WPAC: SARIKA - Post-Tropical

[1900hurricane]

Still no core, and it looks like Sarika is just about out of time. It has struggled mightily since its encounter with Luzon.

[Digital-TC-Chaser]

2016OCT17 183000 5.5 952.9 102.0 5.2 5.8 5.8 NO LIMIT ON OFF 6.94 -65.55 EYE -99 IR 9.1 18.48 -111.79 SPRL HIM-8 39.6
2016OCT17 191000 5.5 952.9 102.0 5.2 5.2 5.2 NO LIMIT ON OFF 15.17 -67.15 EYE/L 38 IR 9.1 18.47 -111.43 FCST HIM-8 39.9
2016OCT17 194000 5.5 952.8 102.0 5.1 4.7 4.7 NO LIMIT ON OFF -5.30 -57.73 EYE/L 64 IR 9.1 18.72 -111.86 SPRL HIM-8 39.7
2016OCT17 201000 5.5 952.7 102.0 5.1 5.0 5.0 NO LIMIT ON OFF -6.48 -64.74 EYE/L 66 IR 9.1 18.97 -111.69 SPRL HIM-8 40.0
2016OCT17 203000 5.5 952.8 102.0 5.2 4.8 4.8 NO LIMIT ON OFF 12.52 -64.73 EYE/L 72 IR 9.1 18.65 -111.17 FCST HIM-8 40.3

[euro6208]

75 knots.

WDPN31 PGTW 172100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (SARIKA) WARNING NR 22//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 24W (SARIKA), LOCATED APPROXIMATELY 233 NM NORTHEAST OF
DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
DEPICTS A SYSTEM BECOMING INCREASINGLY DISORGANIZED AND HAS LOST ITS
RAGGED EYE FEATURE OVER THE LAST SIX HOURS AS IT APPROACHES HAINAN.
A 171646Z AMSR2 91 GHZ IMAGE SHOWS A BROAD LOW LEVEL CIRCULATION
CENTER, GIVING FAIR CONFIDENCE TO THE INITIAL POSITION, WITH A DEEP
BAND OF CONVECTION WRAPPING IN FROM THE WEST AND SOUTHEAST. THE
CURRENT INTENSITY IS ASSESSED AT 75 KNOTS AND IS BASED ON THE
WEAKENING CONVECTIVE STRUCTURE COMBINED WITH CURRENT INTENSITY
DVORAK ESTIMATES AT T4.5 (77 KNOTS). UPPER-LEVEL ANALYSIS SHOWS GOOD
RADIAL OUTFLOW TAPPING INTO A PASSING SHORTWAVE TROUGH TO THE
NORTHWEST AND DOMINANT EASTERLY FLOW ON THE EQUATORWARD SIDE. SEA
SURFACE TEMPERATURES ARE ALSO FAVORABLE NEAR 29 CELSIUS. THE RECENT
DROP IN INTENSITY AND CONVECTIVE STRUCTURE IS ATTRIBUTED TO LAND
INTERACTION WITH HAINAN DESPITE ALL OTHER VARIABLES BEING FAVORABLE.
CURRENTLY TY SARIKA IS TRACKING NORTHWEST ALONG THE PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE TO THE NORTHEAST.3. FORECAST
REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY SARIKA WILL CONTINUE TO TRACK NORTHWEST GUIDED BY THE
CURRENT STEERING RIDGE MAKING LANDFALL OVER HAINAN IN THE NEXT 6 TO
12 HOURS AND WEAKENING SIGNIFICANTLY. THE TRACK WILL CONTINUE OVER
THE GULF OF TONKIN MAINTAINING TROPICAL STORM STRENGTH BEFORE MAKING
LANDFALL NEAR THE VIETNAM-CHINA BORDER AND THEN TURNING NORTHWARD AS
IT ROUNDS THE STEERING RIDGE AXIS. AVAILABLE MODEL GUIDANCE IS IN
VERY GOOD AGREEMENT AS THE SYSTEM TRACKS OVER HAINAN AND INTO
VIETNAM, BUT STARTS TO DIVERGE AS IT TRACKS FURTHER INLAND ROUNDING
THE RIDGE AXIS. OVERALL THERE IS HIGH CONFIDENCE IN THE FORECAST
TRACK.//
NNNN

[Digital-TC-Chaser]

MTCSWA combines information from several data sources to create a mid-level wind analysis which is then adjusted to the surface. Eight products are displayed, most notably an inner core scale surface wind analysis.

http://www.ssd.noaa.gov/PS/TROP/mtcswa. ... &id=SARIKA

scientific data and sound advisories form agencies ie JMA/JTWC/NOAA will always trump non- pro amature analysis.

