Interesting, JTWC are calling it a cyclone, BOM are saying that it wont turn cyclonic?


JTWC:
112100Z POSITION NEAR 18.9S 115.7E.
11MAR20. TROPICAL CYCLONE (TC) 21S (TWENTYONE), LOCATED APPROXIMATELY
255 NM NORTH-NORTHEAST OF LEARMONTH, AUSTRALIA, HAS TRACKED
SOUTHWESTWARD AT 10 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION IS SEVERELY
SHEARED EASTWARD, FULLY EXPOSING THE LOW LEVEL CIRCULATION CENTER.
THE INITIAL POSITION IS BASED ON THE ABOVE ANIMATION WITH HIGH
CONFIDENCE. THE INITIAL INTENSITY OF 35KTS IS BASED ON THE HIGH END
OF AGENCY DVORAK ESTIMATES OF T1.5/25KTS AND SATCON OF 42KTS.
ANALYSES INDICATE A HOSTILE ENVIRONMENT WITH STRONG (25KTS+) RELATIVE
VERTICAL WIND SHEAR (VWS) AND COLD DRY AIR ENTRAINMENT NEAR THE
SURFACE. TC 21S WILL CONTINUE TRACKING SOUTHWESTWARD ALONG THE
NORTHWEST PERIPHERY OF THE SUBTROPICAL RIDGE TO THE SOUTHEAST. THE
VWS IS EXPECTED TO ONLY GET WORSE AS THE CYCLONE TRACKS MORE POLEWARD
AND THE COLD AIR ADVECTION WILL NOT ABATE, LEADING TO DISSIPATION BY
TAU 12. THE WEAK REMNANTS WILL MAKE LANDFALL OVER LEARMONTH SHORTLY
AFTER TAU 24. THIS IS THE FINAL WARNING ON THIS SYSTEM BY THE JOINT
TYPHOON WRNCEN PEARL HARBOR HI. THE SYSTEM WILL BE CLOSELY MONITORED
FOR SIGNS OF REGENERATION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 111800Z
IS 12 FEET.

BOM:

Potential Cyclones:

A tropical low was located near 19.4S 114.9E at 11am WST Thursday, about 250km northwest of Karratha and 290km north northeast of Exmouth. This system is forecast to move south southwest towards the northwest of Western Australia and lie near the far west Pilbara coast late Thursday evening, and just to the west of Exmouth early Friday morning. This system is unlikely to develop into a tropical cyclone, however squally conditions and heavy rainfall are possible over the far western Pilbara from later on Thursday as the system moves by. A Severe Weather Warning has been issued and for more details refer to http://www.bom.gov.au/products/IDW21037.shtml

The low is expected to weaken on Friday, however moisture from the low is expected produce areas of rainfall over southwestern WA on the weekend.


Likelihood of this system being a tropical cyclone in the Western Region on:
Friday:Very Low
Saturday:Very Low
Sunday:Very Low