Subject: Pacific-NW: Subj/prognostic Reasoning For Tropical Depression 01w Warning Nr 02//

From: SIU Weather Processor <[email-masked]>
Date: Sun, 13 Jan 2008 08:19:05 -0600

WDPN31 PGTW 131500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 01W WARNING NR 02//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TROPICAL DEPRESSION (TD) 01W (NONAME) HAS CONSOLIDATED IN THE
CENTRAL SOUTH CHINA SEA OVER THE PAST 12 HOURS AFTER CROSSING THE
PHILIPPINE ISLANDS. A CENTRAL DENSE OVERCAST HAS DEVELOPED AS THE
STORM HAS MOVED OVER A REGION OF FAVORABLE SEA SURFACE TEMPERATURES.
THE STORM HAS BEEN STEERED WEST-NORTHWESTWARD BY THE SUBTROPICAL RIDGE
TO ITS NORTHEAST. A MID LEVEL TROUGH LYING OVER SOUTHEASTERN CHINA HAS
CREATED A SLIGHT WEAKNESS IN THIS SUBTROPICAL RIDGE ALLOWING FOR THE
WEST-NORTHWESTWARD TRACK.
   B. THE WARNING POSITION IS BASED ON ANIMATED ENHANCED INFRARED
IMAGERY AND SURFACE SYNOPTIC ANALYSIS. THE INITIAL INTENSITY IS BASED
ON DVORAK ESTIMATES OF 2.0 FROM KNES AND PGTW. ADDITIONALLY, A
13/0123Z ASCAT SCATTEROMETRY PASS REVEALS WINDS OF 25 KTS ON THE
NORTHWEST PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE
SYSTEM REMAINS IN A REGION OF GOOD UPPER LEVEL DIFFLUENCE. SYNOPTIC-
ALLY, A COLD, DRY AIR SURGE HAS SET UP WITH STRONG NORTH-NORTHEASTERLY
WINDS BUILDING TO THE NORTH AND WEST OF THE STORM. MICROWAVE SATELLITE
IMAGERY AND THE TOTAL PRECIPITABLE WATER CIMMS PRODUCTS SHOW
ENCROACHING CONTINENTAL POLAR AIR PRECARIOUSLY CLOSE TO THE SYSTEM.
 3. FORECAST REASONING
   A. FORECAST PHILOSOPHY HAS NOT DEVIATED SINCE THE LAST FORECAST.
   B. THE SUBTROPICAL RIDGE WILL REBUILD NORTH OF THE SYSTEM
BY TAU 12, STEERING THE SYSTEM WESTWARD AND THEN SOUTHWESTWARD. THE
STORM HAS MOST LIKELY REACHED ITS MAXIMUM INTENSITY, AND WILL WEAKEN
DUE TO DRIER AIR ENTRAINMENT AND LOWER OCEAN HEAT CONTENT AFTER TAU 24.
BY TAU 36, THE STORM IS EXPECTED TO HAVE COMPLETELY DISSIPATED. THE
CONSENSUS MODEL AIDS ARE IN GOOD AGREEMENT WITH THE EXCEPTION OF WBAR.
WBAR FORECASTS A HIGHLY UNLIKELY SCENARIO IN WHICH THE STORM WOULD
TRACK DIRECTLY INTO THE COLD NORTHEASTERLY FLOW.
FORECAST TEAM: BRAVO//

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