Tropical Storm MALAKAS Advisory Sa, 09.04.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 02W (MALAKAS)
WARNING NR 009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 7.0N 144.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 19 NM SOUTH-SOUTHEAST OF IFALIK
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) REVEALS AN EXPOSED
LOW-LEVEL CIRCULATION CENTER (LLCC) TO THE EAST-SOUTHEAST OF A DEEP
CONVECTIVE BURST THAT HAS PERSISTED FOR THE PAST 6 HOURS.
UPPER-LEVEL CIRRUS CLOUDS ARE SEEN STREAMING OVER THE LLCC FROM THE
EAST, DENOTING THE STRONG SOUTHEASTERLY TO EASTERLY VERTICAL SHEAR
CURRENTLY IMPACTING THE CYCLONE. THE INITIAL INTENSITY REMAINS 40
KT BASED ON SUBJECTIVE DVORAK ESTIMATES OF T3.0 (45 KT) FROM PGTW
AND T2.5 (35 KT) FROM RJTD, AS WELL AS REPRESENTATIVE WIND
ESTIMATES FROM A 082043Z SMAP PASS. THE LLCC HAS WOBBLED BACK
NORTHWARD DURING THE PAST 6 HOURS AFTER TAKING A WESTWARD JOG
DURING THE PRECEDING 6 HOURS. SUCH WOBBLES ARE COMMON WHEN DEEP
CONVECTION IS OFFSET FROM THE VORTEX CENTER.
INITIAL WIND RADII BASIS: COMBINATION OF SMAP DATA AND PERSISTENCE
CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE
NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.5 - 55 KTS
   CIMSS SATCON: 42 KTS AT 082210Z
   CIMSS ADT: 43 KTS AT 082340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE WESTWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: MEDIUM
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: FORECAST DISCUSSION: TROPICAL STORM 02W
(MALAKAS) CONTINUES TO BE EMBATTLED BY UPPER-LEVEL SOUTHEASTERLY
FLOW
THAT MAXIMIZES AT 25 KT AROUND 300 MB, JUST BELOW THE OUTFLOW LAYER,
AS ANALYZED BY THE GFS AND ECMWF MODELS. THE RESULTING CONVECTIVE
STRUCTURE LACKS ANY SIGNS OF PROGRESS TOWARD AXISYMMETRY, IMPLYING
THAT MALAKAS MAY STRUGGLE TO MAKE SIGNIFICANT GAINS IN INTENSITY
DURING THE NEAR TERM. HOWEVER, THE 300 MB ENVIRONMENTAL FLOW IS
FORECAST TO DECREASE TO 20 KT BY 24 HOURS, AND 15 KT BY 36 HOURS,
LEADING TO A DECREASE IN VERTICAL SHEAR THAT SHOULD ALLOW CONVECTION
TO WRAP FURTHER AROUND THE CIRCULATION CENTER AND FACILITATE
INTENSIFICATION. MALAKAS IS FORECAST TO REACH TYPHOON INTENSITY
AFTER 48 HOURS AND CONTINUE INTENSIFYING TO A PEAK OF 90 KT IN 96
HOURS IN AN ENVIRONMENT OF WEAK VERTICAL SHEAR AND WARM SEA
SURFACE TEMPERATURES. BEYOND 96 HOURS, THE CYCLONE WILL APPROACH
COOLER WATERS AROUND LATITUDE 19N AND POTENTIALLY BEGIN ENTRAINING AN
AMBIENT DRY SUBTROPICAL AIR MASS, WHICH SHOULD ARREST THE
INTENSIFICATION. THE TRACK FORECAST IS MORE STRAIGHT-FORWARD THAN
IN PREVIOUS WARNINGS, WITH MODEL GUIDANCE IN TIGHT AGREEMENT
THROUGH 48 HOURS, TAKING MALAKAS NORTHWESTWARD WELL SOUTHWEST OF
GUAM, STEERED BY THE DEEP-LAYER SUBTROPICAL RIDGE EAST OF THE
MARIANAS. A TURN NORTHWARD AROUND THE WESTERN PERIPHERY OF THIS
RIDGE IS EXPECTED AROUND 72 HOURS, AT WHICH POINT MODEL SPREAD
INCREASES, ESPECIALLY IN THE ALONG-TRACK DIRECTION. STEERING
CURRENTS MAY WEAKEN AS THE MID-LATITUDE JET REMAINS WELL NORTH OF
THE CYCLONE AND A SHORTWAVE TROUGH CROSSES KYUSHU AND BEGINS ERODING
THE STEERING RIDGE. ADDITIONALLY, TROPICAL DEPRESSION 03W TO THE
SOUTHWEST OF MALAKAS COULD INDUCE A TEMPORARY WESTWARD JOG IN THE
TRACK OF MALAKAS DURING THE 72-96 HOUR PERIOD AS THE TWO VORTICES
INTERACT, DEPENDING ON HOW STRONG 03W BECOMES AND THE EXACT
PROXIMITY OF THE TWO CIRCULATIONS. SUCH A JOG, IF ANY, IS EXPECTED
TO BE SMALL GIVEN THE MUCH LARGER SIZE OF 02W (MALAKAS). GIVEN THESE
FACTORS, CONFIDENCE IN THE TRACK FORECAST AFTER 72 HOURS IS MEDIUM.
MODEL DISCUSSION: THE JTWC TRACK FORECAST IS CLOSE TO THE
MULTI-MODEL CONSENSUS AND SLIGHTLY FASTER THAN THE PREVIOUS
FORECAST. THE JTWC INTENSITY FORECAST IS SLIGHTLY BELOW THE MULTI-
MODEL CONSENSUS THROUGH 36 HOURS DUE TO EXPECTED IMPEDIMENTS TO
INTENSIFICATION, AND SLIGHTLY ABOVE THE CONSENSUS THEREAFTER.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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