FLORIDA
STORMS
Hurricane Sam
LOCATED
465 MI SSE OF CAPE RACE NEWFOUNDLAND
WINDS
105 MPH
PRESSURE
957 MB
MOVING
NE AT 30 MPH
From the National Hurricane Center at 500 AM AST Mon Oct 04 2021
Sam north of the Gulf stream and expected to weaken soon.
TAP LINKS BELOW TO FOCUS
key messages
Alerts
hazards
summary
DISCUSSION

1. Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the eastern United States and Atlantic Canada for the next couple of days. These swells could cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

1. Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, Bermuda, the eastern United States and Atlantic Canada for the next couple of days. These swells could cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

There are no coastal watches or warnings in effect.

There are no coastal watches or warnings in effect.

Key messages for Sam can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC, and on the web at hurricanes.gov/graphics_at3.shtml?key_messages.

SURF: Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, the eastern United States and Atlantic Canada for the next couple of days. These swells could cause life threatening surf and rip current conditions. Please consult products from your local weather office.

Key messages for Sam can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC, and on the web at hurricanes.gov/graphics_at3.shtml?key_messages.

SURF: Swells generated by Sam will impact the northern Leeward Islands, the Greater Antilles, the Bahamas, the eastern United States and Atlantic Canada for the next couple of days. These swells could cause life threatening surf and rip current conditions. Please consult products from your local weather office.

At 500 AM AST (0900 UTC), the center of Hurricane Sam was located near latitude 40.8 North, longitude 48.7 West. Sam is moving toward the northeast near 30 mph (48 km/h). A northeastward motion at a faster forward speed is expected over the next couple of days. The cyclone is forecast to slow down over the far north Atlantic southwest of Iceland around midweek. Maximum sustained winds remain near 105 mph (165 km/h) with higher gusts. Gradual weakening is forecast during the next few days, and Sam is expected to transition into a powerful post tropical cyclone by early Tuesday. Sam is a large hurricane. Hurricane force winds extend outward up to 70 miles (110 km) from the center and tropical storm force winds extend outward up to 255 miles (405 km). The estimated minimum central pressure is 957 mb (28.26 inches).

At 500 AM AST (0900 UTC), the center of Hurricane Sam was located near latitude 40.8 North, longitude 48.7 West. Sam is moving toward the northeast near 30 mph (48 km/h). A northeastward motion at a faster forward speed is expected over the next couple of days. The cyclone is forecast to slow down over the far north Atlantic southwest of Iceland around midweek. Maximum sustained winds remain near 105 mph (165 km/h) with higher gusts. Gradual weakening is forecast during the next few days, and Sam is expected to transition into a powerful post tropical cyclone by early Tuesday. Sam is a large hurricane. Hurricane force winds extend outward up to 70 miles (110 km) from the center and tropical storm force winds extend outward up to 255 miles (405 km). The estimated minimum central pressure is 957 mb (28.26 inches).

A 0255Z GPM microwave pass indicated that Sam had continued to go through an eyewall replacement cycle, consisting of a 20-nmi-wide inner eye and an 85-nmi-wide outer eye. The inner eye was rapidly eroding on the northwest side compared to microwave data from just a few hours earlier. Additionally, late-arriving ASCAT surface wind data from 0000-0100Z indicated that the inner-core wind field had contracted or weakened, while the outer wind field (34-kt radii) had continued to expand in all quadrants. Satellite intensity estimates have decreased to around 80 kt. However, the advisory intensity has been maintained at 90 kt based on the 10-kt increase in forward speed, which should offset any weakening of the tangential winds. Gradual weakening is expected now that Sam has passed north of the warm Gulf Stream and is moving over sub-25-deg-C sea-surface temperatures (SST), with much colder SSTs lying ahead of the hurricane. Vertical wind shear is forecast to increase to more than 30 kt by 18 h, which should cause further weakening. By 24 h and beyond, interaction with a strong upper-level trough/low should cause Sam to transition into a powerful extratropical cyclone by early Tuesday to the east of Newfoundland. This baroclinic interaction is expected to cause extratropical-Sam to maintain hurricane-force winds until early Wednesday. Slow weakening is forecast thereafter as the very large cyclone slowly spins down as an occluded low pressure system. No significant changes were made to the previous intensity forecast.

Sam has continued to accelerate and is now moving at 045/26 kt. A northeastward motion along with continued acceleration is forecast through today as Sam moves into stronger southwesterly flow ahead of an approaching mid-latitude trough. The large cyclone is expected to remain the primary surface low center as it merges with the trough in a couple days. A gradual turn toward the north and northwest is expected on days 4 and 5 when extratropical-Sam moves around another high-latitude trough. The new NHC forecast track is essentially just an update of the previous advisory track, and lies close to the tightly packed consensus track models.

A 0255Z GPM microwave pass indicated that Sam had continued to go through an eyewall replacement cycle, consisting of a 20-nmi-wide inner eye and an 85-nmi-wide outer eye. The inner eye was rapidly eroding on the northwest side compared to microwave data from just a few hours earlier. Additionally, late-arriving ASCAT surface wind data from 0000-0100Z indicated that the inner-core wind field had contracted or weakened, while the outer wind field (34-kt radii) had continued to expand in all quadrants. Satellite intensity estimates have decreased to around 80 kt. However, the advisory intensity has been maintained at 90 kt based on the 10-kt increase in forward speed, which should offset any weakening of the tangential winds. Gradual weakening is expected now that Sam has passed north of the warm Gulf Stream and is moving over sub-25-deg-C sea-surface temperatures (SST), with much colder SSTs lying ahead of the hurricane. Vertical wind shear is forecast to increase to more than 30 kt by 18 h, which should cause further weakening. By 24 h and beyond, interaction with a strong upper-level trough/low should cause Sam to transition into a powerful extratropical cyclone by early Tuesday to the east of Newfoundland. This baroclinic interaction is expected to cause extratropical-Sam to maintain hurricane-force winds until early Wednesday. Slow weakening is forecast thereafter as the very large cyclone slowly spins down as an occluded low pressure system. No significant changes were made to the previous intensity forecast.

Sam has continued to accelerate and is now moving at 045/26 kt. A northeastward motion along with continued acceleration is forecast through today as Sam moves into stronger southwesterly flow ahead of an approaching mid-latitude trough. The large cyclone is expected to remain the primary surface low center as it merges with the trough in a couple days. A gradual turn toward the north and northwest is expected on days 4 and 5 when extratropical-Sam moves around another high-latitude trough. The new NHC forecast track is essentially just an update of the previous advisory track, and lies close to the tightly packed consensus track models.

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