FLORIDA
STORMS
Subtropical Storm Wanda
LOCATED
935 MI WSW OF THE AZORES
WINDS
45 MPH
PRESSURE
993 MB
MOVING
E AT 6 MPH
From the National Hurricane Center at 300 PM GMT Mon Nov 01 2021
Wanda wandering across the north Atlantic west of the azores.
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Alerts
hazards
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DISCUSSION

There are no coastal watches or warnings in effect.

There are no coastal watches or warnings in effect.

None.

None.

At 300 PM GMT (1500 UTC), the center of Subtropical Storm Wanda was located near latitude 34.0 North, longitude 43.0 West. The storm is moving toward the east near 6 mph (9 km/h), and this general motion should continue this morning. A turn toward the northeast is expected by tonight, followed by a turn toward the north by late Tuesday. Maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts. Some slight fluctuations in strength are anticipated during the next few days. However, Wanda could still become a tropical storm on Tuesday. Winds of 40 mph extend outward up to 70 miles (110 km) from the center. The estimated minimum central pressure is 993 mb (29.33 inches).

At 300 PM GMT (1500 UTC), the center of Subtropical Storm Wanda was located near latitude 34.0 North, longitude 43.0 West. The storm is moving toward the east near 6 mph (9 km/h), and this general motion should continue this morning. A turn toward the northeast is expected by tonight, followed by a turn toward the north by late Tuesday. Maximum sustained winds have decreased to near 45 mph (75 km/h) with higher gusts. Some slight fluctuations in strength are anticipated during the next few days. However, Wanda could still become a tropical storm on Tuesday. Winds of 40 mph extend outward up to 70 miles (110 km) from the center. The estimated minimum central pressure is 993 mb (29.33 inches).

Wanda has been moving southeastward since the previous advisory and has now moved back underneath the axis of the upper-level trough that the cyclone is embedded in. However, strong northwesterly vertical wind shear of 30-35 kt has persisted and has displaced the deep convection into the southeastern quadrant. The initial intensity has been lowered to 40 kt based on a blend of satellite intensity estimates of 35 kt from TAFB, and 39 kt and 41 kt from UW-CIMSS ADT and SATCON, respectively.

Although Wanda had been moving southeastward at 10-11 kt as of 1200 UTC, the most recent motion vector appears to be slowly eastward or 090/05 kt. Wanda and the parent upper-level trough should move eastward this late morning and early afternoon, and then turn northeastward by this evening, followed by a northward motion by late Tuesday as southerly steering flow gradually develops between a larger mid-latitude trough to the west and a ridge to the east. By day 3, another mid-latitude ridge is forecast to build between Wanda and the aforementioned larger trough, causing the cyclone to turn eastward and then southward toward the westernmost Azores. The latest NHC track guidance has shifted sharply to the east of the previous forecast track through 72 hours, and the new official track forecast has followed suit. However, the new advisory track lies along the western edge of the guidance through day 3, and then lies in the middle of the track guidance envelope on days 4 and 5.

Although Wanda has weakened slightly, some slight restrengthening will be possible in the 24-60-h period when the shear is forecast to decrease sharply down to around 10 kt while the cyclone remains over 23.5-24-deg-C sea-surface temperatures. The weaker shear conditions should also help Wanda transition to a tropical cyclone. By 96 h, however, Wanda is forecast to devolve into a post-tropical low due to the cyclone moving over sub-20-deg-C water temperatures, into a significantly drier air mass, and into strong southerly vertical wind shear -- a detrimental combination that should cause the convection to erode near the center. The new NHC intensity forecast is essentially unchanged from the previous advisory.

Wanda is now moving east-northeastward and, as a result, has moved to the east of the upper-level trough axis, while the parent upper-low has detached and pulled out to the north. As a result, Wanda has now made the transition from a subtropical cyclone to a tropical cyclone. This meteorological metamorphosis has been confirmed by ASCAT data from 1200-1300 UTC that showed Wanda now has a small radius of maximum winds (RMW) of 30-35 nmi, and that the outer wind field has weakened and also contracted in size. The intensity is being held at 40 kt based on the earlier ASCAT data showing winds of 33-34 kt, and assuming that there is undersampling owing to the relatively large footprint/resolution of the scatterometer instrument.

The initial motion estimate is 070/06 kt. A complex steering flow pattern is forecast to evolve across the northern Atlantic during the next several days as a series of troughs and ridges in the mid-latitude westerlies pass over and to the north of Wanda. This will cause Wanda to make a zig-zag track across the north-central Atlantic, moving poleward ahead of the troughs and equatorward ahead of the ridges, resulting in a net eastward propagation toward the western Azores. The latest NHC model guidance is in fairly good agreement on the forecast track through day 3, but then diverge on days 4 and 5, with the GFS and ECMWF taking the cyclone more southward closer to the Azores and the remaining dynamical models lifting out Wanda to the north of the Azores. The new NHC official track forecast is similar to the previous advisory track, and follows a blend of the GFEX (GFS-ECMWF) and TVCA simple-consensus models.

