759
WTNT45 KNHC 160258
TCDAT5
HURRICANE ERIN DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025
1100 PM AST FRI AUG 15 2025
ERIN APPEARS TO BE STARTING A PERIOD OF RAPID INTENSIFICATION
TONIGHT. THE STRUCTURE ON SATELLITE IMAGERY HAS IMPROVED QUITE
DRAMATICALLY, WITH A SMALL EYE BECOMING MORE APPARENT ON INFRARED
SATELLITE IMAGES WITHIN A SMALL BUT COLD CENTRAL DENSE OVERCAST.
GOES-19 1-MINUTE IMAGERY ALSO SHOWS CONVECTIVE HOT TOWERS ROTATING
CYCLONICALLY AROUND, HELPING TO MAKE THE HURRICANE'S CORE MORE
AXIS-SYMMETRIC. WE HAVE HAD A WEALTH OF DATA FROM BOTH THE NOAA AND
AIR FORCE RESERVE HURRICANE HUNTERS THIS EVENING. THE TAIL DOPPLER
RADAR DATA ON BOARD THE NOAA-P3 SHOWED THAT THE WIND FIELD HAS
BECOME MUCH BETTER ORGANIZED, ESPECIALLY IN THE NORTHERN
SEMI-CIRCLE, WITH TILT DIAGNOSTICS SHOWING ERIN'S DEEP-LAYER
CIRCULATION NOW VERTICALLY ALIGNED. WITHIN THE PAST HOUR, THE AIR
FORCE C-130 AIRCRAFT FOUND 700-MB FLIGHT-LEVEL WINDS OF 92 KT IN THE
NORTHWESTERN QUADRANT. THIS REDUCES TO A SUSTAINED WIND OF 85 KT,
MAKING ERIN A CATEGORY 2 HURRICANE.
THE HURRICANE MOVED A LITTLE RIGHT OF TRACK EARLIER THIS EVENING,
BUT SMOOTHING OUT THE WOBBLES, THE LATEST MOTION STILL APPEARS TO BE
WEST-NORTHWESTWARD AT 290/16 KT. NOT MUCH HAS CHANGED WITH THE TRACK
PHILOSOPHY, WITH A LARGE SUBTROPICAL ANTICYCLONE
HELPING TO STEER ERIN OFF TO THE WEST-NORTHWEST FOR AT LEAST THE
NEXT 24-48 HOURS. THEREAFTER, A WEAKNESS IN THIS RIDGE BEGINS TO
DEVELOP, THANKS IN PART TO A SERIES OF DIGGING SHORTWAVES ALONG A
BROAD LONGWAVE TROUGH CENTERED JUST WEST OF ATLANTIC CANADA. THIS
EVOLUTION IN THE SYNOPTIC PATTERN SHOULD ALLOW ERIN TO TURN
NORTHWESTWARD AND THEN NORTHWARD BY THE END OF THE FORECAST PERIOD.
THE TRACK GUIDANCE REMAINS IN PRETTY GOOD AGREEMENT FOR THE FIRST
2-3 DAYS OF THE PERIOD, BUT ACROSS-TRACK SPREAD DOES INCREASE BY DAY
5, WITH THE ECMWF MODEL ON THE LEFT SIDE OF THE GUIDANCE ENVELOPE,
AND THE GFS ON THE RIGHT SIDE. THE LATEST NHC TRACK FORECAST IS
QUITE SIMILAR TO THE PRIOR ONE, AND ELECTS TO SPLIT THE DIFFERENCE
BETWEEN THESE SOLUTIONS, CLOSE TO THE HCCA AND GDMI TRACK SOLUTIONS.
