老農民版夜神月

  熱帶風暴  
編號：22 L
名稱：Beta

  基本資料  
擾動編號日期：2020 年 09 月 16 日 18 時
命名日期　　：2020 年 09 月 19 日 05 時
撤編日期　　：2020 年 09 月 25 日 22 時
登陸地點　　：無

  巔峰時期資料  
近中心最強風速 ：50  kt( TS )
海平面最低氣壓 ：995 百帕
  擾動編號資料    
90L.INVEST.25kts-1009mb-20.5N-95W

老農民版夜神月

NHC展望提升至Medium,40%

1. An area of low pressure over the southwestern Gulf of Mexico is
producing showers and thunderstorms that have become a little better
organized during the past several hours.  Upper-level winds are
forecast to gradually become more conducive for development, and a
tropical depression could form late this week or over the weekend
while the low meanders over the southern Gulf of Mexico for the
next several days.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

老農民版夜神月

NHC展望大幅提升至70%/90%

1. Thunderstorm activity associated with a low pressure system located
over the southwestern Gulf of Mexico has increased in coverage and
organization this morning. In addition, recent satellite-derived
surface wind data indicate that the low has become better defined.
Upper-level winds are expected to gradually become more conducive
for development, and a tropical depression is likely to form during
the next day or so while the low meanders over the southwestern Gulf
of Mexico. An Air Force Reserve reconnaissance aircraft is scheduled
to investigate the disturbance later today, if necessary.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

老農民版夜神月

FWC-N發布TCFA,NHC展望亦提升90%,可能即將升格

WTNT21 KNGU 171100
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/1.FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE
WITHIN A 100 NM RADIUS OF 21.1N 94.9W WITHIN THE NEXT 00 TO
24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY ISSUANCE OF NUMBERED
TROPICAL CYCLONE WARNINGS AT THIS TIME. WINDS IN THE AREA ARE
ESTIMATED TO BE 15 TO 20 KNOTS. METSAT IMAGERY AT 170900Z INDICATES
THAT A CIRCULATION CENTER IS LOCATED NEAR 22.0N 96.0W.
THE SYSTEM IS QUASI-STATIONARY AT 00 KNOTS.
2.REMARKS: AN AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS A FEW
HUNDRED MILES NORTH-NORTHWEST OF THE YUCATAN PENINSULA IS ASSOCIATED
WITH A BROAD AREA OF LOW PRESSURE. ENVIRONMENTAL CONDITIONS ARE
MARGINALLY CONDUCIVE FOR DEVELOPMENT OF THIS SYSTEM AND A TROPICAL
DEPRESSION IS LIKELY TO FORM DURING THE NEXT 24 HOURS.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED
BY 181100Z.//
BT
#0001
NNNN

1. Thunderstorm activity has continued to increase and become better
organized this morning in association with a well-defined low
pressure system located over the southwestern Gulf of Mexico.
Upper-level winds are gradually becoming more conducive for
development and, if this recent development trend continues, a
tropical depression or a tropical storm could form later today. The
low is expected to meander over the southwestern Gulf of Mexico for
the next day or so before moving slowly northward to northeastward
on Friday and Saturday.  An Air Force Reserve reconnaissance
aircraft is scheduled to investigate the disturbance this afternoon.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

霧峰追風者

252
WTNT42 KNHC 172300
TCDAT2

Tropical Depression Twenty-Two Special Discussion Number   1
NWS National Hurricane Center Miami FL       AL222020
600 PM CDT Thu Sep 17 2020

Reports from an Air Force Reserve Hurricane Hunter aircraft indicate
that the low pressure area over the southwestern Gulf of Mexico has
developed a sufficiently well-defined circulation, with SFMR wind
data suggesting an intensity of about 30 kt.  In addition, the
associated convection is organized enough for SAB and TAFB to
provide Dvorak satellite intensity estimates of 30 kt.  Based on
this information, advisories are being initiated on Tropical
Depression Twenty-Two.

The initial motion is a somewhat uncertain 035/4.  During the
next 48 h or so, the cyclone should be steered slowly
north-northeastward by a mid- to upper-level trough over Texas and
northern Mexico.  After that time, the global models are in good
agreement that this trough will weaken and lift out to the
northeast, with a weak mid-level ridge building to the north of the
cyclone.  This should result in a gradual turn toward the west at a
continued slow forward speed.  Although the cyclone is relatively
close to land, the vast majority of the track guidance keeps the
system offshore for the next five days.  The official forecast will
follow this scenario, with the forecast track being between the HCCA
corrected consensus and the other consensus models.

The large-scale models suggest that the cyclone will be in an
environment of light to moderate vertical wind shear for the next
several days.  Some dry air entrainment may occur after 48 h.  
The bulk of the intensity guidance keeps the system below hurricane
strength during the forecast period.  The official intensity
forecast follows the trend of the guidance and shows the system
peaking as a tropical storm, but it lies a little above the
intensity consensus.

