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TROPICAL DEPRESSION FIONA DISCUSSION NUMBER 26
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062016
500 AM AST TUE AUG 23 2016
Fiona is barely holding on as a tropical cyclone with a small burst
of deep convection confined mainly to the southeastern quadrant due
to moderate to strong northwesterly vertical wind shear. The
initial intensity is being maintained at 30 kt based on a Dvorak
intensity estimate of 2.0/30 kt from TAFB, and an ADT estimate of
T2.2/32 kt from UW-CIMSS.
The initial motion is a little slower at 290/11 kt. Fiona is
forecast to gradually turn northwestward and decelerate as the
small cyclone moves toward and into a break in the Bermuda-Azores
ridge. The NHC forecast track is down the middle of the tightly
packed model guidance, and lies close to consensus track model TVCN.
Strong westerly to northwesterly vertical wind shear that has been
plaguing Fiona for the past several days is forecast to weaken
considerably during the next 36 hours, which would normally support
some strengthening. However, the small cyclone is expected to remain
embedded in a region of dry mid-level air with humidity values
less than 60 percent during that time, decreasing to less than 50
percent by 72 hours, which should inhibit the development of
persistent deep convection near the center. The result is that Fiona
is forecast to degenerate into a remnant low in 48 hours, if not
sooner. The official intensity forecast remains below the consensus
model IVCN and the SHIPS/LGEM models, and instead follows the
weakening trend depicted in the global models.
FORECAST POSITIONS AND MAX WINDS
INIT 23/0900Z 25.8N 63.4W 30 KT 35 MPH
12H 23/1800Z 26.2N 65.0W 30 KT 35 MPH
24H 24/0600Z 27.1N 67.0W 25 KT 30 MPH
36H 24/1800Z 28.1N 68.6W 25 KT 30 MPH
48H 25/0600Z 28.9N 69.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 26/0600Z 30.0N 70.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 27/0600Z 30.6N 71.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 28/0600Z...DISSIPATED
$$
Forecaster Stewart
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