IN THE SHORT-TERM, ALL FACTORS APPEAR FAVORABLE FOR ERIN TO
INTENSIFY, LIKELY RAPIDLY, OVER THE NEXT DAY OR TWO. WITH THE
DEVELOPMENT OF A SMALL INNER CORE, LOW SHEAR, WARM SEA-SURFACE
TEMPERATURES, AND AMPLE MID-LEVEL MOISTURE. DTOPS GUIDANCE SHOWS A
GREATER THAN 75 PERCENT CHANCE OF A 30 KT INCREASE IN INTENSITY OVER
THE NEXT 24 H, AND THE LATEST NHC INTENSITY FORECAST NOW SHOWS THAT
AMOUNT OF INTENSIFICATION OVER THE NEXT DAY, BRINGING ERIN TO
CATEGORY 4 INTENSITY BY TOMORROW NIGHT, AND PEAKING AT 125 KT IN 36
H. THE TRICKY PART OF THE FORECAST COMES AFTER THE NEXT DAY, WHERE
IT SEEMS LIKELY THERE WILL BE SOME INNER-CORE FLUCTUATIONS DUE TO
EYEWALL REPLACEMENT CYCLES, WHICH ARE DIFFICULT TO PREDICT WITH MUCH
LEAD TIME. IN ADDITION, THE MODELS CONTINUE TO SHOW THE POTENTIAL
FOR AN INCREASE IN NORTHWESTERLY VERTICAL WIND SHEAR TO 20-30 KT AT
48-72 HOURS. IN FACT, THE HAFS-A/B SIMULATED SATELLITE IMAGERY SHOW
A SIGNIFICANT DEGRADATION IN STRUCTURE OVER THIS TIME PERIOD, SO THE
NHC INTENSITY FORECAST NOW SHOWS A LITTLE WEAKENING BEYOND 36 H, AND
IT COULD WEAKEN MORE IF THESE HURRICANE-REGIONAL MODELS VERIFY.
REGARDLESS, THE COMBINATION OF EYEWALL REPLACEMENT CYCLES AND
VERTICAL WIND SHEAR WILL LIKELY LEAD TO A DRAMATIC EXPANSION OF THE
WIND FIELD OF ERIN, MAKING IT A LARGE AND POWERFUL HURRICANE TOWARDS
THE END OF THE FORECAST.
KEY MESSAGES:
1. HEAVY RAINFALL TONIGHT THROUGH SUNDAY ACROSS THE NORTHERN LEEWARD
ISLANDS, THE VIRGIN ISLANDS, AND PUERTO RICO MAY LEAD TO ISOLATED
AND LOCALLY CONSIDERABLE FLASH AND URBAN FLOODING, ALONG WITH
LANDSLIDES OR MUDSLIDES.
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. GUSTS TO TROPICAL STORM FORCE ARE POSSIBLE IN
RAINBANDS OVER PORTIONS OF THE VIRGIN ISLANDS AND PUERTO RICO LATER
IN THE WEEKEND.
3. WHILE THE THREAT OF DIRECT IMPACTS IN THE BAHAMAS AND ALONG THE
EAST COAST OF THE UNITED STATES APPEARS TO BE GRADUALLY DECREASING,
THERE WILL STILL BE A SIGNIFICANT RISK OF DANGEROUS SURF AND RIP
CURRENTS ALONG WESTERN ATLANTIC BEACHES NEXT WEEK.
4. INTERESTS IN BERMUDA SHOULD CONTINUE TO MONITOR THE PROGRESS OF
ERIN SINCE THERE IS STILL A RISK OF STRONG WINDS, HEAVY RAINFALL,
AND HIGH SURF BY THE MIDDLE PART OF NEXT WEEK.
FORECAST POSITIONS AND MAX WINDS
INIT 16/0300Z 19.5N 59.5W 85 KT 100 MPH
12H 16/1200Z 20.2N 61.6W 100 KT 115 MPH
24H 17/0000Z 20.9N 64.2W 115 KT 130 MPH
36H 17/1200Z 21.7N 66.3W 125 KT 145 MPH
48H 18/0000Z 22.9N 67.9W 120 KT 140 MPH
60H 18/1200Z 24.0N 68.9W 115 KT 130 MPH
72H 19/0000Z 25.6N 69.8W 110 KT 125 MPH
96H 20/0000Z 28.9N 70.5W 105 KT 120 MPH
120H 21/0000Z 33.5N 69.0W 100 KT 115 MPH
FORECASTER PAPIN
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