Dr. Jeff Masters' WunderBlog

I don;'t have much to say here except the waters in the Carribean Sea are really warm. I would like to hear some people opinions and forecasts for this region over the next while as these water will continue to heat up until something significant moves through that area.

Why is it that Rita is not expected to stall?

I saw some postings about nasty weather in the Lake Erie area. Here are some excerpts about Lake Erie's answer to a storm surge.

On Lake Erie, there have been seiche incidents in 1882, 1929, 1933 and 1947. The deadliest Lake Erie seiche hit close to home and claimed seven lives in the early morning hours of May 31, 1942.
Weather experts say a seiche can occur on the lake without warning, so boaters and shore users need to listen to National Weather Service forecasts for warnings of conditions favorable to seiche development.
Madison-on-the-Lake reportedly received the brunt of the wave, which stretched from Bay Village to Conneaut. Height of the first wave was reported at 4 to 20 feet; the second surge, which hit 15 minutes later, was 6 to 8 feet tall. Goddard?s book states that the wave hit the shore at 80 miles per hour and was up to 25 feet in height.
No seismic activity was reported that night, leading experts to believe that the waves were induced by a sudden change in atmospheric pressure over the lake.

The Pug doesnt hold much confidence in the predictions of the weather services. Seems like the more credentuled you are, the more difficulty you have predicting storm tracks. Wow did they mess this one up or what. Rita Will move up thru Arkansas and Tennesse and disapate to the north. Correolis effect, check it out.

caneguy -- I've lost all faith in these guys and the models, 24hrs ago they said stall and 25-30" rain in tx-la with a sw turn. Now the storm is moving on rather quickly to the n ne, I think you and I have as good an idea as the rest on the future. They use what I call a SWAG (scientific wild ass guess). If the computers can't figure it out what makes you think we can.

Why do americans feel that 1000 dead is such a catastrophe, I remember 100 thousand plus in bangladesh didn't seem so bad to most here in the US. Are the lives of americans who have more information and should have known to run, worth more than the lives of those that don't have the information and did not know?

ConvectPUG do you have pugs? I raise them...

well I see that Rita could go back into the gulf...I think that is just so wrong...Why is it that they just about all make a loop???

Where did you see that taco? i'd like to look.

Well I was looking at the water vapor in the gulf and the High Pressure is building back in and it looks like rita will get caught by it and go back into the gulf... That's what I see..

Here in Mobile we are getting flooded by tons of Rain from Rita and they say here that it will be like that for the rest of the week...

hey doc. posted this in the other blog but i will post it here for u again


doc the problem with me si that with the pressure what it was 930 u have to assume there are cat4 winds somewhere in the circulation. thye started using 20 percent in styead of the 10 they used since she was a cat 2. if they had used 10 she would have been 130-140 mph

I think leffty said it the best last night. Expect the worst and hope for the best...

(please excuse the non-tropical weather posts)
Jedkins - I think that wind measurement is a fairly mature technology, so I am not sure why you mark pre-1980 measurements as being non-believable. Can you point out some post-1980 technological advance that led to significantly more accurate measurements?

Also, 100+ mile winds not associated with tropical systems can and do take place over large land areas. Anyways, here is a link to info on another storm that I vividly recall. It took place over Ohio in 1969 and had 100 mph straight line winds in a squall covering a large area. We called it simply the "4th of July Storm", it was memorable in that it uprooted so many trees in the area, like around 20% of the total:

Link

Wind damage was similar to that of a CAT 1 hurricane.

