ATL : HARVEY - Tropical Depression - Discussion

[dwsqos2]

ASCAT pass from 15:27Z has a quite sharp surface trough.

[SouthDadeFish]

Hmmmm, ASCAT pass:

[SouthDadeFish]

Judging by the ASCAT pass there a few spots with calm wind, and if I were a betting man, I bet recon would have found a few very light west winds.

[wxman57]

I don't think they're going to upgrade.

[Aric Dunn]

Judging by the ASCAT pass there a few spots with calm wind, and if I were a betting man, I bet recon would have found a few very light west winds.

exactly. someone correct if im wrong... but most scat data is prone to errors due rain contamination. I can see plenty of evidence for a closed surface circ.

[Aric Dunn]

I don't think they're going to upgrade.

Unless they have some other data we cant see... I dont think they will either.. just because.

[SouthDadeFish]

I don't think they're going to upgrade.

We have to see the progress over the next three hours. I find it hard to believe this won't be a TD by at least 11pm...

[wxman57]

I don't think they're going to upgrade.

We have to see the progress over the next three hours. I find it hard to believe this won't be a TD by at least 11pm...

I didn't say it wasn't a TD, just that I didn't think they'd upgrade yet.

[SouthDadeFish]

I don't think they're going to upgrade.

We have to see the progress over the next three hours. I find it hard to believe this won't be a TD by at least 11pm...

I didn't say it wasn't a TD, just that I didn't think they'd upgrade yet.

I see. Well then I agree with you. Btw the 12Z GFDL really brought this thing north. Near the Belize/Mexico border.

[ozonepete]

Judging by the ASCAT pass there a few spots with calm wind, and if I were a betting man, I bet recon would have found a few very light west winds.

exactly. someone correct if im wrong... but most scat data is prone to errors due rain contamination. I can see plenty of evidence for a closed surface circ.

You are not wrong at all. You are quite right. ASCAT and its predecessor QuikScat have alot of errors due to rain contamination. Since they read winds near the surface based on the motion of sea spray and small water droplets, they can't "see" through heavy rain and produce bad data. Still a great tool, but it is not reliable once a CDO or considerable convection sets up.

[Aric Dunn]

Judging by the ASCAT pass there a few spots with calm wind, and if I were a betting man, I bet recon would have found a few very light west winds.

exactly. someone correct if im wrong... but most scat data is prone to errors due rain contamination. I can see plenty of evidence for a closed surface circ.

You are not wrong at all. You are quite right. ASCAT and its predecessor QuikScat have alot of errors due to rain contamination. Since they read winds near the surface based on the motion of sea spray and small water droplets, they can't "see" through heavy rain and produce bad data. Still a great tool, but it is not reliable once a CDO or considerable convection sets up.

right I was much more familiar with quikscat, but never really read the differences between it and ASCAT.

[SouthDadeFish]

I think dry air is still messing with this thing. I can see quite a few arc clouds getting shot out to the N over the past few hours. Convection is having a hard time building.

[HURAKAN]

18/1745 UTC 15.7N 80.5W T2.0/2.0 93L

30 knots

[Aric Dunn]

18/1745 UTC 15.7N 80.5W T2.0/2.0 93L

30 knots

Thats right where I have it..

[jlauderdal]

Miami NWS says only a tropical wave, whats the big deal...


THE LONG RANGE MODELS
LINING UP AND AGREEING THAT A DEVELOPING TROPICAL WAVE APPROACHES
THE AREA LATE NEXT WEEK. AT THIS TIME...LOADING ECMWF WINDS AND
LEAVING WEATHER AS IS PENDING ADDITIONAL GUIDANCE/DEVELOPMENT.

[ozonepete]

Aric, they're pretty much the same technique. ASCAT just takes smaller swaths unfortunately. Here's the original ASCAT pass from 18Z (from NOAA page) that shows where the rain contamination is (black barbs). Bear in mind that the orientation is often off by a number of miles, so don't concentrate on the circulation's position relative to where you see it on satellite. But notice where the center is, and how it couldn't read any of the winds on the south side of it. That is why I haven't used the EUMETSAT version yet - it's much more nicely presented, but I can't find where and how they deal with the contaminated readings. Their help function isn't very helpful.

[wxman57]

Only 190nm to the coat of Honduras. That's 12 more hours over water unless it jogs northward.

[ozonepete]

Miami NWS says only a tropical wave, whats the big deal...


THE LONG RANGE MODELS
LINING UP AND AGREEING THAT A DEVELOPING TROPICAL WAVE APPROACHES
THE AREA LATE NEXT WEEK. AT THIS TIME...LOADING ECMWF WINDS AND
LEAVING WEATHER AS IS PENDING ADDITIONAL GUIDANCE/DEVELOPMENT.

That's a reference to 97L, not this one, isn't it?

[ozonepete]

Only 190nm to the coat of Honduras. That's 12 more hours over water unless it jogs northward.

Isn't it about to slow down considerably?

[jlauderdal]

Miami NWS says only a tropical wave, whats the big deal...


THE LONG RANGE MODELS
LINING UP AND AGREEING THAT A DEVELOPING TROPICAL WAVE APPROACHES
THE AREA LATE NEXT WEEK. AT THIS TIME...LOADING ECMWF WINDS AND
LEAVING WEATHER AS IS PENDING ADDITIONAL GUIDANCE/DEVELOPMENT.

That's a reference to 97L, not this one, isn't it?

yep, my error