(1) AN AREA OF CONVECTION (INVEST 91A) HAS PERSISTED NEAR 9.2N
57.3E, APPROXIMATELY 280 NM SOUTHEAST OF SOCOTRA ISLAND. ANIMATED
INFRARED SATELLITE IMAGERY SHOWS DISORGANIZED FLARING CONVECTION. A
141605Z MHS 89GHZ MICROWAVE IMAGE REVEALS SCATTERED AREAS OF DEEP
CONVECTION AND LITTLE LOW LEVEL ORGANIZATION. UPPER LEVEL ANALYSIS
INDICATES LIMITED DIFFLUENCE ALOFT BUT LOW (5-10 KT) VERTICAL WIND
SHEAR IN THE REGION. SEA SURFACE TEMPERATURES (29-32 DEGREES
CELSIUS) ARE FAVORABLE FOR DEVELOPMENT. NUMERICAL MODEL GUIDANCE
MAINTAINS TIGHT TROUGHING OR A SMALL CIRCULATION IN THE ARABIAN SEA,
AND SOME PREDICT DEVELOPMENT SOMETIME AFTER 3 DAYS AS IT PROPAGATES
WESTWARD. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1010 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS LOW.
B. TROPICAL DISTURBANCE SUMMARY:
(1) THE AREA OF CONVECTION (INVEST 91A) PREVIOUSLY LOCATED
NEAR 9.2N 57.3E, IS NOW LOCATED NEAR 10.4N 54.5E, APPROXIMATELY 129
NM SOUTH-SOUTHEAST OF SOCOTRA ISLAND. ANIMATED MULTI-SPECTRAL
SATELLITE IMAGERY AND A 150615Z METOP-A 89GHZ IMAGE DEPICT WEAK
FORMATIVE BANDING ASSOCIATED WITH A SLOWLY CONSOLIDATING LOW LEVEL
CIRCULATION (LLC). ENVIRONMENTAL ANALYSIS SHOWS THE DISTURBANCE
IS LOCATED IN AN AREA OF LIGHT TO MODERATE (10-20 KNOT) VERTICAL
WIND SHEAR WITH STRONG DIFFLUENCE ALOFT. WARM SEA SURFACE
TEMPERATURES (29-32 DEGREES CELSIUS) ARE SUPPORTIVE FOR DEVELOPMENT.
A RECENT ASCAT PASS SHOWS 15-20 KNOT WIND BARBS LOCATED IN THE
WESTERN QUADRANT OF THE LLC. GLOBAL MODELS INDICATE THAT 91A WILL
TRACK NORTHWESTWARD OVER THE NEXT 48 HOURS INTO THE GULF OF ADEN.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1006 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.
ARB/02/2018
Dated: 15.05.2018
A LOW PRESSURE AREA FORMED OVER SOUTHWEST ARABIAN SEA ON 14TH MAY. IT LIES AS WELL MARKED LOW PRESSURE AREA OVER THE SAME REGION ON 15TH MAY. TO MOVE WEST NORTHWESTWARDS TOWARDS GULF OF ADEN AND ADJOINING AREAS AND CONCENTRATE INTO A DEPRESSION DURING NEXT 48 HOURS.
WTIO21 PGTW 160300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
160 NM EITHER SIDE OF A LINE FROM 11.4N 53.5E TO 12.7N 49.1E
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 28 TO 33 KNOTS. METSAT
IMAGERY AT 160000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 11.8N 53.2E. THE SYSTEM IS MOVING NORTHWESTWARD AT 08 KNOTS.
2. REMARKS: THE AREA OF CONVECTION (INVEST 91A) PREVIOUSLY LOCATED
NEAR 11.0N 54.0E, IS NOW LOCATED NEAR 11.8N 53.2E, APPROXIMATELY 55
NM SOUTHWEST OF SOCOTRA ISLAND. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS FLARING CONVECTION TO THE NORTHWEST OF THE LLC, WHICH
WAS SHEARED BUT IS NOW SLIDING BACK UNDER THE CONVECTION, AND
NASCENT CONVECTION TO THE SOUTH OF THE LLC AS WELL. A 160003Z SSMIS
91GHZ MICROWAVE IMAGE REVEALS THE DEEPEST CONVECTION IS NORTHWEST OF
THE CENTER, AND LOW LEVEL BANDING IS WRAPPING INTO THE LLC. UPPER
LEVEL ANALYSIS INDICATES IMPROVING POLEWARD OUTFLOW AND DIVERGENCE
ALOFT THAT IS SUPPORTING DEEPER CONVECTION. 91A IS LOCATED IN AN
AREA OF LIGHT TO MODERATE (10-20 KT) VERTICAL WIND SHEAR. SEA
SURFACE TEMPERATURES ARE VERY WARM (30-31 DEGREES CELSIUS) AND
SUPPORT FURTHER DEVELOPMENT. NUMERICAL MODELS PREDICT THAT 91A WILL
TRACK WESTWARD INTO THE GULF OF ADEN AND REMAIN OVER WATER FOR
SEVERAL DAYS. AS IT TRACKS WESTWARD OVER WARM WATER WITH FAVORABLE
ENVIRONMENTAL CONDITIONS, MODELS PREDICT 91A WILL INTENSIFY TO A
BORDERLINE TROPICAL CYCLONE WITHIN 24 HOURS. MAXIMUM SUSTAINED
SURFACE WINDS ARE ESTIMATED AT 28 TO 33 KNOTS. MINIMUM SEA LEVEL
PRESSURE IS ESTIMATED TO BE NEAR 998 MB. THE POTENTIAL FOR THE
DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
170300Z.
//
NNNN
VORTEX OVER SW ARSEA ADJ GULF OF ADEN CENTRED WITHIN HALF A DEG OF 12.9N/50.0E (.) INTERSITY T1.5 (.) ASSTD SCT LOW/MED CLOUDS WITH EMBDD INT TO V INT CONVTN OVER AREA BET LAT 08.5N TO 17.0N WEST OF 57.0E GULF OF ADEN ADJ YEMEN(.)
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