WDW Weather Forecast - August 31-Sept 16, 2007

[Strmchsr]

I was getting excited and almost doing a snoopy dance when I saw Dean was out of the picture until I read the rest of the post and that another one is in sight.... Hopefully it won't dampen our spirit or plans for the dates you mentioned

Thanks so much, and don't get discouraged!! At first the models had Dean hitting FL, too, and this new system is still a few days off. There's absolutely no telling what it will end up doing until it actually forms and gets close. It could turn away from the US, go into the Gulf like Dean, or any number of other solutions. They're all possible right now. I'll keep you informed!

[GrumpyFan]

Somewhat nervously watching Dean to see what's going to happen to us here in South East Texas. Erin has brought us a bunch of rain today, but not much else, thankfully.

[Strmchsr]

Yeah, definitely keep a watch on it. Dean is going to be a monster before all of this is through. Cat 4 at least at some point. The models have been taking Dean into Mexico with a good bit of consistency, but the last 2 runs have shifted north, especially the GFDL, so Texas most certainly isn't out of the woods.

[Lucyrella]

Grumpyfan,

I hope that Dean will not cause any more problems than what Erin has done. I have been watching the weather chanel alot lately and I think Texas has had its fair share for now. Sending positive go away rain vibes your way.

[Strmchsr]

Sending positive go away rain vibes your way.

As long as you're sending some positive vibes to the rain, how about sending it over to Alabama. Texas has been stealing our rain all year. We're over 20" below normal on rainfall, lakes and rivers are at record lows, and we're just now entering the "dry" season, so we need some rain!!!

[Strmchsr]

One of my dear friends in the weather business wrote a great blog about the track of Dean. I thought ya'll would find it interesting:

There is lot’s of interest in our area on the future track of Hurricane Dean. Dean is the first hurricane of the 2007 hurricane season, and it also a special class of storm called a Cape Verde storm. These storms form south of the Cape Verde Islands and track a long distance across the Atlantic, some re-curving and others marching into the Caribbean and perhaps the Gulf of Mexico.

There is always a great deal of speculation on where these storms are going, and there is almost no skill in making those assessments very far into the future. But because the GFS, Global Forecast System model, is generated out to 384 hours, it’s interesting to watch the changes with time.

I wished that I had started earlier, but around August 14th I began to write down the projected landfall positions from each model run of the GFS. Initially, just as suspected, the GFS had some wild swings in landfall positions. But starting with the 06Z run on August 15, the GFS has been very consistent with a landfall in Mexico. The position has gradually moved northward in Mexico, and the last run prior to this writing, the 17th 06Z model run, almost has it in South Texas, but the center is still crossing the coast in Mexico, albeit extreme northern Mexico.

Here is my tabulation of GFS landfall positions:
14/00Z SC/NC on 8/22/07 at 00Z
14/06Z S FL on 8/22/07 at 06Z
14/12Z TX on 8/24/07 at 12Z
14/18Z LA/SETX on 8/24/07 at 06Z
15/00Z TX/LA on 8/24/07 at 12Z
15/06Z Mexico on 8/23/07 at 06Z
15/12Z Mexico on 8/23/07 at 18Z
15/18Z Mexico on 8/23/07 at 18Z
16/00Z Mexico on 8/23/07 at 12Z
16/06Z Mexico on 8/23/07 at 06Z
16/12Z Mexico on 8/23/07 at 00Z
16/18Z Mexico on 8/23/07 at 00Z
17/00Z Mexico on 8/23/07 at 18Z
17/06Z Mexico on 8/23/07 at 12Z

So beginning almost 8 days out, the GFS began to focus in on one location. We’re still watching to see how well the GFS will do - or other models for that matter.

When looking at the forecast today, there are many factors that lead to great uncertainty. One of those is Erin and what the remnants of that storm do to affect the synoptic pattern that could play a role in the future course of Dean. Or that huge high over the Southeast US - what will its exact position be when Dean enters the Gulf of Mexico? Or that little upper low that began showing up on the GFS in the Central Gulf yesterday - what impact will that have in determining the final future course of Dean? Will a small weakness in the upper ridge be exploited by Dean and perhaps bring about a more northward turn?

Those are all BIG questions that meteorologists are struggling to evaluate. And I can’t help but think back to 1985 and Hurricane Elena. At one point as Elena was coming into the Gulf, the major computer guidance painted a near perfect five pointed star with future points near New Orleans, Tampa, Brownsville, South Florida, and the Bay of Campeche. Talk about divergence!! And it ended up that two of them were right - Elena was influenced by a trough over the US that turned it toward Central Florida, but the two features de-coupled, Elena stalled, and then moved back northwest to a point just east-northeast of New Orleans. That was certainly one for the books!

One item that I did not put on my list was the strength of Dean at landfall. I think there is little doubt that Dean could be a major hurricane when it does come ashore wherever that might be.

[Lucyrella]

Chris,

I have a brother in Mobile, so I have been sending rain vibes that way. I am in my home office doing the Evansville IN rendition of a rain dance... I hope it gets there soon, Evansville had thunderstorms yesterday, so maybe they are coming your way?

[GrumpyFan]

Chris, that was a fantastic article, thanks for posting it.

BTW: who wrote it?

[Strmchsr]

Chris, that was a fantastic article, thanks for posting it.

BTW: who wrote it?

Brian Peters, a forecaster out of Birmingham.

