Atlantic Tropical Action 2012 - Part II

[am19psu]

Hate

[Superstorm93]

Lame Lemon is now 91L.

Not that anyone cares.

[HurricaneJosh]

Hate

Yeah.

I'm offended that a lemon would even form at this point.

[Ed Lizard]

Mandarin...

TROPICAL WEATHER OUTLOOK NWS NATIONAL HURRICANE CENTER

MIAMI FL 700 PM EST FRI NOV 30 2012 FOR THE NORTH ATLANTIC..

.CARIBBEAN SEA AND THE GULF OF MEXICO... SHOWER ACTIVITY ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE OVER THE CENTRAL ATLANTIC OCEAN ABOUT 1350 MILES EAST-NORTHEAST OF THE LEEWARD ISLANDS HAS BECOME A LITTLE BETTER ORGANIZED. SOME ADDITIONAL DEVELOPMENT OF THIS LOW IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS IT MOVES GENERALLY TO THE NORTH AT 10 TO 15 MPH. THIS SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS. SPECIAL TROPICAL WEATHER OUTLOOKS WILL BE ISSUED FOR THIS SYSTEM ON SATURDAY...IF NECESSARY.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE NEXT 48 HOURS. THIS IS THE LAST REGULAR TROPICAL WEATHER OUTLOOK OF THE 2012 ATLANTIC HURRICANE SEASON. THE NEXT REGULAR TROPICAL WEATHER OUTLOOK WILL BE ISSUED ON JUNE 1 2013. SPECIAL TROPICAL WEATHER OUTLOOKS WILL BE ISSUED AS NEEDED IF A SIGNIFICANT WEATHER SYSTEM FORMS DURING THE OFF-SEASON. $$ FORECASTER BEVEN

[HurricaneJosh]

It's in that same stupid area as everything else this season.

Just a total schlock season. Except for Ernie in Mexico and Sandy in Cuba, the season simply ate sh*t-- was devoid of anything even remotely sexy. The crazy number of storms is just an insult on top of injury.

At least in 1983-- which was off-the-charts slow-- you had one really cool, interesting cyclone.

Glad this sh*t season is done.

[HurricaneJosh]

The NHC has ratified the reanalysis results for 1936-1940, which includes the great "Long Island Express" hurricane of 1938.

The official landfall intensity on Long Island, NY, is a whopping 941 mb/105 kt. The CT/RI landfall is 946 mb/100 kt. It's deemed a Cat 3 for NY, CT, and RI, and a Cat 2 for MA.

Andrew Hagen, who helped with the reanalysis effort, told me tonight about a critical piece of data that I wasn't aware of: a sustained (1-min) wind of 95 kt measured on Fishers Island, NY, before the anemometer blew away. The observer said the wind continued to increase and peaked ~15 mins after the instrument failed. This reading was heavily vetted and researched by Hagen, Beven, and Landsea and is believed to be representative. The anemometer was perhaps a tad high-- maybe between 10 and 15 m-- but it was also approx. 0.5 mi inland, so the various bias factors are deemed to have canceled out. This reading was apparently critical to the final landfall-intensity verdict.

Before they found this reading, the highest known representative (non-topographically-enhanced) reading was 76 kt from Block Island, RI, which was ~10 n mi E of the RMW. Actually-- and this is really fascinating-- Andrew thinks even the E tip of Long Island might have been ~5 n mi outside (E of) of the RMW. This really shows that 1938 was no Sandy-- it had a relatively compact wind core, with an RMW of only ~40 n mi (not small, but not really that large for this latitude).

Thanks to Andrew Hagen for these fascinating bits of additional info Re: this analysis.

[CT Rain]

The NHC has ratified the reanalysis results for 1936-1940, which includes the great "Long Island Express" hurricane of 1938.

The official landfall intensity on Long Island, NY, is a whopping 941 mb/105 kt. The CT/RI landfall is 946 mb/100 kt. It's deemed a Cat 3 for NY, CT, and RI, and a Cat 2 for MA.

Andrew Hagen, who helped with the reanalysis effort, told me tonight about a critical piece of data that I wasn't aware of: a sustained (1-min) wind of 95 kt measured on Fishers Island, NY, before the anemometer blew away. The observer said the wind continued to increase and peaked ~15 mins after the instrument failed. This reading was heavily vetted and researched by Hagen, Beven, and Landsea and is believed to be representative. The anemometer was perhaps a tad high-- maybe between 10 and 15 m-- but it was also approx. 0.5 mi inland, so the various bias factors are deemed to have canceled out. This reading was apparently critical to the final landfall-intensity verdict.

Before they found this reading, the highest known representative (non-topographically-enhanced) reading was 76 kt from Block Island, RI, which was ~10 n mi E of the RMW. Actually-- and this is really fascinating-- Andrew thinks even the E tip of Long Island might have been ~5 n mi outside (E of) of the RMW. This really shows that 1938 was no Sandy-- it had a relatively compact wind core, with an RMW of only ~40 n mi (not small, but not really that large for this latitude).

Thanks to Andrew Hagen for these fascinating bits of additional info Re: this analysis.

Cool stuff, Josh. Is there a link to the official report?

Re: Fishers Island I'm not surprised. It's also important to note that Fisher's Island is basically on the CT shore (just a bit south of KGON) so you'd have to imagine some spots on Fire Island on the south shore of LI were at least 10 knots higher.

[HurricaneJosh]

Cool stuff, Josh. Is there a link to the official report?

Re: Fishers Island I'm not surprised. It's also important to note that Fisher's Island is basically on the CT shore (just a bit south of KGON) so you'd have to imagine some spots on Fire Island on the south shore of LI were at least 10 knots higher.

Hey, Ryan!

Yeah, you know that New London basically got those same winds observed on Fishers Island and got totally raked. I didn't realize until looking at the reanalysis data that New London was in the RMW and may have had some of the highest winds in all of New England and-- since Long Island wasn't densely-populated back then-- New London may have been the hardest-hit population center in the entire event. And it makes sense, given how badly smashed the city was.

You can see the changes to the landfall data at these links:

List of US Hurricane Landfalls: http://www.aoml.noaa...Hurricanes.html

Detailed Landfall Data (for nerds ): http://www.aoml.noaa...s-detailed.html

There isn't any report-- just my conversation with Andrew and the official metadata, which Andrew shared with me but which apparently hasn't been put online yet. Here it is, pasted from a conversation we had. I imagine it'll be online shortly:

The highest official reliable wind observation recorded on land that was not

influenced by terrain effects was 95 kt (1-minute) at Fishers Island, NY (41.3N, 72.0W) at 2020Z. An

investigation into obtaining the height of this anemometer reveals that it was likely in the range of 10

to 15 meters. The observer at Fishers Island noted that the anemometer failed at 2020Z, right after the

95 kt value was recorded. The observer estimated a highest one-minute wind of 104 kt at 2035Z. Estimated

maximum velocity reported by the observer at the Watch Hill Coast Guard Station (41.3N, 71.8W) in Westerly,

Rhode Island was 105 kt. A secondary source states that the anemometer of a ship in the harbor at New

London, CT at 41.35 degrees N, 71.1W recorded a value of exactly 87 kt before the anemometer blew away.

The RMW of this hurricane was located between New London, CT and Westerly, RI. At Block Island, RI (41.2N,

71.6W), a maximum 5-minute wind of 71 kt SE (14 m) converts to a 10 m 1-min wind of 74 kt. Block Island’s

fastest mile wind was measured at 79 kt, which converts to a 10m 1-min wind of 76 kt. Block Island was

located about 10 to 15 nmi outside of the right RMW. Other stations’ maximum winds, after converting to

10m 1-min values are: Providence, RI: 68 kt; Boston, MA: 64 or 71 kt (depending whether you convert from

5-min or from fastest mile). It is estimated that the maximum surface sustained winds at the Long Island,

NY landfall were about 105 kt, which is slightly below the Schwerdt et al.'s and Boose et al.'s value

(110 kt) and significantly above that suggested by Kaplan and DeMaria (85 kt) and that shown originally

in HURDAT (also 85 kt). (Kaplan and DeMaria's analysis focused solely upon observed wind values, and did

not utilize the Army Corps source where the 95 kt observation was found. Other than the winds mentioned

above, the wind data coverage on the right side of the hurricane was rather sparse. The right RMW is

analyzed to have crossed eastern Long Island. This retains the hurricane as a Category 3 at the first

(NY) landfall. For the Connecticut landfall, winds are suggested to have dropped slightly to 100 kt.

