#154 Postby cycloneye » Thu Oct 22, 2009 10:05 am
WTPA42 PHFO 221450
TCDCP2
HURRICANE NEKI DISCUSSION NUMBER 16
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP032009
500 AM HST THU OCT 22 2009
HURRICANE NEKI REACHED PEAK INTENSITY LAST NIGHT AND HAS BEGUN TO
WEAKEN...ALTHOUGH ONLY EVER SO SLIGHTLY THIS MORNING. FIXES FROM
PHFO AND JTWC GAVE CI VALUES OF 5.5 AND 5.0 WHILE SAB GAVE
6.0...WITH JTWC REPORTING THE INTENSITY DROP OVER THE PAST 6 HOURS.
SATELLITE LOOP SHOWS A CONTINUED CLOUD-FILLED EYE AND A BIT OF
EROSION INTO THE EYEWALL ALONG ITS SOUTHEAST FLANK. THE INITIAL
INTENSITY IS SET AT 100 KT AS A COMPROMISE BETWEEN PHFO AND JTWC
INTENSITIES. OUTFLOW HAS BECOME HAMPERED ALONG THE SOUTHWEST
FLANK...BUT REMAINS GOOD ELSEWHERE. SOUTHWEST SHEAR IS
INCREASING...WITH THE 1200 UTC UW-CIMSS VERTICAL SHEAR PRODUCT NOW
SHOWING OVER 25 KT OF SHEAR. THIS APPEARS TO BE MORE THAN ENOUGH TO
AFFECT THE CORE. NEKI REMAINS OVER 28 DEGREE C WATER...BUT THANKS
TO THE SHEAR GRADUAL WEAKENING IS EXPECTED. THE CENTER OF NEKI IS
OFF THE WESTERN LIMB OF THE CLOSEST SCATTEROMETER PASS...BUT IT
SEEMS CLEAR THAT THE 34 KT WIND RADIUS IS CONSIDERABLY LESS THAN IT
WAS 12 TO 24 HOURS AGO...ESPECIALLY IN THE NORTHEAST QUADRANT. THIS
RADIUS HAS BEEN TRIMMED BACK TO 180 NM FOR THIS BULLETIN CYCLE.
NEKI ALSO REACHED THE WESTERNMOST POINT OF ITS TRACK LAST
NIGHT...WITH A SLIGHTLY MORE PRONOUNCED EAST COMPONENT NOTED IN LAST
6 HOUR MOTION. INITIAL MOTION IS SET AT 020 DEGREES AT 9 KT. A FRONT
MOVING SOUTHEASTWARD NEAR LISIANSKI IS ERODING THE SUBTROPICAL
RIDGE...URGING NEKI TO GAIN LATITUDE. NEKI IS EXPECTED TO GRADUALLY
SHIFT TO A MORE NORTHEASTERLY TRACK AS IT INTERACTS WITH THE
ENCROACHING FRONT AND ITS ASSOCIATED UPPER LEVEL TROUGH. TRACK
GUIDANCE SEEMS TO BE HAVING TROUBLE HANDLING THE RECURVATURE OF NEKI
THIS TIME AROUND...WITH ALL BUT BAMD IGNORING THE PAST 6 AND 12
HOURS MOTION AND WANTING TO KEEP MOVING NEKI DUE NORTH...AT LEAST
INITIALLY. THE FORECAST TRACK FOLLOWS BAMD THROUGH 24 HOURS...THEN
EASES INTO AN ARC PARALLEL TO AND JUST RIGHT OF GFDL AND HWRF. THE
FORECAST TRACK IS THEREFORE ALSO SLIGHTLY TO THE RIGHT OF THE
PREVIOUS ONE.
NEKI WILL REMAIN IN 26 C OR WARMER WATER THROUGH 48 HOURS...THEN
MOVE ACROSS COOLER WATER THROUGH THE REST OF ITS FORECAST TRACK.
HOWEVER...UW-CIMSS NOW SHOWS UNFAVORABLE SHEAR IMPACT ON THIS
SYSTEM THROUGH 24 HOURS. NEKI IS FORECAST TO WEAKEN TO A TROPICAL
STORM AFTER 72 HOURS...THEN TO A DEPRESSION AT 120 HOURS. THE LONG
RANGE INTENSITY FORECAST MAY CHANGE DEPENDING ON HOW NEKI INTERACTS
WITH THE FRONT AND UPPER TROUGH.
ON ITS CURRENT TRACK...NEKI WILL BE APPROACHING THE
PAPAHANAUMOKUAKEA NATIONAL MONUMENT BETWEEN FRENCH FRIGATE SHOALS
AND NIHOA ON FRIDAY...AND A HURRICANE WARNING REMAINS FOR THE
MONUMENT FROM NIHOA ISLAND TO MARO REEF. THE TROPICAL STORM WATCH
FROM MARO REEF TO LISIANSKI HAS BEEN CANCELLED. LARGE SWELLS FROM
THE SOUTH WILL BUILD AND CONDITIONS WILL DETERIORATE ACROSS
PORTIONS OF THE WARNING AREA TODAY...WITH SEAS GREATER THAN 20 FT
AND SURF UP 25 FT EXPECTED.
FORECAST POSITIONS AND MAX WINDS
INITIAL 22/1500Z 20.4N 166.0W 100 KT
12HR VT 23/0000Z 21.7N 165.5W 100 KT
24HR VT 23/1200Z 23.4N 164.8W 95 KT
36HR VT 24/0000Z 24.9N 163.9W 85 KT
48HR VT 24/1200Z 26.4N 162.7W 75 KT
72HR VT 25/1200Z 29.3N 160.4W 65 KT
96HR VT 26/1200Z 32.7N 157.3W 50 KT
120HR VT 27/1200Z 36.4N 153.4W 30 KT
$$
FORECASTER POWELL
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