290
WTNT44 KNHC 270237
TCDAT4
POTENTIAL TROPICAL CYCLONE NINE DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092025
1100 PM EDT FRI SEP 26 2025
MANY THANKS TO THE CREW OF A NOAA P-3 HURRICANE HUNTER AIRCRAFT,
WHICH HAS BEEN FLYING A SURVEILLANCE MISSION IN THE DISTURBANCE THIS
EVENING. DROPSONDE DATA FROM THIS FLIGHT, AS WELL AS SURFACE
OBSERVATIONS FROM CUBA, SUGGEST THAT THE SYSTEM IS STILL A TROUGH
OF LOW PRESSURE, AND THE TROUGH AXIS IS A LITTLE FARTHER WEST THAN
PREVIOUSLY ESTIMATED. MAXIMUM WINDS REMAIN NEAR 30 KT, AND THE
PRESSURE HAS DROPPED SLIGHTLY TO 1007 MB BASED ON THE DROPSONDE
DATA.
THE CURRENT MOTION IS NOW ESTIMATED TO BE NORTHWESTWARD, OR 305/8
KT. THE SYSTEM IS EXPECTED TO SLOW DOWN AND TURN
NORTH-NORTHWESTWARD BY SATURDAY MORNING AND CONTINUE THAT TRAJECTORY
OVER THE WEEKEND, EMBEDDED IN THE SOUTHERLY FLOW BETWEEN A
DEEP-LAYER TROUGH OVER THE SOUTHEASTERN U.S. AND A RIDGE OVER THE
WEST-CENTRAL ATLANTIC. THE TRACK MODELS ARE IN GOOD AGREEMENT FOR
THE FIRST 3 DAYS OF THE FORECAST. THE NEW NHC FORECAST TRACK HAS
BEEN SHIFTED WESTWARD DURING THAT PERIOD, MAINLY DUE TO THE
WESTWARD ADJUSTMENT OF THE INITIAL POSITION, BUT IT IS ALSO A BIT
SLOWER THAN THE PREVIOUS PREDICTION BASED ON THE LATEST GUIDANCE.
THERE IS SIGNIFICANTLY MORE UNCERTAINTY IN THE TRACK FORECAST AFTER
DAY 3, BUT AT THE VERY LEAST IT APPEARS THAT THE SYSTEM WILL SLOW
DOWN CONSIDERABLY AND PERHAPS EVEN STALL NEAR THE COAST OF SOUTH
CAROLINA. INTERESTINGLY, THE 18Z GFS AND ECMWF SOLUTIONS NO LONGER
SHOW THE SYSTEM MOVING INLAND OVER THE SOUTHEASTERN U.S. AND HAVE
COME MORE IN LINE WITH THEIR RESPECTIVE ENSEMBLE MEANS, AS WELL AS
THE HCCA CONSENSUS AID AND GOOGLE DEEPMIND MEAN. FOR THIS NEW
FORECAST, A VERY SLOW, NEARLY STATIONARY MOTION IS SHOWN ON DAY 5,
WITH PERHAPS SOME HINT OF THE START OF A NORTHEASTWARD MOTION.
THAT SAID, EVEN IF THE SYSTEM STALLS JUST OFFSHORE, IT WOULD STILL
BE LARGE ENOUGH TO CAUSE WIND AND COASTAL FLOODING IMPACTS ALONG
THE SOUTHEASTERN U.S. COAST, AS WELL AS HEAVY RAINFALL/FLOODING
CONCERNS IN INLAND AREAS.
GLOBAL MODELS SUGGEST IT WILL STILL TAKE ANOTHER 24 HOURS OR SO FOR
THE SYSTEM TO DEVELOP A WELL-DEFINED CIRCULATION AND ORGANIZED
CONVECTION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. AFTER THAT
TIME, STRENGTHENING IS EXPECTED WHILE THE SYSTEM MOVES OVER VERY
WARM WATERS AND WITHIN A DIVERGENT UPPER-LEVEL ENVIRONMENT. THE
NHC FORECAST CONTINUES TO SHOW THE SYSTEM REACHING HURRICANE
STRENGTH IN 3-4 DAYS, WHICH IS CLOSE TO THE HCCA AND IVCN CONSENSUS
AIDS. STRONGER SHEAR, AND POSSIBLY THE BEGINNINGS OF AN
INTERACTION WITH A NEARBY FRONTAL BOUNDARY, COULD CAUSE SOME
WEAKENING BY DAY 5.
KEY MESSAGES:
1. THE DISTURBANCE IS FORECAST TO BECOME A TROPICAL STORM THIS
WEEKEND AND BRING TROPICAL STORM CONDITIONS TO PORTIONS OF THE
CENTRAL AND NORTHWESTERN BAHAMAS, WHERE TROPICAL STORM WARNINGS AND
WATCHES, RESPECTIVELY, ARE IN EFFECT. RAINFALL ASSOCIATED WITH
THIS SYSTEM WILL IMPACT EASTERN CUBA, HISPANIOLA, JAMAICA, AND THE
BAHAMAS THROUGH THE WEEKEND.
2. THERE IS AN INCREASING THREAT OF HEAVY RAINFALL EARLY NEXT
WEEK FROM COASTAL GEORGIA THROUGH THE CAROLINAS AND INTO THE
SOUTHERN MID-ATLANTIC STATES, WHICH COULD CAUSE FLASH, URBAN, AND
RIVER FLOODING.
3. THE SYSTEM IS EXPECTED TO BE AT OR NEAR HURRICANE INTENSITY
WHEN IT APPROACHES THE SOUTHEAST U.S. COAST EARLY NEXT WEEK, WHERE
THERE IS A RISK OF STORM SURGE AND WIND IMPACTS. RESIDENTS IN THAT
AREA SHOULD MONITOR UPDATES TO THE FORECAST AND ENSURE THEY HAVE
THEIR HURRICANE PLAN IN PLACE.
FORECAST POSITIONS AND MAX WINDS
INIT 27/0300Z 21.5N 76.0W 30 KT 35 MPH...POTENTIAL TROP CYCLONE
12H 27/1200Z 22.2N 76.6W 30 KT 35 MPH...POTENTIAL TROP CYCLONE
24H 28/0000Z 23.3N 77.0W 30 KT 35 MPH...TROPICAL CYCLONE
36H 28/1200Z 24.8N 77.5W 35 KT 40 MPH
48H 29/0000Z 26.3N 77.9W 45 KT 50 MPH
60H 29/1200Z 28.2N 78.3W 55 KT 65 MPH
72H 30/0000Z 30.1N 78.9W 65 KT 75 MPH
96H 01/0000Z 32.0N 79.2W 65 KT 75 MPH
120H 02/0000Z 32.4N 78.7W 55 KT 65 MPH
FORECASTER BERG
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