Category 3 winds are likely to have been felt along the immediate coast of eastern Connecticut and

extreme western Rhode Island in a tiny area between 72.0W-71.8W. However, Massachusetts impact was

analyzed to be about Category 2, which is a downgrade from Category 3 originally estimated in HURDAT.

[Amped]

Was the forward speed of the 1938 storm updated in reanalysis?

[HurricaneJosh]

Was the forward speed of the 1938 storm updated in reanalysis?

Yes. The reanalyzed forward speed at landfall in NY and CT/RI is indicated to be 41 kt. That's a tad slower than some of the legends and lore indicate. (Over the years, I've heard estimates as high as 60 kt!)

[Amped]

Yes. The reanalyzed forward speed at landfall in NY and CT/RI is indicated to be 41 kt. That's a tad slower than some of the legends and lore indicate. (Over the years, I've heard estimates as high as 60 kt!)

Thanks, the issue hasn't been debated on the forum, but I've heard several conflicting numbers from various sources. This clears it up.

[LongBeachSurfFreak]

Thanks, the issue hasn't been debated on the forum, but I've heard several conflicting numbers from various sources. This clears it up.

The question now becomes was it still the fastest Western Atlantic hurricane of all time? I think it likely was moving faster South of long Island based on the amazing time from off Hatteras to Long Island. It likely was feeling the block that caused the track by the time it hit Long Islands Latitude and was into its future slow down.

[HurricaneJosh]

The question now becomes was it still the fastest Western Atlantic hurricane of all time? I think it likely was moving faster South of long Island based on the amazing time from off Hatteras to Long Island. It likely was feeling the block that caused the track by the time it hit Long Islands Latitude and was into its future slow down.

From what I've heard, you're right. I've always been under the impression that the cyclone was decelerating by the time the center reached Long Island, and that the peak speed was reached off NJ.

[HurricaneJosh]

Here are all of the hurricanes to hit the Northeast USA in the last century, with the approximate forward speeds at the time of landfall. (I used wxmx's great research tool for the calculations: http://db.hellohelp....torm_search.php.) For some, I had to give a range, as the landfall happened between fixes of different speeds.

1938: 41 kt

Edna 1954: 36->43 kt (accelerating)

Gloria 1985: 36 kt

Donna 1960: 30->34 kt (accelerating)

Carol 1954: 31 kt

Bob 1991: 29 kt

1944: 30->25 kt (decelerating)

Belle 1976: 22 kt

As you can see, 1938 deserves its reputation as the fastest to hit the region. Gloria 1985 was one of the fastest, which makes sense. I went through that one-- the exact center passed right over my town on Long Island-- and I remember how fast the cyclone came and went. The destructive core winds passed within about an hour. Belle was the slowpoke of the group-- and, not surprisingly, the weakest at landfall (980 mb/65 kt).

An honorable mention goes to Hazel 1954 which, although no longer a tropical cyclone, blasted through the Mid-Atlantic states at over 40 kt.

[LongBeachSurfFreak]

From what I've heard, you're right. I've always been under the impression that the cyclone was decelerating by the time the center reached Long Island, and that the peak speed was reached off NJ.

That would partially explain the insane localized IKE numbers as the surge was very localized. As opposed to Sandy which had a large surge area were I live on Western LI the 38 surge was impressive but far less then in a more tropical clone! I have talked to neighbors that were the original inhabitants of my neighborhood and as bad as they say that 38 was it was a couple feet lower then Sandy. That would support my feeling that while Sandy was a historic wide spread (more like a Nor'easter disaster) 38 was more of a true tropical hurricane.

[HurricaneJosh]

Here's a nice map I made, showing the reanalyzed track, landfall points, and key observations mentioned above, including that critical Fishers Island ob.

The RMW was essentially over Fishers Island (red) and New London (green)-- meaning the middle part of Long Island's South Fork, including the Hamptons, probably had the highest winds seen anywhere. Block Island (purple), on the other hand, was 10-15 n mi outside of the RMW:

[Amped]

Sandy tried to form a core up until the final few hours. The sub 20c water temps and cool air temps over the m/a were just too much. It proved the point though that a tc core can survive inside a noreaster.