As mentioned above, the cyclone is likely to stay offshore during
the forecast period.  Therefore, it is too early to tell which parts
of the coast of the Gulf of Mexico will get wind, storm surge, and
rain impacts from this system  


Key Messages:

1.  The system is expected to strengthen to a tropical storm while
moving slowly over the western Gulf of Mexico during the next few
days.

2.  While it is too early to determine what areas could see direct
wind, storm surge, and rainfall impacts from this system, interests
throughout the western Gulf of Mexico should monitor the progress of
this system and future updates to the forecast.


FORECAST POSITIONS AND MAX WINDS

INIT  17/2300Z 21.9N  94.3W   30 KT  35 MPH
12H  18/0600Z 22.7N  94.0W   30 KT  35 MPH
24H  18/1800Z 23.8N  93.5W   35 KT  40 MPH
36H  19/0600Z 24.8N  93.0W   45 KT  50 MPH
48H  19/1800Z 25.4N  92.9W   55 KT  65 MPH
60H  20/0600Z 25.8N  93.1W   60 KT  70 MPH
72H  20/1800Z 26.1N  93.8W   60 KT  70 MPH
96H  21/1800Z 26.1N  95.1W   55 KT  65 MPH
120H  22/1800Z 25.6N  96.1W   50 KT  60 MPH

$$
Forecaster Berg/Beven

老農民版夜神月

21Z升格TS,命名Beta,並上望一級颶風65KT

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM

Tropical Storm Beta Discussion Number   5
NWS National Hurricane Center Miami FL       AL222020
400 PM CDT Fri Sep 18 2020

Satellite imagery indicates that the circulation of Tropical
Depression 22 has become better defined, and most objective and
subjective satellite intensity estimates are now 35 kt.  Based on
this, along with 33 kt 1-mi average winds from NOAA buoy 42002, the
depression is upgraded to Tropical Storm Beta with an initial
intensity of 35 kt.  Although the system is now a tropical storm,
satellite imagery shows that the convective pattern is becoming
elongated due to the effects of southwesterly vertical wind shear.

Visible imagery and scatterometer data showed that the center of
Beta was a bit farther east than previously thought, and the initial
motion is a somewhat uncertain 025/8.  This motion should continue
for the next 12-24 h as the storm is steered by a mid- to
upper-level trough over Texas and northeastern Mexico.  After that
time, the trough should weaken and lift out to the northeast, with a
mid-level ridge building to the north of the cyclone above an
already present low-level ridge.  This ridge should act as a Beta
blocker, causing the storm to turn westward toward the western Gulf
coast.  Between 72-120 h, the mid-level ridge weakens as another
mid-latitude trough moves through the central United States, and
this is expected to cause the storm to slowly recurve toward the
northeast.  One change in the track guidance since the previous
forecast is that the GFS and ECMWF are a bit faster on the westward
motion and show the center near the Texas coast in about 72 h.  The
latter part of the new track forecast also shifts westward, but it
is still to the east of the GFS/ECMWF.  There is also a chance that
Beta could move more northward than forecast before the trough lifts
out, which adds an additional touch of uncertainty to the track
forecast.  So, it is critical that users not focus on the exact
forecast track, especially at days 3 to 5.

The global models suggest that the current shear may decrease a
little after 24 h when the upper-level trough moves away from Beta.
However, there is a chance of at least some dry air entrainment
that would hamper strengthening.  The intensity guidance for the
most part continues to forecast Beta to reach a peak intensity
below hurricane strength, although the latest SHIPS model forecasts
a peak intensity near 65 kt.  The new intensity forecast is again
unchanged in making Beta a hurricane at 60 and 72 h, and it lies at
the upper edge of the intensity guidance.

Key Messages:

1.  Beta is expected to strengthen and possibly become a hurricane,
while moving slowly over the western Gulf of Mexico during the next
few days.

2. There is an increasing risk of heavy rainfall and flooding along
the northwest Gulf Coast Sunday through at least the middle of next
week as Beta is forecast to move slowly toward and along or offshore
of the coast through that time. For additional information, see
products from your local National Weather Service office.

3.  While it is too early to determine what areas could see direct
wind and storm surge impacts from Beta, interests throughout
the western Gulf of Mexico should monitor the progress of this
system and future updates to the forecast. Storm Surge and
Tropical Storm or Hurricane watches could be issued tonight or
Saturday.  

FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 24.3N  93.1W   35 KT  40 MPH
12H  19/0600Z 25.1N  92.9W   40 KT  45 MPH
24H  19/1800Z 25.9N  93.0W   45 KT  50 MPH
36H  20/0600Z 26.1N  93.7W   50 KT  60 MPH
48H  20/1800Z 26.3N  94.6W   60 KT  70 MPH
60H  21/0600Z 26.5N  95.5W   65 KT  75 MPH
72H  21/1800Z 26.8N  96.3W   65 KT  75 MPH
96H  22/1800Z 27.5N  96.5W   60 KT  70 MPH
120H  23/1800Z 28.5N  96.0W   55 KT  65 MPH

$$
Forecaster Beven

NNNN

老農民版夜神月

逐漸增強,15Z定強50節,持續上望C1

INIT  19/1500Z 26.6N  92.6W   50 KT  60 MPH
12H  20/0000Z 26.9N  93.0W   50 KT  60 MPH
24H  20/1200Z 27.1N  93.8W   55 KT  65 MPH
36H  21/0000Z 27.5N  94.8W   60 KT  70 MPH
48H  21/1200Z 27.8N  95.5W   65 KT  75 MPH
60H  22/0000Z 28.2N  96.2W   65 KT  75 MPH
72H  22/1200Z 28.6N  96.2W   55 KT  65 MPH...INLAND
96H  23/1200Z 29.5N  95.0W   45 KT  50 MPH...INLAND
120H  24/1200Z 30.5N  93.0W   30 KT  35 MPH...INLAND

t02436

已不再上望更高強度。

ZCZC MIATCDAT2 ALL
TTAA00 KNHC DDHHMM

Tropical Storm Beta Discussion Number  10
NWS National Hurricane Center Miami FL       AL222020
1000 PM CDT Sat Sep 19 2020

Beta's deep convection has been waning this evening.  An Air Force
Reserve Hurricane Hunter aircraft has found that the central
pressure rose several millibars since this morning, but the plane
also still measured surface winds around 50 kt from the SFMR
instrument.  The strongest winds appear to be located near on old
frontal boundary which extends north and east of Beta's center, and
in fact sustained tropical-storm-force winds are just grazing the
coast of south-central Louisiana.

The aircraft fixes indicated that Beta drifted north-northeastward
during the day.  Right now, the cyclone is embedded within weak
steering currents between two areas of high pressure centered near
the Bahamas and west Texas/southern New Mexico.  The western high
pressure area is expected to slide eastward across the Southern
Plains into the southeastern U.S. through Sunday night, which should
force Beta to move slowly toward the west-northwest toward the Texas
coast.  The center is now expected to reach the coast between 48-60
hours, at which point it is likely to recurve around the mid-level
high and move slowly northeastward near or inland of the upper
Texas coast on days 3 and 4.  Because of Beta's drift today, the
new guidance envelope has shifted a bit northward.  For this
forecast cycle, the NHC official forecast split the difference
between the previous interpolated forecast and the HFIP Corrected
Consensus guidance.  This keeps the forecast to the east of the
ECMWF, HCCA, and TVCN multi-model consensus during Beta's slow
recurvature.

The air mass behind the old front appears to have won out.  Beta's
circulation is embedded in a dry environment of mid-level
relative humidities around 50 percent, and the air mass could
actually become more stable as Beta moves closer to the Texas
coast.  On top of that, the moderate southwesterly shear is not
expected to diminish much at all.  As a result, the intensity
guidance has continued to trend downward, and the new official
forecast now flatlines Beta's intensity at 50 kt until landfall
soon after 48 hours.  This forecast still lies near the top end of
the guidance envelope, closest to the SHIPS model.  After 48 hours,
weakening is expected assuming Beta's center remains over land, and
it is now expected to become a remnant low over Louisiana by day 5.

While the chances that Beta will become a hurricane continue to
decrease, the Hurricane Watch for portions of the coast of Texas are
being maintained out of an abundance of caution given the
uncertainty in the forecast.


Key Messages:

1. The expected slow motion of Beta has the potential to expand a
long duration rainfall event from the Louisiana coast westward into
southeast Texas on Sunday and northward into the Mid-South by mid
next week. The potentially prolonged period of rainfall could cause
flash, urban, and river flooding, especially where tide levels are
above normal.

2. There is the danger of life-threatening storm surge near times of
high tide from Sunday through Tuesday along portions of the Texas
and Louisiana coasts within the storm surge warning areas.
Residents in these areas should follow advice given by local
officials.

3. Tropical storm force winds are expected to begin along portions
of the northwestern Gulf Coast overnight within the tropical storm
warning area in Louisiana and will spread westward to the Texas
coast Sunday through Monday.  Hurricane-force winds are possible
along portions of the Texas coast late Monday and Monday night,
where a hurricane watch is in effect.


FORECAST POSITIONS AND MAX WINDS

INIT  20/0300Z 26.8N  92.2W   50 KT  60 MPH
12H  20/1200Z 27.1N  93.0W   50 KT  60 MPH
24H  21/0000Z 27.4N  94.1W   50 KT  60 MPH
36H  21/1200Z 27.9N  95.2W   50 KT  60 MPH
48H  22/0000Z 28.4N  96.0W   50 KT  60 MPH
60H  22/1200Z 28.9N  96.3W   40 KT  45 MPH...INLAND
72H  23/0000Z 29.3N  96.0W   35 KT  40 MPH...INLAND
96H  24/0000Z 30.2N  94.1W   30 KT  35 MPH...INLAND
120H  25/0000Z 31.4N  92.1W   25 KT  30 MPH...POST-TROP/INLAND

$$
Forecaster Berg

NNNN