303
WTNT42 KNHC 250246
TCDAT2
TROPICAL STORM GONZALO DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072026
200 AM CVT FRI SEP 25 2026
SATELLITE IMAGERY INDICATES THAT THE AREA OF LOW PRESSURE (INVEST
AL90) HAS DEVELOPED A CLOSED, ALBEIT SLIGHTLY ELONGATED, LOW-LEVEL
CIRCULATION THIS MORNING ALONG WITH ORGANIZED DEEP CONVECTION.
THIS CONVECTION IS CURRENTLY DISPLACED MAINLY OVER THE EASTERN AND
SOUTHERN SEMICIRCLES OF THE CIRCULATION DUE TO MODERATE WESTERLY
VERTICAL WIND SHEAR. RECENT SCATTEROMETER DATA SHOW MAXIMUM WINDS
NEAR 40 KT IN THE NORTHEASTERN QUADRANT, AND TAFB PROVIDED A
SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATE OF T2.5/35 KT. BASED
ON THESE DATA, ADVISORIES ARE BEING INITIATED ON TROPICAL STORM
GONZALO WITH AN INITIAL INTENSITY OF 40 KT. A TROPICAL STORM WARNING
HAS BEEN ISSUED FOR ALL THE CABO VERDE ISLANDS.
THE INITIAL MOTION IS SOMEWHAT UNCERTAIN GIVEN THE RECENT FORMATION
OF THE CENTER, BUT THE BEST ESTIMATE IS 330/7 KT. GONZALO IS
EXPECTED TO MOVE NORTH-NORTHWESTWARD DURING THE NEXT COUPLE OF DAYS,
STEERED BY THE FLOW OF A DEEP MID-LEVEL TROUGH OVER THE EASTERN
ATLANTIC. AS THIS TROUGH LIFTS NORTHEASTWARD LATER IN THE FORECAST
PERIOD, THE CYCLONE WILL BE LEFT BEHIND IN A VERY WEAK STEERING
ENVIRONMENT, CAUSING IT TO DRIFT SLOWLY OVER THE EASTERN ATLANTIC.
ON THE FORECAST TRACK, THE CENTER WILL PASS NEAR OR OVER PORTIONS OF
THE CABO VERDE ISLANDS TODAY AND TONIGHT. TRACK GUIDANCE IS IN
FAIRLY GOOD AGREEMENT IN THE SHORT TERM, THOUGH CROSS- AND
ALONG-TRACK DIFFERENCES EMERGE BEYOND DAY 2. THE OFFICIAL NHC TRACK
FORECAST LIES NEAR THE HCCA CORRECTED CONSENSUS AND THE TVCN SIMPLE
CONSENSUS AIDS.
GONZALO IS CURRENTLY LOCATED WITHIN A MARGINALLY CONDUCIVE
ENVIRONMENT THAT COULD ALLOW FOR SOME SLIGHT STRENGTHENING,
CHARACTERIZED BY SEA SURFACE TEMPERATURES NEAR 27-28C AND MID-LEVEL
RELATIVE HUMIDITY VALUES AROUND 60 PERCENT. IN ABOUT 24 HOURS,
VERTICAL WIND SHEAR IS FORECAST TO INCREASE TO MODERATE-TO-STRONG
LEVELS. THIS INCREASE IN SHEAR, COMBINED WITH COOLING SSTS AND A
PROGRESSIVELY DRIER MID-LEVEL ENVIRONMENT, WILL CAUSE A GRADUAL
WEAKENING TREND. THE NHC INTENSITY FORECAST LIES NEAR THE HCCA
CORRECTED CONSENSUS AID. GLOBAL MODEL SIMULATED INFRARED SATELLITE
IMAGERY DEPICTS GONZALO LOSING ORGANIZED DEEP CONVECTION IN ABOUT 3
DAYS, AND THE FORECAST SHOWS THE SYSTEM BECOMING A POST-TROPICAL
REMNANT LOW AT THAT TIME, AND REMAINING A REMNANT LOW THROUGH THE
REMAINDER OF THE FORECAST PERIOD.
KEY MESSAGES:
1. TROPICAL STORM CONDITIONS ARE EXPECTED TO SPREAD ACROSS PORTIONS
OF THE CABO VERDE ISLANDS, WHERE A TROPICAL STORM WARNING IS IN
EFFECT, LATER TODAY AND WILL CONTINUE THROUGH TONIGHT.
2. HEAVY RAINS FROM GONZALO COULD AFFECT THE EASTERN ISLANDS OF CABO
VERDE AND THE WESTERN COAST OF AFRICA BETWEEN GUINEA-BISSAU TO
SENEGAL TODAY THROUGH SATURDAY. AREAS OF FLASH FLOODING WILL BE
POSSIBLE ALONG THE WESTERN COAST OF AFRICA WITH SOME ISOLATED FLASH
FLOOD CONCERNS FOR THE EASTERN ISLANDS OF CABO VERDE.
FORECAST POSITIONS AND MAX WINDS
INIT 25/0300Z 13.2N 22.1W 40 KT 45 MPH
12H 25/1200Z 14.2N 22.6W 45 KT 50 MPH
24H 26/0000Z 15.6N 23.2W 45 KT 50 MPH
36H 26/1200Z 17.2N 23.5W 40 KT 45 MPH
48H 27/0000Z 18.7N 23.9W 35 KT 40 MPH
60H 27/1200Z 19.8N 24.2W 30 KT 35 MPH
72H 28/0000Z 20.2N 24.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 29/0000Z 20.9N 24.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 30/0000Z 21.7N 26.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
FORECASTER KELLY
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