老農民版夜神月

ASCAT稍早前風場,LLCC型態仍不算好
18Z亦依然判定性質為LO,就看21Z報出來時如何認定了

老農民版夜神月

NHC初報認定為PTC,並上望40KT

880
WTNT43 KNHC 172034
TCDAT3

Potential Tropical Cyclone Three Discussion Number   1
NWS National Hurricane Center Miami FL       AL032021
400 PM CDT Thu Jun 17 2021

Visible satellite images show that the cloud pattern associated with
the broad area of low pressure located over the southwestern Gulf of
Mexico is gradually becoming better organized.  Deep convection is
beginning to form a broad curved band over the eastern portion of
the system, similar to what one might see in a developing
subtropical cyclone.  Although the upper-level winds are not
particularly favorable for development, with lots of westerly shear
over the area, the global models do suggest tropical/subtropical
cyclogenesis within the next 12 hours or so.  Given the proximity of
the disturbance to land, which requires tropical storm warnings at
this time, advisories are being initiated on this system as a  
potential tropical cyclone.

Earlier scatterometer data suggested that the circulation was still
rather broad.  An Air Force Hurricane Hunter plane is currently
investigating the system and has not yet found a well-defined
center.  Maximum winds based on surface observations and the
scatterometer pass are near 25 kt.  Numerical intensity guidance do
not indicate a great deal of strengthening before the system
reaches the coastline, and the official forecast is at the high end
of the guidance.

Since the center is not that well-defined at this time, the initial
motion estimate, 360/8 is quite uncertain.  The system is expected
to move northward into a weakness in the subtropical ridge for the
next day or so and then, after landfall along the central Gulf
Coast, turn toward the northeast on the northwest side of a
mid-level anticyclone near Florida.  The official track forecast is
closest to the GFS and ECMWF predictions.  It should be noted,
however, that these models suggest some reformation of the center
near the Louisiana coast rather than just motion from the southwest
Gulf to the expected coastal landfall point.

Given the current and anticipated structure of this system, users
should not focus on the exact track of the center, as rainfall and
wind hazards are likely to extend well east of the center and arrive
well in advance of landfall.

Key Messages:

1. The system is expected to produce heavy rainfall and considerable
flash, urban, and small stream flooding beginning Friday and
continuing through the weekend along the central Gulf coast and
spreading northeastward into the Southern Appalachians.  

2. Tropical storm conditions are expected to begin Friday in areas
near and well to the east of the center along portions of the
central Gulf Coast from Intracoastal City, Louisiana, to the
Alabama/Florida border, including New Orleans.

FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 22.9N  92.4W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
12H  18/0600Z 24.5N  92.5W   25 KT  30 MPH...TROPICAL CYCLONE
24H  18/1800Z 26.5N  92.5W   35 KT  40 MPH
36H  19/0600Z 29.0N  92.0W   40 KT  45 MPH
48H  19/1800Z 31.5N  89.5W   30 KT  35 MPH...INLAND
60H  20/0600Z 34.0N  87.0W   25 KT  30 MPH...INLAND
72H  20/1800Z 35.0N  84.0W   20 KT  25 MPH...INLAND
96H  21/1800Z...DISSIPATED

$$
Forecaster Pasch/Brennan

老農民版夜神月

即將登陸,NHC21Z仍維持潛在熱帶氣旋

000
WTNT43 KNHC 182033
TCDAT3

Potential Tropical Cyclone Three Discussion Number   5
NWS National Hurricane Center Miami FL       AL032021
400 PM CDT Fri Jun 18 2021

A few hours ago, an ASCAT-A pass indicated that maximum winds were
about 40 kt well east of the ill-defined center of circulation, and
the initial wind speed was increased to that value at the
intermediate advisory at 18Z.  Recent surface observations just
offshore of southeastern Louisiana have been reporting maximum winds
between 30 and 40 kt.  Based on a combination of these data, and
since the structure of the system has not changed much during the
past few hours, the initial intensity is held at 40 kt for this
advisory.  Although the disturbance has wind speeds of tropical
storm intensity, it has not been named a tropical storm yet since
its center is ill defined and broad as evident in the Air Force
Hurricane Hunter data and surface observations.  Regardless of its
status, heavy rains and tropical-storm-force winds are spreading
across portions of the northern Gulf coast, and these conditions
will spread inland through tonight.