Lefty got it right "expect the worst, hope for the best." I've lived by that for most of my life. I think you call us pessimistic optimists. ;-)

Leffty is not a exact science. You go with the data you have and past data.
And you work with that. Dont worry about the recons. You were reading the data that was being provided It is a learning exsperience. You did a great job. We have 60 days to go in this season. And October might prove to most interesting

I guess maybe 10% of the country's total refinery capacity lies in the area that was hit. Excerpt from posting on another website:


"A list of coastal refineries. The refineries are much less spread out than the CNN map would suggest. Refinery capacity figures are thousand bbl per day. Percentages are of the ~17mbpd total US operable refining capacity figure used in the EIA weekly reports. (the numbers are below the fold)

Louisiana Border area 1120k(TX) 590k(LA) (10%) [Revised]
Lake Charles (LA) Calcasieu 30k
Lake Charles (LA) Citgo 324k
Westlake (LA) ConocoPhillips 239k
Beaumont ExxonMobil 349k
Port Arthur Motiva 285k
Port Arthur Premcor 255k
Port Arthur Total 234k"

For those lurkers out there that want to know what to do in these situations.

"expect the worst, hope for the best". That's the key, Prepare and Plan. If you wait, it will be too late, plan your escape and take care of your own, no one else will until it's too late. I know it sounds geeky, but get a map and plan alt routes out of your area now. You saw what it gets like in a mass ex., go for the little used routes and you'll save hours and gallons of gas.

California dont sale your Exon/Mobil stock just yet. I guess the comsumers are going to get raped again like usual.

getting a nasty thunder boomer though here right now.

I heard, correct me if I'm wrong, and I know you will:) 25% of the refinery capacity in the US is in the gulf states, specifically, TX and LA.

Lefty - Looking for information on how NHC converts flight-level wind speeds to surface wind speeds. Although this is somewhat tangential to your questions, it is interesting (full link below),

"For the first decade or so of airborne reconnaissance, surface winds were estimated mostly by visual inspection of the sea surface. Beginning in the early 1950s, radar altimeters aboard the aircraft made possible an accurate determination of the aircraft’s absolute altitude. When combined with direct pressure measurements, this gives a good estimate of geopotential height at flight level. Surface pressure can then be estimated using empirical relationships between surface and flight level pressure. This technique, developed during the 1950s, was used without significant modification through the end of aircraft reconnaissance in the western North Pacific and until the advent of accurate dropwindsondes in the North Atlantic. Minimum surface pressure estimates were converted to maximum sustained surface wind using semi-empirical wind-pressure relations which, however, have evolved with time. For the North Atlantic, Landsea [3] has documented a change in that took place in 1970, leading to lower wind speed estimates."

Link

We might infer from the above that NHC changed the formula for surface winds based on dropwindsondes data it was getting.

On a side note, if only 10% of the refinery capacity of the US was affected, why then would the price of gas jump >10%. There should be reserve capacity in the other 90% shouldn't there?

yeah guygee. it states that dropsonde data alonre would give u to weak a storm and dvorak or t-number would give u to strong a storm which is why both are used. the problem with rita was that her t-number sugested she was 145mph but i figured she was 130mph. now with that said the flight level winds were the same when she was 145 and 120. the differenc was a lower t-number and higher pressure. her pressure was 15mbs higher at 930 and her t-number was 5.7-6.0. so thats why i say she was 130 not 120. the nhc deducted 20 percent for surface winds when they were deducting 10 percent. thats why i say its all subjective.

dropsondes, dropsondes.... so what, what about the reports of ground stations? are they not relevant anymore?... everybody takes for granted the dropsondes, guess what? that's one point at one time, and an average at that. Those things are only as good as they build'em and some of those guys aren't that good, not all, but some. I know some of them that build them were tossed in the early 90's from the AF and Navy.

grd good point but ground recordings not good when storm over water lol, also they tend to give out in the 60-120 range and they are stuck to the ground so they only give you the wind sopeeds for that one spot. if the fastes winds do not travel by that spot they never get recorded

Oh wait, did I mention that those that were tossed are the supervisors, the ones that fabricate the dropsondes are trained at votech schools.

lefty got it right all the nhc info and the inland wind speed reports were all wrong he knows best so all you bad pepole stop ... now tell him how go he is and how bad max is....

