FLORIDA
STORMS
Tropical Storm Henri
LOCATED
415 MI SSE OF CAPE HATTERAS NORTH CAROLINA
WINDS
65 MPH
PRESSURE
997 MB
MOVING
WNW AT 8 MPH
From the National Hurricane Center at 1100 PM EDT Thu Aug 19 2021
Henri holding on against shear and maintaining 65-mph winds.
TAP LINKS BELOW TO FOCUS
key messages
Alerts
hazards
summary
DISCUSSION

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.

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.

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.

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.

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.

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.

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).

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).

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.

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.

Partners of the Florida Public Radio Emergency Network include:  WDNA (Miami), WFIT (Melbourne), WMFE (Orlando), WFSU (Tallahassee), WGCU (Fort Myers), WJCT (Jacksonville), WKGC (Panama City), WLRN (Miami), WMNF (Tampa-Sarasota), WQCS (Fort Pierce), WUFT (Gainesville-Ocala), WUSF (Tampa), WUWF (Pensacola) and Florida Public Media.

1885 Stadium Road

PO Box 118400

Gainesville, FL 32611

(352) 392-5551

Loading...
linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram