[2021] 2102号热带气旋“舒力基”(02W.Surigae)JTWC预报理由翻译帖

ty2019

1.本产品供专业气象人员使用

2.六小时总结与分析
超级台风舒力基（02W）位于菲律宾马尼拉以东约367海里处，过去六小时以6节的速度向西北偏西方向移动。增强红外线云图（EIR）动画显示，系统出现显著的云顶温度下降，以及中心密集云区的扩大和对流解体。直径约10海里的风眼虽然已经部分堵塞，但依然清晰可见，因此我们对其初始位置的确定有较高信心。18日0515Z的AMSR2 89GHZ图像显示，内眼墙明显消散，因此舒力基的眼壁置换已经完成。在AMSR扫描图像中，底层风眼清晰可见，并且在增强红外线云图上也有明显的风眼。机构对PGTW、RJTD及KNES的德法分析中，Final T值正在下降，目前为T6.5（127kts），ADT客观评估为T6.6（130kts）。综合以上分析，我们取其中的较高值并将初始强度确定为135kts。分析显示，目前垂直风切变较低（5-10kt），海表温度较高（29-30°C），但北侧中有纬度槽的压制，极向高空流出减弱，因此环境稍有转差。系统正沿着副热带高压脊西缘向东移动。

3.预报理由
A. 与之前的预报相比，本报预报原理没有变化。
B. 随着副热带高压脊的经向度加大，超级台风02W将更加偏向于向西北偏北方向移动，流出的减弱将抵消低风切和高海温的作用，因此系统强度逐渐减弱，72小时后减弱至95kts。即使各家数值预报对路径的发散度逐渐加大，72小时后达176海里，但仍较为一致。JTWC的路径预报综合了多家数值预报的结果，因此对这段时间内的路径预报有较高信心。
72小时后，超级台风舒力基将来到副热带高压脊的中轴附近，开始在其北边转向，向西北方向加速。垂直风切变的加大将使得02W加速减弱，120小时后减弱为75kt，多家数值对120小时后的路径预报发散度为130海里，因此我们的后期路径预报可信度较高。

WDPN31 PGTW 180900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 02W (SURIGAE) WARNING
NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON 02W (SURIGAE), LOCATED APPROXIMATELY 367 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 06 KNOTS OVER
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY
SHOWS SIGNIFICANTLY WARMED CONVECTIVE TOPS OVER AN ENLARGED CENTRAL
DENSE OVERCAST AND UNRAVELING OF FEEDER BANDS. THE EYE, APPROXIMATELY
10NM IN DIAMETER, HAS BECOME PARTIALLY FILLED BUT REMAINS DISCERNIBLE
AND LENDS HIGH CONFIDENCE IN THE INITIAL POSITION. IT APPEARS THAT
EYEWALL REPLACEMENT HAS COMPLETED AS EVIDENCED BY THE DISAPPEARANCE OF
THE MOAT FEATURE IN THE 180515Z AMSR2 89GHZ IMAGE. A MICROWAVE EYE IS
ALSO EVIDENT IN THE AMSR2 IMAGE AND LINED UP PERFECTLY WITH THE EIR
EYE. THE INITIAL INTENSITY OF 135KTS IS BASED ON THE HIGHER END OF
WEAKENING AGENCY DVORAK FINAL-T ESTIMATES FROM PGTW, RJTD, AND KNES OF
T6.5/127KTS; AND THE OBJECTIVE ESTIMATE OF T6.6/130KTS FROM ADT.
ANALYSIS INDICATES THE ENVIRONMENT HAS BECOME LESS FAVORABLE WITH THE
LOW (5-10KT) VERTICAL WIND SHEAR (VWS) AND WARM (29-30C) SEA SURFACE
TEMPERATURES (SSTS) IN THE PHILIPPINE SEA OFFSET BY DIMINISHING
POLEWARD OUTFLOW THAT IS SUPPRESSED BY THE MIDLATITUDE TROUGH TO THE
NORTH. THE CYCLONE IS TRACKING ALONG THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 02W WILL TRACK MORE TO THE NORTH-NORTHWEST AS THE STR
ELONGATES MERIDIONALLY. THE DIMINISHING OUTFLOW OFFSETTING THE LOW VWS
AND WARM SSTS WILL PRIMARILY BE RESPONSIBLE FOR ITS GRADUAL WEAKENING,
DOWN TO 95KTS BY TAU 72. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A
GRADUAL AND EVEN CROSS-TRACK SPREAD TO 176NM BY TAU 72, LENDING FAIR
CONFIDENCE IN THIS PORTION OF THE JTWC FORECAST TRACK, WHICH IS LAID
CLOSE TO THE MULTI-MODEL CONSENSUS.
   C. AFTER TAU 72, STY SURIGAE WILL CREST THE STR AXIS AND BEGIN ITS
RECURVE ON THE POLEWARD SIDE, ACCELERATING NORTHWEASTWARD. INCREASING
VWS WILL CONTRIBUTE TO A MORE RAPID DECAY, DOWN TO 75KTS BY TAU 120.
THE NUMERICAL MODELS CLUSTER CLOSER TO 130NM AT TAU 120, LENDING ALSO
FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC TRACK FORECAST.//
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ty2019

