ATL: KATIA - Post Tropical - Discussion

[KWT]

Well looking at themodels this system still has a good 8-9 days as a tropical cyclone, and hurricane strength from today onwards is quite possible given the expected imprvoing conditions.

[GCANE]

At least that ridiculous cut-off low is gone from the gfs.

Huge difference in 24 hrs, no sign of it at all.

Of trend continues, with the building of the ridge on the USA / Canadian border, I would suspect we'll see landfall in about 3 or 4 runs.


http://www.atmos.albany.edu/student/cor ... ecast.html

[meriland23]

At least that ridiculous cut-off low is gone from the gfs.

Huge difference in 24 hrs, no sign of it at all.

Of trend continues, with the building of the ridge on the USA / Canadian border, I would suspect we'll see landfall in about 3 or 4 runs.


http://www.atmos.albany.edu/student/cor ... ecast.html

Forgive me for being new, but what exactly is a cut off low and how is it effecting the trend?

[CrazyC83]

Based on that ASCAT pass, I would have it at 65 kt now personally, and when it looked better I would guess it peaked at 75 kt.

[GCANE]

At least that ridiculous cut-off low is gone from the gfs.

Huge difference in 24 hrs, no sign of it at all.

Of trend continues, with the building of the ridge on the USA / Canadian border, I would suspect we'll see landfall in about 3 or 4 runs.


http://www.atmos.albany.edu/student/cor ... ecast.html

Forgive me for being new, but what exactly is a cut off low and how is it effecting the trend?

No need to apologize, glad to see you on board and enjoy your posts.

Cut-off low is a low-pressure area in the mid to upper troposphere.

It basically is generated from a deep trough.

The one forecasted by GFS yesterday was to spin up over the OH valley and then move east catching Katia and pulling her north.

Today, GFS shows no sign of it.

Instead it is now building an UL ridge over the Great Lakes.

So, nothing to really pull Katia north as she approaches the coast.

Need to keep an eye on this for future runs if the ridge is forecast to build more.

Hope that helps, let us know if any other questions.

[SFLcane]

I know this might sound like a ridiculous question, but could Katia potentially be a problem for SFL?

Very very very unlikely.

I'd second that. Not with that semi perminent eastcoast trof in place.

[RL3AO]

BEST TRACK: AL12, 175N 521W, 65kts, 991mb, HU KATIA

Seems like we have a hurricane again at 11.

[cycloneye]

Based on that ASCAT pass, I would have it at 65 kt now personally, and when it looked better I would guess it peaked at 75 kt.

There you go.

12z Best track

AL, 12, 2011090212, , BEST, 0, 175N, 521W, 65, 991, HU

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 011.invest

[meriland23]

Huge difference in 24 hrs, no sign of it at all.

Of trend continues, with the building of the ridge on the USA / Canadian border, I would suspect we'll see landfall in about 3 or 4 runs.


http://www.atmos.albany.edu/student/cor ... ecast.html

Forgive me for being new, but what exactly is a cut off low and how is it effecting the trend?[/quote]


No need to apologize, glad to see you on board and enjoy your posts.

Cut-off low is a low-pressure area in the mid to upper troposphere.

It basically is generated from a deep trough.

The one forecasted by GFS yesterday was to spin up over the OH valley and then move east catching Katia and pulling her north.

Today, GFS shows no sign of it.

Instead it is now building an UL ridge over the Great Lakes.

So, nothing to really pull Katia north as she approaches the coast.

Need to keep an eye on this for future runs if the ridge is forecast to build more.

Hope that helps, let us know if any other questions.[/quote]

Thank you, that is what I originally thought, but was not sure. I am surprised she headed north at all in the last model run since it was no present.

[KWT]

The ECM and all the models still erode the W.ridge enough to allow it to recurve.

In theory there is no chance of a landfall above 35N in that set-up...but IF the upper ridge takes longer to get eroded and the systemi s further south to start with, there is a threat to Florida and GA/SC...above that location and the upper flow turns westerly qwuite quickly, hence the sharp recurve on the models.

[KWT]

I know this might sound like a ridiculous question, but could Katia potentially be a problem for SFL?

Very very very unlikely.

I'd second that. Not with that semi perminent eastcoast trof in place.

Whilst S.florida should be ok, IF it is going to make landfall anywhere it'd be along the SE states NOT further north.

Odds still quite good it recurves, esp as the models are quite keen to erode the upper ridge and Lee helps that process move onwards....but not totally a done deal.

Sorta reminds me of Frances.

Also no surprise its going to be a hurricane again, its been wrapping up quite well, should strengthen more and more from now on, shear looks low ahead.

[GCANE]

Your welcome Meriland23

Pressure is not the only thing that steers hurricanes.

Another steering mechanism is the beta-effect.

This has to do with the spinning force of the hurricane and the spin of the earth (Coriolis Force).

The two effects couple together and the net effect is a poleward force on the hurricane.

So, that is why tropical waves move east to west; but once they get a closed spin going, then they start to have a poleward drift to them.

The stronger the hurricane is, the more the poleward tug on it.

[canes04]

Florida is not in the clear. I suggest you ready the 5am disc.

[GCANE]

Very deep warm-core

[KWT]

Looks pretty textbook there GCANE, the track out to 180hrs looks like such a classic looking CV type track.

[GCANE]

FIMY shows landfall on Long-Island

http://fim.noaa.gov/FIMscp/jsloop.cgi?dsKeys=fimy:&runTime=2011090200&plotName=mslp_sfc&fcstInc=360&numFcsts=41&model=fim&ptitle=Experimental%20FIM%20Model%20Fields&maxFcstLen=240&fcstStrLen=-1&resizePlot=1&domain=244&wjet=1

[Macrocane]

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

The systems this year have been kind of rebel, they strengthen when they're not expected to do so and they weaken when the forecast calls for strenghtening, wouldn't be surprised if Katia becomes a high end cat 1 today, although it seems that the dry air and the upper trough are not going anywhere yet.

[RL3AO]

0906z



1120z



Southern eyewall closed off.

[KWT]

Yeah Macrocane, the system is wrapping up actually quite well, the last microwave imagery showed quite a good inner core all things being considered.

[jhpigott]

Southern eyewall closed off.

doesn't look like it has gained much in the way of latitude between those two microwave passes.