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.

$$