BoB: INVEST 91B

[zzh]

91B INVEST 220314 0600 3.7N 87.5E IO 15 0

[doomhaMwx]

Oh, is this the one that models show forming from a westerly wind burst in the Indian Ocean? It got designated much earlier than I expected. Models basically have it doing nothing over the next 5 days though. Even the GFS which is currently the most aggressive only develops it 5-6 days from now.

[zzh]

[Hurricane2021]

 https://twitter.com/WxTca/status/1503475736384000002

[Hurricane2021]

 https://twitter.com/LckyTuba/status/1503511546961481731

[doomhaMwx]

ABIO10 PGTW 141800

AN AREA OF CONVECTION (INVEST 91B) HAS PERSISTED NEAR 3.6N
87.8E, APPROXIMATELY 683 NM SOUTHWEST OF PHUKET, THAILAND. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS PERSISTENT FLARING
CONVECTION OVER A BROAD LOW LEVEL CIRCULATION (LLC). RECENT PARTIAL
SCATTEROMETER PASSES SHOW 20-25 KNOTS EMBEDDED WITHIN THE LLC. UPPER
LEVEL ANALYSIS INDICATES 91B IS IN A MARGINALLY FAVORABLE
ENVIRONMENT WITH GOOD POLEWARD OUTFLOW AND WARM (26-27C) SEA SURFACE
TEMPERATURES BEING OFFSET BY HIGH (25-30KT) VERTICAL WIND SHEAR.
GLOBAL MODELS ARE IN AGREEMENT THAT 91B WILL REMAIN QUASI-STATIONARY
BEFORE TRACKING NORTHWARD BY TAU 84. HOWEVER, THERE IS DISPARITY
BETWEEN THE MODELS WITH INTENSITY OF THE SYSTEM. GFS AND NAVGEM
STRENGTHEN THE SYSTEM CONSISTENTLY OVER THE COMING DAYS, WITH ECMWF
SHOWING LITTLE TO NO DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS
ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS
ESTIMATED TO BE NEAR 1008 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.

Update: Up to medium.

ABIO10 PGTW 150200 COR

THE AREA OF CONVECTION (INVEST 91B) PREVIOUSLY LOCATED
NEAR 3.6N 87.8E IS NOW LOCATED NEAR 2.1N 86.5E, APPROXIMATELY 490 NM
SOUTHEAST OF COLOMBO, SRI LANKA. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY REVEALS PERSISTENT FLARING CONVECTION OVER A BROAD
LOW LEVEL CIRCULATION (LLC). A 142230Z SSMIS 91GHZ COLOR COMPOSITE
IMAGE REVEALS CONVECTION IS ORGANIZED ALONG A BROAD SPIRAL BAND
WRAPPING INTO A DEVELOPING LLC CENTER. UPPER LEVEL ANALYSIS
INDICATES 91B IS IN A MARGINALLY FAVORABLE ENVIRONMENT WITH GOOD
POLEWARD OUTFLOW AND WARM (26-27C) SEA SURFACE TEMPERATURES BEING
OFFSET BY HIGH (25-30KT) VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN
AGREEMENT THAT 91B WILL TRACK NORTHWARD WITH GFS AND NAVGEM
INDICATING INTENSIFICATION TO WARNING CRITERIA WITHIN 72 TO 96
HOURS. HOWEVER, THE CURRENT LEVEL OF ORGANIZATIONAL IMPROVEMENT
SUGGESTS THIS MAY OCCUR MORE RAPIDLY THAN MODELS ARE DEPICTING.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS UPGRADED TO MEDIUM.

[doomhaMwx]

Looks like this is finally doing something.

WTIO21 PGTW 200300

REMARKS:
THE AREA OF CONVECTION (INVEST 91B) PREVIOUSLY LOCATED
NEAR 09.9S 93.7E IS NOW LOCATED NEAR 10.5S 93.8E, APPROXIMATELY
401NM SOUTH-SOUTH WEST OF YANGON, MYANMAR. ANIMATED ENHANCED
INFRARED SATELLITE IMAGERY DEPICTS A CONSOLIDATING LOW-LEVEL
CIRCULATION WITH IMPROVING CONVECTIVE BANDING. A 192234Z SSMIS 91GHZ
MICROWAVE IMAGE DEPICTS IMPROVED LOW LEVEL BANDING FEATURES AND
FRAGMENTED CONVECTIVE BANDS ON THE NORTHEAST SIDE EXTENDING TO THE
SOUTH IN VICINITY OF THE NICOBAR ISLANDS. UPPER-LEVEL ANALYSIS
INDICATES A FAVORABLE ENVIRONMENT WITH INCREASING POLEWARD OUTFLOW,
AND LOW (05-10 KNOTS) VERTICAL WIND SHEAR (VWS). SEA SURFACE
TEMPERATURE VALUES (29-30C) ARE CONDUCIVE FOR FURTHER DEVELOPMENT.
TRACK GUIDANCE INDICATES A NORTHERLY TRACK OVER THE NEXT 48 HOURS,
WITH A POSSIBLE LANDFALL ALONG THE WESTERN PORTION OF THE MYANMAR
COAST. THE BULK OF THE INTENSITY GUIDANCE SUGGESTS RELATIVELY STEADY
BUT SLOW INTENSIFICATION OVER THE NEXT 24 TO 48 HOURS, WHILE THE
HWRF SUGGESTS MORE RAPID INTENSIFICATION WITH A TRACK MORE OVER
WATER. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 23 TO 28
KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1000 MB.
THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS IS HIGH.

The Depression over southeast Bay of Bengal and adjoining south Andaman
Sea, moved north-northeastwards at a speed of 12 kmph and lay centered at 1130
hours IST of today, the 20th March, over the same region, near latitude 10.4°N and
longitude 92.8°E, about 140 km north of Car Nicobar (Nicobar Islands), 140 km south
of Port Blair (Andaman Islands) and 800 km south-southwest of Yangon (Myanmar).
It is likely to move nearly northwards along & off Andaman & Nicobar Islands,
intensify into a deep depression during next 24 hours and into a cyclonic storm during
subsequent 12 hours.

[doomhaMwx]

This has recently made landfall over Myanmar's Irrawaddy Delta. While it was not formally upgraded by any agency (IMD has it as a deep depression and JTWC canceled their TCFA), this likely hit land as a minimal tropical storm based on an ASCAT pass right before landfall. This would be notable as the delta does not usually see TC landfalls — last one was Cyclone Nargis in 2008.