Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Storm 10w Warning Nr 14//

From: SIU Weather Processor <[email-masked]>
Date: Sat, 4 Sep 2010 21:34:20 -0500

WDPN33 PGTW 050300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W WARNING NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL STORM (TS) 10W (MALOU), LOCATED APPROXIMATELY 320 NM
SOUTH-SOUTHWEST OF CHEJU ISLAND, HAS TRACKED WEST-NORTHWESTWARD AT
13 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY (MSI) SHOWS AN EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC)
WITH DEEP CONVECTION FLARING APPROXIMATELY 125 NM TO THE NORTHEAST.
THIS CONVECTION MAY BE ASSOCIATED WITH STRONGER GRADIENT FLOW ALONG
THE NORTHEASTERN FLANK OF THE LLCC, OR A POSSIBLE DEVELOPING LOW
LEVEL CIRCULATION EMBEDDED WITHIN THE BROAD GYRE-LIKE PATTERN.  MSI
AND A 042317Z SSMIS 91 GHZ MICROWAVE PASS CONFIRM THE LOCATION OF
THE EXPOSED LLCC WITH HIGH CONFIDENCE. THE CURRENT INTENSITY IS
BASED ON DVORAK ESTIMATES OF 35 KNOTS FROM PGTW, KNES, AND RJTD.
3. FORECAST REASONING.
   A. THE PEAK INTENSITY HAS BEEN WEAKENED SLIGHTLY FROM THE
PREVIOUS FORECAST, HOWEVER THE FUNDAMENTAL PHILOSOPHY OF THE TRACK
AND INTENSITY FORECASTS REMAINS THE SAME.
   B. TS 10W IS CURRENTLY TRACKING WEST-NORTHWESTWARD UNDER THE
INFLUENCE OF A LOW TO MID-LEVEL EXTENSION OF THE SUBTROPICAL
STEERING RIDGE. THE SYSTEM IS EXPECTED TO INTENSIFY SLIGHTLY AND
TRACK POLEWARD AS IT ROUNDS THE SUBTROPICAL RIDGE AXIS. AFTER TAU
48, TS 10W IS FORECAST TO GRADUALLY WEAKEN DUE TO INTERACTION WITH
THE MID-LATITUDE WESTERLIES. THERE IS A POSSIBILITY THAT DIRECT
CYCLONE INTERACTION (DCI) WITH THE DEVELOPING LOW LEVEL CIRCULATION
NORTHEAST OF TS 10W WILL CAUSE THE SYSTEM TO LOOP CYCLONICALLY
BEFORE CONTINUING TO TRACK NORTH-NORTHWESTWARD.
   C. TS 10W IS FORECAST TO MAKE LANDFALL NORTH OF KUNSAN AB, SOUTH
KOREA BETWEEN TAU 48 AND TAU 72. AFTER TAU 72, TS 10W WILL BE
ABSORBED BY THE BAROCLINIC BOUNDARY TO THE NORTH. NUMERICAL MODEL
GUIDANCE IS IN FAIR AGREEMENT, WITH THE EXCEPTION OF GFS AND GFDN
WHICH LOSE THE SYSTEM AS IT WEAKENS AND TRACKS WESTWARD IN THE LOW
LEVEL FLOW. THIS FORECAST FAVORS A TRACK NORTH AND WEST OF MODEL
CONSENSUS, BASED ON UPPER AIR ANALYSIS OF THE LOW TO MID-LEVEL
STEERING RIDGE AND THE PREVIOUS JTWC FORECAST. //

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