Ivan and Retreating Trough?

HouTXmetro · #1 Postby **HouTXmetro** » Mon Sep 13, 2004 8:42 am

What are the implications of the Trough retreating? This is what I'm seeing on the WV loop.

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

#2 Postby **PurdueWx80** » Mon Sep 13, 2004 8:59 am

So far, it appears as if Ivan is too far away from the trough to be affected. It has placed a little shear on the NW side, but the outflow is again expanding in that direction. The ridge behind this trough seems to be building rather rapidly as the west coast trough digs like mad w/ that incoming jet. The implications of the trough retreat are a slow-moving storm in the Gulf as the ridge rebuilds to it's north and east. Ivan would have to wait for the West Coast trough to weaken the east coast ridge, and that would likely mean a landfall further west than the NHC forecasts now. Several models imply this, and while I don't yet believe the 00Z GEM ensembles (most agree on a SE TX hit while the operational says SW LA), it is becoming more likely that Ivan will affect the central US Gulf coast.

Guest · #3 Postby **Guest** » Mon Sep 13, 2004 9:01 am

There will be another.

#4 Postby **melhow** » Mon Sep 13, 2004 9:15 am

NC...another what?

stormy1959 · #5 Postby **stormy1959** » Mon Sep 13, 2004 9:23 am

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

This loop makes Ivan appear that it is being squeezed and possibly in the process of possibly making a big time move to the right. I hope not as I do not need a 3rd storm. I live on 1 1/2 acres in Winter Springs Fl. and have lost 3/4 of my oaks from Charley and Francis. Thankfully minor home damage.

#6 Postby **Air Force Met** » Mon Sep 13, 2004 9:31 am

PurdueWx80 wrote:So far, it appears as if Ivan is too far away from the trough to be affected. The ridge behind this trough seems to be building rather rapidly as the west coast trough digs like mad w/ that incoming jet.

That's what I've been seeing. The trough is moving out and there is a high pressure cell sitting over the red river valley and it is moving se. It will be over SE tx tonight and head eastward tomorrow to join the atlantic ridge. The only reason it goes away is because the models move the system into it. If the models are wrong with their north motion...this ridge will be stronger. Looking very much like a central GOM event.

#7 Postby **loon** » Mon Sep 13, 2004 9:33 am

If the ridge is stronger, doesn't that call for a speeding up of Ivan?

HouTXmetro · #8 Postby **HouTXmetro** » Mon Sep 13, 2004 10:04 am

http://www.goes.noaa.gov/GSSLOOPS/ecwv.html

Does the clear dry air indicate High Pressure? If so you can see HP building eastward over Louisiana. Basically Ivan needs to Begin to move RAPIDLY towards the N now!! Otherwise this thing is gonna get pushed further west. I live in Houston and have family in SW-Central Louisian. We DON'T NEED THIS. :eek:

#9 Postby **LAwxrgal** » Mon Sep 13, 2004 10:07 am

Well, isn't the storm now moving NW according to the 11 am advisory?

snowflake · #10 Postby **snowflake** » Mon Sep 13, 2004 10:11 am

melhow wrote:NC...another what?

Another trough is expected to come down.

HouTXmetro · #11 Postby **HouTXmetro** » Mon Sep 13, 2004 10:20 am

LAwxrgal wrote:Well, isn't the storm now moving NW according to the 11 am advisory?

Yes, but it's crawling and the trough is slowly retreating itself. So the question for me is will it turn north and move faster. The slower it goes the WNW movement may resume IMO.

HouTXmetro · #12 Postby **HouTXmetro** » Mon Sep 13, 2004 11:25 am

http://www.goes.noaa.gov/GSSLOOPS/ecwv.html

I still see the trough slowly backing off... High Pressure over Louisiana is continues it's push East. If anything I can see the HP blocking IVAN from moving North in the future. IMO Ivan will resume a WNW treck.

