525
WTNT45 KNHC 150250
TCDAT5
TROPICAL STORM ERIN DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
1100 PM AST THU AUG 14 2025
ERIN HAS INTENSIFIED TONIGHT. THE FIRST NOAA-P3 RECONNAISSANCE
MISSION INTO THE STORM FOUND THAT THE CENTER WAS A LITTLE MORE
EMBEDDED IN THE DEEP CONVECTION THAN EARLIER WITH A COMPACT WIND
FIELD PARTICULARLY STRONG ON THE EASTERN FLANK. TAIL DOPPLER RADAR
DATA FROM THE AIRCRAFT INDICATED THE CENTER IS STARTING TO BECOME
BETTER ALIGNED, THOUGH SOME RESIDUAL SOUTHWARD TILT WITH HEIGHT
STILL EXISTS, WHICH CAN ALSO BE SEEN ON A 2339 UTC GMI MICROWAVE
PASS. IN THE MOST RECENT LEG, PEAK 700-MB FLIGHT LEVEL WINDS FROM
THE NOAA AIRCRAFT WERE 69 KT IN THE NORTHEAST QUADRANT. THIS
VALUE REDUCES TO SURFACE WIND NEAR 60 KT, JUST SHY OF
HURRICANE INTENSITY.
ERIN IS NOW STARTING TO MOVE WEST-NORTHWESTWARD AT 285/15 KT. AN
EXTENSIVE MID-LEVEL RIDGE STRETCHED FROM OFF THE EASTERN UNITED
STATES COAST ALL THE WAY TO THE EASTERN ATLANTIC REMAINS IN PLACE
HELPING TO STEER THE STORM GENERALLY WEST-NORTHWESTWARD FOR AT LEAST
THE NEXT 2 TO 3 DAYS WITH IT GRADUALLY SLOWING DOWN. DURING THIS
TIME-SPAN, A MID-LATITUDE TROUGH MOVING INTO THE NORTHWESTERN
ATLANTIC IS EXPECTED TO DIG EQUATORWARD TO THE NORTHEAST OF BERMUDA,
WITH ANOTHER REINFORCING SHORTWAVE MOVING INTO ATLANTIC CANADA
TOWARDS THE END OF THE FORECAST PERIOD. THESE FEATURES SHOULD CREATE
A WEAKNESS IN THE SUBTROPICAL RIDGE THAT ERIN IS EXPECTED TO TURN
NORTHWESTWARD AND NORTH-NORTHWESTWARD INTO. THE LATEST TRACK
GUIDANCE WAS QUITE SIMILAR TO THE PRIOR CYCLE, JUST A LITTLE FASTER
THAN BEFORE TOWARDS THE END OF THE FORECAST PERIOD, AND ONLY SMALL
ADJUSTMENTS WERE MADE TO THE NHC FORECAST TRACK. THIS TRACK ROUGHLY
SPLITS THE LATEST FORECAST FROM THE GOOGLE DEEP MIND (GDMI) AND HCCA
CONSENSUS AID. STILL, THERE IS A HEALTHY AMOUNT OF SPREAD IN THE
GUIDANCE AND UNCERTAINTY REMAINS ABOUT WHAT IMPACTS ERIN MAY BRING
TO PORTIONS OF THE BAHAMAS, THE EAST COAST OF THE UNITED STATES, AND
BERMUDA IN THE LONG RANGE.
