A bit frustrated with NHC

[caneflyer]

Joe Bastardi asks when has anyone seen a 987 mb pressure at 70 west south of 20 that was not a hurricane.

Well, the historical record has 5 such tropical storm occurrences south of 20N:

1 AL121988 KEITH 985.00 1121.00
2 AL101995 IRIS 985.00 828.12
3 AL131996 MARCO 985.00 1122.06
4 AL031961 CARLA 987.00 906.06
5 AL152000 KEITH 987.00 930.06

The last column is mmdd.hh.

If you want to stretch it and include tropical storms with pressures of 988 mb, then you get a few more:

6 AL051935 - 988.00 1024.12
7 AL111979 FREDERIC 988.00 901.00
8 AL041994 CHRIS 988.00 818.00
9 AL091996 ISIDORE 988.00 926.00
10 AL142000 JOYCE 988.00 929.18
11 AL152001 MICHELLE 988.00 1102.06

So it is clearly possible.

There will not, of course, be any official re-evaluation of what the intensity was at 5 pm, as the best tracks are done at the synoptic times of 0, 6, 12, and 18Z.

[Aslkahuna]

Actually, if you read the discussion from last night on Cindy just before landfall, you will note that the landfalling pressure with Cindy was NOT 992mb because the pressure went up just before landfall and the radar presentation weakened.

Steve

[jasons2k]

I suppose at this point there isn't much we can do except see what the future beholds...

[wafbwx]

Folks...I think there are good points on both sides here, but I also think we all need to relax. In defense of JB and others who think Dennis should have been upgraded earlier, I agree...you cannot have a 4 mb pressure drop in a few hours and not have a corresponding increase in winds. Atmospheric/mathematical equations tell us so. I've often had a problem with the NHC being slow to react to pressure falls...waiting on recon to confirm observations instead. I understand the conservative/safe approach, but I don't necessarily agree. If you were to go back through the Opal advisories in 1995, I believe you would find the NHC was rather slow to react to rapidly falling pressures.

On the other hand...I would argue the 1 hour delay in this particular instance made very little difference since there was not an immediate, impending landfall. It actually hurt people like myself in the media the most since we were scrambling to update graphics for our shows with the new info. The NHC has gotten MUCH better about considering media concerns in recent years, but today gave us a bit of a headache.

As for whether Cindy was a hurricane...that's like debating whether a shirt is light blue or dark blue. Most info points toward Cindy being a strong T.S. at landfall, but it may have been a minimal hurricane. However, does that change anything for the folks who suffered damage or who were without power last night or today? I don't think so. The ob of hurricane force winds at South Timbalier Block was at an elevation of approx. 120 feet (about 90 feet above the standard), so it's a close call as to whether that's enough to upgrade Cindy. However, I do feel like the ob was valid and accurate...the LSU folks responsible for it do a solid job.

Steve

[wafbwx]

Sorry...one last note...while I see many ridiculous criticisms of the NHC, discussions like this can be quite useful. I appreciate feedback on my work...even when it's not all positive ... and constructive criticism (or discussions) from educated people can help the NHC become even better. We have a right to question and criticize within reason and I don't think the original poster was out to rip the NHC.

[Lindaloo]

Well said, Steve.

[gkrangers]

975mb and no wind increase. Hehe.

[jkt21787]

975mb and no wind increase. Hehe.

Recon reported winds did not support a wind increase although the pressure drop did occur. Winds always respond after the pressure drop.

[gkrangers]

975mb and no wind increase. Hehe.

Recon reported winds did not support a wind increase although the pressure drop did occur. Winds always respond after the pressure drop.

I know. I think an AF aircraft is uspposed to be in the storm now or soon. I think it'll find higher winds...center is wrapped very tightly now with a circular eye forming.

[jkt21787]

975mb and no wind increase. Hehe.

Recon reported winds did not support a wind increase although the pressure drop did occur. Winds always respond after the pressure drop.

I know. I think an AF aircraft is uspposed to be in the storm now or soon. I think it'll find higher winds...center is wrapped very tightly now with a circular eye forming.

I'm sure it will be a cat 2 if not a cat 3 within 12 hours. Big intensification going on as we speak...

[george_r_1961]

Dennis is a large storm..so it would take a few..perhaps several hours for the winds to respond to a pressure fall. Inertia folks..basic high school physics. A smaller storm could intensify (and weaken) faster in response to changes in its environment. NHC didnt upgrade it at 5PM because at the time wind data did not support it. When recon found hurricane force winds this info was relayed to NHC..and Dennis was duly upgraded.

[Dmetal81]

Remember Bastardi/Accuweather has an agenda and would love to downplay the NHC/NWS accuracy.
TIM

Always have a critical eye without being prejudiced.

After seeing the legislation put up this year, Im saddened to say (that things like politics creep into science) that I have to agree.

[DoctorHurricane2003]

Okay let me put this in perspective for you

If the background pressure was 502 mb......and the pressure of the storm was 500 mb......it would produce maybe a 10-25 mph wind.

Now with your logic......this would obviously be a category super 26 hurricane......because it has a 500 mb pressure.......and that 15 mph wind it blows is going to blow the earth off its axis....

Come on now, use logic.

[wafbwx]

I'm not going to get wrapped up in a big argument about this because there's no point and it does no one any good, but when the pressure drops 5 mb in 3 hours (as per the advisories), there has to be a corresponding increase in winds.

And, yes, as george_r_1961 points out, it would take a little while for the winds to respond to a drop in pressure, but not all that long.

[jasons2k]

Folks...I think there are good points on both sides here, but I also think we all need to relax. In defense of JB and others who think Dennis should have been upgraded earlier, I agree...you cannot have a 4 mb pressure drop in a few hours and not have a corresponding increase in winds. Atmospheric/mathematical equations tell us so. I've often had a problem with the NHC being slow to react to pressure falls...waiting on recon to confirm observations instead. I understand the conservative/safe approach, but I don't necessarily agree. If you were to go back through the Opal advisories in 1995, I believe you would find the NHC was rather slow to react to rapidly falling pressures.

On the other hand...I would argue the 1 hour delay in this particular instance made very little difference since there was not an immediate, impending landfall. It actually hurt people like myself in the media the most since we were scrambling to update graphics for our shows with the new info. The NHC has gotten MUCH better about considering media concerns in recent years, but today gave us a bit of a headache.

As for whether Cindy was a hurricane...that's like debating whether a shirt is light blue or dark blue. Most info points toward Cindy being a strong T.S. at landfall, but it may have been a minimal hurricane. However, does that change anything for the folks who suffered damage or who were without power last night or today? I don't think so. The ob of hurricane force winds at South Timbalier Block was at an elevation of approx. 120 feet (about 90 feet above the standard), so it's a close call as to whether that's enough to upgrade Cindy. However, I do feel like the ob was valid and accurate...the LSU folks responsible for it do a solid job.

Steve

Hey Steve:

I agree with you here - I think you bring up some great points - I think the NHC overall does a great job but there is always (as with anything) room for improvement. Thanks for the post.