882
WTNT43 KNHC 290839
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL082026
500 AM AST TUE SEP 29 2026
SATELLITE IMAGERY SHOWS HANNA'S CONVECTIVE STRUCTURE HAS NOT CHANGED
MUCH AND STILL DISPLAYS AN EXPOSED LOW-LEVEL CENTER DUE TO STRONG
WESTERLY VERTICAL WIND SHEAR. THE DEEPEST CONVECTION REMAINS
DISPLACED EAST OF THE TROPICAL STORM'S CENTER. A 0225 UTC OSCAT
SCATTEROMETER PASS REVEALED AN ASYMMETRIC WIND FIELD. THE LATEST
TAFB DVORAK FIX WAS T2.0/30 KT, SLIGHTLY BELOW OBJECTIVE ESTIMATES
RANGING BETWEEN 34 AND 43 KT. BASED ON A BLEND OF THESE DATA, THE
INITIAL INTENSITY IS HELD AT 40 KT.
THE INITIAL MOTION CONTINUES EAST-SOUTHEASTWARD AT 105/13 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 H OR SO, WITH A GRADUAL SLOWDOWN IN FORWARD SPEED AS THE
MID-LATITUDE TROUGH LEAVES HANNA BEHIND. MUCH OF THE TRACK GUIDANCE
THEN SHOWS A SLIGHTLY QUICKER 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
WAS LARGELY UNCHANGED FROM THE PREVIOUS ADVISORY, ROUGHLY IN BETWEEN
THE SIMPLE (TVCN) AND CORRECTED CONSENSUS (HCCA) AIDS.
TROPICAL STORM HANNA IS FORECAST TO PERSIST IN A MOISTURE-STARVED
ENVIRONMENT, WITH MODERATE TO STRONG VERTICAL WIND SHEAR PREVAILING
OVER THE NEXT 48 TO 72 H. HOWEVER, SOME NEAR-TERM FLUCTUATIONS IN
INTENSITY ARE POSSIBLE DURING THIS PERIOD AS INTERMITTENT BURSTS OF
DEEP CONVECTION WELL EAST OF THE CENTER MAY ALLOW FOR SLIGHT
INTENSIFICATION. THEREAFTER, 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 29/0900Z 35.2N 46.2W 40 KT 45 MPH
12H 29/1800Z 34.4N 44.6W 45 KT 50 MPH
24H 30/0600Z 33.9N 43.5W 40 KT 45 MPH
36H 30/1800Z 34.2N 42.4W 40 KT 45 MPH
48H 01/0600Z 34.9N 40.5W 35 KT 40 MPH
60H 01/1800Z 35.8N 38.3W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 02/0600Z 37.0N 35.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 03/0600Z...DISSIPATED
FORECASTER PIERCE/PASCH
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