Atlantic Best Track 2008 - Omar 115 kt

[CrazyC83]

I have been searching around on the ATCF site and found that Omar (operationally 110 kt/959mb) has been upgraded to 115 kt/958mb - ftp://ftp.nhc.noaa.gov/atcf/tcweb/inves ... 008.invest and will likely be a Cat 4 in the TCR.

Didn't see any other major updates yet.

[Derek Ortt]

caution

115KT is also used as a cat 3 as well. The Felix report indicated that during its EWRC, it weakened to a 115KT cat 3

[CrazyC83]

caution

115KT is also used as a cat 3 as well. The Felix report indicated that during its EWRC, it weakened to a 115KT cat 3

True, but I think in the Felix report they meant that it dropped to 110 kt between points around 2100/2 (since they mention the pressure was 953mb at some point and the lowest at either point was 951mb at 1800/2).

[Derek Ortt]

I don't think so

also, Frederick struck as a 115KT cat 3 and there are many others as well (Ivan operationally was a 115KT cat 3 at landfall, but that was obviously Great Oneish). This may have also been a top end cat 3

[Cyclenall]

How can 115 knot winds be both category 3 and category 4?

[HurricaneRobert]

I looked at NHC's report. Where did it say Frederic was a category 3 hurricane?

[HURAKAN]

How can 115 knot winds be both category 3 and category 4?

115 * 1.152 = 132.48, which can be rounded to 130 or to 135. Therefore, base on how you round it, it can be a cat. 3 or cat. 4.

[Chacor]

It's actually easier than that to comprehend. A 113 kt (Cat 3) storm would still round to 115 kt, hence a 115 kt storm could still be a Cat 3. Just like how there are 135 kt cat 5s, because cat 5 starts at 136 kt and they're then rounded down.

[Ptarmigan]

115 knots=132 mph or rounded to nearest 5, 135 mph. Category 4, which is 131 to 155 mph. NHC like using base five for their winds. Yes, I know 115 knots can be Category 3, because it is closer to 130 mph.

[Cyclenall]

What would affect the decision to either round up to 115 knots or round down to 110 knots? The way I see it is if a hurricane is 113 knots, round to a CAT4 with 115 knot winds. If it's 112 knots, go to 110 knots (CAT3). The NHC doesn't use mph in it's best track records or advisories (non-public) so I don't see why this is an issue to begin with.

[wxman57]

It's actually easier than that to comprehend. A 113 kt (Cat 3) storm would still round to 115 kt, hence a 115 kt storm could still be a Cat 3. Just like how there are 135 kt cat 5s, because cat 5 starts at 136 kt and they're then rounded down.

Check your math. 135 kts x 1.152 = 155.52 mph = 156 mph = Cat 5

115 kts x 1.152 = 132.48 mph = 132 mph (to nearest mph) = 130 mph if you round to the nearest 5 mph increment.

[Tampa Bay Hurricane]

When Recon goes in, don't they get a specific number, like for
example 129.7 mph SMFR which would be category 3, or
133.8 mph SMFR which is a category 4 by definition?
In that case, if SMFR sound 130.8 mph that is a category 3.
If SMFR found 131.1 mph that is a category 4.
Is this correct? In other words, 131.00 mph is the absolute
criteria for category 4.

[HurricaneRobert]

It's actually easier than that to comprehend. A 113 kt (Cat 3) storm would still round to 115 kt, hence a 115 kt storm could still be a Cat 3. Just like how there are 135 kt cat 5s, because cat 5 starts at 136 kt and they're then rounded down.

Check your math. 135 kts x 1.152 = 155.52 mph = 156 mph = Cat 5

115 kts x 1.152 = 132.48 mph = 132 mph (to nearest mph) = 130 mph if you round to the nearest 5 mph increment.

This is how the NHC appears to do it:

115 knots = 132.339637 mph = 135 mph (rounded to the nearest 5) = category 4
135 knots = 155.355225 mph = 155 mph = category 4

[RL3AO]

Cat 4 starts at 114 knots.

[Alacane2]

I looked at NHC's report. Where did it say Frederic was a category 3 hurricane?

This is not from the Preliminary Report issued by the National Hurricane Center, but rather from the National Weather Service in Mobile (in the 2008 Alabama Hurricane Preparedness booklet).

As one can see from the return period statistics listed above, since 1995, the Alabama coastline is
experiencing hurricanes at a frequency well above what would normally be expected for that time
period. Dennis and Katrina (2005), Ivan (2004) and Frederic (1979) all struck the coastline within 75
miles of the Mobile Bay area as strong Category 3 hurricanes. This is well above the normal frequency
of Category 3 hurricanes that one would expect to affect Alabama during that time period. While there
have been some close calls with Category 4 and 5 hurricanes in recent years, records indicate that the
Alabama coastline has not sustained a direct hit by a Category 4 or 5 hurricane in more than 100 years.Therefore, from the return period statistics listed above, one can clearly see that the Alabama coastline
is very much overdue for such an extreme storm.

Link: http://www.srh.noaa.gov/mob/2008pamphlet.pdf

[Chacor]

It's actually easier than that to comprehend. A 113 kt (Cat 3) storm would still round to 115 kt, hence a 115 kt storm could still be a Cat 3. Just like how there are 135 kt cat 5s, because cat 5 starts at 136 kt and they're then rounded down.

Check your math. 135 kts x 1.152 = 155.52 mph = 156 mph = Cat 5

115 kts x 1.152 = 132.48 mph = 132 mph (to nearest mph) = 130 mph if you round to the nearest 5 mph increment.

Has nothing to do with mph in my calculations. Cat 5 is 136 kt; 135 kt is Cat 4. No mathematics required.

http://www.nhc.noaa.gov/aboutsshs.shtml

Category Five Hurricane:
Winds greater than 155 mph (135 kt or 249 km/hr).