[euro6208]

Very close to making landfall...

[Digital-TC-Chaser]

[euro6208]

Landfall between Wanning and Ling Shui.

[euro6208]

[1900hurricane]

Expert analysis from SAB and JTWC yielded DTs of only 3.5 prior to landfall. SAB ended up using MET for their FT (not a bad move in my opinion considering how ragged convection has been), but a constrained 3.5/4.5 and 4.0/4.5 blend is not a sign of a healthy storm, which is why JTWC dropped to 70 kt at 00Z. This 70 kt estimate also matches well with the 67 kt AMSU estimate from the 2211Z NOAA-15 pass.

TXPQ26 KNES 172129
TCSWNP

A. 24W (SARIKA)

B. 17/2030Z

C. 18.5N

D. 111.4E

E. THREE/HIMAWARI-8

F. T4.0/4.5/D1.0/24HRS

G. IR/EIR/AMSR2

H. REMARKS...10/10 BANDING FOR DT=3.5. MET=4.0. PT=4.0. FT IS BASED
ON MET.

I. ADDL POSITIONS

17/1817Z 18.3N 111.3E AMSR2


...LEE

TPPN11 PGTW 180023

A. TYPHOON 24W (SARIKA)

B. 18/0000Z

C. 18.78N

D. 110.68E

E. FIVE/HMWRI8

F. T3.5/4.5/W0.5/24HRS STT: S0.0/03HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 40A/PBO SBC/ANMTN. .95 WRAP YIELDS A DT OF 3.5. PT
AND MET AGREE. DBO DT.

I. ADDITIONAL POSITIONS:
17/2002Z 18.79N 111.13E MMHS
17/2223Z 18.65N 111.13E MMHS
17/2301Z 18.61N 110.77E SSMS


MARTINEZ

[euro6208]

Looks like Sarika made landfall in a region not populated that much. Good thing. Not seeing any impressive winds so far. Rains and flooding likely will be the main issue.

[euro6208]

WDPN31 PGTW 180300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (SARIKA) WARNING NR 23//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 24W (SARIKA), LOCATED APPROXIMATELY 217 NM NORTHEAST OF
DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 09 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A RAPIDLY WEAKENING SYSTEM ABOUT TO MAKE LANDFALL NEAR
HAINAN. THE INITIAL POSITION IS BASED ON SATELLITE FIXES FROM PGTW
AND RJTD WITH FAIR CONFIDENCE. THE CURRENT INTENSITY IS ASSESSED AT
70 KNOTS AND IS BASED ON THE WEAKENING CONVECTIVE STRUCTURE DUE TO
THE RECENT LAND INTERACTION COMBINED WITH RECENT DVORAK ESTIMATES
RANGING FROM T3.5 TO T4.5 (55 TO 77 KNOTS). UPPER-LEVEL ANALYSIS
SHOWS GOOD RADIAL OUTFLOW TAPPING INTO A PASSING SHORTWAVE TROUGH TO
THE NORTHWEST AND DOMINANT EASTERLY FLOW ON THE EQUATORWARD SIDE.
CURRENTLY TY SARIKA IS TRACKING NORTHWEST ALONG THE PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE TO THE NORTHEAST.3. FORECAST
REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TY SARIKA WILL CONTINUE TO TRACK NORTHWEST GUIDED BY THE
CURRENT STEERING RIDGE AS IT MAKES LANDFALL OVER HAINAN AND WEAKENS
SIGNIFICANTLY OVER THE NEXT 12 HOURS. THE TRACK WILL CONTINUE OVER
THE GULF OF TONKIN MAINTAINING TROPICAL STORM STRENGTH BEFORE MAKING
LANDFALL NEAR THE VIETNAM-CHINA BORDER, THEN TURN NORTHWARD AS
IT ROUNDS THE STEERING RIDGE AXIS. AVAILABLE MODEL GUIDANCE IS IN
VERY GOOD AGREEMENT AS THE SYSTEM TRACKS OVER HAINAN AND INTO
VIETNAM, BUT STARTS TO DIVERGE AS IT TRACKS FURTHER INLAND ROUNDING
THE RIDGE AXIS. OVERALL THERE IS HIGH CONFIDENCE IN THE FORECAST
TRACK.//
NNNN

[euro6208]

Sarika made landfall near Wanning which saw a pressure of 955mb...

