPEN TROUGH OR FORMING A CLOSED LOW. OVER THE PAST
COUPLE DAYS BOTH GFS AND ECMWF RUNS HAVE DEPICTED EITHER OPTION.
THE 00Z ECMWF REVERTED BACK TO THE OPEN TROUGH SCENARIO AFTER THE
PREVIOUS TWO RUNS WERE AMONG THE MOST AGGRESSIVE SOLUTIONS IN
TERMS OF DIGGING THE TROUGH AND CUTTING OFF AN UPPER LOW OVER THE
LOWER MS VALLEY. THE 00Z GFS HAD CLOSED OFF A LOW A LITTLE
FARTHER EAST BUT THE 06Z RUN RETURNED TO AN OPEN TROUGH. WHILE
THERE IS ROOM IN THE MEAN PATTERN FOR AN UPPER LOW, EXPECTED
PERSISTENCE OF THE WESTERN RIDGE AND TELECONNECTIONS RELATIVE TO
THE CORE OF NORTHERN ATLANTIC POSITIVE HEIGHT ANOMALIES SEEM TO
PROVIDE MORE SUPPORT FOR AN OPEN TROUGH. THE PREFERRED FORECAST
BLEND INCORPORATING THE 06Z GFS/GEFS MEAN AND 00Z ECMWF/ECMWF MEAN
MAINTAIN THE OPEN TROUGH SCENARIO. THE MAIN ADJUSTMENT FROM
CONTINUITY IS A MODESTLY SLOWER TREND FOR THE UPPER TROUGH AND
LEADING SURFACE FRONT WHICH MAY HAVE SOME EMBEDDED WAVES. NOTE
THAT CONFIDENCE IS STILL NOT PARTICULARLY HIGH GIVEN THE
INCONSISTENT GUIDANCE SIGNALS AND SENSITIVITY TO UPSTREAM DETAILS

[wxman57]

So much for the 48hrs until it became a major again. Irma looks more impressive now than it did before the EWRC.

And also much bigger too...

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

[JPmia]

 https://twitter.com/pppapin/status/903447364811227138

[txwatcher91]

So much for the 48hrs until it became a major again. Irma looks more impressive now than it did before the EWRC.

And also much bigger too...

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

Awesome, thanks for sharing this! It looks like models don't really begin to expand the size until it reaches an area north of PR.. which is where the models go bonkers with this growing in size and the wind really spreading out over a large area. I assume some of that is due to an increasing gradient from the strong HP and then also the storm gradually increasing in size from multiple EWRC's having completed.

[Ken711]

So much for the 48hrs until it became a major again. Irma looks more impressive now than it did before the EWRC.

And also much bigger too...

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

How does compare with Matthew size-wise?

[BensonTCwatcher]

Interesting to plot the storms ( 80 of them) that passed through 96 hour NHC forecast point. Looks to almost half hit the US. No way this means Irma will, but despite the model changes on the latest runs, seems like we're about 50/50 on that. Seems like a classic setup:
1. Vigorous CV storm
2. High pressure ridging in place
3. Trough digging across the central US
4. All about timing of the synoptics
See Link
http://bit.ly/2eqraxx

[J_J99]

And also much bigger too...

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

How does compare with Matthew size-wise?

Looks about the same size as it was near Florida now.... but Matthew right at landfall in Haiti was a pure monster, completely round and took up quite a large area.

[JPmia]

Shows the low probability, but potential high impact if it happens:

 https://twitter.com/michaelrlowry/status/903272408798420997

[Aric Dunn]

deep convection establishing itself all around the ever clearing eye .. should begin to deepen pretty quick soon.

[weathaguyry]

Looks like the EWRC will start to wrap up soon, convection also filled in nicely throughout the day.

[KWT]

Interesting to plot the storms ( 80 of them) that passed through 96 hour NHC forecast point. Looks to almost half hit the US. No way this means Irma will, but despite the model changes on the latest runs, seems like we're about 50/50 on that. Seems like a classic setup:
1. Vigorous CV storm
2. High pressure ridging in place
3. Trough digging across the central US
4. All about timing of the synoptics
See Link
http://bit.ly/2eqraxx

Yep, its a far higher percentage hit from where the system will be in a few days compared to where it is presently, where you have a very low risk of a landfalling cane.

Just goes to show how signficant the WSW motion is. As you say, every chance it misses to the east still, but the models are still generally in an area of the basin that needs to be closely watched and this far out there is still plenty of time for adjustments and relatively small ones could make a big difference.

[Cunxi Huang]

TXNT26 KNES 011803
TCSNTL

A. 11L (IRMA)

B. 01/1745Z

C. 18.8N

D. 38.4W

E. ONE/GOES-E

F. T5.0/5.0/W0.5/24HRS

G. IR/EIR/VIS

H. REMARKS...DT=5.0 BASED ON OW EYE EMBEDDED AND SURROUNDED BY
LG. PT=5.0. MET=5.5. FT IS BASED ON DT.

I. ADDL POSITIONS

NIL


...SCHWARTZ

SAB T5.0/5.0.

[Sanibel]

I think I'll wait til Monday to start watching it because the synoptics are too far out right now...

[wxman57]

And also much bigger too...

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

How does compare with Matthew size-wise?

Similar. Irma may be just a little larger than Matthew at its peak.

[Ken711]

I'm measuring it on my workstation, from the top feeder band to the bottom, it's about 25-30 miles larger than yesterday at this time. Same for the central round core. Just a little bigger, but still smaller than average. Size will increase a bit more with each ERC. Eye is about 14 miles across now.

How does compare with Matthew size-wise?

Similar. Irma may be just a little larger than Matthew at its peak.

Thank you.

[Aric Dunn]

Say we end up with a 130 mph cat 4 by 11pm..

[Blinhart]

Say we end up with a 130 mph cat 4 by 11pm..

I agree since it looks like the EWRC is almost complete.

[Aric Dunn]

LIkely already back to a major should see it deepend quickly now..

https://weather.msfc.nasa.gov/goes/abi/ ... K6goQj.jpg

[Mouton]

To me, this is beginning to have the look of Dora in 64. Highs blocking to the north and a turn in Fl mid upper peninsula. Categor 4 at peak, 3 at land fall. I just don't see this storm running the ally between the high cells merging above it. Think of a running back looking to go off tackle, seeing the hole blocked and making for the end sweep. Lastly, the move north is not going to be very fast in forward motion either.

Another interesting variable is the projected storm following. Hopefully it can shear it a bit.