#15 Postby euro6208 » Mon Jul 31, 2017 11:24 pm
WDPN31 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN)
WARNING NR 001//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 13W (THIRTEEN), LOCATED APPROXIMATELY 496 NM
NORTH-NORTHEAST OF WAKE ISLAND, HAS TRACKED EASTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS FLARING DEEP CONVECTION IS CURRENTLY CONFINED TO THE SOUTH
AND EAST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL
POSITION IS PLACED WITH FAIR CONFIDENCE BASED ON BOTH SATELLITE FIX
POSITIONS AND A 312323Z 89 GHZ AMSU-B MICROWAVE IMAGE WHICH CONFIRMS
WEAK CONVECTIVE BANDING INTO THE LLCC WITH THE MAJORITY OF THE MOST
INTENSE CONVECTION LIMITED TO THE SOUTHEAST QUADRANT. THE INITIAL
INTENSITY ASSESSMENT OF 25 KNOTS IS BASED ON A SUBJECTIVE DVORAK
INTENSITY ESTIMATE OF 1.5 FROM RJTD AND ANALYSIS OF A 312324 METOP-B
ASCAT PASS, SHOWING A BROAD SWATH OF 25 KNOT WINDS IN THE SOUTHERN
AND EASTERN QUADRANTS OF THE SYSTEM AND 20 KNOT WINDS NEARLY
ENCIRCLING THE COMPACT LLCC. ENVIRONMENTAL ANALYSIS INDICATES THE
SYSTEM RESIDES IN A FAVORABLE AREA, WITH LOW (5-10 KNOTS) VERTICAL
WIND SHEAR (VWS), WARM SSTS NEAR 28 CELSIUS, AND GOOD OUTFLOW BEING
PROVIDED BY STRONG EASTWARD OUTFLOW CHANNEL EXTENDING INTO
EQUATORWARD CHANNEL TO THE SOUTH OF A TUTT CELL NEAR THE DATELINE.
TD 13W IS TRACKING EASTWARD ALONG THE NORTHERN PERIPHERY OF A
NORTHWARD DISPLACED NEAR EQUATORIAL RIDGE (NER).
3. FORECAST REASONING.
A. THIS IS THE FIRST WARNING ON THIS SYSTEM AND ESTABLISHES THE
FORECAST REASONING.
B. TD 13W WILL CONTINUE TRACKING GENERALLY EASTWARD OVER THE NEXT
24 HOURS ALONG THE NORTHERN EDGE OF THE NER. THE SYSTEM WILL RAPIDLY
DECELERATE BY TAU 24 AS A NORTH-SOUTH ORIENTED RIDGE DEVELOPS JUST
EAST OF THE DATELINE, BLOCKING FURTHER EASTWARD MOVEMENT. AS THIS
BLOCKING PATTERN INTENSIFIES BY TAU 36, TD 13W WILL TRANSITION TO A
NORTH-NORTHWESTWARD TRACK AND BEGIN TO ACCELERATE TOWARDS A WEAKNESS
IN THE RIDGE PATTERN CAUSED BY THE APPROACH OF A MID-LATITUDE TROUGH
FROM THE NORTHWEST. TD 13W IS FORECAST TO STEADILY INTENSIFY THROUGH
THE FIRST 48 HOURS, PEAKING AT 50 KNOTS BY TAU 48 AS ENVIRONMENTAL
CONDITIONS WILL REMAIN MODERATELY FAVORABLE. THE SYSTEM WILL
CONTINUE TO TAP INTO THE EASTWARD OUTFLOW PATTERN PROVIDING EXHAUST
WHILE SSTS CONTINUE TO BE SUPPORTIVE THROUGH TAU 72. AVAILABLE
NUMERICAL MODEL GUIDANCE IS IN RELATIVELY GOOD AGREEMENT ON THE
OVERALL SCENARIO WITH SOME DISAGREEMENT ON THE TIMING AND SHARPNESS
OF THE NORTHWARD TURN.
C. AFTER TAU 72, TD 13W IS FORECAST TO RAPIDLY TRANSIT NORTH-
NORTHWESTWARD ALONG THE WESTERN BOUNDARY OF THE BLOCKING RIDGE TO
THE EAST. THE SYSTEM WILL BEGIN TO RAPIDLY WEAKEN AFTER TAU 72 UNDER
INCREASING VWS AND DECREASING SSTS, AND TRANSITION TO AN EXTRA-
TROPICAL SYSTEM BY TAU 120. NUMERICAL MODEL GUIDANCE ALL AGREE ON
THE NORTH-NORTHWESTWARD TRACK BUT WITH A BROAD SPREAD IN THE
POTENTIAL TRACKS. HWRF IS THE EASTERN OUTLIER AND THE UKMET MODEL
MARKING THE WESTERN BOUNDARY. DUE TO THE HIGH UNCERTAINTY IN THE
TRACK BEYOND TAU 72, THERE IS LOW CONFIDENCE IN THE OVERALL 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...
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