Tropical Storm LEKIMA Advisory So, 04.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 10W (TEN) WARNING
NR 01//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 10W (TEN), LOCATED APPROXIMATELY 659 NM
SOUTH-SOUTHEAST OF KADENA AB, HAS TRACKED EAST-NORTHEASTWARD AT 06
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) REVEALS AN AREA EMBEDDED IN A BROAD CIRCULATION WHERE
SUSTAINED CONVECTION APPEARS TO BE CAUSING CONSOLIDATION. THERE IS
VERY LOW CONFIDENCE IN THE INITIAL POSITION, PLACED NEAR THE
APPARENT CONSOLIDATION IN THE MSI IMAGERY AND CONSISTENT WITH A
032009 AMSU 89 GHZ MICROWAVE IMAGE. THE INITIAL INTENSITY OF 25 KTS
IS BASED ON RJTD AND KNES DVORAK CURRENT INTENSITY ESTIMATES OF T1.5
(25 KTS) BUT THERE HAS BEEN A LARGE AREA OF APPROXIMATELY 30 KT
WESTERLY WINDS OVER 100 NM TO THE SOUTH OF THE CURRENT POSITION. THE
ENVIRONMENT IS MARGINAL WITH EXCELLENT EQUATORWARD OUTFLOW AND WARM
(29-30 CELSIUS) SEA SURFACE TEMPERATURE OFFSETTING MODERATE (10-20
KT) VERTICAL WIND SHEAR (VWS). NOTABLY, THERE IS AN ADJACENT AREA OF
FAVORABLE WIND SHEAR JUST NORTH OF THE CURRENT POSITION AND IN THE
PATH OF THE SYSTEM. TD 10W IS DRIFTING GENERALLY POLEWARD UNDER WEAK
STEERING INFLUENCE FROM A SUBTROPICAL RIDGE (STR) THAT EXTENDS FROM
THE NORTH TO THE EAST.
3. FORECAST REASONING.
   A. THIS IS THE INITIAL PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY. TD 10W IS STILL CONSOLIDATING SO INITIAL UNCERTAINTY IS
HIGH. INTENSITY IS ANTICIPATED TO REACH 35 KTS IN ABOUT 24 HOURS,
NECESSITATING A WARNING.
   B. THROUGH TAU 48, TD 10W IS EXPECTED TO DRIFT SLOWLY POLEWARD BY
THE EASTERN EXTENSION OF THE STR. BETWEEN TAU 48 AND 72, THE STR
EXTENSION TO THE NORTH WILL TAKE OVER AS THE PRIMARY STEERING
INFLUENCE AND THE TRACK SHOULD SHIFT MORE NORTHWESTWARD. AS TD 10W
MOVES INTO A MORE FAVORABLE VWS REGION, THE CYCLONE IS EXPECTED TO
STEADILY INTENSIFY, REACHING 55 KTS BY TAU 72. MOST OF THE
UNCERTAINTY IN THE MODEL GUIDANCE FOR THIS PORTION OF THE FORECAST
IS IN THE EARLY TAUS AS THE MODEL TRACKERS ARE LIKELY HAVING
DIFFICULTY IDENTIFYING THE LLCC IN THE BROADER CIRCULATION. BY TAU
36, NAVGEM STARTS TO APPEAR AS A SOUTHERN OUTLIER RELATIVE TO THE
OTHER MEMBERS. OVERALL, THERE IS VERY LOW CONFIDENCE IN THE EARLY
PORTION OF THE FORECAST, LARGELY OWING TO HIGH UNCERTAINTY IN THE
INITIAL POSITION AND SUBSEQUENT UNCERTAINTY IN THE MODEL TRACK
GUIDANCE.
   C. BEYOND TAU 72, TD 10W IS EXPECTED TO CONTINUE ON A
NORTHWESTWARD TRACK ALONG THE SOUTHWEST PERIPHERY OF THE STR AND TO
STEADILY INCREASE INTENSITY TO 70 KTS BY TAU 120. FOR THE MOST PART,
ALL THE INTENSITY GUIDANCE SHOWS A SIMILAR TREND TO THE FORECAST
INTENSITY; HOWEVER, THE ENVELOPE OF POSSIBILITIES IS QUITE LARGE (50-
85 KTS) BY THE END OF THE FORECAST. THE JTWC INTENSITY FORECAST IS
HEDGED JUST ABOVE THE INTENSITY CONSENSUS ONLY DUE TO THE
ENVIRONMENT APPEARING TO REMAIN FAVORABLE FOR THE DURATION OF THE
FORECAST. TRACK GUIDANCE, WITH THE EXCEPTION OF NAVGEM, IS IN FAIR
AGREEMENT BUT CONFIDENCE IN THE EXTENDED FORECAST IS VERY LOW
PRIMARILY DUE TO HIGH UNCERTAINTY IN THE INITIAL POSITION.//
NNNN
NNNN