There has not been much change to the track forecast reasoning. The
cyclone is moving northward at about 14 kt, and a general north to
north-northeast motion is expected through landfall, which is likely
to occur overnight or early Saturday morning.  After the system
moves inland, a turn to the northeast and then east-northeast
across the southeast U.S. is predicted when the cyclone becomes
embedded in the westerlies on the north side of the subtropical
ridge.  The models remain in relatively good agreement, and only
small changes were made to the previous track forecast.

There is some opportunity for a little strengthening during the next
6 to 12 hours before the system makes landfall.  However,
significant intensification is not expected due to the cyclone's
broad and asymmetric structure, and ongoing west-southwesterly
vertical wind shear.  After landfall, weakening is forecast, and
dissipation is still predicted to occur by 72 hours. However, it
should be noted that the ECMWF and UKMET models hold onto the
vortex for a while longer.

Given the current and anticipated structure of this system, users
should not focus on the exact track of the center, as rainfall and
wind hazards are likely to extend well east of the center.

Key Messages:

1. The system is expected to produce heavy rainfall and considerable
flash, urban and small stream flooding tonight and through the
weekend along the Central Gulf coast.  Flood impacts will spread
northeastward into the Southern Appalachians.

2. Tropical storm conditions have begun along portions of the
central Gulf Coast from east of Morgan City, Louisiana, to the
Okaloosa/Walton County line, Florida, including New Orleans.  These
winds will spread inland and continue into Saturday.


FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 27.9N  91.2W   40 KT  45 MPH...POTENTIAL TROP CYCLONE
12H  19/0600Z 29.5N  90.8W   40 KT  45 MPH...INLAND
24H  19/1800Z 31.4N  89.4W   35 KT  40 MPH...INLAND
36H  20/0600Z 32.8N  87.4W   30 KT  35 MPH...INLAND
48H  20/1800Z 33.8N  84.9W   25 KT  30 MPH...INLAND
60H  21/0600Z 34.7N  81.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
72H  21/1800Z...DISSIPATED

$$
Forecaster Cangialosi

老農民版夜神月

ASCAT最新風場及AMSR2最新底層掃描

dom

NHC命名Claudette，判定達到巔峰並登陸紐奧良，出海後有望短暫增強為TS

000
WTNT43 KNHC 190859
TCDAT3

Tropical Storm Claudette Discussion Number   7
NWS National Hurricane Center Miami FL       AL032021
400 AM CDT Sat Jun 19 2021

The system that we have been tracking for a few days finally has
enough of a well-defined center and organized convection to be
considered a tropical storm.  While the organization is not
classical by any means, and there are some hybrid characteristics,
the cyclone most resembles a sheared tropical storm, so the system
is now Tropical Storm Claudette.  The initial wind speed remains 40
kt, in line with surface observations and radar.  These winds are
primarily occurring in a strong band on the eastern side of the
cyclone well away from the center.

Claudette is moving north-northeastward at about 10 kt.  The storm
should turn northeastward and east-northeastward over the next day
or so while it moves around the northern side of the subtropical
ridge and gradually weakens to a depression/post-tropical cyclone.  
The biggest change to the forecast is that almost all of the
reliable global models, save the GFS, are showing the system
regenerating near or offshore of the North Carolina coast in 60 to
72 hours.  Thus the forecast has been extended from the last one
and now shows the system as a tropical cyclone over the western
Atlantic Ocean.  The new intensity forecast is more conservative
than most of the guidance, but is higher than the previous advisory.
Extratropical transition is expected by 96 hours near Nova Scotia.

Given the current and anticipated structure of this system, users
should not focus on the exact track of the center, as rainfall and
wind hazards are likely to extend well east of the center.  Impacts
along the northern Gulf coast will continue.

Key Messages:

1. Claudette is expected to produce heavy rainfall and
life-threatening flash flooding across coastal Mississippi and
Alabama, and the far western Florida Panhandle through the
afternoon. Considerable flash, urban, and small stream flooding,
will continue through the weekend along the central Gulf Coast,
with flood impacts spreading northeastward into interior portions
of the Southeast.  

