#193 Postby euro6208 » Sat Aug 10, 2013 10:08 pm
WDPN31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 11W (UTOR) WARNING NR 10//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TYPHOON 11W (UTOR), LOCATED APPROXIMATELY 285 NM EASTWARD OF
MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST
SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
STEADY EXPANSION OF THE CENTRAL CONVECTION OVER THE PAST SIX HOURS,
AS WELL AS WHAT APPEARS TO BE A RE-FORMATION OF THE PIN-HOLE EYE.
THE CURRENT POSITION IS BASED ON THE AFOREMENTIONED MSI AND POSITION
FIXES FROM PGTW AND RJTD WITH HIGH CONFIDENCE. THE CURRENT
INTENSITY IS ASSESSED AT 100 KNOTS, BASED ON THE PGTW DVORAK
ESTIMATE OF 102 KNOTS, AND TAKING INTO ACCOUNT THE IMPROVEMENT IN
THE SATELLITE PRESENTATION. UPPER LEVEL ANALYSIS INDICATES TY 11W
REMAINS IN A FAVORABLE ENVIRONMENT, WITH DIFFLUENCE ALOFT, LOW TO
MODERATE (10-15 KNOTS) VERTICAL WIND SHEAR (VWS), AND GOOD RADIAL
OUTFLOW WHICH IS BEING ENHANCED THROUGH INTERACTION WITH A TROPICAL
UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE NORTHWEST. TY 11W IS
TRACKING WESTWARD ALONG THE SOUTHERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
B. TY 11W WILL CONTINUE TRACKING WESTWARD TO WEST-NORTHWESTWARD
ALONG THE SOUTHERN PERIPHERY OF THE CURRENT STEERING RIDGE THROUGH
TAU 72. GIVEN THE FAVORABLE ENVIRONMENT, STEADY INTENSIFICATION TO A
PEAK NEAR 110 KNOTS IS FORECAST FOR THE NEXT APPROXIMATELY 18 HOURS,
PRIOR TO LANDFALL OVER LUZON. WHILE TRACKING OVER LUZON, TERRAIN AND
FRICTIONAL EFFECTS WILL WEAKEN THE SYSTEM CONSIDERABLY. ONCE TY 11W
RE-EMERGES IN THE SOUTH CHINA SEA, GENERALLY FAVORABLE CONDITIONS
SHOULD ALLOW FOR GRADUAL RE-INTENSIFICATION THROUGH TAU 72.
DYNAMICAL MODELS REMAIN IN GOOD AGREEMENT THROUGH TAU 72, WITH THE
EXCEPTION OF THE JAPANESE ENSEMBLE MEAN WHICH IS A SIGNIFICANT
EASTWARD OUTLIER. THE CURRENT FORECAST LIES CLOSE TO THE MULTI-MODEL
CONSENSUS AND PRIOR FORECASTS. GIVEN A STRAIGHTFORWARD STEERING
ENVIRONMENT AND GOOD MODEL AGREEMENT, FORECAST TRACK CONFIDENCE IS
HIGH IN THE NEAR TO MEDIUM TERM.
C. IN THE EXTENDED PERIOD, DYNAMICAL MODELS HAVE COME INTO MUCH
BETTER AGREEMENT ON A MORE WESTWARD TRACK, CONSISTENT WITH JTWC
TRACK FORECAST PHILOSOPHY. WITH THE EXCEPTION OF THE JAPANESE
ENSEMBLE MEAN, THE DYNAMICAL MODELS INDICATE THAT THE APPROACHING
SHORTWAVE TROUGH WILL NOT SIGNIFICANTLY ALTER THE STRENGTH OR
ORIENTATION OF THE STEERING STR. THE JTWC FORECAST LIES SLIGHTLY
EQUATORWARD OF THE MULTI-MODEL CONSENSUS IN THE EXTENDED PERIOD TO
OFFSET THE IMPACT OF THE OUTLIER ON THE CONSENSUS, AND IS LAID
ALMOST DIRECTLY OVER THE PREVIOUS FORECAST TRACK. AROUND TAU 72,
DECREASING SEA SURFACE TEMPERATURES AND INCREASING VWS WILL BEGIN TO
WEAKEN THE SYSTEM OVER WATER, WITH RAPID DISSIPATION AFTER LANDFALL
OVER SOUTHERN CHINA. DUE TO IMPROVED AGREEMENT AMONG THE JTWC
CONSENSUS MODELS, FORECAST TRACK CONFIDENCE IN THE TAU 72 TO 120
PERIOD IS NOW HIGH.//
NNNN
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