大家好我是K.Richard 松々
初次发文之前都在潜水XD
在昨天由温带气旋变性为副热带气旋的Alex，
昨天一整天几乎都有着相当清晰的风眼，
在稍早更得到了暖心结构，变性为一级飓风，
风速提升至75节，
成为北大西洋1955年以来，
一月最强的飓风，
并且预测最大风速仍有再增强至80节之机会，
若成真将会并列1955年Alice飓风成为北大西洋一月史上最强飓风之一。
更特别的是这飓风所处在的海温，
只有摄氏约“20度C”，
完全颠覆了教科书上，
海温必须达到24~26度C以上才能够支持一个热带气旋发展的说法，
是一个“非常”特殊的案例。
在这里想跟大家讨论，
究竟是什么机制让这个飓风再如此低的海温下，
还能够继续增强甚至发展出如此完整的风眼结构？
以下是这个飓风的相相关资料与图片...
MODIS - Terra 高解析影像
http://i.imgur.com/aAzQ0Yp.jpg
NRL -IR-Color 2016.01.16 1515Z UTC
http://i.imgur.com/RBw5Kab.jpg
OHC = "0"
http://i.imgur.com/cYYeYpT.gif
SST 约20℃左右
http://i.imgur.com/OyaYntu.png
NHC路径预测图
http://i.imgur.com/VKyccpn.gif
NHC文字报告
000
WTNT41 KNHC 141434
TCDAT1
HURRICANE ALEX DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012016
1100 AM AST THU JAN 14 2016
Remarkably, Alex has undergone the transformation into a hurricane.
A distinct eye is present, embedded within a fairly symmetric mass
of deep convection. Water vapor imagery shows that the upper-level
trough is now west of the cyclone, with divergent flow over the
center - indicative of a tropical transition. It is very unusual to
have a hurricane over waters that are near 20 deg C, but the
upper-tropospheric temperatures are estimated to be around -60 deg
C, which is significantly colder than the tropical mean. The
resulting instability is likely the main factor contributing to the
tropical transition and intensification of Alex. With these
changes, the government of the Azores has issued warnings for most
of the Azores islands.
The initial intensity is set to 75 kt in accordance with the
analyzed Dvorak T-number of 4.5. Only slight additional
intensification seems possible since the system will be passing
over even colder waters during the next day or two. In 36 hours,
the global models suggest that the cyclone will become
extratropical as it begins to merge with a large low pressure area
at high latitude. The post-tropical cyclone is then likely to lose
its identity after 48 hours.
The initial motion is north-northeastward or 020/17 kt. Alex is
being steered by a shortwave mid-level trough that is rotating
around a larger trough to the northwest. This should cause the
cyclone to turn northward and north-northwestward and accelerate
over the next couple of days. The official track forecast is very
similar to the previous one and also quite close to the consensus
of the tightly-packed dynamical model forecast tracks.
Alex is the first hurricane to form in the month of January since
1938, and the first hurricane to occur in this month since Alice of
1955.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 31.5N 28.4W 75 KT 85 MPH
12H 15/0000Z 34.3N 27.7W 80 KT 90 MPH
24H 15/1200Z 38.9N 27.7W 75 KT 85 MPH
36H 16/0000Z 45.3N 28.6W 60 KT 70 MPH...POST-TROP/EXTRATROP
48H 16/1200Z 53.0N 31.5W 60 KT 70 MPH...POST-TROP/EXTRATROP
72H 17/1200Z...DISSIPATED
$$
Forecaster Pasch
总而言之，太神啦~~~