2. Tropical storm conditions are occurring along portions of the
central Gulf Coast from east of Morgan City, Louisiana, to the
Okaloosa/Walton County line, Florida, including New Orleans.  These
winds will spread inland and continue through this afternoon.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 29.6N  90.7W   40 KT  45 MPH...INLAND
12H  19/1800Z 30.9N  89.7W   35 KT  40 MPH...INLAND
24H  20/0600Z 32.2N  87.6W   25 KT  30 MPH...INLAND
36H  20/1800Z 33.3N  84.2W   25 KT  30 MPH...POST-TROP/INLAND
48H  21/0600Z 34.2N  80.5W   25 KT  30 MPH...POST-TROP/INLAND
60H  21/1800Z 35.8N  76.0W   30 KT  35 MPH...POST-TROP/INLAND
72H  22/0600Z 38.5N  71.0W   35 KT  40 MPH...TROPICAL CYCLONE
96H  23/0600Z 47.0N  61.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  24/0600Z...DISSIPATED

$$
Forecaster Blake

老農民版夜神月

NHC21Z降格TD

361
WTNT43 KNHC 192033
TCDAT3

Tropical Depression Claudette Discussion Number   9
NWS National Hurricane Center Miami FL       AL032021
400 PM CDT Sat Jun 19 2021

Claudette continues to move inland with its center now located
over southwestern Alabama.  Surface observations indicate that the
system has weakened, and based on that information the initial
intensity is lowered to 30 kt.  This makes Claudette a tropical
depression.  The cyclone is still producing gusty winds and bands
of heavy rain across portions of Mississippi, Alabama, Georgia, and
the Florida Panhandle.

As expected, the tropical depression has turned to the northeast
and accelerated some, with the latest initial motion estimated to
be 040/14 kt.  A turn to the east-northeast is expected
tonight and Sunday as Claudette moves in the westerlies on the
north side of the subtropical ridge.  This motion should take the
system across portions of the southeast U.S. during the next couple
of days and then over the western Atlantic and toward Atlantic
Canada early next week.  The models remain in relatively good
agreement, and the NHC track forecast lies near the middle of the
guidance envelope.  This forecast is very similar to the previous
one, except again a little to the right at the longer range forecast
times.

Some additional weakening seems likely during the next day or so
while Claudette moves across the southeast U.S.  However, most of
the models show the system regaining some strength when it moves
across the Carolinas and over the western Atlantic waters Sunday
night and Monday.  This predicted strengthening is likely due in
part to baroclinic processes. The 12Z ECMWF is weaker than previous
runs, and overall the remainder of the intensity guidance is largely
unchanged from the previous cyclone.  Based on the latest models,
the NHC intensity forecast is just an update of previous one and
lies near the HCCA and IVCN consensus aids. Once the system moves
north of the Gulf Stream Current in a few days, it is forecast to
transition to an extratropical cyclone prior to reaching Atlantic
Canada.

Key Messages:

1. Claudette is expected to produce heavy rainfall and flash
flooding across portions of the Florida Panhandle, eastern Alabama,
and Georgia through tonight, and into the Carolinas on Sunday.
Considerable flash, urban, and small stream flooding impacts are
expected across these areas.

2. Tropical storm conditions are possible along portions of the
North Carolina coast Sunday night and Monday, where a Tropical Storm
Watch is in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  19/2100Z 32.2N  87.9W   30 KT  35 MPH...INLAND
12H  20/0600Z 32.9N  86.0W   25 KT  30 MPH...INLAND
24H  20/1800Z 33.7N  82.7W   25 KT  30 MPH...INLAND
36H  21/0600Z 34.6N  78.5W   35 KT  40 MPH...INLAND
48H  21/1800Z 36.4N  73.8W   40 KT  45 MPH...OVER WATER
60H  22/0600Z 39.1N  68.8W   40 KT  45 MPH
72H  22/1800Z 42.3N  63.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
96H  23/1800Z 51.0N  52.4W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  24/1800Z...DISSIPATED

$$
Forecaster Cangialosi

老農民版夜神月

NHC目前仍將其維持為TD,並預測+24H內將以TS強度出海,+48H後將轉溫

295
WTNT43 KNHC 202032
TCDAT3

Tropical Depression Claudette Discussion Number  13
NWS National Hurricane Center Miami FL       AL032021
500 PM EDT Sun Jun 20 2021

Satellite and surface observations show that Claudette's circulation
has become elongated today and that there is a fairly large area of
light winds near the center.  Observations along the southeastern
U.S. coast and over coastal sections of the Carolinas indicate that
the winds have increased somewhat but these data still support an
initial intensity of 25 kt.   As Claudette approaches the coast
overnight and Monday morning, restrengthening is anticipated, and
the cyclone is forecast to regain tropical storm status before it
exits the coast of North Carolina. Some additional strengthening
is forecast while Claudette moves over the warm waters of the Gulf
Stream and the shear remains low.  The system should become
extratropical Tuesday afternoon when it passes near Nova Scotia,
and the global models indicate that it will degenerate into a
trough of low pressure by Wednesday morning.  The NHC intensity
foreast is close to the intensity model consensus and follows the
trends of the various global models.

