Rapid Weakening? SMFR Data at 120kts?

[logybogy]

Someone at easternuswx posted that the latest pass had 904mb pressure but the interesting part is the highest winds they could find were 138kts and SMFR data was 120kts at the surface.

[GalvestonDuck]

Must be basing it on recon reports -- also posted here http://www.storm2k.org/phpbb2/viewtopic ... &start=780

[JtSmarts]

I would expect a significant rise in pressure for it to be rapid weakening +2mb isn't that much

[Brent]

904 mb is what's baffling me... that's REALLY REALLY low for even a borderline 4/5.

[storms in NC]

won't last long it will build back up you will see

[milankovitch]

Shear seems to have increased slightly I believe this to be the cause of the slight weakning. Not enough time for to much weakning, a strong cat 4 seems like as weak as Katrina could make landfall.

http://cimss.ssec.wisc.edu/tropic/real- ... wg8shr.GIF

[coolwater]

It's going to do nothing but weaken from here on out IMO. The contact with land is probably weakening it. I started a thread earlier saying she looked to be weakening, but it was deleted.

Thank God she is weakening.

[mtm4319]

Even if it is weakening (and btw... 155mph or even 145mph is entirely sufficient to push the damage totals past Andrew), it's doing so with enough time to possibly re-strengthen before landfall.

[InimanaChoogamaga]

Katrina does not appear to be weakening. That tiny rise in pressure won't drop the winds that much and the satellite images don't show signs of weaking.

[ConvergenceZone]

I'm thinking they will be down to either 155 mph or 160 mph with the next advisory. I think they rushed the winds a bit too high to begin with. Nonetheless, it should still be a strong cat 4 I would think by the time it comes on shore.

[gilbert88]

Honestly there's absolutely no reason to think it is weakening "rapidly"... please don't overhype every bit of info as soon as you read it.

[Brent]

Honestly there's absolutely no reason to think it is weakening "rapidly"... please don't overhype every bit of info as soon as you read it.

I agree... I still see a VERY VERY VERY well defined eye on satellite... I remember with Ivan and Dennis it was clear they were weakening rapidly... this is not.

[cycloneye]

If it gets in as a low 5 or a strong cat 4 it wont make a big difference as the effects will be the same catastrofic damage.

[wjs3]

Can anyone give us a quick explanation of what SMFR is and how it works?

[recmod]

These type of false topic posts are extremely irritating ....as well as blatantly misleading.

Katrina is NOT rapidly weakening.....a 2mb rise in pressure does not denote a rapid decay. The recon pass where the 138mph wind was recorded was not presented in a vortex msg....the last vortex msg posted still pegs flight level winds at 160knots.

Why do people do this? I am SURE that the NHC and officials would be the FIRST to rapidly spread the word through the media if Katrina was rapidly weakening to defuse this state of panic and dread that has descended on the Northern Gulf Coast.


Let's keep to posting facts and drop the drama antics!

--Lou

[jkt21787]

I was the person who posted the information on Eastern. However, I got the info from here, in the recon thread, from what StormsAhead reported, 138 was the highest FL in the NE quad pass with 120kts the SFMR estimate. Those are facts.

The 160kts FL data in the vortex message was as of 12:43 PM CDT. That was 6 hours ago.

When I posted that on the other board I was not suggesting rapid weakening, though some took my info and construed it into that thinking. Just reporting the recon facts.

[GalvestonDuck]

Can anyone give us a quick explanation of what SMFR is and how it works?

Hope this helps a bit. Not a forecaster here, so I'm going on what I could find in a search.

http://www.magazine.noaa.gov/stories/mag154.htm

SFMR and Wind Speed Estimates
The ability of the NOAA AOC to provide reliable, frequent surface wind data to NHC in an operational mode was a phenomenal success that was made possible by the
outstanding efforts of HRD and the AOC electronic technicians and engineering staff. The data were collected using the Stepped Frequency Microwave Radiometer (also known as SMFR), which uses remote sensing technology to continuously collect and report wind speeds at a height of 10 meters above the ocean surface. SFMR, which was originally developed at the University of Massachusetts, is an exceptional example of research successfully being transitioned to operations. SFMR is located underneath the aircraft, and were in use on each of NOAA’s WP-3D Orion aircraft this season. (Click NOAA image to the right for a larger view of SMFR/wind speed estimates for Hurricane Jeanne on Sept. 25, 2004. Please credit "NOAA.")

Also important was the onboard data screening of this SFMR data by HRD scientists. Further quality control efforts were completed at NHC using surface wind analysis made possible by HRD employees, who invested countless hours as each storm approached landfall. The collective ability to check the SFMR data against surface wind estimates from industry standard GPS dropsondes (devices that measure wind, temperature, humidity and pressure of storms), and to co-locate the instrument’s location in storm relative coordinates was crucial in establishing its credibility.

HRD made a concerted effort to gather more than 150 real time GPS surface wind observations and compare them to the SFMR surface wind observations to show a mean error of only 2.5 knots. This analysis further enhanced the credibility of the SFMR as an operational tool in hurricane wind observation. (Click NOAA image
to the right for a larger satellite image of Hurricane Jeanne taken on Sept. 23, 2004. Please credit "NOAA.")

[wlfpack81]

Looking at the latest satellite imagery the eye still looks very, very well defined. There's 20kt of sw-ly shear north of Katrina near the coast however, this well defined eye along with 90deg temps IMO should be enough to maintain at least 145mph or so through landfall. So in this case even if it does "weaken" it's all relative as 145mph just east of NO is just as bad as 165mph.

[JtSmarts]

Thanks GalvestonDuck and Wlfpack81 for clearing things up for us.

[StormsAhead]

Pressure is still at 904mb, but the eyewall is open to the SW based on the latest vortex, which you can see in the Recon thread.