WTNT33 KNHC 200255
TCPAT3
BULLETIN
Tropical Storm Henri Advisory Number 17
NWS National Hurricane Center Miami FL AL082021
1100 PM EDT Thu Aug 19 2021
...HENRI HOLDING ON AGAINST SHEAR AND MAINTAINING 65-MPH WINDS...
...INTERESTS IN THE NORTHEASTERN U.S. SHOULD MONITOR ITS PROGRESS...
SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...29.8N 72.3W
ABOUT 415 MI...670 KM SSE OF CAPE HATTERAS NORTH CAROLINA
ABOUT 800 MI...1285 KM S OF NANTUCKET MASSACHUSETTS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...WNW OR 285 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...997 MB...29.44 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. Watches will likely be required for
a portion of this area early Friday.
DISCUSSION AND OUTLOOK
----------------------
At 1100 PM EDT (0300 UTC), the center of Tropical Storm Henri was
located near latitude 29.8 North, longitude 72.3 West. Henri is
moving toward the west-northwest near 8 mph (13 km/h). A sharp turn
to the northwest and north is anticipated on Friday, followed by an
acceleration to the north and north-northeast on Saturday and
Sunday. On the forecast track, the center of Henri will remain well
offshore of the east coast of the United States over the next couple
of days, but it is forecast to be near or over southern New England
on Sunday and Monday.
Maximum sustained winds remain near 65 mph (100 km/h) with higher
gusts. Little change in strength is expected during the next 12
hours, but Henri is forecast to intensify into a hurricane by Friday
night with additional strengthening expected this weekend.
Tropical-storm-force winds extend outward up to 90 miles (150 km)
from the center.
The estimated minimum central pressure is 997 mb (29.44 inches).
HAZARDS AFFECTING LAND
----------------------
RAINFALL: Henri may produce rainfall amounts of 2 to 5 inches over
southeastern New England Sunday into Monday, with isolated maximum
totals near 8 inches. Heavy rainfall from Henri may result in areas
of flash, urban, and small stream flooding.
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 on Friday and
into the 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 EDT.
$$
Forecaster Papin/Beven
879
WTNT43 KNHC 200259
TCDAT3
Tropical Storm Henri Discussion Number 17
NWS National Hurricane Center Miami FL AL082021
1100 PM EDT Thu Aug 19 2021
The satellite presentation on Henri this evening continues to
exhibit a persistent bursting pattern, with the center estimated to
be just to the north and west of the coldest cloud tops which
occasionally have been below -80 C in the overshooting tops. This
current satellite presentation is primarily due to continued
moderate to strong northerly vertical wind shear, which is forcing
the convection underneath the cirrus canopy down-shear of the
low-level center, as seen on a 2230 UTC SSMIS microwave pass. While
the mid-level vortex with the convection also remains tilted
down-shear of the low-level center, it has not completely separated
due to the persistent convection, preventing the low-level center
from escaping poleward in more shallow low-level steering.
Tonight's subjective Dvorak estimates from SAB/TAFB are in
agreement with T3.5/55 kt and given that this value is near what
the earlier Air Force Reconnaissance mission found, the latest
intensity is being maintained at 55 kt for this advisory.
There is a bit of uncertainty determining if Henri has begun a more
poleward motion since the center remains under the convective cirrus
plume, but my best guess is now 285/9 kt. Over the next 12-24 hours,
the mid- to upper-level ridging that has dominated the synoptic
steering pattern for Henri the last few days will quickly break
down, as a shortwave trough drops in from the Great Lakes into the
Mid-Atlantic and cuts off. This feature is now forecast to continue
digging in to the west of Henri. To the east, a new mid-level ridge
is also forecast to build in to the right of Henri. This synoptic
pattern should draw the cyclone poleward with an acceleration to the
north-northeast in the 24-48 h period. Afterwards, the
aforementioned trough takes on a negative tilt to the southwest of
Henri, helping to reorient the mid- to upper-level flow out of the
south-southeast, and this flow could result in a slight leftward
bend in the track between 48-72 h. The majority of guidance this
cycle now is forecasting the mid-level ridge east of Henri to build
poleward with the storm, blocking an easy path for the storm to stay
on a more northeast heading out to sea. Consequently, the latest NHC
forecast track now explicitly shows landfall in southeast
Massachusetts at 72 h. The track guidance this cycle has come into
better agreement, though there remain some leftward (UKMET) and
rightward (ECMWF) outliers. The latest forecast track lies very
close to the HFIP corrected consensus approach (HCCA) guidance,
which is also very near the latest GFS forecast track.