[Donalds Duckie]

Hey GrumpyFan, ya'll doing okay with all of this rain from Erin?

Chris, I, too, am a bit anxious about the prospects of Dean, now officially a Cat 4, paying us a visit here in Texas early next week. Any thoughts on whether it might go on into Mexico or weaken a bit before paying us a call here in the Lone Star State?

I'm scheduled to fly out very early Fri., 8/31 to WDW and return here to Texas, Tues., 9/4. I'll drive to the airport in Austin, connect in Houston, then onto MCO. Reverse that on return. Anything on the horizon?

Although, I'm actually more concerned about Dean coming to Texas and dealing with all that water than I care about WDW at this point.

Thanks in advance. Grumpy Fan, y'all stay safe.

[Strmchsr]

Nancy, I can say with some degree of confidence that, no, Dean won't weaken before it makes final landfall. The conditions are absolutely perfect for continued strengthening. As for whether it will hit Texas - climatology and history favors that scenario, but the models are still firmly fixed on the Tex/Mex boarder. It'll be a couple more days before we know for sure.

As for anything on the horizon, unfortunately, yes. The models are being fairly consistent in bringing another hurricane across FL around Aug 30-31. It looks like an Andrew type storm - coming across FL, then reforming in the Gulf before heading for Louisiana. All of that is just guesswork right now, though. The models are all picking up on it, but the feature they are picking up on is currently just a wave off of Africa, so until it actually develops it's just an interesting feature on the model runs. I'll keep an eye on it, though.

[Lucyrella]

Okay I will be watching for that update with what is going on for Aug. 30 & 31st.... I guess if we can get pass this possible storm threat I am home free. Pleaseand thanks for keeping us updated....

[Donalds Duckie]

Thanks so much, Chris.

I remember now why I stopped going to WDW in Sept., lol. I'm actually going to cancel this solo Sept. trip and put the funds towards my big family trip in April 08. I was just at WDW Memorial Day weekend.

WDW is fun but, my first and main concern is myself and my home. Chris, even if Dean makes landfall at TexMex border, won't that still bring heavy rain here to So. Texas? More rain is one thing Texas doesn't need. We're just saturated. My daily prayers are now that Dean doesn't come straight onto Texas.

Thanks so much for sharing your expertise with us here on Intercot. I can watch Weather Channel easy enough but it's certainly nice to be able to ask a specific question or two.

[Strmchsr]

Chris, even if Dean makes landfall at TexMex border, won't that still bring heavy rain here to So. Texas? More rain is one thing Texas doesn't need. We're just saturated. My daily prayers are now that Dean doesn't come straight onto Texas.

Not necessarily. If the ridge holds strong enough to push Dean into Mexico instead of Texas it should keep funneling the storm westward and Texas should be spared much impact (we here in Alabama, going through the worst drought in the state's history would welcome a good 10" rain, though). If the ridge weakens enough to allow Dean to come north and east at all then Texas will take a direct hit rather than just getting sideswiped with rain. Best case scenario, honestly, is that the storm comes into wester Louisiana where the population density is low and then curves NE coming across MS and AL and bringing some desperately needed rain.

[robyn221]

Thanks so much for sharing your expertise with us here on Intercot. I can watch Weather Channel easy enough but it's certainly nice to be able to ask a specific question or two.

Ditto! I've been checking your postings on the weather everyday. I really appreciate you explaining what's happening and what we can expect in terms that are relatively easy to understand. And the fact that we can ask questions is definitely a big plus too!

Speaking of questions: With what percentage of accuracy do predictions based on those early models (like the one(s) that predicts a hurricane heading to the Gulf and the La. coast in late August) actually result in named storms?

Merci!

Robyn

[Strmchsr]

Speaking of questions: With what percentage of accuracy do predictions based on those early models (like the one(s) that predicts a hurricane heading to the Gulf and the La. coast in late August) actually result in named storms?

Hi, Robyn. De rien!

I'd say that about 85% of the time when the models are picking up on a storm more than 2 runs in a row you will see a named storm eventually develop. Sometimes I'll see a storm on the 06Z run, then not on the 12 or 18Z run, then it reappears on the 00Z run. Those kinds of things tell me that the pattern is right for tropical development, but that nothing specific is actually brewing. When I see several models consistently picking up on something, I know the conditions are favorable, and then a wave comes off the African coast or a low begins to develop in the Caribbean then I know something almost certainly will develop. Right now I feel pretty confident we'll see Felix in 7-10 days, but where he ends up there is no skill whatsoever in forecasting. Right now hurricane prediction is really good 3 days out, moderate at 5 days out, and quite poor beyond 5 days. That's why it'll be Monday before we have a really good handle on where Dean will end up. Hope this answers your question!

[Bethanymouse]

Thanks for your updates!

[Cinderelley]

We'll be there 8/29 - 9/10. If during the day it is 89 - 92, what will the temp be in the evening? Does it drop very much?

[Strmchsr]

We'll be there 8/29 - 9/10. If during the day it is 89 - 92, what will the temp be in the evening? Does it drop very much?

Really moist air neither cools nor heats as efficiently as dry air (that's why during this extreme heat wave Orlando has stayed in the mdi 90s while we in Alabama and other SE states have been well over 100), so I'd expect by evening only about a 5-7 degree drop with the low ending up around 15 degrees below the high.

[Cinderelley]

Thanks soooo much for the info.