TC 22S(HEROLD) and TC 23P(GRETEL) updates at 15/00UTC

TC 22S(HEROLD) SOUTH INDIAN
As of 00:00 UTC Mar 15, 2020:
Location: 15.1°S 51.4°E
Maximum Winds: 70 kt ( 130km/h)
Gusts: 85 kt ( 160km/h)
Minimum Central Pressure: 980 mb
CATEGORY US: 1
REMARKS:
142100Z POSITION NEAR 15.0S 51.2E.
14MAR20. TROPICAL CYCLONE (TC) 22S (HEROLD), LOCATED APPROXIMATELY 312
NM NORTHEAST OF ANTANANARIVO, MADAGASCAR, HAS TRACKED EASTWARD AT 01
KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY REVEALS DIMINISHED CONVECTION ON THE EQUATORWARD
SIDE, DEEP CONVECTION ON THE POLEWARD SIDE, AND ISOLATED CENTRAL
CONVECTION. THE DIMINISHED CONVECTION ON THE EQUATORWARD SIDE IS
LIKELY DUE TO LAND INTERACTION AS RAIN BANDS PASS OVER MADAGASCAR.
THERE IS HIGH CONFIDENCE IN THE INITIAL POSITION, PLACED USING THE EIR
AND A MICROWAVE EYE FEATURE IN A 141410Z SSMIS 91 GHZ IMAGE. THE 65 KT
INITIAL INTENSITY IS HEDGED ABOVE THE PGTW DVORAK CURRENT INTENSITY
ESTIMATE OF T3.5 (55 KTS) DUE TO A 141411Z CIMSS SATCON ESTIMATE OF 67
KTS. WITH ROBUST EQUATORWARD AND POLEWARD OUTFLOW CHANNELS, LOW (10-15
KT) VERTICAL WIND SHEAR (VWS), AND WARM (27-28 CELSIUS) SEA SURFACE
TEMPERATURE, THE ENVIRONMENT IS VERY FAVORABLE. LIKELY, THE KEY REASON
THE SYSTEM IS NOT INTENSIFYING MORE SIGNIFICANTLY IS THE
AFOREMENTIONED LAND INTERACTION. TC 22S IS QUASI-STATIONARY IN A WEAK
STEERING ENVIRONMENT. IN THE NEXT FEW HOURS, A NEAR-EQUATORIAL RIDGE
TO THE NORTHEAST WILL BUILD AND CAUSE TC 22S TO ACCELERATE EAST-
SOUTHEASTWARD TO SOUTHEASTWARD FOR THE REMAINDER OF THE FORECAST. WHEN
THAT ACCELERATION OCCURS, THE HIGHLY FAVORABLE ENVIRONMENT IS EXPECTED
TO CAUSE A 48 HR PERIOD OF SIGNIFICANT INTENSIFICATION, REACHING A
PEAK OF 100 KTS BY TAU 48. THERE IS A POSSIBILITY OF RAPID
INTENSIFICATION DURING THIS PERIOD THAT MAY ALLOW THE PEAK INTENSITY
TO BECOME HIGHER. SHORTLY AFTER TAU 48, HIGH VWS IS EXPECTED TO CAUSE
SIGNIFICANT WEAKENING. AROUND THIS TIME, THE SYSTEM WILL BEGIN
SUBTROPICAL TRANSITION (STT) AS IT INTERACTS WITH THE MID-LATITUDE
BAROCLINIC ZONE. STT SHOULD BE COMPLETE BY TAU 96. NUMERICAL MODEL
GUIDANCE IS IN GENERALLY GOOD TRACK AGREEMENT BUT SPREAD STEADILY
INCREASES THROUGHOUT THE FORECAST PERIOD, REACHING AROUND 300 NM BY
TAU 96. BASED ON THE HIGH OVERALL SPREAD AND UNCERTAINTY SURROUNDING
THE TIMING OF STORM MOTION ACCELERATING, THERE IS LOW CONFIDENCE IN
THE JTWC TRACK FORECAST. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 141800Z IS
18 FEET. NEXT WARNINGS AT 150900Z AND 152100Z.//
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TC 23P(GRETEL) SOUTH PACIFIC
As of 00:00 UTC Mar 15, 2020:
Location: 20.2°S 161.7°E
Maximum Winds: 50 kt ( 95km/h)
Gusts: 65 kt ( 120km/h)
Minimum Central Pressure: 985 mb
REMARKS:
150300Z POSITION NEAR 21.0S 162.5E.
15MAR20. TROPICAL CYCLONE (TC) 23P (GRETEL), LOCATED APPROXIMATELY
271 NM WEST-NORTHWEST OF NOUMEA, NEW CALEDONIA, HAS TRACKED
SOUTHEASTWARD AT 21 KNOTS (KTS) OVER THE PAST SIX HOURS.  ANIMATED
MULTISPECTRAL SATELLITE IMAGERY REVEALS RAIN BANDS SPIRALING INTO A
MOSTLY OBSCURED LOW LEVEL CIRCULATION CENTER. THE INITIAL POSITION
IS BASED ON A COMBINATION OF THE MSI IMAGERY AND EXTRAPOLATION FROM
A 142222Z ASCAT-A PASS WITH FAIR CONFIDENCE. THE 50 KT INITIAL
INTENSITY IS BASED ON 45-50 KT WINDS IN THE NORTHEAST, SOUTHWEST,
AND SOUTHEAST QUADRANTS IN THE AFOREMENTIONED ASCAT PASS. THIS
INTENSITY IS SLIGHTLY ABOVE, BUT CONSISTENT WITH, THE PGTW DVORAK
CURRENT INTENSITY ESTIMATE OF T3.0 (45 KTS). WITH EXCELLENT POLEWARD
OUTFLOW, MODERATE (15-20 KT) VERTICAL WIND SHEAR, AND WARM (28-29
CELSIUS) SEA SURFACE TEMPERATURE, THE ENVIRONMENT IS MARGINAL
OVERALL. FOR THE DURATION OF THE FORECAST, TC 23P WILL TRACK ALONG
THE SOUTHWEST PERIPHERY OF A NEAR-EQUATORIAL RIDGE. THE MARGINALLY
FAVORABLE ENVIRONMENT SHOULD ALLOW SOME INTENSIFICATION BEFORE
STRONG VERTICAL WIND SHEAR CAUSES SLOW WEAKENING. THE MID-LATITUDE
BAROCLINIC ZONE IS JUST SOUTH OF TC 23P. BY TAU 36, THE SYSTEM WILL
BEGIN EXTRATROPICAL TRANSITION (ETT) AS IT BEGINS INTERACTING WITH
THE BAROCLINIC ZONE. ETT SHOULD COMPLETE AROUND TAU 60 WITH TC 23P
BECOMING A GALE STRENGTH, COLD CORE LOW. NUMERICAL MODEL GUIDANCE IS
IN STRONG AGREEMENT THROUGH TAU 48. AFTERWARD, THE MODEL SOLUTIONS
BEGIN TO DIVERGE AND THE SPREAD INCREASES TO ABOUT 200 NM BY TAU 72.
BASED ON THE SPREAD, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK
FORECAST THROUGH TAU 48 AND MODERATE CONFIDENCE AFTERWARD. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 150000Z IS 36 FEET. NEXT WARNINGS AT
150900Z, 151500Z, 152100Z AND 160300Z.//
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