Tropical Storm Henri May Threaten The Area
000
WTNT33 KNHC 190300
TCPAT3
BULLETIN
Tropical Storm Henri Advisory Number 13
NWS National Hurricane Center Miami FL AL082021
1100 PM AST Wed Aug 18 2021
...HENRI MAINTAINING INTENSITY WITH 70 MPH WINDS...
...INTERESTS IN THE NORTHEASTERN U.S. SHOULD MONITOR ITS PROGRESS...
SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...29.8N 68.5W
ABOUT 280 MI...450 KM SW OF BERMUDA
ABOUT 790 MI...1275 KM S OF NANTUCKET MASSACHUSETTS
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...W OR 265 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...995 MB...29.39 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
Interests in the northeastern U.S. and Atlantic Canada should
monitor the progress of Henri.
DISCUSSION AND OUTLOOK
----------------------
At 1100 PM AST (0300 UTC), the center of Tropical Storm Henri was
located near latitude 29.8 North, longitude 68.5 West. Henri is
moving toward the west near 9 mph (15 km/h) and this motion is
expected to continue for the next day or so. A sharp turn to the
north is expected on Friday with a general northward motion
continuing into the weekend.
Maximum sustained winds remain near 70 mph (110 km/h) with higher
gusts. Little change is strength is forecast during the next day or
so, but Henri is expected to become a hurricane on Friday.
Tropical-storm-force winds extend outward up to 80 miles (130 km)
from the center.
The estimated minimum central pressure is 995 mb (29.39 inches).
HAZARDS AFFECTING LAND
----------------------
SURF: Swells generated by Henri should continue to affect Bermuda
during the next day or so. Swells are expected to increase across
much of the east coast of the U.S. and Atlantic Canada later this
week and this weekend. These swells could cause life-threatening
surf and rip current conditions. Please consult products from your
local weather office.
NEXT ADVISORY
-------------
Next complete advisory at 500 AM AST.
$$
Forecaster Papin/Beven
000
WTNT43 KNHC 190300
TCDAT3
Tropical Storm Henri Discussion Number 13
NWS National Hurricane Center Miami FL AL082021
1100 PM AST Wed Aug 18 2021
Henris appearance this evening is one of a tropical cyclone that is
battling vertical wind shear. The satellite structure has evolved
into a large convective plume with overshooting cold -70 to -75 C
cloud top temperatures near the center of the convective mass.
Underneath the cirrus, Henris structure has remained steady-state,
with a SSMIS pass at 2243Z showing a ragged mid-level eye on the 91
GHz channel that remains displaced a bit southeast of the low-level
signature on 37 GHz. The latest satellite intensity estimates have a
large spread in values ranging from 55-kt up to 80-kt. I have
elected to maintain Henris intensity at 60 kt for this advisory,
but there is a larger than normal uncertainty in this estimate.
The initial motion continues to be just south of due west at 265/8
kt. The short-term track guidance is in general agreement that Henri
will continue a general westward motion for the next day or so, as
the cyclone is caught to the south of a pronounced mid- to
upper-level ridge. However, the models disagree on how far westward
Henri is able to advance in the short-term, and these track
differences appear to be related to Henri's intensity and vertical
depth of the circulation. This track dependency is nicely
illustrated by the most recent ECMWF ensemble guidance, where
stronger members move further south and west in the short-term,
ending up on the left-side of the ensemble mean, while weaker
members move slower and more poleward. The deterministic guidance is
similar, with the weaker ECMWF and Canadian runs off to the
east/right while the stronger GFS and UKMET runs are further
left/west. These short-term track differences appear pivotal,
because the ridge over Henri is then expected to quickly erode as a
mid-latitude trough digs in over the Ohio Valley and becomes
negatively tilted over the Mid-Atlantic. The leftward track guidance
has Henri interacting with this trough leading to a track forecast
much closer to the northeastern US, while the rightward track
guidance is not captured by this feature, and stay further offshore
escaping out to sea. In general, the mean of the track guidance is
very similar, or just a shade to the right of the previous cycle. I
have elected to maintain a very similar track to the previous
advisory, splitting the difference between the previous forecast
just left, and the reliable HCCA consensus aid just right. As
mentioned previously, a NOAA Gulfstream IV aircraft has been
scheduled to investigate the synoptic environment of Henri tomorrow
and will hopefully provide more data ingested into the model
guidance to reduce the large track spread seen in the current cycle.
Henri is now under moderate northerly shear that is forecast to
increase to 25-30 knots over the next 24 hours. While this would
ordinarily weaken the tropical cyclone, the system also remains
under very warm 29-30 C sea-surface temperatures that are somewhat
above normal for this time of year. Due to these offsetting factors,
the latest NHC intensity forecast maintains Henri at 60-kt for the
next 24 hours. Afterwards, the shear is forecast to decrease as the
storm turns more poleward directly under the upper-level ridge axis.
