熱帶風暴古斯塔夫-12 - 颱風討論

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WTNT42 KNHC 280250
TCDAT2
TROPICAL STORM GUSTAV DISCUSSION NUMBER 12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008
1100 PM EDT WED AUG 27 2008

THE LAST RECONNAISSANCE FIX WAS AT 23Z. DATA FROM THE AIRCRAFT
INDICATED THAT THE CENTER OF GUSTAV BEGAN TO MOVE WEST-
SOUTHWESTWARD AND AWAY FROM THE DEEP CONVECTION. PEAK FLIGHT-LEVEL
WINDS WERE 39 KT AND THE HIGHEST RECENT BELIEVABLE SFMR WINDS WERE
41 KT. THE ADVISORY INTENSITY IS LOWERED TO 40 KT BASED ON THESE
OBSERVATIONS.

最後一次偵查定位於23Z. 從飛機資料顯示[古斯塔夫]的中心開始朝西南西移動
並離開深對流. 飛航高度風尖峰為三十九節以及現有的SFMR最高風速為四十一節.
根據這些觀察強度報告已降低到四十節

THE INITIAL MOTION IS NOW ESTIMATED TO BE 250/7...ALTHOUGH THE
CENTER HAS BEEN VERY HARD TO TRACK SINCE THE TIME OF THE LAST FIX
AND MIGHT BE A LITTLE SOUTH OF MY ADVISORY POSITION. A DEEP-LAYER
RIDGE...ORIENTED NORTHEAST-SOUTHWEST...IS CENTERED OVER THE FLORIDA
PENINSULA. THIS RIDGE HAS IMPARTED A BIT OF A SOUTHERLY COMPONENT
OF MOTION THAT SOME MODELS SHOW PERSISTING FOR ANOTHER 24 HOURS OR
SO. AFTER THAT...GUSTAV IS EXPECTED TO ROUND THE PERIPHERY OF THE
RIDGE AND TURN TO THE NORTHWEST IN THE EASTERN GULF OF MEXICO.
COMPLICATING THE FORECAST IN THE LATTER PART OF THE PERIOD IS THE
EVOLUTION AND IMPACT OF AN UPPER-LEVEL TROUGH EXPECTED TO BE IN THE
CENTRAL OR WESTERN GULF OF MEXICO...AS WELL AS THE DEVELOPMENT OF A
BLOCKING HIGH AT THE END OF THE PERIOD REMINISCENT OF WHAT HAPPENED
WITH FAY A WEEK OR SO AGO. GIVEN THESE FACTORS...THE MODEL GUIDANCE
IS IN SURPRISINGLY GOOD AGREEMENT. THE OFFICIAL FORECAST RELIES
MOST STRONGLY ON A BLEND OF THE ECMWF...UKMET...GFDL...AND
GFS...WHICH IS NOW FOLLOWING THE VORTEX FAIRLY WELL...AND IS JUST
TO THE LEFT OF THE PREVIOUS ADVISORY TRACK. THE DYNAMICAL MODEL
CONSENSUS IS A LITTLE FARTHER TO THE LEFT.

現在的現行運動估計為二五零度/七浬... 儘管中心次從最後定位以來已經非常難以追蹤,
可能比我的報告的位置稍南點. 一個深層脊... 以東北-西南走向的... 位於佛州半島上
空.
此脊傳遞了一點在模型中二十四小時持續出現的南向動力. 之後... 預期古斯塔夫在
墨西哥灣東部的脊邊緣轉向西北. 在後期複雜的預報中預期會在中部或西墨西哥灣
發生的是一個高層槽的演化與衝擊.而且在周期末端的一個阻塞高壓的發展令人聯想
到在一周前發生在費依身上的情況. 根據這些因素... 導向模型出人意外地一致. 官方
預報強烈地依賴混合ECMWF...UKMET...GFDL...以及GFS... 無論哪個模式現正良好的
跟隨VORTEX...以及正好在前個路徑報告向左. 動態模型的共識是更加向左一點

GUSTAV HAS BEEN SIGNIFICANTLY DISPRUPTED BY ITS ENCOUNTER WITH THE
TERRAIN OF HAITI. IN ADDITION...MID-LEVEL DRY AIR APPEARS TO BE
OVERTAKING THE CYCLONE FROM THE NORTHEAST. IN ANOTHER 24-36
HOURS...HOWEVER...GUSTAV SHOULD FIND ITSELF UNDER AN UPPER
ANTICYCLONE AND OVER THE VERY DEEP WARM WATERS OF THE NORTHWESTERN
CARIBBEAN...AND SO THE CYCLONE SHOULD HAVE AN OPPORTUNITY TO
RESTRENGTHEN. IN ADDITION...THE FORECAST TRACK TAKES GUSTAV OVER
THE LOOP CURRENT IN THE SOUTHEASTERN GULF. AFTER THAT...GLOBAL
MODELS SUGGEST THE POSSIBILITY OF SOUTHWESTERLY SHEAR IN THE GULF
ASSOCIATED WITH THE UPPER TROUGH THAT COULD SLOW THE
INTENSIFICATION RATE. THE OFFICIAL FORECAST SHOWS A SLOWER
RESTRENGTHENING THAN THE PREVIOUS ADVISORY INITIALLY...BUT IS
OTHERWISE SIMILAR...AND ROUGHLY SPLITS THE DIFFERENCE BETWEEN THE
SHIPS AND GFDL GUIDANCE.

古斯塔夫在接觸海地的地形時明顯地分裂. 此外...中層乾空氣似乎要從東北追上氣旋.
在接下來二四到三六小時...無論如何..古斯塔夫應該尋找自己在高層反氣旋之下以及
在加勒比海西北部的極深暖水域上空...所以氣旋有再次增強的良機. 此外...預報追蹤
導引古斯塔夫於灣區東南的墨西哥灣套流上空. 之後...全球模型推測灣區的
西南向風切和高層槽組合的可能性應該能降低增強幅度. 官方預報顯示出一個比之前
一開始的預報較慢的再增強...BUT IS OTHERWISE SIMILAR...以及粗略地在SHIPS和
GFDL GUIDANCE分開

IT PROBABLY WOULDN'T HURT TO REMIND EVERYONE THAT THE AVERAGE 5-DAY
OFFICIAL TRACK ERROR IS ABOUT 300 MILES...AND THE AVERAGE 5-DAY
INTENSITY ERROR IS ABOUT 25 MPH.

這大該不會傷害提醒每一個人官方五日路徑預測平均誤差約三百浬...以及
五日強度預誤差測約時速二十五哩

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