Lefty - Definitely subjective. Apparently what was (is?) used is some simplistic empirical formula that no longer fits quite right due to climate change. The Chris Landsea article referred to in the above gives some more interesting information (full link below):

"A simplified but useful empirical relationship between the maximum sustained wind speeds and lowest surface pressures of Atlantic basin tropical cyclones was given by Kraft (1961).

Vmax = Sqrt(1013-Pc),

Vmax in this relation is the maximum sustained wind speed in m/s and Pc is the minimum sea level pressure in mb."

However, C. Landsea goes on to say something like this formula is biased due to changes in climate, then he goes back through the historical record to adjust for the bias for the purpose of estimating what the "correct" percentage of Major hurricanes compared to total named systems.

Here is the link to his paper in full:
Link

Lefty, last post on other board:

Posted By: DocNDswamp at 4:34 AM GMT on September 25, 2005.

Lefty...good point. 20 percent seems indicative of lack of confidence in the samples...or the methodology. I think we will see physical proof of actual wind speeds on the ground tomorrow. My neighbor works for Chevron, early flight over W Gulf facilities/Cameron tomorrow. Let you know what I hear.

lefty that's fine, but nhc only goes with dropsondes not sat feeds unless a bird isn't out there. that leads to misinformation. The sats are better at it than sondes. They don't have enough bouys out there and they disregard ship reprorts, what gives?

here u go guys. check out this chart. it equates t-nummber with pressure and windspeed. its how t-numbers are used to equate strength. check it out and give me ur comments. also remebr i said t-number was 5.7-6.0 with pressure of 930mb. now tell me what intesity she should have been

Link

grd, thye use a combo of t-number, pressure and dropsondes now. thats how they determine surface wind speed. look at the chart and see what intenisty she should have been


Link

lefty -- I don't know what to think of the readings, I only know for sure how the sensors work. I do know that multiple reports put the intensity of katrina higher than official. Visisble damage is higher also, so where do you go from there. NHC and meteos in general need to take a step back and consider. Rita went all over the place, and no one knew where she was going or what she would be, they still don't.

grd thats the basis for how t-numbers are used. the nhc stated in the 5pm advisory yesterday of the t-numbers increased they would increse the intensity. it did back to 5.8-6.0 and flight level winds were around the same but they left her where she was. that chart states that a t-number higher than 5.5 and less pressure than 948 would be atlest 115kts. thats 132 cat4. thats what i was saying. 5.7-6.0 with 930 pressure should have atlest been a 115 cat 4. i did not make the t-number up. but ur right. katrina should have been atlest a 156mph cat 5

What in the world are we arguing about now?

I think i've picked up on the discussion, so I have a question.

I've seen the T-Number stuff before, but never really payed attention to it. What exactly is it, and how is it calculated or derived?

Also, im not sure what the point of all of this is - what does it matter, especially to the people who lost their homes, what the category is? Sound to me like it would be better if the strength of these storms was undervalued at landfall. If Rita was "only" a cat 3, and Katrina "only" a cat 4, it should make residents more afraid of a true cat 4 or 5, right?

JV

lol valence just doing what they do after every storm. disect it.


ps, no where did i say i know more than nhc. winds speed is subjectuve and if u don;t know that i am sorry

lefty -- also, one night we had 2 aircraft in the storm at the same time, with different readings!!!! The Sat was saying stonger and the birds were saying weaker. What do you go with. I saw colder cloud tops all around and a closed eye. The bird reprted open SE, on DIVORAK you could see a slight opening and EWRC maybe. You said so, so I went with it. I don't think wind and pressure are so relevant without time, this year is different these things are making thier own rules, after all we have never seen a cycle like this.

Lefty - If you ignore the 930 mb pressure and just use the Dvorak number, 5.7 gives about 123 MPH. The Dvorak numbers you gave do not correspond with the pressure readings: the two don't match up in the chart, so the estimate must have gotten subjective.

