083
WTNT43 KNHC 282043
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082026
500 PM AST MON SEP 28 2026
SINCE THIS MORNING, HANNA'S CONVECTIVE STRUCTURE HAS BECOME A LITTLE
MORE DISHEVELED WITH THE TROPICAL STORM IS AFFECTED BY 20-25 KT OF
WESTERLY VERTICAL WIND SHEAR. THERE HAS NOT BEEN AN APPRECIABLE
CHANGE IN THE SUBJECTIVE OR OBJECTIVE INTENSITY ESTIMATES THIS
AFTERNOON, AND THE INITIAL INTENSITY IS HELD AT 40 KT.
THE INITIAL MOTION OF HANNA IS EAST-SOUTHEASTWARD AT 115 DEGREES AT
15 KT. HANNA IS EMBEDDED IN THE FLOW IN BETWEEN A LONGWAVE TROUGH TO
ITS NORTHEAST, AND A LARGER SUBTROPICAL RIDGE TO ITS SOUTH. THIS
SYNOPTIC PATTERN SHOULD RESULT IN A CONTINUED EAST-SOUTHEASTWARD
MOTION OVER THE NEXT 24-36 HOURS WITH SOME GRADUALLY SLOW DOWN IN
THE TRACK AS THE MID-LATITUDE TROUGH LEAVES HANNA BEHIND. MUCH OF
THE TRACK GUIDANCE THEN SHOWS A SLOW EAST-NORTHEASTWARD MOTION
AFTER THE CYCLONE BECOMES MORE VERTICALLY SHALLOW AND BECOMES
INFLUENCED BY A LOW-LEVEL RIDGE CENTERED SOUTH OF THE AZORES. THE
NHC TRACK FORECAST IS VERY SIMILAR TO THE PREVIOUS ONE, ROUGHLY IN
BETWEEN THE SIMPLE (TVCN) AND CORRECTED CONSENSUS (HCCA) AIDS.
VERTICAL WIND SHEAR OVER HANNA IS EXPECTED TO PERSIST IN OVER THE
NEXT 48-72 H, THOUGH BECAUSE THE TROPICAL STORM IS CURRENTLY MOVING
IN THE SAME DIRECTION AS THE SHEAR VECTOR, BURSTS OF DEEP CONVECTION
DOWN-SHEAR OF THE CENTER MAY ALLOW FOR SOME SLIGHT INTENSIFICATION,
WHICH IS REFLECTED IN THE HCCA INTENSITY GUIDANCE. HOWEVER, WHEN
HANNA SLOWS DOWN AND TURNED MORE EAST-NORTHEASTWARD, THE SHEAR IS
EXPECTED TO SHIFT MORE OUT OF THE NORTH, IMPORTING VERY DRY
TROPOSPHERIC AIR INTO THE CIRCULATION. SIMULATED SATELLITE IMAGERY
FROM THE ECMWF AND HURRICANE-REGIONAL MODELS STILL SHOW CONVECTION
CEASING OVER THE STORM IN AROUND 60 H, MARKING ITS TRANSITION TO A
POST-TROPICAL CYCLONE IN THE FORECAST.
FORECAST POSITIONS AND MAX WINDS
INIT 28/2100Z 36.5N 48.7W 40 KT 45 MPH
12H 29/0600Z 35.5N 46.1W 45 KT 50 MPH
24H 29/1800Z 34.3N 44.3W 45 KT 50 MPH
36H 30/0600Z 33.9N 43.4W 40 KT 45 MPH
48H 30/1800Z 34.2N 42.5W 35 KT 40 MPH
60H 01/0600Z 34.8N 41.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 01/1800Z 36.0N 38.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 02/1800Z...DISSIPATED
FORECASTER PAPIN
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