451
WTPA44 PHFO 100232
TCDCP4
TROPICAL STORM LOWELL DISCUSSION NUMBER 56
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122026
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
500 PM HST WED SEP 09 2026
LOWELL'S CONVECTIVE STRUCTURE ON SATELLITE IMAGERY IS NOT VERY
IMPRESSIVE, CONSISTING OF A WELL-DEFINED LOW-LEVEL SWIRL WITH SOME
COLDER CLOUD TOPS ATTEMPTING TO FORM ON THE NORTHEAST SIDE OF THE
CIRCULATION. THE STORM IS CLEARLY BEING NEGATIVELY IMPACTED BY
MODERATE WESTERLY SHEAR IMPORTING NEARBY DRY AIR AND MARGINALLY WARM
SEA-SURFACE TEMPERATURES. SCATTEROMETER DATA RECEIVED AFTER THE
PRIOR ADVISORY INDICATED A ROBUST SURFACE WIND FIELD REMAINS, WITH
PEAK WIND-RETRIEVALS IN THE 45 TO 50 KT RANGE. HOWEVER, SUBJECTIVE
AND OBJECTIVE SATELLITE ESTIMATES CONTINUE TO DECREASE, AND ASSUMING
THE LOW-LEVEL CIRCULATION CONTINUES TO SPIN DOWN WITHOUT MUCH DEEP
CONVECTION, THE INITIAL INTENSITY IS SET TO 45 KT FOR THIS ADVISORY.
THE TROPICAL CYCLONE HAS TURNED WESTWARD, WITH THE ESTIMATED MOTION
NOW 280 DEGREES AT 12 KT. LOWELL IS NOW BEING STEERED PRIMARILY BY A
LOW- TO MID-LEVEL RIDGE LOCATED NORTH OF THE TROPICAL STORM, AND
THIS SHOULD MAINTAIN A GENERAL WESTWARD MOTION OVER THE NEXT 24-36
H. AFTER THAT TIME, A MID- TO UPPER-LEVEL TROUGH LOCATED NORTHWEST
OF LOWELL IS ANTICIPATED TO CUTOFF AND INTERACT WITH THE CYCLONE,
WITH THE TRACK GUIDANCE COMING INTO BETTER AGREEMENT THAT THIS WILL
LEAD TO A SHARP TURN TO THE NORTHWEST OR NORTH IN 60-72 H. BY THE
END OF THE FORECAST PERIOD, THE UPPER-LEVEL CUTOFF LOW MOVES EAST
OF LOWELL, LEAVING BEHIND A SHALLOW LOW-LEVEL CIRCULATION SANDWICHED
BETWEEN TWO LOW-LEVEL RIDGES. THE TRACK GUIDANCE RESPONDS TO THIS
CHANGE BY INDICATING A SLOW SOUTHWARD DRIFT AS THE CYCLONE BECOMES A
REMNANT LOW. THE NHC TRACK FORECAST IS VERY SIMILAR TO THE PRIOR ONE
FOR THE FIRST 2-3 DAYS, BUT SHOWS A SHARPER TURN SOUTHWARD
BY THE END OF THE FORECAST. THIS TRACK IS CLOSEST TO THE GOOGLE
DEEPMIND (GDMI) AND HFIP CORRECTED CONSENSUS APPROACH (HCCA) AIDS.
MODERATE WESTERLY VERTICAL WIND SHEAR, ABUNDANT DRY AIR, AND ONLY
MARGINALLY WARM SEA-SURFACE TEMPERATURES ARE LIKELY TO LEAD TO
FURTHER WEAKENING OVER THE NEXT 36 H. IN FACT, LOWELL COULD STRUGGLE
TO PRODUCE ENOUGH CONVECTION TO BE CONSIDERED A TROPICAL CYCLONE
DURING THIS PERIOD. NONETHELESS, THE AFOREMENTIONED TROUGH
INTERACTION IN THE 2-3 DAY TIME FRAME WILL LIKELY REINVIGORATE SOME
CONVECTION ON THE STORM'S DOWN-SHEAR SIDE VIA BAROCLINIC PROCESSES,
WHICH COULD HELP INTENSIFY LOWELL'S WIND FIELD. MOST OF THE
INTENSITY GUIDANCE SHOWS AT LEAST SOME INTENSIFICATION DURING THIS
PERIOD OF INTERACTION, AND THE NHC INTENSITY FORECAST WAS ADJUSTED
SOMEWHAT TO REFLECT THIS SOLUTION, THOUGH IT REMAINS BELOW THE
HAFS-A/B HURRICANE MODELS. AFTER 72 H, THE UPPER-LEVEL LOW
INTERACTING WITH LOWELL WILL PASS IT TO THE EAST, LEAVING THE STORM
IN AN AREA OF ENHANCED SUBSIDENCE THAT WILL LIKELY DIMINISH THE
REMAINING CONVECTION WHEN THE STORM WILL BE OVER SUB-26 C SSTS.
THUS, THE LATEST NHC FORECAST STILL SHOWS LOWELL BECOMING A
POST-TROPICAL LOW IN 96 H. THERE IS STILL A HEALTHY AMOUNT OF TRACK
UNCERTAINTY TOWARDS THE END OF THE FORECAST, THOUGH THE GUIDANCE IS
COMING INTO BETTER AGREEMENT ON LOWELL LOSING ITS TROPICAL
CHARACTERISTICS BY THIS TIME.
KEY MESSAGES:
1. POST-STORM SAFETY: FOLLOW ADVICE OF LOCAL OFFICIALS AND AVOID
AREAS OF DOWNED POWER LINES AND FLOODING. ENSURE GENERATORS ARE
PROPERLY VENTILATED AND PLACED OUTSIDE AT LEAST 20 FEET AWAY FROM
DWELLINGS AND GARAGES TO AVOID CARBON MONOXIDE POISONING. DURING
CLEAN UP, BE CAREFUL WHEN USING CHAINSAWS AND POWER TOOLS. DRINK
PLENTY OF WATER TO AVOID HEAT EXHAUSTION.
FORECAST POSITIONS AND MAX WINDS
INIT 10/0300Z 29.2N 165.1W 45 KT 50 MPH
12H 10/1200Z 29.3N 167.1W 40 KT 45 MPH
24H 11/0000Z 29.2N 169.5W 35 KT 40 MPH
36H 11/1200Z 29.4N 171.2W 35 KT 40 MPH
48H 12/0000Z 30.6N 172.0W 40 KT 45 MPH
60H 12/1200Z 32.2N 172.4W 45 KT 50 MPH
72H 13/0000Z 33.3N 173.4W 40 KT 45 MPH
96H 14/0000Z 32.8N 175.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 15/0000Z 31.6N 175.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
FORECASTER PAPIN
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