Tropical Storm LEKIMA Advisory Fri Oct 25

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (LEKIMA) WARNING NR 19//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 28W (LEKIMA), LOCATED APPROXIMATELY 164 NM EAST OF IWO
TO, HAS TRACKED NORTHWARD AT 14 KNOTS OVER THE PAST SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN INTENSE
SYSTEM WITH A SHARPLY-DEFINED 20 NM EYE SURROUNDED BY A THICK
EYEWALL. THOUGH THE EYE DIAMETER HAS DECREASED BY 3 NM OVER THE LAST
SIX HOURS, CONVECTION HAS SHALLOWED AND THE SYSTEM IS BECOMING
SLIGHTLY ELONGATED ALONG THE NORTHERN FLANK. THIS INDICATES THAT THE
NORTHERN PERIPHERY OF TY 28W IS BEGINNING TO INTERACT WITH THE MID-
LATITUDE WESTERLIES AND SUBSEQUENTLY, STRONGER VERTICAL WIND SHEAR
(VWS). THE INITIAL POSITION IS BASED ON THE EYE FEATURE IN THE MSI
WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 115 KNOTS IS BASED ON
DVORAK ESTIMATES RANGING FROM 100-127 KNOTS FROM PGTW, RJTD, AND
KNES. UPPER LEVEL ANALYSIS INDICATES A POINT SOURCE ANTICYCLONE
CONTINUES TO PROVIDE FAVORABLE RADIAL OUTFLOW. VWS IS CURRENTLY
ASSESSED AS LOW (5-10 KNOTS), BUT EXPECTED TO INCREASE AS THE SYSTEM
TRACKS FURTHER POLEWARD. THE CYCLONE IS TRACKING ALONG THE
SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR)
TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY FROM THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. A MID-LATITUDE TROUGH APPROACHING FROM THE NORTHWEST HAS BEGUN
TO WEAKEN THE STR. IN EFFECT, TY LEKIMA IS EXPECTED TO TRACK MORE
POLEWARD AND ROUND THE WESTERN EDGE OF THE STR OVER THE NEXT 12
HOURS. AFTERWARDS, THE SYSTEM WILL ACCELERATE NORTHEASTWARD AS IT
GETS EMBEDDED IN THE MID-LATITUDE WESTERLIES. DECREASING SEA SURFACE
TEMPERATURES AND INCREASING VWS WILL GRADUALLY ERODE THE SYSTEM. THE
CYCLONE WILL BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 24 AND
COMPLETE ITS TRANSFORMATION INTO A STORM-FORCE COLD-CORE LOW BY THE
END OF THE FORECAST. NUMERIC MODELS REMAIN IN TIGHT AGREEMENT. IN
VIEW OF THIS AND THE WELL-DEFINED STEERING MECHANISM, THERE IS A
HIGH CONFIDENCE IN THE FORECAST WHICH IS LAID CLOSE TO BUT SLIGHTLY
FASTER THAN THE MULTI-MODEL CONSENSUS. THIS STRATEGY IS USED TO
OFFSET KNOWN CLIMATOLOGICAL TRACK TENDENCIES.//
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