TYPHOON NIDA STATIONARY FOR THE PAST 48HRS, 97W INVEST SLOWLY INTENSIFYING

TROPICAL CYCLONE ADVISORY
NOV 30 2009

WIND IMAGERY

THERMAL IR IMAGERY

STEERING WIND/PRESSURE

RAINFALL IMAGERY ANALYSIS

WESTERN PACIFIC IR IMAGERY

TYPHOON NIDA (26W)

TYPHOON (CATEGORY 3) STAGE
CURRENT INTENSITY: MAX: 100kt GUST: 125kt (185-232kph)
CURRENT PRESSURE: 948MB
SURFACE WIND ANALYSIS: 100KT (185KPH) MSLP: 946.3MB
ADVANCE DVORAK TECHNIQUES (ADT): 99.6KT(184KPH) MSLP: 944.9B
CENTRAL REGION TEMP: -12.5C (EYE)
CENTRAL CLOUD TEMP: -61.0C (+15MM/HR)
FORECAST 12HRS: 90KT/167KPH

DISCUSSION:

TYPHOON (TY) 26W (NIDA), LOCATED APPROXIMATELY 330 NM SOUTH-SOUTHWEST OF IWO TO, HAS REMAINED QUASI-STATIONARY (QS) OVER THEPAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTSWEAKENING CONVECTION OVER ALL QUADRANTS WITH A RAGGED 50NM EYE. TY 26W HAS, IN FACT, REMAINED QS OVER THE PAST 36 HOURS AND IS LIKELY WEAKENING DUE TO A COMBINATION OF DRY AIR ENTRAINMENT (DAE) AND COLD WATER UPWELLING. THE TOTAL PRECIPITABLE WATER (TPW) PRODUCTS INDICATE DRY AIR ADVECTION JUST WEST OF THE SYSTEM WITH A WEDGE OF DRY AIR (25-40MM) WRAPPING INTO THE NORTHEAST QUADRANT. A 292032Z SSMI/S IMAGE DEPICTS EYEWALL EROSION TO THE SOUTH AS DRY AIR IS BEING PULLED INTO THE CORE, AND A ROUND 50NM DIAMETER EYE. ANIMATED WATER VAPOR IMAGERY CONTINUES TO SHOW GOOD RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW INTO THE MIDLATITUDE WESTERLIES. THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION AND MOTION DUE TO THE ERRATIC SLOW TRACK AND LARGE EYE, HOWEVER, 37 GHZ MICROWAVE IMAGERY SUPPORTS BOTH. THE CURRENT INTENSITY OF 100 KNOTS IS BASED ON THE HIGHER DVORAK ESTIMATES RANGING FROM 77 TO 102 KNOTS. THE 29/12Z 500 MB ANALYSIS DEPICTS A WEAK MID-LEVEL STEERING ENVIRONMENT WITH TY 26W POSITIONED BETWEEN THE SUBTROPICAL RIDGE (STR) TO THE EAST AND WEST WITH STRONG MIDLATITUDE (ZONAL) WESTERLIES NORTH OF 25N. THE UPPER-LEVEL FLOW REMAINS HIGH ZONAL ACROSS ASIA WITH NO SIGNIFICANT MID-LEVEL SHORT-WAVE TROUGHS EVIDENT IN THE UPSTREAM FLOW (IN IMAGERY AS WELL). THE 30/00Z SURFACE ANALYSIS DEPICTS STRONG LOW-LEVEL RIDGING ENTRENCHED NORTH AND WEST OF TY 26W.

A. NO CHANGES TO FORECAST PHILOSOPHY.

B. NUMERICAL GUIDANCE REMAINS IN POOR AGREEMENT WITH TWODISTINCT CLUSTERS; NOGAPS, GFDN, AND WBAR STILL FAVOR A RECURVATURESCENARIO AND TRACK THE SYSTEM NORTH-NORTHEASTWARD TO NORTHEASTWARDRAPIDLY, WHILE JGSM, TC-LAPS, UKMO, ECMWF, AND GFS FAVOR A SLOWERWESTWARD TRACK WITH DISSIPATION. THE OFFICIAL FORECAST FAVORS THESLOW WESTWARD MOVEMENT WITH DISSIPATION AFTER TAU 72. AS THE SYSTEMWEAKENS, STEERING IS EXPECTED TO SHIFT TO THE LOW-LEVELS AND TY 26WIS LIKELY TO TRACK WESTWARD TO SOUTHWESTWARD UNDER THE NORTHEASTERLYFLOW. THE DISSIPATION SCENARIO IS BASED ON INCREASING VERTICAL WINDSHEAR DUE TO A COMBINATION OF LOW-LEVEL NORTHEASTERLY FLOW, ASSOCIATED WITH THE RIDGE BUILDING NORTH OF THE SYSTEM, AND ZONAL UPPER-LEVEL WESTERLY FLOW AS WELL AS DAE AND COOL WATER UPWELLING.

C. IN THE EXTENDED TAUS, TY 26W WILL CONTINUE TO WEAKEN AND SHOULD TURN SOUTHWESTWARD AND ACCELERATE WITHIN THE LOW-LEVEL FLOW. THERE IS STILL UNCERTAINTY WITH THE TIMING OF THE DISSIPATION AND THE TURN SOUTHWESTWARD. ADDITIONALLY, SEVERAL MODELS INDICATE THAT THE REMNANTS WILL TRACK CYCLONICALLY AND GET ABSORBED INTO A DEVELOPING STORM NEAR OR NORTHWEST OF GUAM.

TROPICAL DISTURBANCE 97W INVEST
SEVERE ALERT (12-24HRS FORMATION) STAGE
CURRENT INTENSITY: MAX: 15kt GUST: 20kt (28-37kph)
CURRENT PRESSURE: 1006MB
SURFACE WIND ANALYSIS: 28KT (52KPH) MSLP: 1005.8MB
ADVANCE DVORAK TECHNIQUES (ADT): 0KT(0KPH) MSLP: 0MB
CENTRAL REGION TEMP: -0C (N/A)
CENTRAL CLOUD TEMP: -0C (+50MM/HR)
FORECAST 12HRS: 0KT/0KPH

DISCUSSION:

THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 2.2N 160.0E, IS NOW LOCATED NEAR 5.6N 153.7E, APPROXIMATELY 150 NM SOUTHEAST OF CHUUK. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A BROAD REGION OF TROUGHING WITH SPORADIC CONVECTION IN THE VICINITY OF THE TROUGHING. CURRENTLY THERE DOES NOT APPEAR TO BE A SINGULAR CIRCULATION DEVELOPING, WITH MULTIPLE REGIONS OF TURNING IDENTIFIED IN THE IMAGERY. A 292329Z ASCAT IMAGE SUPPORTS THE TROUGH EXTENDING FROM CHUUK TO THE SOUTH OF POHNPEI. THE DEEPEST CONVECTION REMAINS TO THE NORTHWEST OF THE TROUGHING. UPPER LEVEL ANALYSIS DEPICTS A POINT SOURCE ANTICYCLONE IS LOCATED TO THE EAST OF THE TROUGHING WITH A REGION OF DIFFLUENCE ASSOCIATED WITH THE ANTICYCLONE EXTENDING OVER THE LOW LEVEL TROUGH, WHICH IS PROVIDING GOOD UPPER LEVEL OUTFLOW SUPPORT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 10 TO 15 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. BASED ON THE POOR ORGANIZATION OF THE LOW LEVEL ENVIRONMENT AND SPORADIC CONVECTION, THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS POOR

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