BULLETIN
Subtropical Storm Alpha Special Advisory Number 1
NWS National Hurricane Center Miami FL AL242020
430 PM GMT Fri Sep 18 2020
...SUBTROPICAL STORM ALPHA FORMS NEAR THE COAST OF PORTUGAL...
...EXPECTED TO BE SHORT-LIVED BUT BRING WINDS AND RAIN TO
PORTIONS OF PORTUGAL...
SUMMARY OF 430 PM GMT...1630 UTC...INFORMATION
----------------------------------------------
LOCATION...39.9N 9.3W
ABOUT 75 MI...125 KM N OF LISBON PORTUGAL
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NE OR 35 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal tropical cyclone watches or warnings in effect.
Interests in Portugal should monitor the progress of Alpha.
Additional information on this system can be found in products from
the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
DISCUSSION AND OUTLOOK
----------------------
At 430 PM GMT (1630 UTC), the center of Subtropical Storm Alpha was
located near latitude 39.9 North, longitude 9.3 West. The storm is
moving toward the northeast near 17 mph (28 km/h), and this general
motion is expected during the next day or so before dissipation.
Alpha should move across the coast of west-central Portugal during
the next couple of days.
Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Little change in strength is expected before landfall, with rapid
weakening over land through the weekend.
Alpha is a small storm. Winds of 40 mph extend outward up to 35
miles (55 km) from the center.
The estimated minimum central pressure is 999 mb (29.50 inches).
HAZARDS AFFECTING LAND
----------------------
WIND...Information on wind hazards from Alpha can be found in
products from the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
RAINFALL...Alpha is expected to produce 1 to 2 inches (25 to 50 mm)
of rainfall, with isolated amounts of 3 inches (75 mm) over the
northern portion of Portugal and into west-central Spain through
Saturday morning.
NEXT ADVISORY
-------------
Next complete advisory at 900 PM GMT.
$$
Forecaster Blake
Subtropical Storm Alpha Special Discussion Number 1
NWS National Hurricane Center Miami FL AL242020
430 PM GMT Fri Sep 18 2020
The small low pressure area that has been rotating around a larger
extratropical low in the far northeastern Atlantic has become better
organized this morning. Moderate-to-deep convection has persisted
near the center since last night, scatterometer data shows a closed
40-kt low, and radar images from Portugal show a definite organized
convective pattern. While the system is still in the cyclonic
envelope of the large extratropical low and likely neutral- or
cold-core, it has developed enough tropical characteristics to be
considered a subtropical storm. The initial intensity is set to 45
kt in accordance with the scatterometer data, assuming some
undersampling for this small system.
Little change in strength is forecast until landfall in Portugal
during the next couple of hours. Global models show the small low
moving northeastward at about 15 kt for the next 24 hours before
dissipating over northern Spain or the Bay of Biscay. The track and
intensity forecasts are consistent with the consensus guidance.
Additional information on the hazards from this system can be found
in products from the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
FORECAST POSITIONS AND MAX WINDS
INIT 18/1630Z 39.9N 9.3W 45 KT 50 MPH
12H 19/0000Z 41.5N 7.5W 30 KT 35 MPH...POST-TROP/INLAND
24H 19/1200Z 44.2N 4.2W 30 KT 35 MPH...POST-TROP/EXTRATROP
36H 20/0000Z...DISSIPATED
$$
Forecaster Blake
Subtropical Storm Alpha Special Advisory Number 1
NWS National Hurricane Center Miami FL AL242020
430 PM GMT Fri Sep 18 2020
...SUBTROPICAL STORM ALPHA FORMS NEAR THE COAST OF PORTUGAL...
...EXPECTED TO BE SHORT-LIVED BUT BRING WINDS AND RAIN TO
PORTIONS OF PORTUGAL...
SUMMARY OF 430 PM GMT...1630 UTC...INFORMATION
----------------------------------------------
LOCATION...39.9N 9.3W
ABOUT 75 MI...125 KM N OF LISBON PORTUGAL
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NE OR 35 DEGREES AT 17 MPH...28 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal tropical cyclone watches or warnings in effect.
Interests in Portugal should monitor the progress of Alpha.
Additional information on this system can be found in products from
the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
DISCUSSION AND OUTLOOK
----------------------
At 430 PM GMT (1630 UTC), the center of Subtropical Storm Alpha was
located near latitude 39.9 North, longitude 9.3 West. The storm is
moving toward the northeast near 17 mph (28 km/h), and this general
motion is expected during the next day or so before dissipation.
Alpha should move across the coast of west-central Portugal during
the next couple of days.
Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Little change in strength is expected before landfall, with rapid
weakening over land through the weekend.
Alpha is a small storm. Winds of 40 mph extend outward up to 35
miles (55 km) from the center.
The estimated minimum central pressure is 999 mb (29.50 inches).
HAZARDS AFFECTING LAND
----------------------
WIND...Information on wind hazards from Alpha can be found in
products from the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
RAINFALL...Alpha is expected to produce 1 to 2 inches (25 to 50 mm)
of rainfall, with isolated amounts of 3 inches (75 mm) over the
northern portion of Portugal and into west-central Spain through
Saturday morning.
NEXT ADVISORY
-------------
Next complete advisory at 900 PM GMT.
$$
Forecaster Blake
Subtropical Storm Alpha Special Discussion Number 1
NWS National Hurricane Center Miami FL AL242020
430 PM GMT Fri Sep 18 2020
The small low pressure area that has been rotating around a larger
extratropical low in the far northeastern Atlantic has become better
organized this morning. Moderate-to-deep convection has persisted
near the center since last night, scatterometer data shows a closed
40-kt low, and radar images from Portugal show a definite organized
convective pattern. While the system is still in the cyclonic
envelope of the large extratropical low and likely neutral- or
cold-core, it has developed enough tropical characteristics to be
considered a subtropical storm. The initial intensity is set to 45
kt in accordance with the scatterometer data, assuming some
undersampling for this small system.
Little change in strength is forecast until landfall in Portugal
during the next couple of hours. Global models show the small low
moving northeastward at about 15 kt for the next 24 hours before
dissipating over northern Spain or the Bay of Biscay. The track and
intensity forecasts are consistent with the consensus guidance.
Additional information on the hazards from this system can be found
in products from the Portuguese Institute for Sea and Atmosphere at
http://www.ipma.pt.
FORECAST POSITIONS AND MAX WINDS
INIT 18/1630Z 39.9N 9.3W 45 KT 50 MPH
12H 19/0000Z 41.5N 7.5W 30 KT 35 MPH...POST-TROP/INLAND
24H 19/1200Z 44.2N 4.2W 30 KT 35 MPH...POST-TROP/EXTRATROP
36H 20/0000Z...DISSIPATED
$$
Forecaster Blake