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Hurricane Katia Part 2, TS Watch for Bermuda

OSUmetstud

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ORH_wxman

ORH_wxman

Posted
Posted

Agreed-- it's a "language" that tropical nerds pick up with time.

P.S. I notice most severe/tornado literature is in mph, so I use mph when working in that arena.

I used to always do mph...but even I picked up knots within a year or so. I'm math savvy, so I won't expect everyone to pick it (the conversion) up that fast, but you do not have to be math savvy to pick it up fast either....you just have to know what a minimal hurricane is like 64 knots...and then understand that mph is about 10mph more than knots until you reach like a cat 3 then you have to start adding 15mph, and so on.

But not to get too OT on this storm. I rarely comment on these storms that are total fish, but I will say that this one is very impressive and its mid-level center is starting to align itself with the sfc which is a good sign for this being an intense storm and trying to intensify more....when hurricanes are "stacked" that is a good thing....unlike Mid-latitude cyclones where they weaken rapidly. I cannot comment on the weird ERCs and such with any skill over any other tropical weenie here.

I know you guys still think it looks ugly on the NW side right now. But the upper levels seem to be aligning better...hopefully it will straighten out in the NW side.

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A-L-E-X

A-L-E-X

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Posted

I used to always do mph...but even I picked up knots within a year or so. I'm math savvy, so I won't expect everyone to pick it (the conversion) up that fast, but you do not have to be math savvy to pick it up fast either....you just have to know what a minimal hurricane is like 64 knots...and then understand that mph is about 10mph more than knots until you reach like a cat 3 then you have to start adding 15mph, and so on.

But not to get too OT on this storm. I rarely comment on these storms that are total fish, but I will say that this one is very impressive and its mid-level center is starting to align itself with the sfc which is a good sign for this being an intense storm and trying to intensify more....when hurricanes are "stacked" that is a good thing....unlike Mid-latitude cyclones where they weaken rapidly. I cannot comment on the weird ERCs and such with any skill over any other tropical weenie here.

I know you guys still think it looks ugly on the NW side right now. But the upper levels seem to be aligning better...hopefully it will straighten out in the NW side.

I love math also, but I have a different way of doing it. I eschew calculators so what I do is convert the 1.15 (approx.) conversion factor into a fraction-- it's approx. 8/7 so what I do is divide the knots by 7 and take the result and add it on to get the mph :)..... for example..... 64 / 7 approx 9.... add it on to the 64 and you get 73 mph. To do the reverse and convert mph to knots you simply multiply the reciprocal of 8/7 by the mph to get knots. It sounds complicated but it's really easy to do in your head.

I dont like the fact that we have all these different measuring units though-- there should be one unified standard.

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phlwx

phlwx

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I used to always do mph...but even I picked up knots within a year or so. I'm math savvy, so I won't expect everyone to pick it (the conversion) up that fast, but you do not have to be math savvy to pick it up fast either....you just have to know what a minimal hurricane is like 64 knots...and then understand that mph is about 10mph more than knots until you reach like a cat 3 then you have to start adding 15mph, and so on.

But not to get too OT on this storm. I rarely comment on these storms that are total fish, but I will say that this one is very impressive and its mid-level center is starting to align itself with the sfc which is a good sign for this being an intense storm and trying to intensify more....when hurricanes are "stacked" that is a good thing....unlike Mid-latitude cyclones where they weaken rapidly. I cannot comment on the weird ERCs and such with any skill over any other tropical weenie here.

I know you guys still think it looks ugly on the NW side right now. But the upper levels seem to be aligning better...hopefully it will straighten out in the NW side.

To add to what you said:

kt to mph conversion: 1.15 x kts = mph or mph/1.15 = kt

If someone is too lazy to use their calculator...

25-45 kts add 5 to get mph

50-80 kts add 10 to get mph

85-110 kts add 15 to get mph

115-145 kts add 20 to get mph

150 and above add 25

(the one that is less "clean" is 115 kts since that technically converts to 132.25 but the NHC will run 115 kts as a Cat 4 since it is technically over 131 mph)

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k***

k***

Posted
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with the increasing shear over the next 12-24 hours and the environmental dry air around Katia I think it may have a similar issue to Irene in not fully completing an eyewall replacement cycle. I don't believe it will strengthen anymore and peaked last night.

if it does it will be all eye...that recent pass is ridiculous

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dtk

dtk

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all the reanalysis data i have seen is in m/s

From the NARR data i'm working with now:

weird, m^2/s^2?

You and Josh are talking about two (sort-of) different things. The TC reanalyses (Chris Landsea, where they go back and reanalyze TCs specifically) use knots for the reasons cited by Josh. Most of the atmospheric reanalyses (NARR, ERA, NCEP/NCAR, MERRA, CFSR) that go back and do full atmosphere analyses use SI units (i.e. m/s) for their fields.

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Ginx snewx

Ginx snewx

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with the increasing shear over the next 12-24 hours and the environmental dry air around Katia I think it may have a similar issue to Irene in not fully completing an eyewall replacement cycle. I don't believe it will strengthen anymore and peaked last night.

Becoming more symmetric since the TRMM pass, might have slowed a tad.

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dan88

dan88

Posted
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12z SHIPS was initialized with 105kt (the likely 11am advisory intensity), but also shows a peak at 0 hours, with only decline to come. For the next 24 hours it shows the only parameters contributing positively to the intensity are the Sample Mean Change (which is always positive), and a very slight (+1 kt) contribution from GOES PREDICTORS.

