CHASING RITA

[timmarshall]

NEW TARGET: Beaumont-Port Arthur

UPDATED TARGET: Beaumont, TX Time of Departure: FRIDAY 7 a.m. What a change in 24 hours, eh. Now it looks like Houston is spared. The high is moving off quicker than I thought. But, as expected, the water vapor loop on satellite shows killer dry air is being drawn southward over the western Gulf and being ingested into the west side of the circulation. The latest satellite loop (IR) shows definite erosion of the west side of this hurricane. If this continues, it will eat away through the southwest eyewall before landfall and kill the winds again -just like in Katrina and Ivan. Just got the latest NHC update, and winds dropped 25 KTS. Yikes.

NWS HOU, sent me an inundation map of the southeast Texas coast. It basically shows that almost all of the area in Jefferson County, south of I-10 goes underwater in a CAT 4 hurricane including the city of Port Arthur. So, I may stay away from that town. According to another colleague, there are parking garages in Beaumont. So, I'll scout them out tomorrow.

Meanwhile, I am thinking of taking Rt. 175 SE down to Rt. 69 south. Please let me know of any traffic snarls or contraflow. I've 25 gallons of extra fuel. Thanks TM

 

[HAltschule]

Tim,

The latest jog to the West and even West-Southwest keeps Galveston/Houston, TX as a landfall favorite for me. Maybe it's that I like to be consistent until some convincing evidence/modeling comes along. But given the jog...I am not sure the models have a good handle yet. The 00z ETA just arrived and brings it onshore exactly at this location. At least the ETA has come back to earth on a track. Of interest is that the model stalls Rita along the coast or slightly inland for like 36-48 + hours. Imagine how devastating that would be if it did that in the place I think landfall will be (or anywhere else on the coast)!!!

 

[Rob_Davis]

Originally posted by David Dildine
I'm going to bring an extra 6-gallon can on the plane with me too. You get two carry-ons.

Haha! I have five bucks that says TSA won't allow it. :lol:

 

[Carrie Halliday]

Originally posted by HAltschule
Tim,

The latest jog to the West and even West-Southwest keeps Galveston/Houston, TX as a landfall favorite for me. Maybe it's that I like to be consistent until some convincing evidence/modeling comes along. But given the jog...I am not sure the models have a good handle yet. The 00z ETA just arrived and brings it onshore exactly at this location. At least the ETA has come back to earth on a track. Of interest is that the model stalls Rita along the coast or slightly inland for like 36-48 + hours. Imagine how devastating that would be if it did that in the place I think landfall will be (or anywhere else on the coast)!!!

I am thinking like you, Howie. Watching the radar(s), seems to me that the wobble is more than just a wobble. Time will tell, but I still think Galveston seawall may have met its match. Many down here went to say goodbye to the island city yesterday. No Mardi Gras at Galveston this year either, possibly.
Crystal Beach is my favorite place to to camp (Bolivar peninsula) and I am sure my favorite spot at the Holiday beach access will no longer be there. :cry:

On TV, they showed an eddy of warm water that Rita is about to enter. Should help her get some strength back before hitting the shallower waters off the coast. Kind of like a shot of espresso give her some momentum. :wink:

 

[Justin Turcotte]

Just a tidbit about Galveston: During the great 1900 storm the city was on the *west* side of the storm.

Before dawn September 8, the water crept ashore and kept rising, despite strengthening north winds that should have repelled the storm.

By now, Cline was worried. \"Unusually heavy swells from the southeast. ... Such high water with opposing winds never observed previously,\" he wrote in a telegram to the bureau's headquarters in Washington....

Water continued to rise until the whole island was submerged by 3 p.m. and by midnight waves 15 high tore buildings apart with contemptuous ease. Cline's own home, battered by the waves and heavy debris, eventually collapsed.

http://archives.cnn.com/2000/WEATHER/09/07...nder/index.html

 

[Anonymous]

Is it just me or does the latest IR it look like the central core is loosing it's
punch?

Mike

 

[Sam Sagnella]

The most recent IR image is two hours old. Once we come out of the eclipse, then we'll know for sure, though I expect many will not like what they see.

 

[MClarkson]

heights have increased about 30m since the last reading of 919, so perhaps the pressure is up another mb or 2. Also the eye still shows a low temperature and saturation. Not very organized in there.

EDIT: dropsonde 921.

 

[Anonymous]

The 5:00 GMT IR image is up now and Rita looks like she's pulling in some dry air. Looks a bit disorganized now

 

[Jeff Snyder]

I would wait until the ERC cycle entirely complete before drawing too many conclusions on strength. Hurricanes really tend to weaken through the cycle, which is what we've seen most of today. The past few VORTEX messages have noted that the inner eyewall is becoming ragged, and the last few satellite images support this, as the inner eye is becoming elongated and cloud tops are warming significantly between in and the outer eyewall. Just as a note, I've never seen new GOES images during the scheduled eclipse. The resolution has been signficantly degraded, but I assume this is a reduced bandwidth issue. I still expect reintensification of Rita to <910mb when the inner eyewall completely erodes and the outer eyewall begins to contract. We're going into hour 18 I think for the current ERC, which seems to be relatively normal. The warming of the inner-core cloud tops in the western part of the storm is interesting however. I'd think that if it were cause by the dry air, we would see that strong band now nearing Houston begin to evaporate. However, this isn't happening, and latest IR indicates that cloud tops in this band are actually cooling. Then again, water vapor is only an indicator of mid and upper level moisture, though surface maps indicate low-70 Tds in southern LA currently (less in TX).

