846
WTNT45 KNHC 090250
TCDAT5
TROPICAL STORM JERRY DISCUSSION NUMBER 7
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102025
1100 PM AST WED OCT 08 2025
A VERY LARGE AND COLD CONVECTIVE BURST HAS FORMED NEAR AND TO THE
EAST OF JERRY THIS EVENING, WITH CLOUD TOP TEMPERATURES BELOW -80 C
AND PLENTY OF ONGOING LIGHTNING NEAR THE OVERSHOOTING TOPS. DURING
THIS PERIOD, AN AIR FORCE RESERVE RECONNAISSANCE MISSION HAS BEEN
SAMPLING THE STORM, AND FOUND A PEAK 850 MB FLIGHT LEVEL WIND OF 66
KT ON THEIR NORTHEAST OUTBOUND LEG OF THE STORM. IN ADDITION, THERE
WAS A DROPSONDE LAUNCHED IN THE INNER MAX WIND BAND NEAR THE CENTER,
WHICH HAD A 500 M MEAN BOUNDARY LAYER WIND OF 71 KT AND A SURFACE
WIND GUST OF 55 KT. USING A 0.8 REDUCTION FACTOR TO THE LAYER MEAN
WIND SUPPORTS THE CURRENT INTENSITY OF 55 KT, WHICH ALSO MATCHED THE
T3.5/55 KT DVORAK ESTIMATE PROVIDED BY TAFB.
JERRY CONTINUES TO MOVE QUICKLY TO THE WEST-NORTHWEST, ALTHOUGH THE
CONVECTIVE BURST MAY HAVE SLOWED DOWN ITS MOTION A TAD, ESTIMATED AT
290/18 KT. THE FORECAST TRACK REASONING REMAINS THE SAME THIS
EVENING, WITH A SUBTROPICAL RIDGE WELL-ESTABLISHED TO THE NORTHEAST
OF THE STORM, AND JERRY WILL LIKELY BE STEERED AROUND THIS FEATURE,
TURNING TO THE NORTHWEST IN 24 HOURS, AND THEN NORTH BY 48 HOURS. ON
THE FORECAST TRACK, THIS TAKES JERRY ABOUT 80-100 N MI TO THE
NORTHEAST OF THE NORTHERN LEEWARD ISLANDS BY LATE TOMORROW. THERE
REMAIN A FEW HURRICANE-REGIONAL MODEL OUTLIERS TO THE WEST (HMON,
HAFS-A), BUT THESE MODELS APPEAR TO BE STRUGGLING TO DEPICT THE
CYCLONE WITHIN THEIR INNER-NESTS. THE OVERALL TRACK GUIDANCE
ENVELOPE HAS REMAINED PRETTY STEADY STATE THIS EVENING, AND THE NHC
FORECAST TRACK IS VERY CLOSE TO THE PRIOR ADVISORY, BLENDING THE
RELIABLE HCCA AND GDMI AIDS. BY EARLY NEXT WEEK, THE TRACK GUIDANCE
HAS MADE A MORE NOTABLE SHIFT SOUTH AS JERRY RECURVES AROUND THE
SUBTROPICAL RIDGE, AND THE TRACK FORECAST WAS NUDGED FURTHER SOUTH
AND EAST IN THE 120 H PERIOD. WHILE THIS TRACK PUTS JERRY SAFELY
SOUTHEAST OF BERMUDA, IT'S A GOOD IDEA TO CONTINUE MONITORING FUTURE
FORECASTS SINCE MODEL SCENARIOS CAN CHANGE, AND NHC TRACK FORECASTS
AT DAY 4 HAVE AN AVERAGE ERROR OF 130 N MI.
DESPITE THE LARGE CONVECTIVE BURST, JERRY STILL REMAINS UNDER
MODERATE TO STRONG NORTHWESTERLY SHEAR, CURRENTLY ESTIMATED AT
AROUND 25 KT PER GFS AND ECMWF-BASED SHIPS. HOWEVER, JERRY HAS BEEN
PUTTING UP A GOOD FIGHT THUS FAR AND ITS WIND FIELD HAS INTENSIFIED
DESPITE THE CONTINUED UNFAVORABLE CONDITIONS, LIKELY BECAUSE OF
OTHER MORE FAVORABLE FACTORS LIKE SEA-SURFACE TEMPERATURES AND AN
UNSTABLE ENVIRONMENT. THE INTENSITY GUIDANCE THIS EVENING PRESENTS A
CHALLENGE. THE 18 UTC GFS, AND THE HURRICANE-REGIONAL MODELS BASED
ON THE GFS, ALL SHOW VERY LITTLE CHANGE IN STRENGTH AND EVEN
DISSIPATE JERRY IN THE 72-96 H TIME FRAME. HOWEVER, A GLANCE AT THE
SHORT-TERM MODEL FORECAST SHOWS THE GFS IS STRUGGLING TO CORRECTLY
DEPICT THE CONVECTIVE STRUCTURE OF JERRY. TO MAKE MATTERS MORE
CONFUSING, THE LAST SEVERAL ECMWF RUNS NOW SHOW A MUCH STRONGER
JERRY IN THE 48-96 H TIME FRAME, WITH THE 18 UTC RUN SHOWING A
STRENGTHENING HURRICANE WITH PRESSURE BELOW 960 MB. ULTIMATELY, I'M
GOING TO SPLIT THE DIFFERENCE BETWEEN THESE TWO EXTREME SOLUTIONS,
SHOWING JERRY SLOWLY INTENSIFYING OVER THE NEXT 24-36 H, THEN
SHOWING A LITTLE MORE INTENSIFICATION AFTER AS THE SHEAR DECREASES
TO 15-20 KT IN 36 H AFTER THE TROPICAL CYCLONE PASSES NORTH OF THE
LEEWARD ISLANDS. NEEDLESS TO SAY THIS IS A LOW CONFIDENCE INTENSITY
FORECAST, AND OVERALL THE NHC FORECAST IS ON THE HIGH SIDE OF
THE GUIDANCE ENVELOPE.
KEY MESSAGES:
1. JERRY COULD BRING TROPICAL STORM CONDITIONS TO PORTIONS OF THE
NORTHERN LEEWARD ISLANDS LATE THURSDAY AND THURSDAY NIGHT.
2. HEAVY RAINFALL WILL IMPACT PORTIONS OF THE LEEWARD ISLANDS,
BRITISH VIRGIN ISLANDS, AND U.S. VIRGIN ISLANDS FROM THURSDAY INTO
SATURDAY MORNING, WHICH COULD RESULT IN FLASH FLOODING, PARTICULARLY
IN AREAS OF STEEP TERRAIN.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0300Z 15.2N 56.1W 55 KT 65 MPH
12H 09/1200Z 16.4N 58.3W 60 KT 70 MPH
24H 10/0000Z 18.0N 60.6W 60 KT 70 MPH
36H 10/1200Z 20.1N 62.2W 65 KT 75 MPH
48H 11/0000Z 22.5N 62.8W 70 KT 80 MPH
60H 11/1200Z 25.0N 62.8W 75 KT 85 MPH
72H 12/0000Z 27.4N 62.3W 75 KT 85 MPH
96H 13/0000Z 31.2N 60.5W 75 KT 85 MPH
120H 14/0000Z 32.3N 56.0W 75 KT 85 MPH
FORECASTER PAPIN
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