MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 07W WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
A. RECENT ANIMATED MULTISPECTRAL IMAGERY SHOWS A VERY BROAD
CIRCULATION (800NM) WITH DEEP CONVECTION AROUND THE PERIPHERY OF A
RELATIVELY CONVECTION SPARSE LOW LEVEL CIRCULATION CENTER (LLCC).
THE CONVECTION IS BECOMING MORE ORGANIZED, BUT HAS YET TO
CONSOLIDATE AROUND THE LLCC. OUTFLOW IS VERY STRONG, AS EVIDENT IN
THE ANIMATED WATER VAPOR IMAGERY, WITH A CROSS EQUATORIAL OUTFLOW
CHANNEL TO THE SOUTHWEST AND A SECOND OUTFLOW CHANNEL INTO A
TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO THE EAST. A 212127Z
SSMIS PASS SHOWS THAT THE DEEP CONVECTION IS NOT VERY WELL ORGANIZED
AND DOES NOT HAVE THE SMOOTH APPEARANCE ASSOCIATED WITH A STRONG
INFLOW PATTERN. THE SYSTEM IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) ANCHORED TO THE NORTHEAST.
POSITION AND INTENSITY ARE BASED ON ANIMATED VISIBLE IMAGERY AND THE
PGTW DVORAK FIX.
3. FORECAST REASONING.
A. THIS IS THE FIRST PROGNOSTIC REASONING AND SETS THE FORECAST
PHILOSOPHY.
B. TS 07W IS EXPECTED TO CONTINUE TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF THE STR THROUGH TAU 48. INTENSIFICATION IS EXPECTED TO
BE SLOW. ORGANIZATION OF A LARGE SYSTEM TAKES LONGER THAN THAT OF A
SMALLER SYSTEM, THE TUTT TO THE EAST IS STARTING TO FILL, AND AN
OMEGA BLOCKING PATTERN IN THE MIDLATITUDE REGIME WILL SUPPRESS A
POLEWARD OUTFLOW CHANNEL AS THE SYSTEM ROUDS THE WESTERN EXTENT OF
THE STR. THE SYSTEM IS EXPECTED TO REACH MAXIMAL TYPHOON INTENSITY
BEFORE MAKING LANDFALL INTO TAIWAN NEAR TAU 72.
C. IN THE EXTENDED FORECAST, TS 07W WILL STEER ALONG THE WESTERN
EXTENT OF THE STR AND MAKE A SECOND LANDFALL IN CHINA BEFORE MOVING
INTO THE MIDLATITUDE WESTERLIES OVER THE YELLOW SEA. NUMERICAL MODEL
GUIDANCE IS IN FAIR AGREEMENT. GFDN AND NOGAPS ARE THE EASTERN
OUTLIERS PULLING THE SYSTEM OVER THE RYUKYU ISLANDS. ECMWF IS THE
WESTERN OUTLIER PULLING THE SYSTEM SOUTH OF TAIWAN INTO SOUTHERN
CHINA. THE DISCREPANCY STEMS FROM AN OMEGA BLOCKING PATTERN SET UP
OVER MONGOLIA AND MANCHURIA, CHINA. THE MODELS THAT HOLD THE PATTERN
LONGER AND MAINTAIN THE STR INTEGRITY (ECMWF) HAVE 07W TRACKING
FURTHER WEST, AND MODELS THAT ARE BREAKING DOWN THE PATTERN SOONER
(NOGAPS) HAVE THE SYSTEM RECURVING FASTER. MOST NUMERICAL GUIDANCE
HAS THE TENDENCY TO MOVE BLOCKING PATTERNS OUT TOO FAST, SO THIS
FORECAST FAVORS A MORE WESTERN TRACK NEAR UKMET, JGSM AND ECMWF.//
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