Meow

RSMC評價100kt 948hPa，配上JTWC的120kt，已鞏固5月南太平洋風王地位。

HURRICANE WARNING 035 ISSUED FROM RSMC NADI May 071903 UTC.

SEVERE TROPICAL CYCLONE DONNA CENTRE 948HPA CATEGORY 4 WAS LOCATED NEAR 16.4
SOUTH 164.7 EAST AT 071800 UTC.
POSITION POOR.
REPEAT POSITION 16.4S 164.7E at 071800 UTC.
CYCLONE MOVING SOUTH-SOUTHEAST AT 09 KNOTS.
EXPECT SUSTAINED WINDS OF 100 KNOTS CLOSE TO THE CENTRE.
EXPECT WINDS OVER 63 KNOTS WITHIN 15 NAUTICAL MILES OF CENTRE,
EXPECT WINDS OVER 47 KNOTS WITHIN 60 NAUTICAL MILES OF CENTRE,
EXPECT WINDS OVER 33 KNOTS WITHIN 120 NAUTICAL MILES IN NE QUADRANT
                       AND WITHIN 160 NAUTICAL MILES IN SE QUADRANT
                       AND WITHIN 160 NAUTICAL MILES IN SW QUADRANT
                       AND WITHIN 120 NAUTICAL MILES IN NW QUADRANT

FORECAST POSITION NEAR 18.0S 165.1E AT 080600 UTC
              AND NEAR 19.4S 165.8E AT 081800 UTC.

ALL VESSELS WITHIN 300 NAUTICAL MILES OF CENTRE ARE REQUESTED TO SEND REPORTS
EVERY THREE HOURS TO RSMC NADI. VOS REPORTING SHIPS USE NORMAL CHANNELS. OTHER
VESSELS FAX PLUS 679 6720190 OR EMAIL NADITCC AT MET DOT GOV DOT FJ

THIS WARNING CANCELS AND REPLACES WARNING 032.

tpm630

(5/7早上)



(最新)





一如模式先前預測，乾空氣逸入的狀況在今天有所改善
早上開始中層大氣回到相對溼度60%的水平，配合低風切和顯著的外流
經過一段時間的結構調整，最新微波影像顯示東側螺旋雨帶對流減弱，同時東側眼牆對流明顯建立
這代表螺旋雨帶對流所伴隨的次環流減弱，降低其下沉作用對眼牆上升運動的影響
同時系統強對流所提供的潛熱釋放也更加集中在中心附近，加熱效率有所提升
進而使颱風的暖心增強，開始有效降低中心氣壓。


預計今天深夜到明天早上Donny的強度將達到巔峰，仍有機會挑戰C4
後續隨著颱風開始接近斜壓區，暖心及正壓結構會被破壞，將開始進行轉化

Meow

Donna形成於5月的南太平洋已經相當稀罕，不僅是1997年June以來南太平洋首個5月熱帶氣旋，也是1986年Namu（斐濟評價80kt、JTWC評價95kt）以來首個5月南太平洋強烈熱帶氣旋，更是南太平洋自衛星時代以來第2個5月強烈熱帶氣旋。

Meow

5月7日萬那杜以西強烈熱帶氣旋唐娜

https://commons.wikimedia.org/wi ... 017-05-07_0248Z.jpg

ben811018

低層風場廣闊
明後天將達顛峰
掠過法屬新喀里多尼亞群島

tpm630

西側外圍環境持續偏乾，特別是中層大氣
乾空氣旋入導致東側眼牆縫縫補補，這也是系統過去一直增強不快的原因
模式認為未來幾天乾空氣的情況有改善的跡象，配合中緯度系統加強外流
在海溫和垂直風切允許前 還是有機會增強到C4上下

t02436

FMS 00Z升格四級強烈熱帶氣旋，06Z維持90節評價。

WTPS11 NFFN 060600
TROPICAL DISTURBANCE ADVISORY NUMBER A14 ISSUED FROM RSMC NADI
May 060724 UTC.

SEVERE TROPICAL CYCLONE DONNA CENTRE 961HPA WAS LOCATED NEAR 13.3S
163.9E AT 060600 UTC.  POSITION POOR BASED ON HR HIMAWARI-8 EIR
IMAGERY AND PERIPHERAL SURFACE REPORTS.  CYCLONE WEST AT ABOUT 03
KTS.  MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 90 KNOTS.

DEEP CONVECTION REDUCED IN RADIAL EXTENT DUE TO DRY AIR ENTRAINMENT
FROM EAST. ORGANIZATION REMAINS GOOD. SYSTEM LIES JUST NORTH OF AN
UPPER RIDGE IN MODERATE SHEARED ENVIRONMENT WITH GOOD POLEWARD
OUTFLOW. SST AROUND 29 DEGREES CELCIUS. SYSTEM STEERED WEST SOUTHWEST
ALONG THE PERIPHERY OF A MID LEVEL SUBTROPICAL HIGH. DVORAK ANALYSIS
BASED ON EMBEDDED CENTER WITH LG SURROUND, YIELDS DT=4.5, MET AND PT
5.0. FT BASED ON MET. THUS YIELDING, T5.0/5.5/D0.5/24HRS.

FORECASTS :
AT 12 HRS VALID AT 061800 UTC 13.8S 163.7E MOV SSW AT 02 KT WITH 85
KT CLOSE TO CENTRE
AT 24 HRS VALID AT 070600 UTC 14.6S 163.7E MOV S AT 03 KT WITH 85 KT
CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 071800 UTC 15.7S 163.8E MOV S AT 04 KT WITH 85 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 080600 UTC 16.9S 164.1E MOV S AT 05 KT WITH 80 KT
CLOSE TO CENTRE

THE NEXT TROPICAL DISTURBANCE ADVISORY ON SEVERE TROPICAL CYCLONE
DONNA WILL BE ISSUED AROUND 061400 UTC.

JTWC評價80節，但巔峰仍上望110節。

NET

    這高層反氣旋似乎是對應跨赤道氣流和信風的切變式輻合而生，而Donna是其中誕生的最強氣旋式輻合。只是不知道為啥高層反氣旋反而坐落在東邊= =
    雖然赤向流出似乎被壓制，但這是同一低壓槽催生的高層反氣旋；這對強度影響可能不大。