Subject: Indian-N: 1. Tropical Cyclone 05b Warning Nr 011

From: SIU Weather Processor <[email-masked]>
Date: Sat, 30 Oct 1999 20:36:42 -0500

618
WTIO31 PGTW 310300
IMMEDIATE DELIVERY REQ TO AMCONSUL CALCUTTA AND AMEMBASSY DHAKA
1. TROPICAL CYCLONE 05B WARNING NR 011
   01 ACTIVE TROPICAL CYCLONE IN NORTHIO
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
    ---
   WARNING POSITION:
   310000Z4 --- NEAR 20.0N2 85.9E2
     MOVEMENT PAST SIX HOURS - 180 DEGREES AT 02 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   RADIUS OF 035 KT WINDS - 050 NM SOUTHEAST SEMICIRCLE
                                   OVER WATER
                            025 NM ELSEWHERE OVER WATER
   REPEAT POSIT: 20.0N2 85.9E2
    ---
   FORECASTS:
   12 HRS, VALID AT:
   311200Z7 --- 19.6N6 85.8E1
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            030 NM ELSEWHERE OVER WATER
   VECTOR TO 24 HR POSIT: 240 DEG/ 04 KTS
    ---
   24 HRS, VALID AT:
   010000Z1 --- 19.2N2 85.1E4
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   RADIUS OF 035 KT WINDS - 055 NM SOUTHEAST SEMICIRCLE
                            030 NM ELSEWHERE OVER WATER
   VECTOR TO 36 HR POSIT: 255 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   011200Z4 --- 18.9N8 83.9E0
   MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
310300Z7 POSITION NEAR 19.9N9 85.9E2.
TROPICAL CYCLONE (TC) 05B HAS DRIFTED VERY SLOWLY SOUTH-
SOUTHEASTWARD TOWARD THE INDIAN COASTLINE DURING THE PAST 12 HOURS
IN WEAK ENVIRONMENTAL STEERING BETWEEN TWO MID-LEVEL ANTICYCLONES.
ANIMATED INFRARED SATELLITE IMAGERY INDICATES DEEP CONVECTION IN A
BAND NORTHEAST OF THE SYSTEM CENTER. ALTHOUGH THE EXACT POSITION OF
THE LOW-LEVEL CIRCULATION CENTER IS DIFFICULT TO PINPOINT, A
301502Z1 NRL MICROWAVE IMAGE INDICATES CONVECTION IN BANDS NORTH AND
SOUTH OF THE WARNING POSITION. STRONG VERTICAL WIND SHEAR EXISTS TO
THE NORTH AND TC 05B IS ADVECTING DRY AIR FROM THE INDIAN
SUBCONTINENT, HOWEVER THIS SYSTEM CLEARLY MAINTAINS STRONG LOW-LEVEL
CYCLONIC INFLOW. THE WARNING POSITION IS BASED ON A 302330Z1
INFRARED AND A 302259Z1 TROPICAL RAINFALL MEASURING MISSION (TRMM)
MICROWAVE IMAGE. THE WARNING INTENSITY IS BASED ON INFRARED
SATELLITE INTENSITY ESTIMATES OF T2.5 (35 KNOTS). TROPICAL CYCLONE
05B IS FORECAST TO MOVE SOUTH-SOUTHWESTWARD THROUGH 12 HOURS UNDER
THE ENVIRONMENTAL STEERING INFLUENCE OF THE BUILDING MID-LEVEL
ANTICYCLONE CENTERED OVER THE ARABIAN PENINSULA. TC 05B IS EXPECTED
TO INTENSIFY SLIGHTLY DURING THIS TIME AS IT TRAKCS NEAR THE
INDIAN COAST. AFTER 12 HOURS TC 05B IS EXPECTED TO ACCELERATE
SLIGHTLY AND TURN TOWARD THE WEST-SOUTHWEST, DISSIPATING OVER LAND
DUE TO DRY AIR ENTRAINMENT AND LAND INTERACTION BY 36 HOURS. THE
MAJORITY OF THE OBJECTIVE NUMERICAL FORECAST GUIDANCE SUPPORTS THIS
FORECAST TRACK SCENARIO, INCLUDING THE MAJOR GLOBAL SPECTRAL
MODELS. AN ALTERNATE SCENARIO EXISTS IN WHICH TROPICAL CYCLONE 05B
TRACKS IN A MORE SOUTHWARD DIRECTION AND INTENSIFIES STEADILY OVER
29 DEGREE CELSIUS WATER IN THE WESTERN BAY OF BENGAL. THE
PROBABILITY OF THIS ALTERNATE FORECAST SCENARIO IS CONSIDERED LOW.
MAXIMUM SIGNIFICANT WAVE HEIGHT IS OMITTED BECAUSE THE SYSTEM CENTER
IS OVER LAND. REFER TO WWIO30 RJTX FOR ADDITIONAL SEA HEIGHT
INFORMATION FOR THE INDIAN OCEAN. NEXT WARNING AT 311500Z0 (DTG
311351Z4).//

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