ATL: KATIA - Post Tropical - Discussion

[ROCK]

https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical



18Z NOGAPS looks to recurve...I think its doing so much more quickly..entertainment purposes only....

[ROCK]

should be classified in the morning if convection holds....which I think it will...this is the one JB is ranting over....already....

[ROCK]

0z GFS is running.....60hr

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

GFS 72hr


http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

[ROCK]

84hr

still westward bound with ridge on top of her....

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

[HurricaneWarning92]

Well unless a ridge builds in the western Atlantic, this will only have to go somewhere... through that gap... towards Bermuda... so if that scenario verifies, hed be wrong, by a long shot...

[ROCK]

well below 15N and almost to 50W...at 129hr

still slightly under the ridge....should start gaining some lat soon...

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

171hr...starting to curve on out...

http://mag.ncep.noaa.gov/NCOMAGWEB/appc ... mageSize=M

[Dydion]

I realize JB blogs on a premiere site, a website requiring a pay subscription, but is there anywhere we can read what he says without having to pay for a subscription? His quotes and paraphrases by the members on here has built up my respect for him and I'd really like to follow along with what he says about the "K" storm now a'brewing.

Mucho gracias...

[cycloneye]

Passes very close to the east of Bermuda and then goes north to make landfall in Nova Scotia.

[BigA]

Passes very close to the east of Bermuda and then goes north to make landfall in Nova Scotia.

Interesting run. Im surprised about how it goes due north at about 62 west from 30 north to 43 or so north. Interesting pattern. Is the ridge to the east blocking it from fully recurving?

[cycloneye]

Passes very close to the east of Bermuda and then goes north to make landfall in Nova Scotia.

Interesting run. Im surprised about how it goes due north at about 62 west from 30 north to 43 or so north. Interesting pattern. Is the ridge to the east blocking it from fully recurving?

In other words,the term "fish" does not apply here as it threats Bermuda and makes a landfall.

[WxGuy1]

Let's look at the forecast upper-tropospheric map to find troughs or ridges that will partly determine where this storm can go. Load up the following link, which will show a loop from several of the past GFS model runs of 300 mb heights and winds:

http://www.twisterdata.com/index.php?pr ... hive=false

Every map in that animation/loop is valid for the same time (12z Wednesday, Sept. 7th), with different frames representing model runs from the past few days. Notice that every run shows some sort of trough over the eastern US coastline or far western Atlantic. The details of that trough vary -- some runs show a stronger, more amplified trough, and others show a little weaker, less amplified trough. However, The GFS, at least, remains very consistent on developing a relatively sizeable mid- and upper-level trough over the eastern U.S. and/or the western Atlantic. This would almost certainly push the tropical cyclone to higher latitudes and help prevent a major U.S. hit. There may be a window if the storm can stay very far south (below 15 degrees N), but few models are suggesting that. Of course, there's also the possibility that the forecasts will change. All we know at this time is that the GFS has, over many runs, indicated a large trough that would act to prevent the storm from hitting the U.S.

Remember, as much as we all want to know forecasts with certainty, that's just not possible, particularly since we're talking about something >7 days away, and we're talking about something that hasn't even developed yet. This isn't about "There's 0% chance this will get within 1000 miles of the U.S." vs. "This won't be a fish -- the models will trend west and we'll see a hit on the U.S.". All we can really do is use probabilities (qualitatively or quantitatively). At this point, I'd say that this invest is UNLIKELY to affect the U.S. That doesn't mean it's not possible, certainly, sine it's just not possible to know with certainty right now. I should note that if landfall does occur with this next system, it doesn't mean that it wasn't unlikely to occur at this point in time. We're talking about a very long-range (almost comically long range) forecast of an undeveloped cyclone, after all!

[BigA]

00 GFS ensembles run

http://raleighwx.americanwx.com/models/ ... _Loop.html

Earl-like path in the long run according to the ensembles, it looks like.

Something of an aside, but can someone learned explain to me why the ensembles are well to the west of the operational GFS? Shouldn't the ensembles be on average equally to the right and to the left of the operational, if they work based on slight perturbations in the initial position? Or is there another factor that goes into them that could cause them to deviate greatly from the operational model?


Much thanks!

[cycloneye]

SHOWERS AND THUNDERSTORMS CONTINUE TO BECOME BETTER ORGANIZED IN
ASSOCIATION WITH A LOW PRESSURE SYSTEM LOCATED ABOUT 375 MILES
SOUTH OF THE SOUTHERN CAPE VERDE ISLANDS...AND A TROPICAL
DEPRESSION COULD BE FORMING. IF CURRENT TRENDS CONTINUE...
ADVISORIES WILL LIKELY BE INITIATED LATER THIS MORNING. THIS SYSTEM
HAS A HIGH CHANCE...NEAR 100 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD OR
WEST-NORTHWESTWARD AT AROUND 15 MPH.

[jabman98]

I realize JB blogs on a premiere site, a website requiring a pay subscription, but is there anywhere we can read what he says without having to pay for a subscription? His quotes and paraphrases by the members on here has built up my respect for him and I'd really like to follow along with what he says about the "K" storm now a'brewing.

Mucho gracias...

He's on Twitter, so you could follow him there. You'd get a flavor of what he's thinking, but not full analysis.

92L looks like it's got the makings of a big storm. Feel like I've hardly caught my breath and now here comes another one. Tis the season, I guess.

[HurricaneMaster_PR]

DATE/TIME LAT LON CLASSIFICATION STORM
29/0545 UTC 9.0N 26.5W T1.5/1.5 92L
28/2345 UTC 9.3N 24.4W T1.5/1.5 92L

[HurricaneMaster_PR]

Latest TAFB Surface Forecast (72 hrs)

[Cyclenall]

DATE/TIME LAT LON CLASSIFICATION STORM
29/0545 UTC 9.0N 26.5W T1.5/1.5 92L
28/2345 UTC 9.3N 24.4W T1.5/1.5 92L

Interesting, if I'm reading that correctly future Katia lost some latitude there by 0.3º.

[TwisterFanatic]

EURO not as strong as 12z, and also a bit further west, but overall same story.

[bexar]

now TD12 as per navy site

[Adoquín]

A good argument for this disturbance gaining latitude more quickly than the pre-Irene disturbance would be the general low pressure to its north. For Irene, the SAL was VERY strong due to a massive high to its north. Not so with this disturbance:

Wxman57, If I read you correctly, the strong SAL over Irene impeded her development until she approached 50w + or -. This is not so with 92L so development is likely to happen sooner (as it is already happenning). My question is, couldn't the high to the north impede the gain in latitude even if the SAL is not so strong?

There isn't much of a high to the north compared to when Irene was tracking west across the Atlantic. The earlier development will also significantly increase the chance of it passing north of the Caribbean and recurving out to sea well east of the U.S. The 12z Euro is in through 144 hours, indicating a path north of the eastern Caribbean with a deep trof in its path just west of Bermuda. That would give it a clear shot to recurve between 55-65W.

anything less than a recurve before 60 likely a problem for the northeast caribbean