JTWC's prognostic reasoning
WDPN31 PGTW 120300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (MALAKAS) WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
INITIAL POSITION: 15.4N 135.2E
INITIAL INTENSITY: 70 KTS
GEOGRAPHIC REFERENCE: 393 NM NORTH-NORTHWEST OF YAP
MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 10 KTS
SIGNIFICANT WAVE HEIGHT: 28 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED VISIBLE SATELLITE IMAGERY DEPICTS SPIRAL
CURVED BANDING WRAPPING INTO AN INCREASINGLY WELL DEFINED
CONVECTIVE CORE. SHORTLY AFTER THE 00Z SYNOPTIC HOUR, A FORMATIVE
CLOUD-FILLED EYE APPEARED, WITH TOWERING CONVECTION WRAPPING AROUND
THE CORE INDICATING THAT A LONG-AWAITED RAPID INTESNIFICATION MAY
FINALLY BE STARTING. THE INITIAL POSITION WAS BASED ON A BLEND OF
AGENCY FIXES FROM PGTW, RJTD, AND RCTP, AND SUPPORTED BY A LOW
RESOLUTION 112232Z NOAA-19 AMSU PASS WITH A BANDED CENTER. THE
INTENSITY WAS RAISED TO 70 KNOTS AT THE SYNOPTIC TIME, WITH
SUBJECTIVE DVORAK ESTIMATES RANGING FROM 65 TO 77 KNOTS BASED ON
FINAL-T VALUES OF T4.0 (PGTW AND RJTD) TO T4.5 (RCTP AND KNES). ADT
AND SATCON ARE ON THE LOWER END OF THE ENVELOPE AT 59 TO 62 KNOTS,
RESPECTIVELY, WHILE AIDT WAS 69 KNOTS AND THE MULTI-PLATFORM
SATELLITE WIND ANALYSIS WAS 75 KNOTS. AN 112053Z SMAP PASS WAS
SURPRISNGLY LOW AT 50 KNOTS, BUT PROVIDED A BASIS FOR THE 35 KNOT
WIND RADII ASSESSMENT. TYPHOON MALAKAS IS ROUNDING A SUB-TROPICAL
STEERING RIDGE CENTERED TO THE EAST. UPPER LEVEL WINDS ARE
GENERALLY LIGHT AND IN PHASE WITH THE STEERING MOTION, AND
DUAL-CHANNEL OUTFLOW CONTINUES TO IMPROVE AS THE NORTHERN EXTENT OF
O2W NEARS THE MID-LATITUDE JET. SEA SURFACE TEMPERATURES ARE
ESTIMATED TO BE AROUND 28 DEGREES CELSIUS. THESE FACTORS ARE
POSITIVE FOR FURTHER DEVELOPMENT.
INITIAL WIND RADII BASIS: SMAP AND SCATTEROMETER DATA
CURRENT STEERING MECHANISM: DEEP LAYER SUB-TROPICAL RIDGE (STR) TO
THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
PGTW: T4.0 - 65 KTS
RJTD: T4.0 - 65 KTS
RCTP: T4.5 - 77 KTS
KNES: T4.5 - 77 KTS
CIMSS SATCON: 59 KTS AT 112233Z
CIMSS ADT: 59 KTS AT 112340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
VWS: 0-5 KTS
SST: 27-28 CELSIUS
OUTFLOW: MODERATE DUAL-CHANNEL
ANALYSIS CONFIDENCE:
INITIAL POSITION: MEDIUM
INITIAL INTENSITY: MEDIUM
INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TY MALAKAS WILL CONTINUE TO ROUND THE STR OVER
THE NEXT 12 TO 18 HOURS, AFTER WHICH THE STORM MOTION SHOULD BEGIN
TO RECURVE NORTHEASTWARD. FAVORABLE ENVIRONMENTAL CONDITIONS WILL
CONTINUE FOR THE NEXT 36 HOURS, ALLOWING FURTHER INTENSIFICATION.
THE DEVELOPMENT OF AN EYE IS RAISING THE LIKLIHOOD THAT RAPID
INTENSIFICATION (RI) MAY COMMENCE SHORTLY, IF THE NASCENT EYE CAN
CONTINUE TO CLEAR OUT. THE GFS AND HWRF BOTH DEPICT RAPID
DEEPENING, REACHING MSLP MINIMA OF 947 AND 936 MB, RESPECTIVELY
OVER THE NEXT DAY AND A HALF. ADDITIONALLY, SEVERAL RI AIDS WERE
TRIGGERED THIS CYCLE, SO THE SHORT-TERM FORECAST INTENSITY TREND
WAS INCREASED. A PEAK OF 110 KNOTS IS FORECAST AT TAU 36. THE
FORECAST TRACK HAS REMAINED STEADY IN THE CROSS-TRACK DIRECTION,
HOWEVER GFS NOW TRACKS 02W MUCH MORE QUICKLY IN THE 96 TO 120 HOUR
PERIOD, RESULTING IN A MARKED SHIFT IN THE CONSENSUS MEAN POSITION
AT TAU 120. THE FORECAST POSIT FOR THAT TAU WAS ADJUSTED AHEAD
SLIGTHLY, BUT MAY REQUIRE ADDITIONAL ADJUSTMENT IF THIS TREND
CONTINUES. MODELS CONTINUE TO INDICATE INCREASING VERTICAL WIND
SHEAR WILL OCCUR AFTER TAU 36. BY TAU 72, DRY AIR WILL FURTHER
DISRUPT THE SYSTEM. EXTRA-TROPICAL TRANSITION (ETT) WILL
BEGIN SHORTLY AFTER TAU 72 AND BE COMPLETED BY TAU 120 AS MALAKAS
IS FULLY UNDER THE MID-LATITUDE JET. TY 02W IS EXPECTED TO BECOME A
STRONG GALE-FORCE COLD-CORE LOW WITH A LARGE WIND FIELD.
MODEL DISCUSSION: DYNAMICAL MODEL TRACK GUIDANCE IS TIGHTLY
CLUSTERED IN THE ALONG-TRACK DIRECTION, WITH NO SIGNIFICANT
OUTLIERS. HOWEVER, GFS IS INDICATING A FASTER FORWARD MOTION AS THE
SYSTEM UNDERGOES ETT. LIKEWISE, INTENSITY GUIDANCE IS IN AGREEMENT
WITH INTENSIFICATION OVER THE NEXT 36 TO 42 HOURS.
FORECAST CONFIDENCE:
TRACK 0 - 72 HR: HIGH
TRACK 72-120 HR: MEDIUM
INTENSITY 0 - 72 HR: MEDIUM
INTENSITY 72-120 HR: MEDIUM//
