173
WTNT45 KNHC 112120
TCDAT5
TROPICAL STORM ERIN DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
500 PM AST MON AUG 11 2025
ERIN'S STRUCTURE THIS AFTERNOON LOOKS LIKE A TROPICAL CYCLONE THAT
IS STRUGGLING WITH THE NEARBY THERMODYNAMIC ENVIRONMENT, WITH ONLY A
SMALL PATCH OF DEEP CONVECTION PULSING NEAR THE ESTIMATED CENTER. IT
IS POSSIBLE SOME DRY AIR MAY HAVE BEEN ENTRAINED INTO THE SMALL
CIRCULATION EARLIER TODAY, CAUSING ITS DEGRADED APPEARANCE. FOR NOW,
SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES HAVEN'T CHANGED MUCH
FROM THE PRIOR ADVISORY, HOVERING IN THE 35-42 KT RANGE, SO THE
INITIAL INTENSITY IS HELD AT 40 KT THIS ADVISORY.
ERIN IS STILL MOVING QUICKLY OFF TO THE WEST, WITH THE LATEST
ESTIMATED MOTION AT 270/18 KT. THIS GENERAL MOTION WITH A GRADUAL
SLOWDOWN IN FORWARD SPEED IS EXPECTED OVER THE NEXT 48-72 H AS THE
SYSTEM REMAINS STEERED BY A PROMINENT MID-LEVEL RIDGE TO ITS NORTH.
THIS RIDGE IS FORECAST TO MOVE ALONG WITH THE STORM. TOWARDS THE END
OF THE FORECAST PERIOD, THE RIDGE SHOULD ERODE SOME AND SHIFT
NORTHEASTWARD OF ERIN, WHICH SHOULD ALLOW THE CYCLONE TO BEGIN
GAINING LATITUDE BY 120 H. THE DETERMINISTIC TRACK GUIDANCE
GENERALLY AGREES ON THIS TRACK EVOLUTION, AND WAS ONLY A LITTLE
FASTER THAN THE PRIOR CYCLE. THE NHC TRACK FORECAST IS QUITE SIMILAR
TO THE PREVIOUS ONE, AND LIES CLOSEST TO A BLEND OF THE LATEST 12Z
GFS AND ECMWF FORECASTS (GFEX). HOWEVER, IT SHOULD BE NOTED THAT
SPREAD IN THE ENSEMBLE SOLUTIONS STARTS TO INCREASE SUBSTANTIALLY BY
THE END OF THE FORECAST PERIOD, LIKELY RELATED TO THE MAGNITUDE OF
RIDGING THAT REMAINS POLEWARD OF ERIN IN FIVE DAYS.
AS MENTIONED IN THE PRIOR ADVISORY, WHILE VERTICAL WIND SHEAR OVER
ERIN IS FORECAST TO REMAIN LOW FOR THE NEXT 3-4 DAYS, THE
THERMODYNAMIC ENVIRONMENT IS LESS FAVORABLE IN THE SHORT-TERM, WITH
SEA-SURFACE TEMPERATURES BETWEEN 26-27C, AND PLENTY OF STABLE
STRATOCUMULUS CLOUDS ALONG THE FORECAST PATH OF THE STORM.
NONETHELESS, MOST OF THE HURRICANE-REGIONAL MODELS SHOW ERIN SLOWLY
INTENSIFYING DURING THIS PERIOD. AS THE STORM MOVES INTO WARMER
SEA-SURFACE TEMPERATURES AFTER 48 H, A FASTER RATE OF
INTENSIFICATION IS ANTICIPATED, AS LONG AS THE SHEAR REMAINS LOW AND
IF ERIC IS ABLE TO MIX OUT SOME OF THE DRY AIR IN ITS VICINITY. THE
INTENSITY GUIDANCE IS ACTUALLY A LITTLE HIGHER THAN THE PREVIOUS
CYCLE BEYOND 60 H, BUT THE LATEST NHC INTENSITY FORECAST IS SIMILAR
TO THE PRIOR ONE, SHOWING ERIN BECOMING A HURRICANE IN 60 H AND A
MAJOR HURRICANE IN 120 H. THIS FORECAST IS NOW A LITTLE LOWER THAN
HAFS-A/B, HMON, AND HWRF AT THE END OF THE FORECAST. THERE ARE SOME
INDICATIONS THERE MIGHT SOME NORTHWESTERLY SHEAR IMPINGING ON THE
CYCLONE IN 96-120 H, SO I ELECTED TO STAY UNDER THESE AIDS FOR THIS
CYCLE.
KEY MESSAGES:
1. IT IS STILL TOO EARLY TO DETERMINE WHAT IMPACTS, IF ANY, ERIN MAY
BRING TO THE NORTHERN LEEWARD ISLANDS, BERMUDA, OR THE EAST COAST OF
THE UNITED STATES. AS WE APPROACH THE CLIMATOLOGICAL PEAK OF THE
HURRICANE SEASON, IT IS AN OPPORTUNE TIME TO ENSURE YOUR
PREPAREDNESS PLANS ARE IN PLACE.
FORECAST POSITIONS AND MAX WINDS
INIT 11/2100Z 17.4N 30.3W 40 KT 45 MPH
12H 12/0600Z 17.4N 33.4W 45 KT 50 MPH
24H 12/1800Z 17.3N 37.1W 50 KT 60 MPH
36H 13/0600Z 17.1N 40.5W 55 KT 65 MPH
48H 13/1800Z 17.3N 44.0W 60 KT 70 MPH
60H 14/0600Z 17.8N 47.0W 70 KT 80 MPH
72H 14/1800Z 18.5N 50.0W 80 KT 90 MPH
96H 15/1800Z 20.0N 55.6W 95 KT 110 MPH
120H 16/1800Z 22.0N 60.5W 100 KT 115 MPH
FORECASTER PAPIN
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