1. A deepening, non-tropical low pressure system with gale-force winds
is located a little more than 100 miles southeast of Cape Hatteras,
North Carolina. This gale area is forecast to move
north-northeastward for the next day or so, and could acquire some
subtropical characteristics before it merges with a frontal system
by late Tuesday. The extratropical low is then expected to meander
off the mid-Atlantic and northeast U.S. coasts on Wednesday,
bringing rain and wind impacts to portions of those areas. By
midweek the low is expected to move eastward away from the U.S.
coast, and could again acquire some subtropical characteristics by
the end of the week while it moves eastward or southeastward over
the warmer waters of the central Atlantic. For more information on
this system, including storm warnings, see products issued by your
local National Weather Service office and High Seas Forecasts issued
by the National Weather Service.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...medium...50 percent.
1. A deep, non-tropical low pressure system with storm-force winds is
located less than 100 miles east-southeast of Cape Cod,
Massachusetts. The extratropical low is expected to meander off of
the mid-Atlantic and northeastern U.S. coasts today, bringing rain
and wind impacts to portions of those areas. Thereafter, the low is
expected to move eastward away from the United States, and it could
acquire some subtropical characteristics while it moves eastward or
southeastward over the warmer waters of the central Atlantic through
this weekend. For more information on this system, including storm
warnings, see products issued by your local National Weather Service
office and High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...medium...40 percent.
1. A deep, non-tropical low pressure system with storm-force winds is
centered more than 200 miles south-southeast of Cape Cod,
Massachusetts. The extratropical low is forecast to bring wind
impacts to portions of the northeastern U.S. coast for several more
hours as it begins to move eastward, away from the United States.
Thereafter, the low could acquire some subtropical characteristics
while it moves eastward or southeastward over the warmer waters of
the central Atlantic through this weekend. For more information on
this system, including storm warnings, see products issued by your
local National Weather Service office and High Seas Forecasts issued
by the National Weather Service.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...30 percent.
1. A strong, frontal low pressure system located several hundred miles
south of Cape Race, Newfoundland continues to produce showers and a
few thunderstorms. The nontropical low is forecast to move
east-southeastward and southeastward toward slightly warmer waters
during the next few days, and it could lose its associated fronts
and acquire some subtropical characteristics this weekend or early
next week while over the central Atlantic. For more information on
this system, including gale warnings, see High Seas Forecasts issued
by the National Weather Service.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...30 percent.
. Showers continue to show some signs of organization near a strong,
frontal low pressure system located several hundred miles south of
Cape Race, Newfoundland. The nontropical low is likely to lose its
associated fronts while it moves southeastward toward slightly
warmer waters during the next day or two, and it could make a
transition to a subtropical storm this weekend or early next week
over the central Atlantic. The system is expected to turn northward
back toward colder waters by the middle of next week. For more
information on this system, including gale warnings, see High Seas
Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...50 percent.
High Seas Forecasts issued by the National Weather Service can be
1. A strong low pressure system located several hundred miles
south-southeast of Cape Race, Newfoundland, continues to produce
some shower activity near and to the east of its center while moving
southeastward at around 15 mph. The low appears to be gradually
losing its frontal structure, and the system is likely to transition
to a subtropical storm by early next week while it meanders over the
central subtropical Atlantic. By the middle of next week, the
system is expected to turn northward and move toward colder waters.
For more information on this system, including gale warnings, see
High Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...70 percent.
SUBJ/TROPICAL CYCLONE FORMATION ALERT (94L)//
WTNT21 KNGU 302100
RMKS/1.FORMATION OF A SUBTROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 37.4N 47.9W TO 32.7N 43.1W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 40 TO 50 KNOTS. METSAT
IMAGERY AT 211800Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 37.5N 47.9W. THE SYSTEM IS MOVING SOUTHEASTWARD AT 13 KNOTS.
2.REMARKS: A STRONG LOW PRESSURE SYSTEM
LOCATED SEVERAL HUNDRED MILES SOUTH-SOUTHEAST OF CAPE RACE,
NEWFOUNDLAND, CONTINUES TO MOVE SOUTHEASTWARD AT AROUND
13KT. THE LOW APPEARS TO BE LOSING ITS FRONTAL STRUCTURE AND
CONVECTION HAS DEEPENED NEAR ITS CENTER OVER THE PAST FEW HOURS.
FURTHER DEEPENING AND ORGANIZATION IS EXPECTED AND A SUBTROPICAL
STORM COULD DEVELOP WITHIN THE NEXT DAY OR SO.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY 312100Z.
//
Subtropical Storm Wanda Discussion Number 1
NWS National Hurricane Center Miami FL AL212021
1100 PM AST Sat Oct 30 2021
The non-tropical low that NHC has been monitoring for subtropical
transition over the central Atlantic appears to have completed the
process this evening. Satellite images indicate that there are no
longer fronts attached to the low, and showers and thunderstorms
have become concentrated near the center. The low has some tropical
characteristics (small radius of maximum wind and concentrated
convection) and some subtropical characteristics (co-located with an
upper-level trough and nearby fronts). The system is designated as
a subtropical storm for now since there appears to be more support
for that status. The initial intensity is estimated to be 45 kt
based on recent ASCAT data, which makes the cyclone Subtropical
Storm Wanda.
The storm has been moving east-southeastward at 18 kt. A slower
east-southeast to southeast motion is expected during the next day
or so as Wanda moves with the deep-layer trough that it is embedded
within. After that time, the trough is expected to cut off, and
Wanda will likely meander on Monday before turning sharply northward
or northeastward by the middle of next week when the system moves
in the flow between the low and a building ridge. Most of the
models agree on the general evolution, but there are notable speed
differences. The NHC track forecast lies near the various consensus
aids.
Wanda will likely maintain its strength during the next several
days. Although the system will remain over relatively cool waters
of about 23-24 C during the next couple of days, cold air aloft
should aid in the continued development of deep convection and could
allow the system to strengthen slightly during that time period.
Beyond that time, Wanda should begin to move over cooler waters and
that will likely end its opportunity to gain strength and lead to
post-tropical transition by the end of the forecast period. The
models are in good agreement on keeping Wanda steady state, and the
NHC intensity forecast lies near the middle of the guidance
envelope.
提升卡
千斤頂
