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Marv's Weather
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Marv's Tropical
Weather Report
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credits - in part
our Tropical Weather
Update today has
been put together with
data from
Crown Weather Services,
Mike's Weather Page
and
NOAA
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2021-09-24 - Tropical Weather
Update
- this report is all about
Hurricane Sam
..
.
Hurricane Sam
- Sam is now a hurricane
and rapid strengthening is
expected to continue
.. Sam continues to move on a
westward track and this general
westward motion is expected to
continue into Saturday as the
hurricane is guided by the flow
of a high pressure ridge to the
north ..
.
bottom line - Hurricane Sam
- we STRONGLY urge those of you
in the Leeward Islands, Virgin
Islands and Puerto Rico to keep
an extremely close eye on Sam in
the coming days ..
.
heads up
- check our buoy reports
in your area for wind speed and
wave heights .. if you are not
getting our buoy weather reports
sign up NOW ..
click here to sign up
..
.
note
- the next tropical weather
discussion will be issued about
midday on Saturday ..
.
the end
- of our recap for now .. you
can
stop
reading now
unless you are interested in the
rest of the story ..
additional
details .. see below
..
.
.
Hurricane Sam
11:00 am EDT Statistics ..
Location: 11.5 North Latitude,
42.2 West Longitude or about
1470 miles to the east-southeast
of the Northern Leeward
Islands..
Maximum Winds: 75 mph ..
Minimum Central Pressure: 993
Millibars or 29.33 Inches ..
Forward Movement: West at a
forward speed of 15 mph ..
.
Hurricane Sam
- Sam has been rapidly
strengthening throughout the
last 12-18 hours or so ..
satellite imagery today
indicates that Sam has a small,
but well developed inner core ..
there are some dry slots noted
between the core and the outer
bands and there seems to be some
competition between a band of
convection to the north of Sam
and the hurricane’s
inner core .. once this band
weakens and the entire system
becomes more round in its
overall presentation, it will
likely strengthen much quicker
than what we are seeing right
now ..
.
track -
Sam continues to move on a
westward track and this general
westward motion is expected to
continue into Saturday as the
hurricane is guided by the flow
of a high pressure ridge to the
north ..
.
looking ahead -
the hurricane is expected to
turn more to the west-northwest
from later Saturday into the
first half of next week as it
reaches a weakness between two
high pressure ridges .. as Sam
approaches the northern Leeward
Islands during the middle part
of next week, an upper level
trough of low pressure will move
into the western North Atlantic
and this should cause Sam to
turn more to the northwest ..
.
model guidance
- the big questions are how
quickly will the turn to the
northwest occur and how close
will the hurricane get to the
northern Leeward Islands ..
.
GFS ensemble model guidance
- shows a much faster turn to
the northwest than what the
European ensemble model guidance
shows .. this leads to a huge
difference in how close Sam gets
to the northeastern Caribbean
with the GFS ensemble model
guidance showing no impact at
all ..
.
European ensemble model guidance
- shows at least tropical storm
conditions and very possibly
hurricane conditions for the
northern Leeward Islands .. an
analysis of the steering winds
around Sam right now shows a
wind pattern that would fit
closer to the European model
rather than the GFS model ..
.
UFFDA -
the eye of Hurricane Sam may
pass just barely north and east
of the northeastern Caribbean
Islands on Wednesday night and
Thursday .. this could be close
enough to bring hurricane
conditions to Anguilla, St.
Martin and Sint Maarten late
Wednesday night and Thursday
morning .. the rest of the
northern Leeward Islands and the
Virgin Islands may be close
enough to Sam to receive
tropical storm conditions on
Wednesday night and Thursday
morning .. it’s
also possible that Puerto Rico
may be far enough away from the
center of Sam to receive no
adverse effects at all .. it
should be noted that this is
still a 5-6 day forecast and a
lot can change between now and
the middle part of next week ..
.
looking way ahead -
the weather pattern for late
next week and beyond is
extremely chaotic as there is
likely to be many different
moving pieces around Sam helping
to steer it one way or another.
One weather feature that we’re
watching is the interaction
between a ridge of high pressure
over the Atlantic and a trough
of low pressure moving into the
northeastern United States. Some
of the guidance suggests that
this trough will kick far enough
east to help push Sam out into
the open Atlantic after
threatening or directly
impacting Bermuda. Other
guidance forecasts that the
trough of low pressure may hang
back a little and try to amplify
some. Should this occur, it
could lead to the trough
capturing Sam causing it to try
to slingshot back towards New
England and Atlantic Canada ..
.
bottom line -
the part of the coastline that
may really need to watch Sam for
possible impacts next weekend is
Long Island, New York, New
England and Atlantic Canada,
Fortunately, we have A TON of
time to keep an eye on this ..
.
strength -
the environmental conditions are
expected to be favorable for
additional rapid strengthening
through Saturday as the
hurricane will be moving over
very warm ocean waters within a
low wind shear environment ..
the latest SHIPS rapid
intensification index shows a 41
percent chance that Sam could be
a 105 mph hurricane by this time
tomorrow and a 28 percent chance
that Sam could strengthen into a
125-130 mph hurricane by
tomorrow evening .. this means
that we think that it is very
likely that Sam will be a major
hurricane by Saturday night and
could be at about a 130-135 mph
hurricane by Sunday night into
Monday .. beyond this it’s
possible that the environment
could become a little less
favorable with 10-15 knots of
wind shear affecting Sam .. this
could cause the hurricane to
level out or even weaken a
little during next week ..
either way though, Sam is very
likely to be a major hurricane
for several days beginning
tomorrow ..
.
heads up - The Leeward Islands,
Virgin Islands and
Puerto Rico
..
we still think that Sam poses a
significant hurricane threat to
the northern Leeward Islands and
especially the islands of Sint
Maarten, St. Martin and
Anguilla, as well as the US and
British Virgin Islands for
around Wednesday into Thursday
of next week. Sam may end up
staying too far north to bring
adverse effects to Puerto Rico.
With that said, those of you on
the island of Puerto Rico should
also very closely monitor Sam as
the track forecast may shift
around in the coming days ..
.
bottom bottom line
- we
STRONGLY
urge those of you in the Leeward
Islands, Virgin Islands and
Puerto Rico to keep an extremely
close eye on Sam in the coming
days ..
.
.
heads up
- check our buoy reports in
your area for wind speed and
wave heights .. if you are
not getting our buoy weather
reports sign up now ..
click here ..
..
.
.
.
.
Our Tropical Weather
reports - for the most
part are put together only
during tropical weather
season .. our reports are
based on a number of online
sources and are based on our
past experience dealing with
tropical weather .. we also
occasionally include
non-tropical weather that
would affect the area /
footprint that we cover ..
.
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disclaimer - all
forecasts herein are made to the best
ability of the forecaster .. however, due to
standard forecasting error, these forecasts
cannot be guaranteed .. any action or
inaction taken by users of this forecast is
the sole responsibility of that user .. |
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