Maybe they just used the low-end Dvorak number? Really I cannot figure out what they did based on the numbers you gave me and the chart...

ok here what t-numbers are valence

The Dvorak technique is a method using enhanced Infrared and/or visible satellite imagery to quantitatively estimate the intensity of a tropical system.

so basicaly its another way to look at a staelite image. like ir. now theres a couple of different techinques to do this based on the curren state of the storm and the state of the storm for 3,6,12,24 hrs. thats how u get the t-number. no i can not determine it myself so i go to the unoversity of wisconsin website where they have the 3-4 deifferent t-numbers listed. thats where i get my 5.7-6.0 range. and with the chart you can see a t-number of 5.7 or higher and a pressure of 930 she should have been set at 115kt intesnity at least

This also goes back to something I've been harping on since I've been posting on here.

I think its time to create a new scale for hurricanes. Nothing wrong with the Saf-Sim scale, its just that max suf winds are not a true measure of a hurricanes power, and therefore its total destructive force.

For example, wouldn't a hurricane with 115mph winds, but with a windfield of hurricane force winds that extend 100 miles from the center be more destructive than a 130mph storm whose winds are only 40 miles from the center?

JV

guygee, the ignored the pressure and went wiht the recon to set ur down to 125, than estimated her down to 120 based on the t-number dropping off for abput and hour. from that point on till landfall her t-number was atleast 5/8. remebr all the deep convection. that hellped to increase her t-number. her intensity from the university of wisconsin ahd her set at t-number 6/934mb/120kts so shows you i am not alone at thinking she was stronger

exactly valence. that was my feeling as well

lefty-

When you say "quantatively estimate", you mean a bunch of meterologists looking at the enhanced sat pics and estimating the intensity? That sould a whole lot more subjective than estimating the surface conditions based on whats being measured by the Recon flights.

JV

Leffty what makes the GD difference? Move on.

grd, my biggest complain is that they were using 10 percent of flight level and than started using 20 when they down graded her, even though her lfight level winds were the same
they are subjective here the proof

this recon she was only 120 mph
URNT12 KNHC 232322Z
VORTEX DATA MESSAGE
A. 23/2303Z
B. 28 DEG 28 MIN N
92 DEG 54 MIN W
C. 700 MB 2492 MA
D. NA
E. NA
F. 151 DEG 121 KT
G. 061 DEG 17 NM
H. 930 MB
I. 12 C/ 3050 M
J. 20 C/ 3061 M
K. 15 C/ NA
L. OPEN E-SW
M. E 080-30-20
N. 12345/7
O. 1/1 NM
P. NOAA3 2318A RITA OB 31
MAX FL WIND 121 KT NE QUAD 2258Z
MAX FLT LVL TEMP 060/10 NM FROM CNTR

this recon she was 145 mph
A. 22/19:22:40Z
B. 25 deg 44 min N
089 deg 15 min W
C. NA mb NA m
D. NA kt
E. NA deg nm
F. 149 deg 122 kt
G. 062 deg 012 nm
H. EXTRAP 914 mb
I. 9 C/ 3658 m
J. 17 C/ 3658 m
K. 10 C/ NA
L. OPEN E
M. C16
N. 12345/NA
O. 0.02 / 1 nm
P. AF306 WX18A RITA01 OB 02
MAX FL WIND 122 KT NE QUAD 19:19:30 Z

Lefty I was watching right along with you, so the NHC surface wind estimates did not match up with Dvorak number nor what you would expect from the pressure...

So don't we have some good doppler esimates of velocity once she got into range? That would seem to be some useful data to bring into the discussion.

The system needs to take into account the kinetic energy built up at sea, if she drops in pressure then rises, the surge may not drop. That depends on the time she was at that intensity, Katrina burst all the records except wind and pressure. Andrew only busted.... what i don't know, oh, she hit close to a major city with media coverage.