Some slight restrengthening will be possible during the next 48 h or so due to a significant decrease in the deep-layer vertical wind shear while Wanda moves over slightly warmer sea-surface temperatures (SST) near 24 deg C. By 96-120 h, Wanda is forecast to devolve into a post-tropical cyclone due to the unfavorable combination of sub-20-deg-C SSTs, a significantly drier air mass, and strong southerly wind shear in excess of 30 kt. The new NHC intensity forecast remains unchanged from the previous advisory and is basically in the middle of the tightly packed intensity guidance suite.

Wanda has been moving southeastward since the previous advisory and has now moved back underneath the axis of the upper-level trough that the cyclone is embedded in. However, strong northwesterly vertical wind shear of 30-35 kt has persisted and has displaced the deep convection into the southeastern quadrant. The initial intensity has been lowered to 40 kt based on a blend of satellite intensity estimates of 35 kt from TAFB, and 39 kt and 41 kt from UW-CIMSS ADT and SATCON, respectively.

Although Wanda had been moving southeastward at 10-11 kt as of 1200 UTC, the most recent motion vector appears to be slowly eastward or 090/05 kt. Wanda and the parent upper-level trough should move eastward this late morning and early afternoon, and then turn northeastward by this evening, followed by a northward motion by late Tuesday as southerly steering flow gradually develops between a larger mid-latitude trough to the west and a ridge to the east. By day 3, another mid-latitude ridge is forecast to build between Wanda and the aforementioned larger trough, causing the cyclone to turn eastward and then southward toward the westernmost Azores. The latest NHC track guidance has shifted sharply to the east of the previous forecast track through 72 hours, and the new official track forecast has followed suit. However, the new advisory track lies along the western edge of the guidance through day 3, and then lies in the middle of the track guidance envelope on days 4 and 5.

Although Wanda has weakened slightly, some slight restrengthening will be possible in the 24-60-h period when the shear is forecast to decrease sharply down to around 10 kt while the cyclone remains over 23.5-24-deg-C sea-surface temperatures. The weaker shear conditions should also help Wanda transition to a tropical cyclone. By 96 h, however, Wanda is forecast to devolve into a post-tropical low due to the cyclone moving over sub-20-deg-C water temperatures, into a significantly drier air mass, and into strong southerly vertical wind shear -- a detrimental combination that should cause the convection to erode near the center. The new NHC intensity forecast is essentially unchanged from the previous advisory.

Wanda is now moving east-northeastward and, as a result, has moved to the east of the upper-level trough axis, while the parent upper-low has detached and pulled out to the north. As a result, Wanda has now made the transition from a subtropical cyclone to a tropical cyclone. This meteorological metamorphosis has been confirmed by ASCAT data from 1200-1300 UTC that showed Wanda now has a small radius of maximum winds (RMW) of 30-35 nmi, and that the outer wind field has weakened and also contracted in size. The intensity is being held at 40 kt based on the earlier ASCAT data showing winds of 33-34 kt, and assuming that there is undersampling owing to the relatively large footprint/resolution of the scatterometer instrument.

The initial motion estimate is 070/06 kt. A complex steering flow pattern is forecast to evolve across the northern Atlantic during the next several days as a series of troughs and ridges in the mid-latitude westerlies pass over and to the north of Wanda. This will cause Wanda to make a zig-zag track across the north-central Atlantic, moving poleward ahead of the troughs and equatorward ahead of the ridges, resulting in a net eastward propagation toward the western Azores. The latest NHC model guidance is in fairly good agreement on the forecast track through day 3, but then diverge on days 4 and 5, with the GFS and ECMWF taking the cyclone more southward closer to the Azores and the remaining dynamical models lifting out Wanda to the north of the Azores. The new NHC official track forecast is similar to the previous advisory track, and follows a blend of the GFEX (GFS-ECMWF) and TVCA simple-consensus models.

Some slight restrengthening will be possible during the next 48 h or so due to a significant decrease in the deep-layer vertical wind shear while Wanda moves over slightly warmer sea-surface temperatures (SST) near 24 deg C. By 96-120 h, Wanda is forecast to devolve into a post-tropical cyclone due to the unfavorable combination of sub-20-deg-C SSTs, a significantly drier air mass, and strong southerly wind shear in excess of 30 kt. The new NHC intensity forecast remains unchanged from the previous advisory and is basically in the middle of the tightly packed intensity guidance suite.

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