1.本产品供专业气象人员使用

2.六小时总结与分析
台风舒力基（02W）位于菲律宾马尼拉以东约284海里处，过去六小时以3节的速度向偏北方向移动。增强红外线云图（EIR）显示，舒力基继续保持一个较大且清晰的风眼，风眼直径约30海里。注意到，内眼中的一些深对流消散，在直径30海里的眼墙和直径60海里的深对流环之间，周期性地形成了一个干区。从19日1951Z的SSMIS微波扫描图像中可以看出这种特征相当显著。基于PGTW综合分析的T6.0/6.5和ADT评估的T6.0，我们将初始强度稍微降低至115kts。HWRF/HYCOM海洋耦合分析表明，
大台风可能会导致下垫面海水冷却，这导致了当前核心对流和强度逐渐减弱。舒力基位于200mb脊轴线的正南方，垂直风切变较弱，只有5-10kt，因此仍处于较有利的环境中。水汽云图显示，中纬度有一股干冷气团正在台风西侧的吕宋岛上空向南移动。但是，目前没有证据表明这股气团正在被卷入风暴的核心。

3.预报理由
A. 与之前预报相比，本报预报原理没有变化。
B. 预计在未来48小时内，由于东边的弱高空脊将继续引导一股弱偏南气流转向，舒力基将继续缓慢地向西北偏北方向移动。这股偏转气流可能会稍微加强高空副热带急流（stj）内一个低振幅的脊，并使其从台湾附近东移到台风北侧。因此，未来12-24小时，台风的移动速度将比目前有所加快。48小时后，一个短波槽将从西北向中国东部靠近，此时舒力基将绕过脊的西北边缘并向东移动。因此，中层西风将增强，使得气旋在72小时后加速向东北方向移动。与前一报相比，72小时的路径预测稍微向东调整，这也是短期路径更偏向北的原因，这种预测仍然具有较高的可信度。未来48小时的强度预报主要考虑舒力基所在的下垫面冷却，由于台风移动缓慢，这种状况将持续。预计48小时后减弱至100kts。此后，中层西风增强，海表温度从28°C下降到26°C，台风转为东北方向移动的同时，垂直风切变也会增大。在这种情况下，48小时后舒力基的减弱速度会更快。
C.在未来96-100小时里，舒力基将与一个从日本南部向南穿过琉球群岛的斜压系统发生相互作用，这将促使其向温带气旋转化。当一个正斜压的短波槽经过气旋西侧的东海时，由于与副热带西风急流相互作用引发的斜压对台风的强度重新加强不是很有利，所以预报120小时后减弱为台风以下强度。与前一报相似，我们将120小时的路径稍微向数值预报最新达成的共识方向调整。由于向温带气旋转化的过程中，其前进的速度存在不确定性，我们的预报可信度中等。