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gymengineer

gymengineer

Posted
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It just makes more sense.... everything from the Beaufort Scale to the Saffir Simpson Scale looks much more elegant in knots ;):wub::hug:

But, as we discussed back in the Easternweather board last year, the older literature (TCR's, MWR's) used to use mph, as did the original Saffir Simpson Scale. The switchover to kts created the inconsistent boundary cases, like at 115 kt, for the SS scale ratings. Gilbert's Jamaica landfall was 115 kt, but 130 mph, not the 135 mph that the NHC uses currently and that we're reflexively used to. I'm glad the Hurricane Center has gone ahead and proposed modifications to the boundaries of the SSHWS since they have switched over to kts themselves. (http://www.nhc.noaa.gov/feedback/2011/sshws.php)

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Cory

Cory

Posted
Posted

Josh if you want to get "technical" most ATMS peer review literature now uses meters per second rather than knots. At least this has been the general shift in the past decade or so.

Meters per second pisses me off and I quit reading any article that uses it, which has really cut down on my scientific reading burden. I think most meteorologists are fine with using knots and it's easier to communicate that way. I wonder how many scientists read those articles and know right away what 50 m/s means without having to break out a converter? Meters per second (and hectopascals) are pretentious bull****.

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Ginx snewx

Ginx snewx

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Meters per second pisses me off and I quit reading any article that uses it, which has really cut down on my scientific reading burden. I think most meteorologists are fine with using knots and it's easier to communicate that way. I wonder how many scientists read those articles and know right away what 50 m/s means without having to break out a converter? Meters per second (and hectopascals) are pretentious bull****.

Glad you said it.

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OSUmetstud

OSUmetstud

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Meters per second pisses me off and I quit reading any article that uses it, which has really cut down on my scientific reading burden. I think most meteorologists are fine with using knots and it's easier to communicate that way. I wonder how many scientists read those articles and know right away what 50 m/s means without having to break out a converter? Meters per second (and hectopascals) are pretentious bull****.

AMS journals are big on SI units...so I'm not sure it's that easy to get around. hPA and millibars are the same anyway.

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LocoAko

LocoAko

Posted
Posted

Rotations per hour and tangential wind speeds will not be completely correlated. If we were to measure this rotations per hour at the distance away from the center where the fastest winds are: for a hypothetical hurricane with a 150 mph storm with a 30 mile wide eye, and assuming for the sake of argument that there is a ring ~20 miles from the center of the storm in the eyewall of 150 mph winds (even though in reality the fastest winds would only be in a small portion of the eye wall). The "eyewall" portion of the hurricane is rotating completely once every 50 minutes (.83 r/hr). For a storm with a 10 mile wide eye and ~ 10 mile ring, we have half the rotational velocity (.41 r/hr); however, both storms are the same intensity. The rotational speed really tells us nothing useful.

They do not. The wind vectors are tilted inward.

Thanks! This is all what I suspected but wasn't completely sure.

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LocoAko

LocoAko

Posted
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Meters per second pisses me off and I quit reading any article that uses it, which has really cut down on my scientific reading burden. I think most meteorologists are fine with using knots and it's easier to communicate that way. I wonder how many scientists read those articles and know right away what 50 m/s means without having to break out a converter? Meters per second (and hectopascals) are pretentious bull****.

I don't have an intuitive grasp for m s-1 (is raising it to the -1 more pretentious than using a slash? :P) either but I consider that my own fault. You really consider hPa to be pretentious? It is what we learn in class and what I've gotten used to using. It makes sense to stay within SI units, no? At least you don't have a conversion issue on that one... lol.

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Ed Lizard

Ed Lizard

Posted
Posted

Knots are cool, because certain sites, like some college sites and the ECMWF that give winds in meters/second, obvously not an exact conversion, but double the number for wind speed in knots. And the sites like utah.edu that give wind speeds in knots use barbs as 5 m/s and a flag as 25 m/s, so one doesn't have to think.

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Gray-Wolf

Gray-Wolf

Posted
Posted

Katia must be hella boring given this knots v m/s v mph stuff. BTW you know you're an elitist when....

Not on this side of the pond! We are still uhming and arhing as to whether we get the remnants to the North of us (and we have a brief return of summer) or we get the low bang on us and then it could be a tad unpleasant for a day or so!

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phil882

phil882

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I don't have an intuitive grasp for m s-1 (is raising it to the -1 more pretentious than using a slash? :P) either but I consider that my own fault. You really consider hPa to be pretentious? It is what we learn in class and what I've gotten used to using. It makes sense to stay within SI units, no? At least you don't have a conversion issue on that one... lol.

hPa = millibars... don't see what the big deal is there. m/s is obviously a little harder for people to make a natural conversion, and I haven't myself either, but if you go from km/hr its a lot simpler to convert thanks to the wonderful metric system :P

You did yesterday.

Yep... maybe hes looking for a pinhole eye storm though, in which we might have one coming up in the GOM if it can stay in the Bay of Campeche. devilsmiley.gif

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Chicago Storm

Chicago Storm

Posted
Posted

First recon pass was SW/NE...

Pressure much higher than the NHC 11AM estimate, sitting at 963mb.

Max FL wind of 114kts in the NE quad.

URNT12 KNHC 061725

VORTEX DATA MESSAGE AL122011

A. 06/16:55:00Z

B. 27 deg 10 min N

066 deg 14 min W

C. 700 mb 2768 m

D. 66 kt

E. 223 deg 36 nm

F. 313 deg 85 kt

G. 223 deg 40 nm

H. 963 mb

I. 12 C / 3047 m

J. 16 C / 3045 m

K. 13 C / NA

L. NA

M. NA

N. 12345 / 7

O. 0.02 / 1 nm

P. AF304 0112A KATIA OB 04

MAX FL WIND 85 KT SW QUAD 16:43:30Z

MAX OUTBOUND FL WIND 114 KT NE QUAD 17:11:00Z

MAX FL TEMP 17 C 220 / 6 NM FROM FL CNTR

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