[Digital-TC-Chaser]

earlier half pass with a core.

[euro6208]

I thought looks don't matter right in the Atlantic?

just stop with your over hyping, please. In the Atlantic, we have AIRCRAFT. Looks do not matter there. In the Pacific, we nearly only have Dvorak and some satellite data. Given the open eyewall, as well as the cool eye on IR, a reasonable determination can be made this was weaker than the raw DTs had this at (and one should NEVER use raw DTs to make an intensity estimate

Well that's what I've been saying. Looks don't matter. Following Atlantic storms, recon always led Dvorak and satellite 80 percent of the time. Not hyping just stating the fact.

One should never use RAW DT's?

When mattrew was upgraded to a Cat 5, the Raw objective T- number was at 7.0 and agreed with recon to their first Cat 5 in 9 years.

[NotoSans]

Well that's what I've been saying. Looks don't matter. Following Atlantic storms, recon always led Dvorak and satellite 80 percent of the time. Not hyping just stating the fact.

Knaff actually published a paper about the bias of Dvorak estimates back in 2010 using the Atlantic samples. (You can refer to the paper here: http://journals.ametsoc.org/doi/pdf/10. ... F2222375.1). The research shows that Dvorak has a tendency to underestimate storms with intensities ranging from 35 to 55 knots and greater than 125 knots. On the other hand, Dvorak sometimes overestimates storms with intensities between 75 and 105 knots, which may be attributable to the weakening rules proposed by the original Dvorak paper. Generally speaking, Dvorak works best between 90 to 125 knots with little bias, and Sarika, of course, falls into this range.

For the weaker storms, Dvorak is usually less skillful because (a) it is difficult to have a high-confidence wrap estimate (i.e. determining the start and end of a curved band) on infrared imagery; (b) it is difficult to pinpoint the location of the LLCC on infrared imagery, leading to unrepresentative shear estimates; (c) diurnal cycles may cause convective changes that are not representative of the true intensity. It is inappropriate to make a conclusion that Dvorak underestimates all storms just based on the samples of weaker storms, because Dvorak uses different patterns and techniques to estimate intensities of different storms.

It may be somehow surprising to see that Dvorak underestimates the storms with intensities greater than 125 knots, because the eye scene type is generally considered the most objective pattern. This may be attributable to (a) the higher tropopause temperature in the Atlantic basin, making it difficult to produce a ring of 'white' cloud top that meets the width requirement (b) Dvorak underestimates small but intense storms (e.g. Felix) (c) Dvorak underestimates storms with pinhole eyes because the eye temperatures cannot be resolved well. One counter-example to these explanations would be Megi, which was found by recon to be 150 knots and 175 knots when Dvorak estimates were at T7.0 and T7.5, respectively. However, speaking from a statistical perspective, there aren't enough samples to make a meaningful conclusion.

Of course, recon is still the best way to determine the intensity of a storm, and it is difficult to make an intensity estimate without in-situ data. However, it doesn't mean that Dvorak is completely useless and underestimates all the storms.

[euro6208]

Of course, recon is still the best way to determine the intensity of a storm, and it is difficult to make an intensity estimate without in-situ data. However, it doesn't mean that Dvorak is completely useless and underestimates all the storms

Of course. But still useless when it comes to very strong typhoons especially the Cat 5's.

[xtyphooncyclonex]

JMA now at 100 kts. JTWC at 140... Most likely, intensification is taking place and I'm hoping for the best and prayers for Northern & Central Luzon. It's not only the winds and direct effects of Haima that worry us, but also the enhancement of the Southwest monsoon and obviously, floods at the capital.

[edit: Sorry, wrong storm!! ]

[xtyphooncyclonex]

Of course, recon is still the best way to determine the intensity of a storm, and it is difficult to make an intensity estimate without in-situ data. However, it doesn't mean that Dvorak is completely useless and underestimates all the storms

Of course. But still useless when it comes to very strong typhoons especially the Cat 5's.

Some storms in the Atlantic have found Dvorak levels of 7.4 (notably Michelle, Lenny and Isidore) yet the actual intensity of Michelle and Lenny was cat 4. Heck, Isidore was even proven by recon to be only 110 knots! Recon is useful, weaker or stronger.

