444
WTNT42 KNHC 140248
TCDAT2
TROPICAL STORM LORENZO DISCUSSION NUMBER 4
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122025
1100 PM AST MON OCT 13 2025
SATELLITE IMAGES SHOWS THAT LORENZO IS PRODUCING A SMALL AREA OF
DEEP CONVECTION NEAR THE CENTER OF THE TROPICAL STORM, WITH THE BULK
OF ITS ASSOCIATED THUNDERSTORM ACTIVITY WELL TO THE EAST. WHILE THE
SYSTEM DOESN'T APPEAR THAT WELL ORGANIZED ON CONVENTIONAL SATELLITE,
WSF-M MICROWAVE IMAGES FROM A FEW HOURS AGO REVEALED THAT LORENZO
HAS A SMALL CENTRAL CORE WITH SOME CHARACTER. ADDITIONALLY, RECENT
SCATTEROMETER DATA INDICATED A LARGE AREA OF 45-KT WINDS WERE
PRESENT. THE INITIAL WIND SPEED IS SET TO 50 KT, ASSUMING SOME
UNDERSAMPLING BASED ON THE COARSE ASCAT RESOLUTION.
LORENZO IS MOVING NORTHWESTWARD AT 11 KT, AND THAT MOTION SHOULD
CONTINUE OVERNIGHT. A GRADUAL TURN TO THE NORTH AND NORTHEAST WITH
AN INCREASE IN FORWARD SPEED IS ANTICIPATED LATE TUESDAY INTO
WEDNESDAY DUE TO THE STORM MOVING AROUND THE NORTHWESTERN PERIPHERY
OF THE SUBTROPICAL RIDGE INTO A FASTER FLOW REGIME. THE BIGGEST
CHANGE TO NOTE TO THIS FORECAST IS THAT MOST OF THE GUIDANCE NOW
TURN THE SYSTEM TO THE EAST LATE THIS WEEK AND THEN TO THE SOUTH AS
THE CYCLONE, OR ITS REMNANTS, GET TRAPPED WITHIN THE SUBTROPICAL
RIDGE. LITTLE CHANGE WAS MADE TO THE PREVIOUS FORECAST DURING THE
FIRST COUPLE OF DAYS, THEN A LARGE EASTWARD AND SOUTHWARD ADJUSTMENT
WAS MADE AT LONG RANGE, RESULTING IN A SHARP EQUATORWARD HOOK OF
LORENZO THIS WEEKEND.
THE INTENSITY FORECAST IS QUITE CHALLENGING. AN UPPER-LEVEL LOW
THAT HAS BEEN SHEARING LORENZO IS FORECAST TO DROP TO THE
SOUTHWEST, RESULTING IN DECREASING SHEAR DURING THE NEXT COUPLE OF
DAYS. THIS SYNOPTIC EVOLUTION IS HISTORICALLY WELL KNOWN FOR
INTENSIFICATION GIVEN THE RECENT FORMATION OF THE SMALL INNER CORE
OVER WARM WATERS. HOWEVER, VERY DRY AIR IS PRESENT IN THE
ENVIRONMENT, AND LORENZO SHOULD EMBED ITSELF DEEP INTO A RECENT
SAHARAN AIR LAYER (SAL) OUTBREAK TO THE NORTH WITHIN A COUPLE OF
DAYS. THERE ARE CREDIBLE MODELS THAT RESPOND TO THESE FACTORS BY
WEAKENING THIS INTO A TROPICAL DEPRESSION IN A FEW DAYS, LIKE THE
HAFS-A/B, OR A CATEGORY 1/2 HURRICANE, LIKE THE HWRF/HMON. THE NEW
FORECAST SPLITS THESE EXTREMES, ENDING UP A BIT HIGHER THAN THE
PREVIOUS OFFICIAL FORECAST BUT NEAR THE HFIP CORRECTED CONSENSUS
MODEL HCCA. IT SHOULD BE EMPHASIZED THAT THIS IS A LOW-CONFIDENCE
PREDICTION FOR ALL OF THE CONDITIONS LISTED ABOVE AND THE CYCLONE'S
SMALL SIZE, MAKING IT SUSCEPTIBLE TO LARGE UPWARD OR DOWNWARD
CHANGES IN A SHORT PERIOD OF TIME.
FORECAST POSITIONS AND MAX WINDS
INIT 14/0300Z 16.2N 42.8W 50 KT 60 MPH
12H 14/1200Z 17.4N 43.9W 50 KT 60 MPH
24H 15/0000Z 19.3N 44.5W 50 KT 60 MPH
36H 15/1200Z 21.6N 44.2W 55 KT 65 MPH
48H 16/0000Z 24.3N 41.9W 60 KT 70 MPH
60H 16/1200Z 26.6N 39.0W 60 KT 70 MPH
72H 17/0000Z 29.0N 35.0W 55 KT 65 MPH
96H 18/0000Z 29.0N 28.9W 50 KT 60 MPH
120H 19/0000Z 26.0N 31.0W 45 KT 50 MPH...POST-TROPICAL
FORECASTER BLAKE
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