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EPAC Tropical Action 2011


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74kt flight level SE quad, 70kt estimated at surface, 989.5mb extrap

180100 1620N 10242W 8430 01470 9986 +168 +111 246058 061 058 004 00

180130 1621N 10243W 8422 01471 9979 +164 +108 249064 066 058 001 00

180200 1623N 10244W 8434 01451 9970 +167 +105 245063 066 062 007 00

180230 1624N 10244W 8432 01442 9965 +159 +102 249067 069 066 022 00

180300 1626N 10245W 8430 01441 9960 +152 +099 247069 074 070 025 00

180330 1628N 10245W 8426 01435 9950 +153 +096 248062 071 065 025 00

180400 1629N 10246W 8432 01424 9939 +158 +095 247035 045 057 020 03

180430 1631N 10246W 8422 01426 9922 +180 +093 236032 035 037 003 00

180500 1632N 10247W 8434 01415 9918 +190 +094 235029 031 032 003 03

180530 1633N 10248W 8427 01417 9912 +192 +098 226025 027 029 001 03

180600 1635N 10249W 8435 01407 9909 +194 +102 223018 022 025 000 00

180630 1636N 10251W 8430 01411 9907 +195 +106 203011 013 024 000 00

180700 1637N 10252W 8424 01418 9898 +213 +109 184008 010 024 001 03

180730 1638N 10254W 8430 01409 9895 +216 +113 112006 009 029 002 03

180800 1638N 10255W 8430 01412 9902 +205 +119 045013 018 038 002 00

180830 1639N 10257W 8425 01420 9911 +193 +124 015024 027 043 000 03

180900 1640N 10258W 8429 01418 9919 +182 +127 019032 033 049 001 03

180930 1641N 10259W 8426 01426 9924 +182 +128 027036 039 053 002 00

181000 1642N 10300W 8432 01423 9929 +184 +128 030047 049 057 003 00

181030 1643N 10301W 8432 01432 9936 +183 +128 031056 058 058 001 00

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It just goes to show the real limitations with satellite intensity estimates. You just never know.

Yes, they have their limitations, but in this case, they were rather accurate, it's just that Beatriz has probably been steadily intensifying since.

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It looks like we have a cane...

URPN12 KNHC 201826

VORTEX DATA MESSAGE EP022011

A. 20/18:07:20Z

B. 16 deg 37 min N

102 deg 53 min W

C. 850 mb 1342 m

D. 70 kt

E. 144 deg 14 nm

F. 245 deg 74 kt

G. 143 deg 13 nm

H. 991 mb

I. 17 C / 1518 m

J. 22 C / 1520 m

K. 11 C / NA

L. NA

M. NA

N. 12345 / 8

O. 0.02 / 2.5 nm

P. AF302 0102E BEATRIZ OB 09

MAX FL WIND 74 KT SE QUAD 18:03:20Z

CURVED BAND S THRU NW

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Yes, they have their limitations, but in this case, they were rather accurate, it's just that Beatriz has probably been steadily intensifying since.

Yeah, I was just thinking that. The 8 am PDT intensity was 55 kt and I imagine they kept the 11 am intensity the same simply because they were about to get hard data. This having been said, if it is 70 kt now, I do think it's a tad stronger than they would have estimated, based strictly on current satellite imagery.

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Yeah, I was just thinking that. The 8 am PDT intensity was 55 kt and I imagine they kept the 11 am intensity the same simply because they were about to get hard data. This having been said, if it is 70 kt now, I do think it's a tad stronger than they would have estimated, based strictly on current satellite imagery.

Yep, probably, there's probably an underestimating bias in strengthening cyclones.

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Second VDM out and supports a Hurricane as well...