You can't say that just because a category 5 is "underestimated," it would be hyped to 150+ knots. There is always a possibility of a higher and weaker intensity. Some storms may have impressive pinhole eyes but are actually weaker than you think; they can also have drastically stronger intensities like Wilma and Parma.

What Alyono meant was to not hyperbolate a storm which is impressive in appearance. Observations show that Sarika was at most borderline cat 4 at landfall, as was the case with Rammasun at Sorsogon last year.

I had my mistake too last year when I exaggerated the strength of the subtropical ridge

[euro6208]

WDPN31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (SARIKA) WARNING NR
25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 24W (SARIKA), LOCATED APPROXIMATELY 189 NM
EAST-SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A RAPIDLY WEAKENING LOW-LEVEL CIRCULATION CENTER
(LLCC) DISORGANIZED DEEP CONVECTION. A 181058Z SSMIS 91GHZ IMAGE
SHOWS TIGHTLY-CURVED SHALLOW BANDING, HOWEVER, DEEP CONVECTIVE
STRUCTURE HAS DETERIORATED AND THE CENTER IS OBSCURED. OVERALL,
THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION BASED ON THE
AVAILABLE IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS
BASED ON DVORAK ESTIMATES RANGING FROM 45 TO 65 KNOTS. UPPER-LEVEL
ANALYSIS SHOWS GOOD RADIAL OUTFLOW AHEAD OF AN APPROACHING SHORTWAVE
TROUGH TO THE NORTHWEST, WITH LOW (10 KNOTS) VERTICAL WIND SHEAR
(VWS). CURRENTLY TS SARIKA IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS SARIKA WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD ALONG
THE STR OVER THE NEXT 12 HOURS, PRIOR TO FINAL LANDFALL. VWS WILL
INCREASE AS THE SHORTWAVE TROUGH PASSES, HOWEVER THE WEAKENING TREND
WILL BE PARTIALLY OFFSET BY GOOD OUTFLOW AND THE WARM 28 DEGREE
CELSIUS WATERS OF THE GULF OF TONKIN. AFTER LANDFALL, THE SYSTEM
WILL DISSIPATE DUE TO LAND EFFECTS AS SARIKA ROUNDS THE STR AND
TURNS TO THE NORTH-NORTHEAST. AVAILABLE MODEL GUIDANCE IS IN GOOD
AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.//
NNNN

[euro6208]

WDPN31 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (SARIKA) WARNING NR
26//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 24W (SARIKA), LOCATED APPROXIMATELY 138 NM EAST-
SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 10 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY AND A 181437Z MHS IMAGE DEPICTS A RAPIDLY DETERIORATING
SYSTEM BECOMING SLIGHTLY ELONGATED WITH ONLY A SHALLOW BAND OF
CONVECTION ON THE NORTHERN PERIPHERY. THE SYSTEM HAS EMERGED BACK
OVER WATER IN THE GULF OF TONKIN EXHIBITING SIGNS OF SOME WIND SHEAR
PRESENT. THE POSITION IS BASED ON SATELLITE FIXES FROM RJTD AND PGTW
WITH FAIR CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS
AND IS BASED ON DVORAK ESTIMATES RANGING FROM T2.5 TO T3.5 (35 TO 55
KNOTS) AND A PARTIAL 181438Z METOP-B ASCAT IMAGE SHOWING AT LEAST 40
KNOTS ON THE WESTERN SIDE OF THE LOW LEVEL CIRCULATION CENTER.
CURRENTLY TS SARIKA IS TRACKING NORTHWESTWARD ALONG THE SOUTHERN
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE.
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
B. TS SARIKA WILL CONTINUE ON ITS CURRENT TRACK NORTHWESTWARD
MAINTAINING TROPICAL STORM INTENSITY. LANDFALL OVER NORTHERN
VIETNAM IS EXPECTED IN THE NEXT SIX TO TWELVE HOURS WHERE THE
INTENSITY IS EXPECTED TO DROP CONSIDERABLY. TS SARIKA IS EXPECTED TO
FULLY DISSIPATE BY TAU 36. DYNAMIC MODEL GUIDANCE IS IN FAIRLY GOOD
AGREEMENT TO THE STORM TRACK OVER THE NEXT TWELVE HOURS AS IT TRACKS
OVER WATER. HOWEVER, AS THE SYSTEM WEAKENS OVER LAND, MODEL
SOLUTIONS SHOW CONSIDERABLE SPREAD IN THE DIRECTION OF THE VORTEX
MOVEMENT. OVERALL THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK.//
NNNN