#71 Postby euro6208 » Thu Jul 27, 2017 5:44 pm
WDPN34 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (NESAT) WARNING NR
08//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM 11W (NESAT), LOCATED APPROXIMATELY 426 NM SOUTH OF
KADENA AB, HAS TRACKED NORTH-NORTHWESTWARD AT 10 KNOTS OVER THE
PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY
INDICATES THAT THE CENTRAL CONVECTION HAS WEAKENED OVER THE PAST
SIX HOURS, WITH WARMING CLOUD TOPS. THE SYSTEM STILL SHOWS A
SLIGHTLY ELONGATED APPEARANCE INDICATIVE OF SOME NORTHEASTERLY
SHEAR BUT IS BECOMING MORE SYMMETRICAL IN PAST COUPLE OF HOURS.
EARLIER IMAGERY INDICATED THAT THE LOW LEVEL CIRCULATION CENTER
(LLCC) WAS DISPLACED ALONG THE NORTHERN EDGE OF THE CONVECTION, BUT
OVER THE PAST THREE TO FOUR HOURS, IT HAS TUCKED BACK UNDER THE
CONVECTION. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON RECENT SATELLITE FIXES AND A MICROWAVE EYE OBSERVED IN A
271821Z 91GHZ COMPOSITE GPM MICROWAVE IMAGE. THE INITIAL INTENSITY
IS ASSESSED AT 55 KNOTS AND IS BASED ON DVORAK ESTIMATES FROM ALL
AGENCIES OF T3.5 (55 TO 70 KNOTS). ENVIRONMENTAL CONDITIONS ARE
CURRENTLY FAVORABLE WITH ROBUST EQUATORWARD LOW VERTICAL WIND SHEAR
(VWS). THERE IS SOME PRESSURE ON THE NORTHEAST SIDE OF THE SYSTEM,
AS INDICATED BY THE SHARP POLEWARD EDGE OF THE CLOUD FIELD, IS
SOMEWHAT RESTRICTING POLEWARD OUTFLOW, BUT THE DEVELOPMENT OF A
POINT SOURCE OVER THE SYSTEM IS COUNTERACTING THIS PRESSURE. SSTS
OVER 31 DEG CELSIUS ARE VERY CONDUCIVE FOR INTENSIFICATION. TS 11W
IS TRACKING NORTHWESTWARD ALONG THE WESTERN BOUNDARY OF A WEAK MID
TO LOW LEVEL, NORTHWEST TO SOUTHEAST ORIENTED SUBTROPICAL RIDGE
(STR).
3. FORECAST REASONING.
A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
B. TS 11W IS FORECAST TO CONTINUE TRACKING NORTHWESTWARD AS
ANOTHER RIDGE ANCHORED OVER THE EAST CHINA SEA ASSUMES STEERING.
VWS IS EXPECTED TO RELAX AND OUTFLOW TO IMPROVE OVER THE NEXT 36
HOURS, AND TS 11W IS FORECAST TO STEADILY INTENSIFY IN RESPONSE,
REACHING A PEAK INTENSITY OF 85 KNOTS JUST PRIOR TO MAKING LANDFALL
IN CENTRAL TAIWAN. INCREASING NORTHEASTERLY VWS WILL RESULT IN A
SLIGHT WEAKENING JUST BEFORE MAKING LANDFALL. INTERACTION WITH THE
MOUNTAINOUS TERRAIN OF CENTRAL TAIWAN WILL LEAD TO A SIGNIFICANT
SLOWDOWN IN FORWARD MOTION AND RAPID WEAKENING AFTER TAU 48, THOUGH
THE SYSTEM WILL REEMERGE INTO THE TAIWAN STRAIT BY TAU 72 AS A WEAK
TROPICAL STORM.
C. IN THE EXTENDED FORECAST PERIOD TS 11W WILL TRACK ACROSS
TAIWAN STRAIT AND MAKE A SECOND LANDFALL IN EASTERN CHINA SHORTLY
THEREAFTER. AT THE SAME TIME, THE PRIMARY STEERING RIDGE WILL
REORIENT TO A NORTH-SOUTH AXIS, STEERING THE REMNANTS OF TS 11W
NORTHWARD. TS 11W WILL REMAIN OVER LAND AS A TROPICAL DEPRESSION
AND THERE IS THE POSSIBILITY THAT IT COULD REEMERGE INTO THE EAST
CHINA SEA NEAR SHANGHAI BEYOND THE FORECAST PERIOD. DYNAMIC MODEL
GUIDANCE IS TIGHT AGREEMENT THROUGH TAU 72, WITH INCREASING
UNCERTAINTY THEREAFTER. THE SOUTHERN OUTLIER REMAINS ECMWF, WHILE
THE NORTHERN OUTLIER IS HWRF. THE JTWC TRACK LIES NEAR THE MULTI-
MODEL CONSENSUS TRACK. DUE TO THE IMPROVED GUIDANCE, THERE HIGH
CONFIDENCE IN THE FORECAST TRACK.//
NNNN
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Remember, all of my post aren't official. For official warnings and discussions, Please refer to your local NWS products...
NWS for the Western Pacifichttps://www.weather.gov/gum/