URPN12 KNHC 202029

VORTEX DATA MESSAGE EP022011

A. 20/20:01:10Z

B. 16 deg 51 min N

102 deg 59 min W

C. 850 mb 1337 m

D. 62 kt

E. 255 deg 24 nm

F. 359 deg 63 kt

G. 257 deg 8 nm

H. 989 mb

I. 17 C / 1527 m

J. 22 C / 1522 m

K. 14 C / NA

L. OPEN N

M. C16

N. 12345 / 8

O. 0.02 / 4 nm

P. AF302 0102E BEATRIZ OB 16

MAX FL WIND 74 KT SE QUAD 18:03:20Z

MAX OUTBOUND FL WIND 71 KT NE QUAD 20:06:00Z

MAX FL TEMP 24 C 053 / 19 NM FROM FL CNTR

FIXED ALONG SW EDGE OF THIN INNER EYE ON RADAR

SECONDARY BROKEN BAND CIRCULAR 28 NM OPEN NE

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Reduction factor ftw...

THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT FOUND THAT BEATRIZ

IS JUST BELOW HURRICANE STRENGTH. A BLEND OF THE 850-MB FLIGHT

LEVEL WIND MAXIMUM OF 74 KT AND DROPSONDE DATA WERE USED TO SET THE

INITIAL INTENSITY AT 60 KT FOR THIS ADVISORY. THE SATELLITE

PRESENTATION HAS IMPROVED OVER THE PAST FEW HOURS...WITH WELL-

ESTABLISHED OUTFLOW...ESPECIALLY IN THE NORTHERN SEMICIRCLE.

BEATRIZ SHOULD CONTINUE TO STRENGTHEN IN A FAVORABLE ENVIRONMENT.

THE NEW OFFICIAL FORECAST SHOWS A BROAD PEAK OF 80 KT FROM 24 TO 36

HOURS...A LITTLE ABOVE BOTH THE SHIPS AND LGEM.

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The new discussion mentions the 850-mb wind of 74 kt, and says that is one of the values behind the currency intensity estimate of 60 kt. I'm surprised, because I'd think they would use a higher conversion factor-- more like 90%-- for a healthy, strengthening cyclone in the tropics. I'm not second guessing them-- more just realizing I don't understand the rules as well as I thought.

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There is one helluva battle between the dynamical and statistical intensity guidance.

NHC clearly went with the latter, as all dynamical guidance predicts that we are at peak, and it's downhill from here. Statistical peaks at 36-48 hours. So far statistical has beaten the crap out of the dynamical guidance.

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The new discussion mentions the 850-mb wind of 74 kt, and says that is one of the values behind the currency intensity estimate of 60 kt. I'm surprised, because I'd think they would use a higher conversion factor-- more like 90%-- for a healthy, strengthening cyclone in the tropics. I'm not second guessing them-- more just realizing I don't understand the rules as well as I thought.

I think it's about 80% from 850mb. Link

JLF_Fig1.jpg

Table 1. Mean Hurricane Eyewall Wind Variation With Elevation
Height
(ft)	#
Storys	Wind
(% surface)	Pressure Force
(% surface)
33 (sfc)	3	100	100
50	5	103	106
100	10	108	117
150	15	111	123
200	20	115	132
250	25	117	137
300	30	119	142
400	40	121	146
500	50	123	151
600	60	125	156
750	75	128	164
1000	100	131	172

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NHC clearly went with the latter, as all dynamical guidance predicts that we are at peak, and it's downhill from here. Statistical peaks at 36-48 hours. So far statistical has beaten the crap out of the dynamical guidance.

Yeah. I'm excited to see what happens over the next 24 hours. I went for a peak at 12z tomorrow, then rapid weakening after with a remnant low by 12z Thursday.

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Ah, OK. Well the ya have it. I think I was getting 850 mb confused with another height. (I've never been an expert at interpreting raw recon data.)

But it's strange to me that the VDM indicated an estimated *surface* wind of 70 kt.

While it is true that the SFMR estimated surface winds of 70kts during the first pass, this was in a region where recon indicated a heavy rain rate (25 mm/hr), which is likely the basis for not using it for the advisory.

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While it is true that the SFMR estimated surface winds of 70kts during the first pass, this was in a region where recon indicated a heavy rain rate (25 mm/hr), which is likely the basis for not using it for the advisory.

Yeah, perhaps you're right. I'd like for once to hear about a SFMR estimate from an eyewall that is not rain-contaminated!

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