961
WTNT42 KNHC 172044
TCDAT2
TROPICAL STORM GABRIELLE DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072025
ISSUED BY THE NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 PM AST WED SEP 17 2025
THE BIGGEST CHANGE WITH GABRIELLE TODAY HAS BEEN THAT THE CENTER
HAS RE-FORMED FARTHER TO THE NORTH COMPARED WITH THE PREVIOUS
ADVISORY, SIMILAR TO EARLIER MODEL FORECASTS. WHILE SATELLITE
IMAGERY CONTINUES TO INDICATE AN ELONGATED CIRCULATION WITH
MULTIPLE EMBEDDED SWIRLS, IT HAS BECOME BETTER DEFINED THAN THIS
MORNING, AND WE HAVE CONTINUED TO MAKE THE CENTER POSITION ON THE
ADVISORY A MEAN OF THOSE SWIRLS. A SECOND SCATTEROMETER PASS THAT
INTERSECTED THE NORTHERN SEMICIRCLE OF THE STORM AFTER THE 15Z
ADVISORY DID SHOW A LARGE AREA OF 40-45 KT WINDS. THEREFORE, THE
INITIAL INTENSITY HAS BEEN INCREASED TO 45 KNOTS, EVEN THOUGH THE
SYSTEM DOES NOT APPEAR APPRECIABLY MORE ORGANIZED.
THE FIRST PART OF THE TRACK FORECAST HAS BEEN SHIFTED TO THE NORTH
BASED ON THE RECENT CENTER RE-FORMATION. GABRIELLE IS MOVING
NORTHWESTWARD NOW, AND A WEST-NORTHWESTWARD TO NORTHWESTWARD TRACK
IS ANTICIPATED FOR THE NEXT FEW DAYS DUE TO STEERING FROM THE
SUBTROPICAL RIDGE. THE FUNDAMENTAL FORECAST QUESTION FOR BOTH
TRACK AND INTENSITY IS RELATED TO THE WIND SHEAR GABRIELLE WILL
EXPERIENCE AND THE STRUCTURAL CHANGE. LITTLE INTENSITY CHANGE IS
SHOWN FOR THE NEXT COUPLE OF DAYS WHILE THE STORM REMAINS IN A
HIGH-SHEAR BUT HIGH SST/INSTABILITY ENVIRONMENT. THERE ACTUALLY
APPEARS TO BE GOOD CONSENSUS THAT THE SHEAR WILL RELAX AFTER FRIDAY,
BUT THERE ARE SIGNIFICANT MODEL DIFFERENCES ON HOW MUCH. THIS LEADS
TO A CONSIDERABLE AMOUNT OF TRACK AND INTENSITY SPREAD AS THE
FORECAST PROGRESSES INTO THE WEEKEND. GENERALLY THE MODELS THAT
RELAX THE SHEAR MORE SUBSTANTIALLY, TO AROUND 10 KNOTS OR LESS, SHOW
MORE INTENSIFICATION AND A TRACK TO THE RIGHT OF MODEL CONSENSUS.
SINCE THE NHC INTENSITY FORECAST IS A BIT ABOVE THE MODEL AVERAGE
(SIMILAR TO THE LAST PREDICTION), WE FAVOR A TRACK FORECAST TO THE
RIGHT OF THE MODEL BLEND, MORE CONSISTENT WITH THE HCCA CORRECTED
CONSENSUS, GOOGLE DEEP MIND ENSEMBLE, AND ECMWF ENSEMBLE.
OVERALL, FORECAST CONFIDENCE REMAINS RELATIVELY LOW. BASED ON THE
RECENT TRENDS, THIS SYSTEM SHOULD PASS WELL EAST AND NORTH OF THE
WINDWARD AND LEEWARD ISLANDS, BUT INTERESTS IN BERMUDA SHOULD
MONITOR FORECASTS DURING THE NEXT SEVERAL DAYS.
FORECAST POSITIONS AND MAX WINDS
INIT 17/2100Z 19.4N 48.0W 45 KT 50 MPH
12H 18/0600Z 20.6N 49.7W 45 KT 50 MPH
24H 18/1800Z 21.7N 51.6W 45 KT 50 MPH
36H 19/0600Z 22.7N 53.5W 45 KT 50 MPH
48H 19/1800Z 23.5N 55.5W 45 KT 50 MPH
60H 20/0600Z 24.7N 57.4W 50 KT 60 MPH
72H 20/1800Z 26.2N 59.0W 55 KT 65 MPH
96H 21/1800Z 29.0N 62.0W 65 KT 75 MPH
120H 22/1800Z 32.0N 62.5W 75 KT 85 MPH
FORECASTER LAMERS/BLAKE
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