046
WTNT43 KNHC 290243
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082026
1100 PM AST MON SEP 28 2026
SATELLITE IMAGERY SHOWS HANNA'S CONVECTIVE STRUCTURE REMAINS
HIGHLY SHEARED WITH AN EXPOSED CENTER. THE DEEPEST CONVECTION
REMAINS DISPLACED TO THE EAST OF THE TROPICAL STORM'S CENTER DUE TO
STRONG WESTERLY VERTICAL WIND SHEAR. SUBJECTIVE DVORAK ESTIMATES
FROM TAFB CAME IN AT T2.0/30 KT, SLIGHTLY BELOW OBJECTIVE ESTIMATES
RANGING BETWEEN 35 AND 50 KT. BASED ON A BLEND OF THESE DATA, THE
INITIAL INTENSITY IS HELD AT 40 KT.
THE INITIAL MOTION CONTINUES EAST-SOUTHEASTWARD AT 105/12 KT. HANNA
IS EMBEDDED IN THE FLOW 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 A GRADUAL SLOWDOWN 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 VERTICALLY
SHALLOW AND INFLUENCED BY A LOW-LEVEL RIDGE CENTERED SOUTH OF THE
AZORES. THE UPDATED NHC TRACK FORECAST IS A BLEND OF THE PREVIOUS
ADVISORY AND THE CORRECTED CONSENSUS (HCCA) AID, NUDGING THE TRACK
SLIGHTLY SOUTHWARD.
HANNA IS EXPECTED TO REMAIN IN A HOSTILE ENVIRONMENT, WITH MODERATE
TO STRONG VERTICAL WIND SHEAR PREVAILING OVER THE NEXT 48–72 H.
HOWEVER, BECAUSE THE TROPICAL STORM IS GENERALLY MOVING IN THE SAME
DIRECTION AS THE SHEAR VECTOR, DEEPER CONVECTION WELL EAST OF THE
CENTER MAY ALLOW FOR SLIGHT INTENSIFICATION, AS PORTRAYED IN SOME
RELIABLE GUIDANCE. SHIPS GUIDANCE INDICATES THAT VERTICAL WIND SHEAR
WILL ONLY INCREASE THROUGHOUT THE FORECAST PERIOD, WHILE MID-LEVEL
RH VALUES SHOW THE STORM BEING STARVED OF MOISTURE, WHICH MAY WEAKEN
THE SYSTEM. HANNA IS EXPECTED TO BE DEVOID OF DEEP CONVECTION AROUND
THE 60 H MARK, DEGENERATING INTO A POST-TROPICAL CYCLONE AT THAT
TIME.
FORECAST POSITIONS AND MAX WINDS
INIT 29/0300Z 36.0N 47.7W 40 KT 45 MPH
12H 29/1200Z 34.9N 45.7W 45 KT 50 MPH
24H 30/0000Z 34.1N 44.3W 45 KT 50 MPH
36H 30/1200Z 34.0N 43.5W 40 KT 45 MPH
48H 01/0000Z 34.4N 42.2W 35 KT 40 MPH
60H 01/1200Z 35.2N 40.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 02/0000Z 36.3N 38.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 03/0000Z...DISSIPATED
FORECASTER PIERCE/REINHART
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