Data from the NOAA G-IV synoptic mission around Henri shows that
just north of the tropical cyclone there remains some very dry
mid-latitude air, which is being advected into the storm by 20-25
kt of northerly vertical wind shear. Over the next 24-36 hours,
this shear is forecast to gradual subside, as Henri moves near the
center of an upper-level ridge axis. By 36-48 hours, the vertical
wind shear is forecast to be under 10-kt by both the GFS- and
ECWMF-based SHIPS guidance, while the storm is also traversing
28-29 C sea-surface temperatures (SSTs). Thus, the latest NHC
intensity forecast still calls for strengthening beginning after 12
hours, and the rate of strengthening could be a bit quicker as the
storm moves over the warm gulf stream waters between 36-48 hours.
Thereafter, Henri will cross a very sharp SST gradient with
sea-surface temperatures down below 23 C near the New England coast
to the east of Long Island. Henri is forecast to begin weakening
after 48 hours, but the storm could still be near hurricane
intensity by the time Henri is forecast to be near the Northeast
coastline. Transition to a post-tropical storm is expected to begin
shortly thereafter which should be sometime in the 96-h to 120-h
points as deep convection ceases over the storm over cold SSTs
As noted previously, the wind field of Henri is expected to expand,
especially as it interacts with a mid-latitude trough located to its
west. Therefore, users are reminded to not focus on the exact
forecast points as impacts will extend far from the center.
Key Messages:
1. Henri is forecast to be near the northeast coast of the U.S.
on Sunday and Monday, and the risks of storm surge, wind, and rain
impacts in portions of southern New England and eastern Long Island
are increasing. Watches will likely be required for portions of
this area early Friday.
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.
3. Heavy rainfall may lead to flash, urban, and small stream
flooding over portions of southeastern New England Sunday into
Monday.
FORECAST POSITIONS AND MAX WINDS
INIT 20/0300Z 29.8N 72.3W 55 KT 65 MPH
12H 20/1200Z 30.3N 73.2W 55 KT 65 MPH
24H 21/0000Z 31.8N 73.3W 60 KT 70 MPH
36H 21/1200Z 34.4N 72.2W 65 KT 75 MPH
48H 22/0000Z 37.6N 71.0W 80 KT 90 MPH
60H 22/1200Z 40.1N 70.6W 75 KT 85 MPH
72H 23/0000Z 41.7N 70.8W 60 KT 70 MPH...INLAND
96H 24/0000Z 42.5N 70.1W 40 KT 45 MPH...OVER WATER
120H 25/0000Z 43.7N 65.4W 35 KT 40 MPH...POST-TROPICAL
$$
Forecaster Papin/Brown
000
FXUS61 KCAR 200114
AFDCAR
Area Forecast Discussion
National Weather Service Caribou ME
914 PM EDT Thu Aug 19 2021
.SYNOPSIS...
The remnants of Fred will approach overnight and track along
the Maine coast into Friday morning. High pressure will build
over the area Saturday. Tropical Storm Henri will approach the
area later Sunday and may impact the region on Monday, and pull
away from the area by Tuesday.....
......LONG TERM /SUNDAY THROUGH THURSDAY/...
