954
WTPZ44 KNHC 230243
TCDEP4
TROPICAL STORM NARDA DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP142025
900 PM CST MON SEP 22 2025
THE SATELLITE PRESENTATION OF NARDA HAS CONTINUED TO IMPROVE SINCE
THE PREVIOUS ADVISORY, WITH DEEP CONVECTION FEATURING CLOUD TOPS
COLDER THAN -80C BURSTING OVER THE LOW-LEVEL CENTER. A RECENT 0034
UTC WSFM MICROWAVE IMAGE CONFIRMS THE IMPROVED ORGANIZATION, SHOWING
NARDA BEGINNING TO DEVELOP AN INNER-CORE STRUCTURE. SUBJECTIVE
DVORAK ESTIMATES FROM TAFB AND SAB WERE BOTH 3.5/55 KT, WHILE
OBJECTIVE ESTIMATES FROM UW-CIMSS RANGED FROM 44 TO 60 KT. A BLEND
OF THESE DATA, ALONG WITH THE IMPROVED SATELLITE APPEARANCE,
SUPPORTS RAISING THE INITIAL INTENSITY TO 55 KT FOR THIS ADVISORY.
NARDA IS MOVING DUE WEST, OR 270 DEGREES, AT 11 KT. THIS MOTION IS
EXPECTED TO CONTINUE FOR THE NEXT SEVERAL DAYS AS THE CYCLONE IS
STEERED BY A STRENGTHENING SUBTROPICAL RIDGE TO ITS NORTH AND
NORTHWEST. BY LATE IN THE PERIOD, A MID-LEVEL LOW OVER SOUTHERN
CALIFORNIA IS FORECAST TO ERODE THE EASTERN PORTION OF THE RIDGE,
CAUSING THE CYCLONE TO SLOW DOWN AND TURN NORTHWESTWARD AROUND DAY
5. THE OFFICIAL FORECAST TRACK HAS BEEN ADJUSTED SLIGHTLY SOUTH OF
THE PREVIOUS PREDICTION DURING THE NEXT COUPLE OF DAYS TO ACCOUNT
FOR THE WESTWARD MOTION THAT HAS NOW BEGUN, BUT IT REMAINS VERY
CLOSE TO THE PRIOR FORECAST FROM DAY 3 ONWARD. THE TRACK FORECAST
FOLLOWS A BLEND OF THE HCCA, TVCE, AND FSSE CONSENSUS AIDS, AS WELL
AS THE GOOGLE DEEPMIND/NOAA EAGLE AI GUIDANCE.
NARDA WILL REMAIN EMBEDDED WITHIN A MOIST AIR MASS, OVER VERY WARM
WATERS, AND IN AN ENVIRONMENT OF LIGHT TO MODERATE EASTERLY SHEAR
DURING THE NEXT COUPLE OF DAYS. THESE FACTORS SHOULD SUPPORT STEADY
STRENGTHENING. THE LATEST GFS- AND ECMWF-BASED SHIPS GUIDANCE
INDICATES ABOUT A 50 PERCENT PROBABILITY OF A 25-KT INCREASE WITHIN
24 HOURS, AND THE INTENSITY FORECAST REFLECTS THIS. NARDA IS
EXPECTED TO BECOME A HURRICANE LATER TONIGHT OR EARLY TUESDAY AND
COULD APPROACH MAJOR HURRICANE STATUS WITHIN A COUPLE OF DAYS. BY
LATE IN THE FORECAST PERIOD, HOWEVER, NARDA WILL MOVE INTO AN
ENVIRONMENT WITH MID-LEVEL HUMIDITY BELOW 50 PERCENT AND OVER WATERS
COOLER THAN 26C, WHICH SHOULD RESULT IN STEADY TO RAPID WEAKENING BY
DAY 5. THE OFFICIAL INTENSITY FORECAST REMAINS NEAR THE UPPER END OF
THE GUIDANCE ENVELOPE AND IS MOST CLOSELY ALIGNED WITH THE SHIPS AND
HCCA AIDS.
FORECAST POSITIONS AND MAX WINDS
INIT 23/0300Z 15.9N 105.1W 55 KT 65 MPH
12H 23/1200Z 15.9N 106.8W 70 KT 80 MPH
24H 24/0000Z 15.8N 109.1W 80 KT 90 MPH
36H 24/1200Z 15.7N 111.4W 90 KT 105 MPH
48H 25/0000Z 15.6N 113.8W 95 KT 110 MPH
60H 25/1200Z 15.7N 116.4W 95 KT 110 MPH
72H 26/0000Z 16.1N 118.9W 95 KT 110 MPH
96H 27/0000Z 17.1N 122.9W 90 KT 105 MPH
120H 28/0000Z 18.7N 125.1W 70 KT 80 MPH
FORECASTER JELSEMA (CPHC)
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