Tropical Storm LEKIMA Advisory 8月5日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (LEKIMA) WARNING NR
04//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 10W (LEKIMA), LOCATED APPROXIMATELY 513 NM
SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED NORTHWESTWARD AT 10 KNOTS
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY (EIR) REVEALS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION
(LLC) WITH DEEP CONVECTION TO THE WEST AND SOUTH. THERE IS LOW
CONFIDENCE IN THE INITIAL POSITION WHICH WAS PLACED USING THE EIR
IMAGERY AND SHALLOW BANDING VISIBLE IN A PARTIAL 041633Z AMSR2 89
GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 35 KTS IS CONSISTENT
WITH MULTI-AGENCY DVORAK ESTIMATES OF T2.5 (35 KTS). THE INTENSITY
AND WIND RADII ARE CONSISTENT WITH A 041251Z METOP-B ASCAT PASS THAT
SHOWED A LARGE AREA OF 35 KTS (WITH A FEW 40-45 KT BARBS IN DEEP
CONVECTION) TO THE SOUTH OF THE BROAD LLC. THE ENVIRONMENT IS
FAVORABLE WITH RADIAL OUTFLOW, WARM (29-30 CELSIUS) SEA SURFACE
TEMPERATURE, AND LOW (5-15 KT) VERTICAL WIND SHEAR (VWS). TS 10W IS
TRACKING GENERALLY POLEWARD UNDER THE STEERING INFLUENCE OF A
SUBTROPICAL RIDGE (STR) STRETCHING FROM THE NORTH TO THE EAST OF THE
LLC.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE OVERALL FORECAST PHILOSOPHY SINCE
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. THROUGH TAU 48, TS 10W IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD AND SLOWLY ACCELERATE AS THE STR REORIENTS AND BUILDS
SLIGHTLY. BY TAU 72, THE FORWARD SPEED IS EXPECTED TO BE AROUND 10
KTS. THE INTENSITY GUIDANCE SUPPORTS A STEADY INTENSIFICATION RATE
AND THE SYSTEM SHOULD REACH 70 KTS BY TAU 72. UNCERTAINTY IN THE
MODEL TRACK GUIDANCE FOR THIS PORTION OF THE FORECAST IS VERY HIGH
AS TWO MEMBERS (UKMET AND GALWEM) SHOW A POLEWARD TRACK WHILE ONE
MEMBER (NAVGEM) SHOWS A WESTWARD TRACK. THE REMAINING GUIDANCE IS IN
GOOD AGREEMENT WITH THE JTWC TRACK FORECAST. AT TAU 72, SPREAD IS
OVER 330 NM BUT DECREASES TO 114 NM WHEN EXCLUDING THE THREE
AFOREMENTIONED OUTLIERS. FOR THIS PORTION OF THE FORECAST, THERE IS
VERY LOW CONFIDENCE IN FORECAST TRACK DUE TO HIGH UNCERTAINTY IN
BOTH THE INITIAL POSITION AND MODEL TRACK GUIDANCE.
   C. BEYOND TAU 72, TS 10W IS EXPECTED TO CONTINUE ON A
NORTHWESTWARD TRACK ALONG THE SOUTHWEST PERIPHERY OF THE STR AND
INTENSIFY TO 95 KTS BY TAU 120. INTENSITY GUIDANCE BEGINS TO SPREAD
AFTER TAU 72 DUE TO SIGNIFICANT DIFFERENCES IN THE FORECAST TRACK OF
THE MODELS. AS A RESULT, THE INTENSIFICATION RATE FOR THIS PORTION
OF THE FORECAST IS MAINTAINED NEAR THE CLIMATOLOGICAL RATE UNDER
CONTINUED FAVORABLE ENVIRONMENTAL CONDITIONS. POOR AGREEMENT IN THE
TRACK GUIDANCE CONTINUES IN THE EXTENDED PERIOD AND CONFIDENCE IN
THE JTWC TRACK FORECAST REMAINS VERY LOW.//
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