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wusifeng|2013-8-2 16:04
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JTWC #10Prognostic Reasoning
(以下内容我在上海台风研究所台风论坛发表过)
1、供气象专业人士使用
2、6小时概况与分析
热带风暴09W(JEBI)位于越南河内东到东南方大约353海里,过去6小时以时速14节向西北方向移动。多光谱卫星动态图像显示过去6小时,系统结构变得更加对称并且发展出类似风眼结构。起初定位是基于以上动态图像可信度较高。为了反映正在展开的风眼结构,强度则略大于PGTW和RJTD德沃夏克分析得到的55节。高层分析显示09W在副高脊轴线以南6°方向,系统东侧垂直风切变(VWS)中等(15-20节)。然而系统已经建立了中尺度高空反气旋,并增强其高层流出(尤其是西侧)。它正在副高南侧气流引导下逐渐向北移动。
3、预报理由
A 此次预报原理与前一次没有明显区别
B 预计TS JEBI于未来12小时穿过海南北部,随后进入北部湾并再次登陆越南北部地区,最终在河内西-西北部消散。TS 09W可能在登陆海南前的数小时内加强至台风级别。然后,在海南崎岖地形和越南北部地貌的影响下减弱最终消散。机构对强度预报保持高度一致,JTWC路径预报的可信度较高。
WDPN31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (JEBI) WARNING NR
10//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 09W (JEBI), LOCATED APPROXIMATELY 353 NM EAST-
SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS THE SYSTEM HAS BECOME MORE SYMMETRICAL AND HAS DEVELOPED AN
EYE-LIKE FEATURE OVER THE PAST SIX HOURS. THE INITIAL POSITION IS
BASED ON THE ABOVE ANIMATION WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY IS SLIGHTLY HIGHER THAN THE CONGRUENT DVORAK ESTIMATE OF 55
KNOTS FROM PGTW AND RJTD TO REFLECT THE EVOLVING EYE FEATURE. UPPER
LEVEL ANALYSIS INDICATES TS 09W IS 06 DEGREES SOUTH OF THE RIDGE AXIS
IN AN AREA OF MODERATE (15-20 KNOT) EASTERLY VERTICAL WIND SHEAR.
HOWEVER, THE SYSTEM HAS DEVELOPED A MESOSCALE ANTICYCLONE THAT IS
ENHANCING OVERALL OUTFLOW ESPECIALLY IN THE WESTWARD FLANK. THE
CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL
RIDGE TO THE NORTH.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TS JEBI IS EXPECTED TO CROSS THE NORTHERN PORTION OF HAINAN
OVER THE NEXT 12 HOURS THEN DRIFT ACROSS THE GULF OF TONKIN BEFORE
MAKING LANDFALL IN NORTHERN VIETNAM, EVENTUALLY DISSIPATING INLAND
WEST-NORTHWEST OF HANOI. TS 09W MAY REACH TYPHOON INTENSITY OVER THE
NEXT FEW HOURS BEFORE MAKING LANDFALL IN HAINAN. AFTERWARDS,
INTERACTION WITH THE RUGGED TERRAIN OF HAINAN AND, LATER ON, WITH THE
TOPOGRAPHY OF NORTHERN VIETNAM WILL CAUSE ITS DETERIORATION AND
EVENTUAL DISSIPATION. INTENSITY GUIDANCE IS IN TIGHT AGREEMENT AND
LENDS HIGH CONFIDENCE TO THE JTWC TRACK FORECAST. //
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