TD INGRID: Discussions & Images - Last Advisory

[CalmBeforeStorm]

http://www.ssd.noaa.gov/goes/flt/t2/loop-vis.html

Looking at the very tight rotation and the increasing convection near the center I have very little doubt that this is now a tropical storm.

[KWT]

Yeah the convection is getting closer and closer to the LLC, the big question is will the shear ease down and stay in that relaxed state for lnog enough for recon to find a TS. I'll imagine given its current look it could well have 35kts after probably weakening over the last 12hrs but recon will go and find out. Still looks quite void of convection on the northern side.

[seaswing]

WOW 87 pages on a TD!!!

[skysummit]

[Wthrman13]

I finally learned something important about the GFS...thanks to all our ProMets here...that must be remembered. The GFS is to be looked at only for synoptic set up around the storm, but never for storm intensity.

As we saw with our Cat 5's, amongst many other systems, the GFS is usually initialized with weak storms throughout its career of predicting the movement of that storm. What the GFS is really good at showing is not the strength of a system, but of the highs, lows, ridges and fronts AROUND the system and how the system moves as it reacts to those.

The GFS data is absorbed into other models to get a good handle on the surrounding synoptics, and then those other models are better at establishing storm strength.

-at least that was how I finally learned how to appreciate the model. It has its purpose, and is pretty good at doing what it does.

Very good observation. I would add that the GFS and other global models almost never handle a TC's intensity well, not necessarily because the model dynamics or numerics are wrong, but because the resolution of the model (the spacing between grid points, or, in the case of the GFS, the smallest waves that the model can predict) simply is too coarse to resolve the inner core of most TC's. What they are good at, frequently, is getting the overall outer envelope of the TC's circulation, which is by far the most important as far as overall track is concerned, and, as you said, resolving the large scale flow patterns, troughs, ridges, extratropical cyclones, etc.. Intensity, however, depends on resolving the inner core well, which no global model can do at this point, mainly because of computer resource limitations. Look at it this way: doubling the resolution of a model (going from 40 km grid spacing to 20 km, for example) leads to approximately a factor of 8 increase in computational demands. A factor of 4 comes from the fact that you have 4 times a s many grid points now (twice as many in the east-west and north-south directions each, for a total of 4 times as many). The additional factor of 2 comes from the approximate decrease in the time step required to maintain stability of the model. Thus, a factor of 8 increase overall. Double the resolution again, to 10 km, and now suddenly you need ~64 times the computational resources that you did before! In the next couple of decades, we will see even global models get down to very fine grid spacings, perhaps on the order of a few kilometers or less, that could conceivably resolve a TC's inner core and give a better idea of intensity on par with the current limited area dynamical hurricane models such as the GFDL and HWRF.

And, despite what others may tell you, and at the risk of sounding like a broken record, you are absolutely right, the GFS (and other global models to varying degrees) is in general very good at what it does (yes, even TC track prediction)! The problem comes when folks don't understand the strengths and weaknesses of the various types of models.

[Blown Away]

http://hurricane.accuweather.com/hurric ... stormNum=0
Accuweather backing down on their Cat 2 forecast, just a TS for now.

[Deenac813]

http://hurricane.accuweather.com/hurricane/depressions.asp?partner=accuweather&traveler=0&ocean=atlantic&storm=8&imagetype=move&stormNum=0
Accuweather backing down on their Cat 2 forecast, just a TS for now.

Regardless I dont like the track!

[HURAKAN]

Latest:



Looking much better compared to this morning.

[Blown Away]

What info does Accuweather use to come up w/ a track just NW of PR? Their track is much farther S and W of the NHC track and the models we see posted here?

[dswink]

reminds me of TD10/11 in 2005

You mean the TD10 that eventually became TD12 that eventaully became Katrina?

Although somewhat off topic, and just for grins, here's what Stewart had to say back in August of 2005 about that situation...

From August 2005:
THE NWS RULES GOVERNING THE NAMING OF TROPICAL CYCLONES SPECIFY THAT...WITHIN A BASIN...WHEN A CYCLONE FORMS FROM THE REMNANT OF A PREVIOUSLY EXISTING CYCLONE...THE OLD NAME/NUMBER IS RETAINED.
TROPICAL DEPRESSION TWELVE HAS A COMPLEX GENESIS THAT LIKELY INCLUDES A MID-LEVEL REMNANT OF FORMER TROPICAL DEPRESSION TEN. A REVIEW OF SATELLITE AND RAWINSONDE DATA OVER THE PAST WEEK OR SO SUGGESTS THAT A SECOND DISTURBANCE APPROACHED AND COMBINED WITH THE MID-LEVEL REMNANT OF TROPICAL DEPRESSION TEN ON 20 AUGUST. BECAUSE IT IS IMPOSSIBLE TO DETERMINE WHICH OF THESE TWO SYSTEMS IS ASSOCIATED WITH TODAY'S GENESIS...WE HAVE ELECTED TO USE THE DESIGNATION TWELVE RATHER THAN TEN FOR THE NEW DEPRESSION. THIS SITUATION DIFFERS FROM LAST YEAR'S REGENERATION OF IVAN...IN WHICH THE LOW-LEVEL REMNANT OF THAT SYSTEM REMAINED A DISTINCT FEATURE THAT COULD BE FOLLOWED CONTINUOUSLY UNTIL IT REGENERATED.

oops 10/12 the little depression that could
It was killed of by the everyone due to shear many times on its crawl across the atlantic

[Sanibel]

Jumped poleward at around 310*, I would guess, right now, and way above tropical forecast points.