The depression is moving east-northeastward at around 15 kt.  A
mid-latitude trough that is moving into the central United States
should continue to steer Claudette east-northeastward to
northeastward over the next couple of days.  The center of Claudette
is forecast to move offshore of the coast of North Carolina Monday
morning, then pass well offshore of the Mid-Atlantic coast Monday
night, and be near or just southeast of Nova Scotia on Tuesday.
The dynamical model guidance remains in very good agreement and the
NHC forecast again lies near the various consensus aids.


Key Messages:

1. Claudette is expected to produce heavy rainfall and flash
flooding from North Florida and southeastern Georgia into the
Carolinas through Monday morning. Flash, urban, and small stream
flooding impacts are possible across these areas.

2. Isolated tornadoes are possible this evening across parts of the
central and eastern Carolinas.

3. Tropical storm conditions are expected along portions of the
North Carolina coast late tonight and Monday, where a Tropical Storm
Warning is in effect.  Tropical storm conditions are possible in
northeastern South Carolina tonight and Monday, where a Tropical
Storm Watch is in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 34.2N  82.5W   25 KT  30 MPH
12H  21/0600Z 35.0N  79.1W   35 KT  40 MPH...INLAND
24H  21/1800Z 36.9N  74.3W   40 KT  45 MPH...OVER WATER
36H  22/0600Z 39.3N  69.0W   40 KT  45 MPH
48H  22/1800Z 42.4N  63.4W   40 KT  45 MPH...POST-TROP/EXTRATROP
60H  23/0600Z 45.5N  58.4W   35 KT  40 MPH...POST-TROP/EXTRATROP
72H  23/1800Z...DISSIPATED

$$
Forecaster Brown

dom

NHC09Z升格TS

000
WTNT43 KNHC 210841
TCDAT3

Tropical Storm Claudette Discussion Number  15
NWS National Hurricane Center Miami FL       AL032021
500 AM EDT Mon Jun 21 2021

The elongated low-level center of Claudette is located over eastern
North Carolina this morning, while a curved band of convection
continues pushing eastward across the adjacent coastal and offshore
waters. Surface pressures have fallen slightly overnight near the
estimated center position, and Frying Pan Shoals buoy 41013 off the
coast of southeastern North Carolina reported a brief period of
sustained tropical-storm-force winds shortly after 06 UTC.
Therefore, Claudette's initial intensity is raised to 35 kt with
this advisory, making it a tropical storm once again.

Claudette continues to accelerate east-northeastward as it is
steered by a mid- to upper-level trough that is approaching the
eastern United States. The storm will move off the North Carolina
coast within the next few hours, and a bit more strengthening is
possible today as it passes near the north wall of the Gulf Stream.
The official NHC forecast hangs onto Claudette as a tropical cyclone
through tonight, then quickly transitions it to a post-tropical
cyclone by 36 h. The time of dissipation is also moved up a day
earlier with this advisory, which is consistent with the latest
global model fields that show an open trough approaching Atlantic
Canada. Otherwise, the official NHC forecast remains very similar to
the previous one, and the track closely follows the multi-model
consensus.

Some of the global guidance suggests that Claudette could lose its
closed low-level circulation and open up into a trough soon after
emerging into the western Atlantic Ocean later today.  Given the
current poor center definition, it is a plausible alternative
scenario that Claudette dissipates faster than shown below.


Key Messages:

1. Heavy rain from Claudette will continue over the North Carolina
coast this morning. Isolated flash, urban, and small stream
flooding impacts are possible.

2. Tropical storm conditions are expected along portions of the
North Carolina coast through this morning, where a Tropical Storm
Warning is in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  21/0900Z 35.6N  77.6W   35 KT  40 MPH...INLAND
12H  21/1800Z 37.0N  74.1W   40 KT  45 MPH...OVER WATER
24H  22/0600Z 39.5N  68.6W   40 KT  45 MPH
36H  22/1800Z 42.8N  63.3W   40 KT  45 MPH...POST-TROP/EXTRATROP
48H  23/0600Z...DISSIPATED

$$
Forecaster Reinhart/Blake