Now comes the interesting part. Tropical Storm Henri could be
making an impact on the New England region as it head northward
from the western Atlc. Most of the long range guidance
including the Canadian Global show Henri strengthening to near
or at Hurricane strength as it heads toward the New England
coast Sunday night into Monday. This storm could very well have
a big impact from LI, MA up into ME, depending on what track
this storm takes. The ECMWF and Canadian bring the system to
Cape Cod and slow it before it weakens and becomes extra-
tropical. The GFS however, brings the system to near Cape Cod
and then swings it ne through the Gulf of Maine just off the
Maine coast. This track would bring at least tropical storm
conditions to the coast and interior Downeast. As of 3 PM, the
official NHC track brings the storm to the Cape Cod and then
pushes it to the ne keeping it over the outer Gulf of Maine
waters. For now, decided to go w/40% pops into Monday evening.
In the wake of this storm, the upper trof is forecast to swing
across the region on Tuesday w/the sfc cold front. The threat
for showers and possible tstms increases during the day w/some
cooling aloft allowing for destabilization. The cold front is
shown to move through by late Wednesday night and then stall
across central areas on Wednesday. A weak disturbance moving
across the region in the westerly zonal flow aloft coupled w/the
stalled front could be focus for some showers/tstms during the
afternoon. Attm, stayed w/20% pops for Wednesday. Another cold
front expected for later Thursday and another threat for showers
and tstms. Temps during this timeframe will be AOA normal.......
2:59 PM ADT Thursday 19 August 2021
Tropical cyclone information statement for:
Nova Scotia
For Tropical Storm Henri.
THE NEXT INFORMATION STATEMENT IS SCHEDULED FOR 09:00 A.M. ADT FRIDAY.
1. SUMMARY OF BASIC INFORMATION AT 03:00 P.M. ADT.
LOCATION: NEAR 29.5 NORTH 70.8 WEST.
MAXIMUM SUSTAINED WINDS: 110 KILOMETRES PER HOUR.
PRESENT MOVEMENT: WEST AT 17 KILOMETRES PER HOUR.
MINIMUM CENTRAL PRESSURE: 995 MILLIBARS.
2. SUMMARY.
Henri is forecast to move slowly northward this weekend and could strengthen to a Category-2 hurricane quite far north, while east of Virginia. Normally these storms track at an increasing speed when they move north but Henri is expected to slow down as it nears Cape Cod. Also once it moves over colder water it will weaken at a particularly quick pace then move slowly east or northeastward. This storm will likely behave in several non-traditional ways and could track in a manner similar to Hurricane Edouard in 1996. https://www.ec.gc.ca/ouragans-hurricanes/default.asp?lang=en&n=8CC1EF90-1. That storm did bring strong winds and very heavy rainfall, and that scenario is also possible for Henri.
The storm will probably not affect our weather directly until Monday and/or Tuesday, and depending on the intensity and size, may simply bring moderate wind and rain. Larger than normal surf conditions will develop on the Atlantic Coast of Nova Scotia this weekend. The timing/track of course will change over the next several days as usual, so please check for updates regularly from the CHC at www.hurricanes.ca and our twitter feed @ECCC_CHC.
Please continue to monitor alerts issued by the Canadian Hurricane Centre and forecasts issued by Environment Canada.
Hazardous Weather Outlook
National Weather Service Caribou ME
528 AM EDT Thu Aug 19 2021
MEZ001>006-010-011-015>017-029>032-201200-
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-
528 AM EDT Thu Aug 19 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...Today and tonight.
Tonight, heavy rainfall is likely across Southern Piscataquis,
central and southern Penobscot, Hancock and Washington Counties.
Rainfall totals 1.50 to 2.00 inches will be common in these areas,
with locally greater totals expected. Rainfall totals will rapidly
decrease across northern areas. Widespread flooding is not expected
at this time, but ponding may occur in areas with poor drainage.
.DAYS TWO THROUGH SEVEN...Friday through Wednesday.
Monday into Tuesday, there is a possibility of Tropical Storm
Henri, currently southwest of 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 exact track
and intensity of this system, so keep up to date on the forecast for
the latest.
.SPOTTER INFORMATION STATEMENT...
Weather spotters are encouraged to report significant weather
conditions according to Standard Operating Procedures.
$$