Stormtrack03 · #13 Postby **Stormtrack03** » Mon Sep 13, 2004 11:26 am

HouTXmetro wrote:http://www.goes.noaa.gov/GSSLOOPS/ecwv.html

I still see the trough slowly backing off... High Pressure over Louisiana is continues it's push East. If anything I can see the HP blocking IVAN from moving North in the future. IMO Ivan will resume a WNW treck.

Very unlikely.

Weatherboy1 · #14 Postby **Weatherboy1** » Mon Sep 13, 2004 11:53 am

Let me preface this by saying that obviously, you wouldn't have such a strong model consensus if Ivan weren't expected to miss getting caught up by this trough. Instead, the models seem to be suggesting it will just provide a weakness that allows Ivan to come north. And I'm not disagreeing with that forecast ... yet.

But looking at the WV loop, it looks like this is going to be a VERY close call. The trough appears to be "basing" at around 28N. Ivan is almost at 21N. Typically, as I understand things, troughs start affecting a storm's path when they're about 10 degrees away from them and really start "catching" them at about 8 degrees worth of distance. That's about where things are now with Ivan and this shortwave. Also, at one point earlier today, the "cloud shield" of Ivan was pointing more NNE. That eased up a bit this morning. But now, most of the CDO is being displaced to the S and E of the eye.

So my question is this: Is there ANY chance this low/trough could still catch Ivan enough to turn him more N sooner than expected? Or is it 100% certain that he will just make a gradual turn and then eventually hit the north central GOMEX? I only ask because all of us here in Peninsular FL have basically written Ivan off as a Panhandle event and I'm curious if that was a bit too premature.

rtd2 · #15 Postby **rtd2** » Mon Sep 13, 2004 11:58 am

Yes, but it's crawling and the trough is slowly retreating itself. So the question for me is will it turn north and move faster. The slower it goes the WNW movement may resume IMO."

I wouldnt call 9-10 mph a crawl! BUT its slow enough I think It will miss the front.... but what do I know I'm sticking to my track N.O. to P'cola!...guess I can start narrowing my track cone?

#16 Postby **TampaFl** » Mon Sep 13, 2004 12:00 pm

No body here in Tampa has written this off yet. Any thing can happen as we all well know.

calidoug · #17 Postby **calidoug** » Mon Sep 13, 2004 12:10 pm

No, the trough is currently carving up what remains of the ridge in the N Gulf.

Ivan has been moving at 320-325 for the past 6 hours.

He's blocked to the W by ridging. The weakness is to the N and NE.

Besides the eye direction, notice what's been happening to the outflow.

rtd2 · #18 Postby **rtd2** » Mon Sep 13, 2004 12:39 pm

"No, the trough is currently carving up what remains of the ridge in the N Gulf.

Ivan has been moving at 320-325 for the past 6 hours.

He's blocked to the W by ridging. The weakness is to the N and NE.

Besides the eye direction, notice what's been happening to the outflow.

LOOK @ line E AND G on the latest vortex.... even with my tired eyes I dont think its been moving at 320-325? I'M SURE YOU CAN EXPLAIN?

URNT12 KNHC 131725
VORTEX DATA MESSAGE
A. 13/17:04:00Z
B. 20 deg 49 min N
084 deg 35 min W
C. 700 mb 2335 m
D. 80 kt
E. 312 deg 057 nm
F. 035 deg 147 kt
G. 296 deg 011 nm
H. 914 mb
I. 10 C/ 3057 m
J. 19 C/ 3052 m
K. 14 C/ NA
L. CLOSED
M. C27
N. 12345/ 7
O. 0.02 / 1 nm
P. AF304 WXWXA 040913IVAN OB 05
MAX FL WIND 147 KT NW QUAD 17:00:40 Z

rtd2 · #19 Postby **rtd2** » Mon Sep 13, 2004 1:04 pm

Uhmmmm no answer? :idea:

Ivan and Retreating Trough?

Ivan and Retreating Trough?

seems to me this is a VERY close call with the trough

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