WDPN31 PGTW 192100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (SURIGAE) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 02W (SURIGAE), LOCATED APPROXIMATELY 284 NM EAST OF
MANILA, PHILIPPINES, HAS TRACKED NORTHWARD AT 03 KTS OVER THE PAST
SIX HOURS. SURIGAE CONTINUES TO MAINTAIN A LARGE, CLEARLY-DEFINED
EYE OF 30 NM DIAMETER IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE
IMAGERY. SOME EROSION OF DEEP CONVECTION IN THE INNER CORE HAS BEEN
NOTED OVER THE PAST SIX HOURS, PERIODICALLY CAUSING THE APPEARANCE
OF A DRY MOAT BETWEEN THE 30 NM EYEWALL AND A LARGER, OUTER RING OF
DEEP CONVECTION APPROXIMATELY 60 NM IN DIAMETER. THIS OUTER RING
APPEARS TO BE THE DOMINANT FEATURE IN A RECENT 191951Z SSMIS
MICROWAVE IMAGE. THE CURRENT INTENSITY IS LOWERED SLIGHTLY TO 115
KTS, BASED ON THE PGTW FIX OF T6.0/6.5 AND ADT ESTIMATES OF T6.0.
COUPLED HWRF/HYCOM OCEAN ANALYSIS SUGGESTS THAT SLOW MOVEMENT OF THE
LARGE TYPHOON IS INDUCING COOLING OF THE UNDERLYING WATER, POSSIBLY
CONTRIBUTING TO THE CURRENT RAGGEDNESS OF INNER CORE CONVECTION AND
GRADUAL DECREASE IN INTENSITY. SURIGAE REMAINS SITUATED IN AN
OTHERWISE FAVORABLE ENVIRONMENT, LOCATED JUST SOUTH OF THE AXIS OF A
200MB RIDGE, WITH LIGHT VERTICAL WIND SHEAR OF 5-10 KTS. WATER VAPOR
SATELLITE IMAGERY DEPICTS A COOL, DRY MID-LATITUDE AIR MASS GETTING
PULLED SOUTHWARD OVER LUZON ON THE WEST SIDE OF THE TYPHOON, BUT
THERE IS NO EVIDENCE THAT THIS AIR MASS IS GETTING ENTRAINED INTO
THE STORM CORE AT THIS TIME.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. SURIGAE IS EXPECTED TO CONTINUE MOVING SLOWLY NORTH-
NORTHWESTWARD DURING THE NEXT 48 HOURS AS A WEAK UPPER-LEVEL RIDGE
TO ITS EAST CONTINUES TO INDUCE A WEAK SOUTHERLY STEERING FLOW. THIS
STEERING FLOW MAY STRENGTHEN SLIGHTLY AS A LOW-AMPLITUDE UPPER-LEVEL
RIDGE WITHIN THE SUBTROPICAL JET (STJ) TRANSLATES EASTWARD FROM THE
VICINITY OF TAIWAN TO THE NORTH OF THE TYPHOON. THUS, FORWARD SPEED
IS EXPECTED TO INCREASE SLIGHTLY FROM THE CURRENT SLOTHFUL PACE
WITHIN THE NEXT 12-24 HOURS. AFTER 48 HOURS, SURIGAE WILL ROUND THE
NORTHWESTERN PERIPHERY OF THE RIDGE TO ITS EAST, AND A SHORTWAVE
TROUGH WILL APPROACH FROM THE NORTHWEST OVER EASTERN CHINA. THE
RESULTING INCREASE IN MID-LEVEL WESTERLY FLOW WILL ACCELERATE AND
TURN THE CYCLONE NORTHEASTWARD BY 72 HOURS. THE TRACK FORECAST
THROUGH 72 HOURS IS NUDGED SLIGHTLY EASTWARD COMPARED TO THE
PREVIOUS ONE TO ACCOUNT FOR THE MORE NORTHWARD TREND IN SHORT-TERM
MOTION, BUT REMAINS OF HIGH CONFIDENCE. THE INTENSITY FORECAST
THROUGH 48 HOURS IS EXPECTED TO LARGELY BE A FUNCTION OF DYNAMIC
OCEAN COOLING OCCURRING BENEATH SURIGAE, WHICH SHOULD CONTINUE AS
THE TYPHOON MOVES SLOWLY. GRADUAL WEAKENING TO 100 KTS IS FORECAST
BY 48 HOURS. THEREAFTER, VERTICAL WIND SHEAR IS EXPECTED TO INCREASE
AS THE TYPHOON TURNS NORTHEASTWARD, IN RESPONSE TO INCREASING
WESTERLY MID-LEVEL FLOW AND A COOLING OF BACKGROUND SEA SURFACE
TEMPERATURES FROM 28C TO AROUND 26C. QUICKER WEAKENING IS LIKELY
AFTER 48 HOURS AS THIS OCCURS.
   C. DURING THE 96-120 HOUR PERIOD, SURIGAE IS EXPECTED TO INTERACT
WITH A STRONG LOW-LEVEL BAROCLINIC ZONE SOUTH OF JAPAN, PRESSING
SOUTHWARD ACROSS THE RYUKYU ISLANDS. THIS SHOULD CATALYZE THE
PROCESS OF EXTRATROPICAL TRANSITION. WEAKENING BELOW TYPHOON
INTENSITY IS FORECAST THROUGH 120 HOURS, AS THE INTERACTION WITH THE
STJ IS NOT PARTICULARLY FAVORABLE FOR BAROCLINIC-INDUCED
REINTENSIFICATION AS A POSITIVELY-TILTED SHORTWAVE TROUGH DIGS
THROUGH THE EAST CHINA SEA DUE WEST OF THE CYCLONE. THE TRACK
FORECAST REMAINS SIMILAR TO THE PREVIOUS ONE, NUDGED JUST SLIGHTLY
NORTH THROUGH 120 HOURS TOWARD THE NEW MULTI-MODEL CONSENSUS.
CONFIDENCE IS MODERATE DUE TO SOME UNCERTAINTY IN FORWARD SPEED
DURING EXTRATROPICAL TRANSITION. //
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