WITH ERIN'S CORE STRUCTURE IMPROVING THIS EVENING, THE STORM APPEARS
POISED TO INTENSIFY MORE QUICKLY IN THE SHORT TERM. RAPID
INTENSIFICATION PROBABILITIES HAVE INCREASED IN SHIPS GUIDANCE, WITH
NOW A 38-40 PERCENT CHANCE OF A 30 KT INCREASE IN THE NEXT 24 H. THE
ENVIRONMENT CONTINUES TO BECOME MORE THERMODYNAMICALLY FAVORABLE,
WITH ERIN CROSSING INTO 28C AND WARMER SEA-SURFACE TEMPERATURES, AND
MID-LEVEL MOISTURE INCREASING OVER THE FORECAST TIME PERIOD. THUS,
THE NHC INTENSITY FORECAST WILL SHOW MORE INTENSIFICATION OVER THE
NEXT 48-60 HOURS, AND ERIN IS NOW FORECAST TO BECOME A MAJOR
HURRICANE EARLIER AND PEAK AT 115 KT, CATEGORY 4 INTENSITY. AFTER
THAT TIME, THERE REMAINS EVIDENCE IN BOTH SHIPS GUIDANCE AND MODEL
FIELDS THAT NORTHWESTERLY VERTICAL WIND SHEAR COULD INCREASE OVER
THE SYSTEM. IN ADDITION, THERE IS A GOOD CHANCE ERIN MAY BEGIN TO
UNDERGO INNER-CORE STRUCTURAL CHANGES, LIKE EYEWALL REPLACEMENT
CYCLES, THAT COULD BROADEN ITS WIND FIELD BUT ALSO CAUSE ITS
INTENSITY TO PLATEAU. THUS, THE NHC INTENSITY FORECAST NOW SHOWS
SOME GRADUAL WEAKENING AFTER A PEAK INTENSITY IN 72 H, THOUGH THE
MODELS SHOW THE WIND RADII EXPANDING QUITE DRAMATICALLY IN THE DAY
3-5 PERIOD. THE LATEST NHC INTENSITY FORECAST IS A LITTLE ON THE
HIGH SIDE OF THE GUIDANCE, ESPECIALLY IN THE SHORT-TERM, BUT ENDS UP
NEAR THE CONSENSUS AIDS HCCA AND IVCN TOWARDS THE END OF THE
FORECAST PERIOD.
KEY MESSAGES:
1. HEAVY RAINFALL ACROSS THE NORTHERNMOST LEEWARD ISLANDS, THE U.S.
AND BRITISH VIRGIN ISLANDS, AS WELL AS SOUTHERN AND EASTERN PUERTO
RICO, MAY LEAD TO ISOLATED FLASH AND URBAN FLOODING, ALONG WITH
LANDSLIDES OR MUDSLIDES THIS WEEKEND INTO EARLY NEXT WEEK.
2. TROPICAL STORM CONDITIONS ARE POSSIBLE FOR PORTIONS OF THE
NORTHERN LEEWARD ISLANDS, WHERE TROPICAL STORM WATCHES ARE IN
EFFECT, BEGINNING ON SATURDAY AS THE CORE OF ERIN PASSES NORTH OF
THOSE ISLANDS. TROPICAL STORM CONDITIONS COULD ALSO OCCUR IN
PORTIONS OF THE VIRGIN ISLANDS AND PUERTO RICO LATER IN THE WEEKEND,
AND ADDITIONAL WATCHES MAY BE REQUIRED TONIGHT OR ON FRIDAY.
3. WHILE THERE IS STILL UNCERTAINTY IN WHAT IMPACTS MIGHT OCCUR IN
PORTIONS OF THE BAHAMAS, THE EAST COAST OF THE UNITED STATES, AND
BERMUDA NEXT WEEK, THE RISK OF DANGEROUS SURF AND RIP CURRENTS
ACROSS THE WESTERN ATLANTIC BASIN NEXT WEEK CONTINUES TO INCREASE.
FORECAST POSITIONS AND MAX WINDS
INIT 15/0300Z 17.1N 52.7W 60 KT 70 MPH
12H 15/1200Z 17.8N 55.2W 70 KT 80 MPH
24H 16/0000Z 18.6N 58.3W 80 KT 90 MPH
36H 16/1200Z 19.4N 61.0W 90 KT 105 MPH
48H 17/0000Z 20.3N 63.3W 100 KT 115 MPH
60H 17/1200Z 21.3N 65.4W 110 KT 125 MPH
72H 18/0000Z 22.4N 67.0W 115 KT 130 MPH
96H 19/0000Z 25.0N 69.4W 110 KT 125 MPH
120H 20/0000Z 28.0N 70.4W 105 KT 120 MPH
FORECASTER PAPIN
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