 

[Anonymous]

check out the soundings around texas and Lake Charles, LA. Lots of dry air at 700.

 

[Jeff Snyder]

Originally posted by Anonymous
check out the soundings around texas and Lake Charles, LA. Lots of dry air at 700.

Yes, but remember that the storm itself is causing subsidence on the periphery of the circulation. This happens with almost every hurricane. But yes, I agree that there the mid levels are quite dry over TX.

 

[Carrie Halliday]

They are saying that Rita is too big to be too affected by the dry air, she will simply over ride it and saturate the area. No link, said on TV (Anthony Yanez, KPRC met).

Interesting enough, those mets I have seen on TV are fast to show the projected path, and say it can easily go ashore farther west again, but no mention of Rita going more east. Hmmm....

Now, they are talking about it stalling or retrograding down the coast (ala Allison). I have seen that potential for hours, they are just admitting to this scenario. :roll:

 

[cdcollura]

Weakening Factors and Chasing Rita

Happy Friday everyone,

I will not be chasing this one as I already intercepted her as she side-swiped the lower FL keys and I am rather burned out right not chasing so many hurricanes in one year!

Remember when we would chase one hurricane every other YEAR or so?

Now its chasing a hurricane every other WEEK or so!

One thing to consider about the intensity, since I see this happen in MANY landfalling Gulf storms. They almost always weaken just prior to landfall, especially the upper category storms (Cat3 and higher). Hurricanes Lili, Ivan, Dennis, even Katrina all did this to some extent.

What usually happens is that the west side of the storm pulls in dry air from the "continental" air mass, and causes evaporative cooling which erodes the western eyewall of the system. This allows weakening to occur, even when vertical wind shear is no where to be found.

Also, the Gulf coast has a long and sloping continental shelf, go 30 miles offshore, and the water is only 20 feet deep in some places! The bedrock and sand BELOW the water column does not contribute much heat to the water above it since it is on average 50 to 60 degrees (like in a cavern). Only the shallow water has the heat content to fuel the storm.

In practice, a 78.8 degree F SST with a depth of at LEAST 100-200 feet is necessary to fuel a hurricane. Shallow water easily has its heat content "used up" and weakening may ensue.

Eyewall replacement is where an outer eyewall develops around the original "inner" eyewall and chokes off its inflow causing the inner eyewall to dissapate and the outer eyewall becoming the dominant main eyewall there after. The main final eyewall is wider, and like a spinning skater slowing down putting her arms out, has a lower windspeed. Excessive eyewall replacement can weaken a hurricane from Cat4 to Cat2 (remember Lili in October 2002)?

Lastly, there is usually more vertical wind shear over the central USA (that's why we chase there in the spring)! "Shear" is a favorite word for supercells and tornado formation - But NOT for tropical systems. A measly 30 knot wind at 500 mb can destroy a hurricane. The thunderstorms in a hurricane MUST remain OVER the surface low (called a CONVECTIVE VORTEX) to allow the thermal updraft processes to "remove" air from the low and make it stronger (pressure drop). Shear will move the convection away from the low, and weaken it.

Right now, there is little shear on Rita, but some models are bringing shear over the system in 12 hours or so (from time of this writing). The storm HAS been replacing its eyewalls too, and such internal dynamics of a hurricane are the most difficult to ascertain since they are governed by mesoscale fluid dynamics, and as we all know, are very complicated. My judgement is the dry air at low and mid levels issuing into the storm from the west, so I expect a cat3 at landfall.

Remember, a Cat3 is still EXTREMELY DANGEROUS - Complacency kills! This can have 111 to 130 MPH sustained winds, and most likely with Rita, will lean towards the upper end of this range. Also, if the eyewall does erode, it will be on the LEFT side of the eye. The RIGHT side will still have its full marine boundary layer air driving directly on shore (examples: Ivan and Katrina). I also noticed that even a weakening system, that was formerly a Cat5, may have less winds, but the surge, created WHILE it WAS Cat5, takes more time to dissapate (it's a dome or wave of water, and once created, it continues for a while). This is why Katrina had Cat3 winds but a 30 foot surge like that of a strong Cat5! This is why Ivan last year had a 20 foot surge (also like a Cat5) but was Cat3 at landfall. Just something to consider while in that parking garage on the waterfront.

Good luck to all out there and be safe as possible.

 

[AlDanks]

Gotcha. My group's got something like 36 gallons of gas ready to go in DFW atm. I'm going to bring an extra 6-gallon can on the plane with me too. You get two carry-ons.

You should definitely check on whether it is legal to carry gas on a plane. My understanding is that it is not. You really don't want to cause a plane crash.

Al