This favorable synoptic pattern should allow Henri to intensify and
gradual intensification is shown up to a 80-kt peak in 72-h. The NHC
intensity forecast is more or less in the mean of the large guidance
spread, though it should be noted that the regional hurricane models
(HWRF, HMON, COAMPS-TC) have somewhat stronger peak intensities
later in the forecast period.
Key Messages:
1. The forecast track of Henri remains near the northeast coast of
the U.S. this weekend and early next week, and the risks of storm
surge, wind, and rain impacts in portions of the northeastern U.S.
and Atlantic Canada remains a distinct possibility. Interests in
these areas should closely follow the progress of Henri and check
for updates to the forecast.
2. Swells from Henri will begin to reach much of the east coast of
the U.S. and Atlantic Canada by the end of the week and continue
through the weekend. These swells could cause life-threatening surf
and rip currents.
FORECAST POSITIONS AND MAX WINDS
INIT 19/0300Z 29.8N 68.5W 60 KT 70 MPH
12H 19/1200Z 29.8N 69.9W 60 KT 70 MPH
24H 20/0000Z 30.0N 71.8W 60 KT 70 MPH
36H 20/1200Z 30.7N 72.7W 65 KT 75 MPH
48H 21/0000Z 32.3N 72.8W 70 KT 80 MPH
60H 21/1200Z 34.4N 71.8W 75 KT 85 MPH
72H 22/0000Z 36.9N 70.7W 80 KT 90 MPH
96H 23/0000Z 40.4N 69.4W 70 KT 80 MPH
120H 24/0000Z 41.8N 68.3W 60 KT 70 MPH
$$
Forecaster Papin/Beven
000
FXUS61 KCAR 190115
AFDCAR
Area Forecast Discussion
National Weather Service Caribou ME
915 PM EDT Wed Aug 18 2021
.SYNOPSIS...
High pressure will build southeast of the Gulf of Maine
overnight while an upper level disturbance crosses the region.
Another upper level disturbance crosses the region Thursday
night with the remnants of Tropical Depression Fred. A front
will sink south and washout over the coast Friday. High pressure
will build over the area Saturday and will give way to a trough
of low pressure on Sunday. Tropical Storm Henri or the remains
of the system could impact the area by later Monday.....
......LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Saturday looks fairly quiet across the forecast area, but the
greatest uncertainty in the long range forecast begins Sunday
and lasts through Tuesday. The cold front that has been in the
forecast for this time period has weakened and moved off to the
north, leaving Northern Maine under weak flow aloft. This opens
the door for Tropical Storm Henri (currently near Bermuda) to be
a possible player in the weather for Monday night and Tuesday
morning. Forecast models are highly variable on what is going to
happen with this storm, with some models bringing it up the
east coast, and some models pushing it further offshore. At this
point, the greatest possible impacts seem to be mainly high
surf, with some gusty winds along the coast. However, given the
uncertainty, the forecast is very conservative on these items.
As this period gets closer in time, the forecast will be updated
accordingly.
After the possibility of Henri on Monday and Tuesday, there will
be a brief break in weather before a potential cold front passes
Wednesday night. This has the potential to bring showers through
Northern Maine, but also some cooler temperatures and drier air.
Given the uncertainty with Henri, current forecast confidence
for this period is low.....
Hazardous Weather Outlook
National Weather Service Caribou ME
328 PM EDT Wed Aug 18 2021
MEZ001>006-010-011-015>017-029>032-191930-
Northwest Aroostook-Northeast Aroostook-Northern Somerset-
Northern Piscataquis-Northern Penobscot-Southeast Aroostook-
Central Piscataquis-Central Penobscot-Southern Penobscot-
Interior Hancock-Central Washington-Coastal Hancock-
Coastal Washington-Southern Piscataquis-Northern Washington-
328 PM EDT Wed Aug 18 2021
This Hazardous Weather Outlook is for Central Highlands Maine,
Coastal DownEast Maine, Far Eastern Maine, Far Northern Maine,
Interior DownEast Maine, North Woods Maine and Penobscot Valley
Maine.
.DAY ONE...This afternoon and tonight.
Hazardous weather is not expected at this time.
.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.
Thursday night heavy rainfall is likely across Southern Piscataquis,
Penobscot, and Interior Hancock and Washington Counties. The heaviest
amounts will be 1 to 1.5 inches over Southern Piscataquis and
southern Penobscot Counties. Elsewhere 0.5 to 1 inch of rainfall is
expected. Widespread flooding is not expected at this time, but
ponding may occur in areas with poor drainage.
Monday night and Tuesday, there is a possibility of Tropical Storm
Henri (currently near Bermuda) crossing the Gulf of Maine. This could
bring heavy rainfall and strong winds to the Downeast coast, but most
likely significant swell and potential high surf along the shoreline.
There is a lot of uncertainty in the track of this system, so watch
the forecast for updates.
.SPOTTER INFORMATION STATEMENT...
Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.
$$
posted by Advackia at 8:23 PM
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