TD#9

[Matt-hurricanewatcher]

When this LLC dies. In if one can form under that convection this will be a tropical storm. That shear must be 50 knot front winds.

[gkrangers]

Its generally difficult to gauge the health of a mostly naked LLC at night, with no visible.

[wxmann_91]

Looking at satellite imagery, it appears that the LLC is becoming very poorly defined during the past hour or so after it had become better defined during the afternoon due to the convective burst. This depression is really struggling for survival and I strongly doubt that the current LLC will survive the extremely hostile environment it's in and will be in for at least the next 2-3 days.

Don't forget, LLC's can be very tenacious.

[deltadog03]

actually, when the last vis pics where available...it was starting to wind up a bit....looked better...

[Hyperstorm]

Its generally difficult to gauge the health of a mostly naked LLC at night, with no visible.

The best tool for night-time viewing of low-level clouds is Shortwave IR Imagery. Here's a link showing the depression:

http://www.ssd.noaa.gov/PS/TROP/DATA/RT ... -loop.html

Whenever you want to know the health of a LLC, just try looking at the southern half of it. That will tell you the strength of it. If you see many clouds on the southern side moving eastward, that means that it is in good shape. When clouds on the southern half start dissipating and the movement to the east is not as strong as earlier, you can tell it's not in good shape.

This LLC is in a sickening phase...

[gkrangers]

Will agree with you that its not great, but it may survive. Saying if it will or won't, and being correct, would be very difficult at this point.

BTW, who wants to be the first person to say its moving 265?

[Ivanhater]

ok, by that image, the center is moving a little south of west..tell me im not crazy! if so that could be indicative of a stronger ridge

[cinlfla]

I will, I will, I was waiting for someone else to say it. I don't feel like being bashed tonight

[deltadog03]

hey, thats pretty darn close...maybe a WSW jog...lol..

[Matt-hurricanewatcher]

I will say that it is moving west-southwest. That shear must be 40 knots or more to keep this system down like this.

[deltadog03]

well, conditions will become more favorable as it pulls away from the ULL...the further west it goes it will be going away from the ull...

[Frank P]

I think its just a jog... but we'll find out soon enough during the night..

[Ivanhater]

i thought i was seeing it right, well even if its a jog, its not gaining latitude and staying away from the weakness

[flashflood]

It reminds me of the previous waves that were decoupled, one part went north and another went west. However, at this time the LLC looks like it's loosing out to the convection to the east, well for now anyway. It will be interesting to see what the NHC says about this.

[DESTRUCTION5]

I truly don't know where the NHC got thier reasoning? Evey model I lookout is W to WNW wit hone nasty ridge building all the way into the gulf...Take a gander...At all the 12Z's

http://met.psu.edu/tropical/tcgengifs/

[wxmann_91]

It's moving WSW a bit and is already south of the NHC forecast track, and if it doesn't move north of 20N by 50W, I can assure you TD 9 won't be a fish. If it moves north of 20N by 45W (which isn't forecast anyway and isn't probably going to happen) then it's a fish.

So right now it's probably going to move north of 20N by 50W and after 45W despite taking a WSW jog, and so right now this is a VERY problematic and tough forecast, a few degrees of latitude and/or longitude could make all the difference.

And to add to the equation this is also dependent on how fast Harvey moves and how strong the weakness in the ridge is, and how fast TD 9 strengthens, if at all.

[Sanibel]

Storm center is WSW at 257-260*

[elysium]

Well, that was rough 2 hours. Never saw that coming. The high is building in from east to west so strongly that it is squashing T.D.9 as it is forcing T.D. to move more rapidly through some pretty dried out conditions at too fast a pace. It's beyond running out of its convection and between here and 50W you could hit T.D. 9 with a freight train and it would have more than enough left to reorganize.

The main problem now is that it is heading west too soon. The scenario given earlier for T.D. 9 to be positioned north of Puerto Rico works only if you assume that the ridge will build in more resolutely than being depicted by the current models. At this time of the year, the models are highly prone to overestimates on the strength of east coast troughs, and therefore, often greatly underestimate the strength and over-all size of a building subtropical ridge. But if TD 9 moves west now, it will not likely be able to clear the Greater Antilles if the models are indeed underestimating ridge strength 5 days hence. The only other possibility is that TD 9 finds weakness in the ridge at ariound 50W or so in Harvey's wake. There is a very reasonable chance of that happening, it's just how far north will the rabbit be able to pull TD 9?

If TD 9 doesn't attain 23N latitude sometime prior to 70W, the models currently projecting the ridge position 5 to 7 days from now would need to be fairly accurate if we are to avoid having TD 9 take a trip across the spine of the Greater Antilles. You also need to consider that the current models are under the supervision right now of only a weekend skeleton crew. The NWS will have a lot of input Monday morning on rige placement, strength, etc.

The hard turn west hurts in other ways as well.

[deltadog03]

mike posted this with his video update but, look at this... if this system continues to move generally WEST...then it will be in much better conditions...as far as shear goes...

http://cimss.ssec.wisc.edu/tropic/real- ... g8sht.html

[clfenwi]

I truly don't know where the NHC got thier reasoning? Evey model I lookout is W to WNW wit hone nasty ridge building all the way into the gulf...Take a gander...At all the 12Z's

http://met.psu.edu/tropical/tcgengifs/

Gee, I guess you should teach the NHC how to interpret forecast models... they seem to think otherwise. From the 5 PM discussion:

MODEL GUIDANCE IS PERHAPS IN A LITTLE BETTER AGREEMENT THIS AFTERNOON ON A TRACK THAT ULTIMATELY BENDS TO THE RIGHT THROUGH A WEAKNESS IN THE SUBTROPICAL RIDGE ASSOCIATED WITH TROPICAL STORM HARVEY. THE 12Z GFS NOW AGREES WITH THIS SCENARIO.

For a different look at the track guidance offered by the models, here are the global/late 12Zs

http://euler.atmos.colostate.edu/~vigh/ ... /late1.png

and the limited area/early 18Zs

http://euler.atmos.colostate.edu/~vigh/ ... early1.png