082
WTNT45 KNHC 131435
TCDAT5
TROPICAL STORM ERIN DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
1100 AM AST WED AUG 13 2025
ERIN CONTINUES TO HAVE A RAGGED OVERALL APPEARANCE, WITH ONE BURST
OF CONVECTION JUST SOUTHWEST OF THE CENTER AND SKELETAL CONVECTIVE
BANDS ELSEWHERE IN THE NORTHWESTERN SEMICIRCLE. VARIOUS SUBJECTIVE
AND OBJECTIVE SATELLITE INTENSITY ESTIMATES ARE IN THE 30-45 KT
RANGE, AND THESE HAVE CHANGED LITTLE OVER THE PAST SEVERAL HOURS.
A JUST-RECEIVED SCATTEROMETER OVERPASS SHOWS WINDS NEAR 40 KT JUST
NORTH OF THE CENTER, AND BASED ON THESE DATA THE INITIAL INTENSITY
IS HELD AT 40 KT.
ERIN CONTINUES TO STRUGGLE TO INTENSIFY, LIKELY DUE TO ITS TRACK
OVER PERSISTENT SEA SURFACE TEMPERATURES OF 26-27C AND ENTRAINMENT
OF DRY AND STABLE AIR. THE FORECAST TRACK KEEPS THE SYSTEM OVER
THESE MARGINAL SSTS FOR ANOTHER 24 H OR SO, FOLLOWED BY A MOTION
OVER INCREASING SSTS THAT REACH 29-30C BY THE END OF THE FORECAST
PERIOD. THE CYCLONE IS CURRENTLY IN A FAVORABLE LOW- TO
MODERATE-SHEAR ENVIRONMENT, AND THIS IS LIKELY TO CONTINUE FOR THE
NEXT 72 H. THIS EVOLUTION SHOULD ALLOW ERIN TO SIGNIFICANTLY
INTENSIFY, WITH THE CYCLONE FORECAST TO BECOME A HURRICANE BY 48 H
AND A MAJOR HURRICANE BY 96 HR. AFTER 72-96 H, ERIN MAY ENCOUNTER
INCREASED NORTHERLY SHEAR AS IT TRACKS TO THE NORTHEAST OF A
LARGE UPPER-LEVEL ANTICYCLONE FORECAST TO FORM NEAR HISPANIOLA AND
THE SOUTHEASTERN BAHAMAS. ALTHOUGH THE STRENGTH OF SHEAR THE CYCLONE
WILL ENCOUNTER IS UNCERTAIN, THE INTENSITY GUIDANCE SUGGESTS A LOWER
RATE OF INTENSIFICATION AT THAT TIME. THE NEW INTENSITY FORECAST IS
LITTLE CHANGED FROM THE PREVIOUS FORECAST AND IS IN BEST AGREEMENT
WITH THE INTENSITY CONSENSUS.
THE INITIAL MOTION IS NOW 265/15 KT. WHILE A STRONG LOW- TO
MID-LEVEL RIDGE CURRENTLY IS SITUATED TO THE NORTH OF ERIN, IN A DAY
OR TWO A SLIGHT WEAKNESS IS FORECAST TO DEVELOP IN THIS RIDGE NEAR
65W LONGITUDE. THIS SHOULD CAUSE THE TROPICAL CYCLONE TO TURN
WEST-NORTHWESTWARD AFTER 24 H, WITH SOME DECREASE IN FORWARD SPEED
AFTER 72 H. AFTER 96 H, A DEVELOPING BREAK IN THE RIDGE NEAR THE
SOUTHEASTERN COAST OF THE UNITED STATES SHOULD LEAD TO A
NORTHWESTWARD MOTION. THE TRACK GUIDANCE IS IN FAIRLY GOOD
AGREEMENT, AND THE OFFICIAL FORECAST ON THE SOUTHERN SIDE OF THE
GUIDANCE ENVELOPE BETWEEN THE HCCA CORRECTED CONSENSUS AND THE OTHER
CONSENSUS MODELS. THE NEW TRACK IS SIMILAR TO THE PREVIOUS TRACK
THROUGH 72 H AND A LITTLE WEST OF THE PREVIOUS TRACK THEREAFTER.
USERS ARE REMINDED THAT NHC TRACK FORECASTS HAVE AN AVERAGE ERROR OF
150 TO 215 MILES AT DAYS 4 AND 5, AND FUTURE ADJUSTMENTS TO THE
FORECAST ARE STILL POSSIBLE.
KEY MESSAGES:
1. ERIN COULD MOVE CLOSE ENOUGH TO THE NORTHERN LEEWARD ISLANDS, THE
VIRGIN ISLANDS, AND PUERTO RICO OVER THE WEEKEND TO PRODUCE SOME
IMPACTS ON THOSE ISLANDS. HOWEVER, THE MAGNITUDE OF THOSE IMPACTS
IS STILL NOT KNOWN, AND INTERESTS THERE SHOULD CONTINUE TO MONITOR
THE PROGRESS OF THIS STORM.
2. THERE IS EVEN GREATER UNCERTAINTY IN WHAT IMPACTS MIGHT OCCUR IN
PORTIONS OF THE GREATER ANTILLES, THE BAHAMAS, THE EAST COAST OF
THE UNITED STATES, AND BERMUDA NEXT WEEK. AS WE APPROACH THE
CLIMATOLOGICAL PEAK OF THE HURRICANE SEASON, THIS IS AN OPPORTUNE
TIME TO ENSURE YOUR PREPAREDNESS PLANS ARE IN PLACE.
FORECAST POSITIONS AND MAX WINDS
INIT 13/1500Z 16.3N 43.4W 40 KT 45 MPH
12H 14/0000Z 16.3N 45.6W 45 KT 50 MPH
24H 14/1200Z 16.6N 48.6W 50 KT 60 MPH
36H 15/0000Z 17.4N 51.5W 55 KT 65 MPH
48H 15/1200Z 18.2N 54.3W 65 KT 75 MPH
60H 16/0000Z 19.0N 57.2W 75 KT 85 MPH
72H 16/1200Z 19.9N 60.0W 85 KT 100 MPH
96H 17/1200Z 21.7N 64.6W 100 KT 115 MPH
120H 18/1200Z 23.9N 67.3W 105 KT 120 MPH
FORECASTER BEVEN
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