HURRICANE ANA DISCUSSION NUMBER 18
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP022014
500 PM HST FRI OCT 17 2014
THE SATELLITE PRESENTATION OF ANA HAS CHANGED LITTLE DURING
DAYLIGHT HOURS...WITH HINTS OF AN EYE PERIODICALLY OBSERVED IN
VISIBLE IMAGERY. ALL THREE FIX AGENCIES AGAIN CAME IN AT 4.0/65 KT.
U.S. AIR FORCE RECONNAISSANCE AIRCRAFT FOUND THE STRONGEST WINDS IN
THE NORTHWEST QUADRANT TO BE 70 KT...AND THAT WILL BE THE INITIAL
INTENSITY FOR THIS ADVISORY.
HURRICANE ANA DISCUSSION NUMBER 24
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP022014
500 AM HST SUN OCT 19 2014
DESPITE STRONG WESTERLY SHEAR...ANALYZED AS BEING BETWEEN 30 AND
40 KT...ANA HAS BEEN ABLE TO MAINTAIN DEEP CONVECTION OVER THE INNER
CORE THROUGH THE NIGHT. RECENT DATA FROM A U.S. AIR FORCE
RECONNAISSANCE AIRCRAFT CORROBORATE WHAT IS SEEN IN THE LATEST
SATELLITE AND RADAR DATA...THAT THE PERSISTENT SHEAR MAY BE HAVING
AN IMPACT ON THE STRUCTURE OF THE CYCLONE. HOWEVER...THE INITIAL
INTENSITY FOR THIS ADVISORY HAS BEEN HELD AT 70 KT...AS THESE TRENDS
MAY BE ONLY TEMPORARY...AND MAXIMUM FLIGHT LEVEL WINDS AT 1221 UTC
WERE 73 KT.
THE INITIAL MOTION ESTIMATE OF 300/04 KT INDICATES THE FORWARD
MOTION HAS EASED...WITH THE MUCH ANTICIPATED TURN TOWARD THE WEST
UNDERWAY. A DEEP LAYER RIDGE BUILDING NORTH AND NORTHWEST OF THE
CYCLONE IS RESPONSIBLE FOR THIS EVOLUTION...AND THE SYSTEM IS
EXPECTED TO BEGIN MOVING TOWARD NEARLY DUE WEST THIS MORNING...
KEEPING THE CENTER FROM DIRECTLY IMPACTING KAUAI COUNTY.
HOWEVER...TROPICAL STORM FORCE WINDS EXTENDING OUT TO ABOUT 105
MILES ON THE NORTH SIDE REQUIRES A CONTINUATION OF THE TROPICAL
STORM WARNING FOR KAUAI COUNTY. THE UPDATED TRACK FORECAST ALSO
REQUIRES THE ISSUANCE OF A TROPICAL STORM WARNING FOR PORTIONS OF
THE PAPAHANAUMOKUAKEA MARINE NATIONAL MONUMENT...AND AN EXPANSION OF
THE HURRICANE WATCH AREA. THE RIDGE SHUNTING ANA WESTWARD WILL MOVE
PROGRESSIVELY EAST THROUGH THE PERIOD...WITH ANA ROUNDING THE
WESTERN EDGE OF THIS RIDGE ON DAYS 3 THROUGH 5. DIFFERENCES BETWEEN
MODELS REGARDING THE TIMING OF THIS TURN IS RESULTING IN A WIDE
SPREAD IN THE GUIDANCE AT LONGER TIME RANGES. THE LATEST FORECAST
LIES TO THE RIGHT OF THE RELIABLE GUIDANCE IN THE SHORT TERM...THEN
RUNS ALONG THE MIDDLE OF THE GUIDANCE ENVELOPE IN THE LONGER
RANGES...AND SPLITS THE DIFFERENCE BETWEEN THE HWRF/GFDL WHICH ARE
ON THE RIGHT HAND SIDE OF THE ENVELOPE...AND THE ECMWF...WHICH IS ON
THE LEFT HAND SIDE OF THE GUIDANCE.
LITTLE CHANGE IN STRENGTH IS FORECAST THROUGH THE NEXT 3 DAYS...BUT
DECREASING SHEAR ON DAYS 4 AND 5 SHOULD ALLOW ANA TO STRENGTHEN AS
IT ENCOUNTERS THE ANOMALOUSLY WARM WATER THAT EXTENDS AS FAR NORTH
AS 30N. THE UPDATED INTENSITY FORECAST CLOSELY FOLLOWS THE TRENDS
PRESENTED BY LGEM AND SHIPS GUIDANCE...BUT IS WEAKER THAN THE IVCN
CONSENSUS WHICH CONTINUES TO BE DRIVEN UPWARD BY THE HWRF/GFDL
MODELS WHICH DEPICT A STRONGER CYCLONE.
照妖鏡
