Tropical Storm LEKIMA Advisory mar, 22-10

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (LEKIMA) WARNING NR 08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 28W (LEKIMA), LOCATED APPROXIMATELY 706 NM EAST-NORTHEAST
OF ANDERSEN AFB, GUAM, HAS TRACKED NORTHWESTWARD AT 18 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
REVEALS TY 28W HAS RAPIDLY INTENSIFIED AS CONVECTION HAS QUICKLY
DEEPENED AROUND A NOW WELL-DEFINED 15 NM EYE. A 220445Z SSMI
MICROWAVE IMAGE REVEALS AN INTENSE SYSTEM WITH A SYMMETRIC EYEWALL
AND FURTHER IMPROVED DEEP CONVECTIVE BANDING. THE INITIAL POSITION
IS BASED ON THE READILY APPARENT EYE FEATURE IN THE MSI ANIMATION
WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 105 KNOTS IS BASED ON
THE INCREASING STRUCTURE AND DVORAK INTENSITY ESTIMATES FROM PGTW,
KNES, AND RJTD THAT RANGE FROM 102 TO 115 KNOTS. UPPER-LEVEL
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT AS THE SYSTEM IS SOUTH OF
THE RIDGE AXIS IN AN AREA OF WEAK (5 TO 10 KNOT) VERTICAL WIND SHEAR
(VWS) AND GOOD RADIAL OUTFLOW. TY LEKIMA IS CURRENTLY TRACKING ALONG
THE SOUTHWESTERN PERIPHERY OF A 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 ALTHOUGH THE INTENSITY
FORECAST HAS INCREASED DUE TO THE RECENT RAPID INTENSIFICATION.
   B. TY 28W IS EXPECTED TO TRACK TO THE NORTHWEST UNDER THE
STEERING INFLUENCE OF THE STR THROUGH THE NEXT 48 HOURS. AFTER TAU
48, A PRESSING MID-LATITUDE TROUGH WILL MOVE INTO THE AREA AND BEGIN
TO MODIFY THE STR. THIS WILL CAUSE TY 28W TO INITIALLY TRACK TO THE
NORTH AND THEN TO THE NORTHEAST IN A GENERAL RECURVE SCENARIO.
FAVORABLE ENVIRONMENTAL FACTORS OF GOOD OUTFLOW, WARM SEA SURFACE
TEMPERATURES, AND LOW VWS WILL ALLOW TY 28W TO REACH A PEAK OF 140
KNOTS BY TAU 36. AFTER WHICH, DECREASING OCEAN PARAMETERS AND
INCREASING VWS WILL START TO SLOWLY WEAKEN THE SYSTEM.
   C. AFTER TAU 72, TY 28W WILL ACCELERATE TO THE NORTHEAST AS IT
BEGINS EXTRA-TROPICAL TRANSITION (ETT). FURTHER DECREASING
ENVIRONMENTAL FACTORS WILL CONTINUE TO ERODE THE SYSTEM AS IT
QUICKLY MOVES NORTHEASTWARD. EXTRA-TROPICAL TRANSITION IS EXPECTED
TO BE COMPLETE BY TAU 120 WHILE THE SYSTEM BECOMES EMBEDDED IN THE
BAROCLINIC ZONE. NUMERIC MODEL GUIDANCE HAS COME INTO BETTER
AGREEMENT THROUGH TAU 48, BUT INCREASINGLY DIVERGES AFTERWARDS AS
THE SYSTEM ROUNDS THE STR. DUE TO THE TIGHT AGREEMENT IN THE NUMERIC
MODELS, THERE IS A HIGH CONFIDENCE IN THE EARLY PORTION OF THE
FORECAST. HOWEVER, THE SPREAD IN THE GUIDANCE AFTER TAU 48, WHICH
CONTINUES TO INDICATE SOME UNCERTAINTY DURING RECURVATURE, LEADS TO
LOW CONFIDENCE IN THE EXTENDED PORTION OF THE FORECAST.//
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