050
WTNT45 KNHC 122033
TCDAT5
TROPICAL STORM ERIN DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
500 PM AST TUE AUG 12 2025
NOT MUCH HAS CHANGED WITH ERIN'S STRUCTURE SINCE THIS MORNING. A
LITTLE BIT OF CONVECTION HAS FORMED OVER THE LOW-LEVEL CENTER, BUT
OVERALL THE SHOWER AND THUNDERSTORM ACTIVITY REMAINS LIMITED. DUE
TO THE CYCLONE'S FAST MOTION, IT IS ASSUMED THAT THE MAXIMUM WINDS
HAVE NOT DECREASED, SO THE INITIAL INTENSITY IS HELD AT 40 KT.
A QUICK SOUTH-OF-DUE-WEST MOTION IS EXPECTED TO CONTINUE FOR THE
NEXT 24 HOURS, WITH STRONG LOW- TO MID-LEVEL RIDGING LOCATED TO THE
NORTH OVER THE CENTRAL AND EASTERN ATLANTIC. GLOBAL MODELS
INDICATE THAT RIDGE IS LIKELY TO WEAKEN IN A FEW DAYS, WHICH SHOULD
CAUSE ERIN TO BEGIN MOVING WEST-NORTHWESTWARD IN ABOUT 60 HOURS,
WITH THAT MOTION CONTINUING THROUGH DAY 5 (SUNDAY). IN CONTRAST TO
THIS MORNING, THERE WERE NO MAJOR SHIFTS IN THE LATEST TRACK MODEL
SIMULATIONS. THE NEW NHC FORECAST HAS BEEN PLACED ALONG THE
SOUTHERN PART OF THE GUIDANCE ENVELOPE, LYING CLOSEST TO THE HFIP
CORRECTED CONSENSUS (HCCA) AND GOOGLE DEEP MIND (GDM) MODELS. THIS
RESULTS IN THE NEW NHC TRACK FORECAST HAVING NO APPRECIABLE
DIFFERENCE FROM THE MORNING FORECAST, WITH NO ADDITIONAL SHIFTING
TOWARD THE NORTHERN LEEWARD ISLANDS. KEEP IN MIND THAT NHC TRACK
FORECASTS HAVE AN AVERAGE ERROR OF 120-180 N MI (150-215 STATUTE
MILES) AT DAYS 4 AND 5, AND FUTURE ADJUSTMENTS IN THE FORECAST ARE
STILL POSSIBLE.
IT MAY STILL TAKE ERIN A LITTLE BIT OF TIME TO PRODUCE MORE
SIGNIFICANT DEEP CONVECTION WHILE IT CONTINUES TO MOVE OVER
MARGINALLY WARM SEA SURFACE TEMPERATURES AND THROUGH AN ATMOSPHERE
OF ONLY MODEST INSTABILITY AND MOISTURE. SEA SURFACE TEMPERATURES
AND INSTABILITY BEGIN TO INCREASE AFTER ABOUT 24 HOURS, WHICH
SHOULD ALLOW ERIN TO PRODUCE MORE ORGANIZED CONVECTION. GIVEN THAT
THE CYCLONE ALREADY HAS A WELL-DEFINED LOW-LEVEL STRUCTURE, THIS
COULD RESULT IN SIGNIFICANT INTENSIFICATION TOWARD THE LATTER PART
OF THE FORECAST PERIOD, ESPECIALLY SINCE THE GLOBAL MODELS SHOW AN
UPPER-LEVEL ANTICYCLONE BUILDING OVER THE STORM. THE NHC INTENSITY
FORECAST IS NEAR THE LOWER END OF THE GUIDANCE DURING THE FIRST FEW
DAYS OF THE FORECAST, BUT THEN FALLS IN LINE CLOSER TO THE
CONSENSUS AIDS IN 3-5 DAYS. IN THIS SCENARIO, ERIN WOULD STILL
BECOME A MAJOR HURRICANE IN ABOUT 4 OR 5 DAYS.
KEY MESSAGES:
1. ERIN COULD MOVE CLOSE ENOUGH TO THE NORTHERN LEEWARD ISLANDS,
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 12/2100Z 17.0N 38.3W 40 KT 45 MPH
12H 13/0600Z 16.6N 40.8W 40 KT 45 MPH
24H 13/1800Z 16.4N 43.9W 45 KT 50 MPH
36H 14/0600Z 16.6N 46.8W 50 KT 60 MPH
48H 14/1800Z 17.2N 49.9W 60 KT 70 MPH
60H 15/0600Z 17.9N 52.9W 75 KT 85 MPH
72H 15/1800Z 18.6N 56.0W 85 KT 100 MPH
96H 16/1800Z 20.0N 61.5W 95 KT 110 MPH
120H 17/1800Z 22.2N 65.7W 100 KT 115 MPH
FORECASTER BERG
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