Weak steering scenario with weak ridge = poleward.

Plenty of life in this one. But probably out to sea barring any forming ridge.

[aguaviva]

yes, much better than after yesterday's collapse, but will it last...? Also, isn't it south of guidance? Will that matter shear wise or not?

[canegrl04]

reminds me of TD10/11 in 2005

You mean the TD10 that eventually became TD12 that eventaully became Katrina?

Although somewhat off topic, and just for grins, here's what Stewart had to say back in August of 2005 about that situation...

From August 2005:
THE NWS RULES GOVERNING THE NAMING OF TROPICAL CYCLONES SPECIFY THAT...WITHIN A BASIN...WHEN A CYCLONE FORMS FROM THE REMNANT OF A PREVIOUSLY EXISTING CYCLONE...THE OLD NAME/NUMBER IS RETAINED.
TROPICAL DEPRESSION TWELVE HAS A COMPLEX GENESIS THAT LIKELY INCLUDES A MID-LEVEL REMNANT OF FORMER TROPICAL DEPRESSION TEN. A REVIEW OF SATELLITE AND RAWINSONDE DATA OVER THE PAST WEEK OR SO SUGGESTS THAT A SECOND DISTURBANCE APPROACHED AND COMBINED WITH THE MID-LEVEL REMNANT OF TROPICAL DEPRESSION TEN ON 20 AUGUST. BECAUSE IT IS IMPOSSIBLE TO DETERMINE WHICH OF THESE TWO SYSTEMS IS ASSOCIATED WITH TODAY'S GENESIS...WE HAVE ELECTED TO USE THE DESIGNATION TWELVE RATHER THAN TEN FOR THE NEW DEPRESSION. THIS SITUATION DIFFERS FROM LAST YEAR'S REGENERATION OF IVAN...IN WHICH THE LOW-LEVEL REMNANT OF THAT SYSTEM REMAINED A DISTINCT FEATURE THAT COULD BE FOLLOWED CONTINUOUSLY UNTIL IT REGENERATED.

oops 10/12 the little depression that could
It was killed of by the everyone due to shear many times on its crawl across the atlantic

Reminds me of what Andrew was able to do Hopefully not a complete repeat scenario

[KWT]

Sanibel, maybe its lifted upabove the forecast path but the averaged motion seems to be around WNW right now, its sort of stair-stepping its way in that general direction, I'd say 290 over the last 9hrs.

[Brent]

[CourierPR]

Jumped poleward at around 310*, I would guess, right now, and way above tropical forecast points.

Weak steering scenario with weak ridge = poleward.

Plenty of life in this one. But probably out to sea barring any forming ridge.

Sanibel, I just looked at the loop with the forecast points, and it appears to be on forecast track.

[Blown Away]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
254 PM EDT THU SEP 13 2007

Clip...
MON-THU...THE CONTINENTAL RIDGE RIDING BEHIND THE DEVELOPING STORM SYSTEM WILL PUSH INTO NEW ENGLAND EARLY NEXT WEEK WHERE IT WILL MERGE WITH THE ATLC RIDGE. WITH THE RIDGE AXIS LOCATED SO FAR TO THE N...ANY STORM SYSTEMS THAT DEVELOP OVER THE CONUS WILL BE FORCED UP THE BACKSIDE OF THE RIDGE WHERE THEIR ABILITY TO PUSH
THE RIDGE AXIS BACK TO THE S WILL BE GREATLY LIMITED. THE RESULT WILL BE A DOMINANT ERLY FLOW REGIME THROUGH MOST OF NEXT WEEK. THESE ERLIES COULD PUSH A T-WAVE ACROSS FL BY MID WEEK.

I wonder if the T-Wave is TD8? Sounds like the ridge merges? Maybe somebody can explain this better.

There is your Tropical Wave North of TD 8...JB shows interest in this when it reaches the Fl Straights..
http://www.ssd.noaa.gov/goes/east/catl/loop-avn.html

I thought JB was saying TD8 might make it the FL Straits, so your saying another TW is the one going to the FL Straits? TD8 might be in the FL/Bahama's area Mid next week.

[Sanibel]

Look at the surface spiral, not the convection. Maybe 300*

[x-y-no]

What info does Accuweather use to come up w/ a track just NW of PR? Their track is much farther S and W of the NHC track and the models we see posted here?

They have quite a large staff of meteorologists. Whether they actually consult their own mets when making those graphics is something I've often wondered about, though. The information is sometimes so screwy it's very hard to believe any real meteorologist ever looked at it.

[Sanibel]

Ooops! On closer inspection of the zoom, 290* is about right.

Burst covering the center now.