TROPICAL STORM FAY DISCUSSION NUMBER 14 - 颱風討論

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WTNT41 KNHC 190255
TCDAT1
TROPICAL STORM FAY DISCUSSION NUMBER 14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062008
1100 PM EDT MON AUG 18 2008

FAY'S ORGANIZATION HAS WAXED AND WANED THIS EVENING. THE STORM
BECAME QUITE DISORGANIZED IN APPEARANCE ON WSR-88D RADAR
OBSERVATIONS FROM KEY WEST AND MIAMI EARLIER THIS EVENING...AND THEN
SHOWED INCREASED SPIRAL BANDING BUT NO CLOSED EYEWALL STRUCTURE.
AIR FORCE HURRICANE HUNTER OBSERVATIONS SHOWED A FALL IN CENTRAL
PRESSURE BUT NO INCREASE IN FLIGHT-LEVEL WINDS YET. THE TROPICAL
CYCLONE IS EMBEDDED IN A DIFFLUENT UPPER-LEVEL FLOW ENVIRONMENT ON
THE EAST SIDE OF A SHORT WAVE TROUGH OR CYCLONIC SHEAR AXIS AND
THIS ENVIRONMENT IS ALSO IMPARTING MODEST SOUTHWESTERLY SHEAR OVER
FAY. NONETHELESS...THERE IS STILL A CHANCE FOR FAY TO STRENGTHEN
INTO A HURRICANE PRIOR TO CROSSING THE COAST TUESDAY MORNING. OUR
FORECAST FOR FAY'S WEAKENING OVER THE PENINSULA MORE OR LESS
FOLLOWS THE DECAY SHIPS MODEL.

傍晚FAY的組織已經衰化. 在傍晚稍早時從佛羅里達西嶼和邁阿密的WSR-88D雷達
觀察風暴險露出無組織性... 然後出現了旋臂環流彈沒有封閉的風眼結構. 空軍
颶風獵人觀察顯示出中心氣壓的下降但飛行高度風還沒有升高. 這熱帶風暴置於
短波脊東側的高層分流流場環境或是氣旋切軸, 以及此環境正同樣的給予
FAY適度的西南向風切. 無論如何...FAY依然有在星期二通過海岸之前增強
成為颶風的機會. 我們的預報多多少少跟隨著SHIPS衰減模式報FAY在半島上空時
. 減弱


AIRCRAFT AND RADAR FIXES YIELD AN INITIAL MOTION NEAR 360/8. FAY IS
MOVING BETWEEN A MID-LEVEL ANTICYCLONE TO ITS EAST AND A MID- TO
UPPER-LEVEL TROUGH TO ITS WEST AND NORTHWEST. SOME OF THE
DYNAMICAL TRACK GUIDANCE...SUCH AS THE GFDL...HWRF...AND U.K. MET
OFFICE MODELS...HAVE SHIFTED A LITTLE TO THE EAST FOR FAY'S TREK
ACROSS THE FLORIDA PENINSULA...SO THE OFFICIAL FORECAST WAS ALSO
ADJUSTED SLIGHTLY TO THE RIGHT. AFTER 1-2 DAYS...GLOBAL MODELS
INDICATE THAT THE STEERING PATTERN WILL BREAK DOWN AS A
MID-TROPOSPHERIC RIDGE BUILDS OVER THE EASTERN U.S. AND BLOCKS THE
FORWARD PROGRESS OF THE TROPICAL CYCLONE. THERE IS GREAT DIVERSITY
IN THE OBJECTIVE TRACK FORECASTS FOR THE LATTER HALF OF THE
PERIOD...AND THEREFORE LARGER THAN USUAL UNCERTAINTY AS TO WHERE
FAY WILL EVENTUALLY GO. THE OFFICIAL TRACK FORECAST IS ROUGHLY IN
THE MIDDLE OF THE HIGHLY SPREAD MODEL TRACKS. THE FORECAST OF
FAY'S INTENSITY IN THE 72-120 HOUR TIME FRAME IS OF COURSE HIGHLY
DEPENDENT ON HOW MUCH THE SYSTEM MOVES OVER WATER. SHOULD FAY
REMAIN VERY NEAR OR OVER LAND...IT WOULD PROBABLY WEAKEN TO
DISSIPATION SOONER THAN SHOWN HERE.
...AND THEREFORE LARGER THAN USUAL UNCERTAINTY
AS TO WHERE FAY WILL EVENTUALLY GO.


飛機和雷達修正了風暴動態當量於360度/八浬. FAY正於中層反氣旋東側和中到高
層槽西與西北側之間移動. 一些動態行徑追蹤...像是GFDL...HWRF...以及英國的
MET官方模型...對FAY通過佛州半島的路線移動了一點...所以官方預報也同樣地
向右許些修正. 一到二日後...全球模型顯示出當中對流層脊在美國東部建立以及
阻擋了熱帶氣旋的行進,STEERING PATTERN將會破裂. 在後期的物件行徑預報
中有強烈的差異點, AND THEREFORE LARGER THAN USUAL UNCERTAINTY
AS TO WHEREFAY WILL EVENTUALLY GO. 官方預報大體上在高度分歧的模型
路徑中間. 在七十二到一百二十小時之間FAY的強度預報當然高度依賴於有多少
本體位於水域. 萬一FAY依然在陸地或是非常接近陸地...這可能會比預測還早消散.



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