403
WTPA44 PHFO 092035
TCDCP4
TROPICAL STORM LOWELL DISCUSSION NUMBER 55
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP122026
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
1100 AM HST WED SEP 09 2026
LOWELL IS DEALING WITH MODERATE WIND SHEAR AND DRY AIR. RECENT
SATELLITE IMAGERY REVEALS THAT EARLIER DEEP CONVECTION HAS
COLLAPSED, WITH ONLY SHALLOW CONVECTION REMAINING SHEARED TO THE
EASTERN SIDE OF THE CIRCULATION. THE LATEST SUBJECTIVE DVORAK
INTENSITY ESTIMATES FROM PHFO AND JTWC HAVE DECREASED TO T2.5/35 KT,
WHICH IS CONSISTENT WITH THE SYSTEM'S DEGRADED SATELLITE
PRESENTATION. UW-CIMSS OBJECTIVE INTENSITY ESTIMATES CURRENTLY RANGE
FROM 39 TO 49 KT. METOP-B AND METOP-C SCATTEROMETER PASSES ARE
ANTICIPATED OVER LOWELL NEAR THE ADVISORY TIME, WHICH WILL HELP
BETTER ASSESS THE CURRENT INTENSITY AND WIND RADII STRUCTURE.
ALTHOUGH CURRENT SATELLITE ESTIMATES HAVE DECREASED, THE INITIAL
INTENSITY IS HELD AT 50 KT FOR THIS ADVISORY, WHICH MAY BE GENEROUS.
SUBSEQUENT ADJUSTMENTS WILL AWAIT THE INCOMING SCATTEROMETER WIND
DATA.
LOWELL IS EXPECTED TO REMAIN WITHIN A DRY ENVIRONMENT WITH MODERATE
VERTICAL WIND SHEAR. MODEL-SIMULATED INFRARED IMAGERY SUGGESTS THAT
LOWELL WILL CONTINUE TO PRODUCE INTERMITTENT BURSTS OF DEEP
CONVECTION OVER THE NEXT SEVERAL DAYS, AIDED BY SOME UPPER-LEVEL
DIVERGENCE IN ABOUT 48 HOURS. THE OFFICIAL NHC INTENSITY FORECAST
FOLLOWS THE LATEST CONSENSUS MODEL GUIDANCE, DEPICTING A GRADUAL
WEAKENING OF THE SYSTEM THROUGHOUT THE FORECAST PERIOD. BY THE END
OF THE PERIOD, THE CYCLONE IS FORECAST TO MOVE OVER COOLER SEA
SURFACE TEMPERATURES WHILE CONTINUING TO DEAL WITH DRY AIR AND
MODERATE SHEAR. ALTHOUGH SOME UNCERTAINTY REMAINS LATE IN THE PERIOD
DUE TO THE SYSTEM'S EVENTUAL TRACK AND INTERMITTENT CONVECTIVE
BURSTS, THESE HOSTILE ENVIRONMENTAL CONDITIONS SHOULD CAUSE LOWELL
TO BECOME A POST-TROPICAL CYCLONE BY DAY 4.
THE INITIAL MOTION IS NORTHWESTWARD, OR 320/12 KT. LOWELL SHOULD
GRADUALLY TURN WEST-NORTHWESTWARD AND THEN WESTWARD, STEERED BY A
BUILDING MID-LEVEL RIDGE TO THE NORTH AND EAST. IN A FEW DAYS, THE
CYCLONE IS FORECAST TO ROUND THE WESTERN PERIPHERY OF THE RIDGE AND
SLOW FORWARD SPEED. THIS DECREASE IN FORWARD SPEED WILL OCCUR AS THE
STEERING PATTERN COLLAPSES, LEAVING LOWELL CAUGHT BETWEEN
HIGH-PRESSURE RIDGES OVER THE NORTHWESTERN AND NORTHEASTERN PACIFIC.
TRACK MODEL GUIDANCE BEGINS TO DIVERGE CONSIDERABLY LATE IN THE
PERIOD. THIS SPREAD IN THE GUIDANCE LARGELY DEPENDS ON THE VERTICAL
DEPTH OF THE CYCLONE, AND IF THE SYSTEM REMAINS A SHALLOW LOW, IT
COULD BEGIN TO MOVE SOUTHWESTWARD, STEERED BY THE LOW-LEVEL FLOW ON
THE EASTERN EDGE OF THE NORTHWESTERN PACIFIC RIDGE. THE OFFICIAL NHC
TRACK FORECAST LIES NEAR THE HCCA AND GDMI CONSENSUS AIDS IN THE
NEAR TERM, AND THEN SHIFTS TOWARD THE SIMPLE CONSENSUS LATER IN THE
PERIOD, REFLECTING THE HIGHER UNCERTAINTY TOWARD THE END OF THE
FORECAST CYCLE.
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 09/2100Z 28.9N 163.7W 50 KT 60 MPH
12H 10/0600Z 29.3N 165.7W 45 KT 50 MPH
24H 10/1800Z 29.3N 168.1W 45 KT 50 MPH
36H 11/0600Z 29.3N 170.5W 40 KT 45 MPH
48H 11/1800Z 29.9N 171.7W 40 KT 45 MPH
60H 12/0600Z 30.9N 171.8W 40 KT 45 MPH
72H 12/1800Z 32.3N 172.3W 40 KT 45 MPH
96H 13/1800Z 33.2N 174.8W 35 KT 40 MPH...POST-TROPICAL
120H 14/1800Z 32.7N 176.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
FORECASTER KELLY
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