Severe TC GITA

Nev · Unread post by **Nev** » Wed 14/02/2018 09:08

RSMC Nadi have upgraded Gita to Cat 5 this morning…

HURRICANE WARNING 033 ISSUED FROM RSMC NADI Feb 131908 UTC.

TROPICAL CYCLONE GITA CENTRE 927HPA CATEGORY 5 WAS LOCATED NEAR 20.9 SOUTH 178.5
EAST AT 131800 UTC.
POSITION GOOD.
REPEAT POSITION 20.9S 178.5E AT 131800 UTC.
CYCLONE MOVING WEST NORTHWEST AT 8 KNOTS.
EXPECT SUSTAINED WINDS OF 110 KNOTS CLOSE TO THE CENTRE.

EXPECT WINDS OVER 63 KNOTS WITHIN 55 NAUTICAL MILES OF CENTRE
EXPECT WINDS OVER 47 KNOTS WITHIN 75 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 110 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 110 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 70 NAUTICAL MILES IN NW QUADRANT
EXPECT WINDS OVER 33 KNOTS WITHIN 130 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 210 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 210 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 120 NAUTICAL MILES IN NW QUADRANT

FORECAST POSITION NEAR 21.2S 176.8E AT 140600 UTC
AND NEAR 21.4S 175.2E AT 141800 UTC.

ALL VESSELS WITHIN 300 NAUTICAL MILES OF CENTRE ARE REQUESTED TO SEND REPORTS
EVERY THREE HOURS TO RSMC NADI. VOS REPORTING SHIPS USE NORMAL CHANNELS. OTHER
VESSELS FAX PLUS 679 6720190 OR EMAIL NADITCC AT MET DOT GOV DOT FJ

THIS WARNING CANCELS AND REPLACES WARNING 032.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 14/02/2018 13:19

GITA is currently at a latitude of 21.06 S. Yesterday at this time she was 22.22 S. No sign of any poleward turn at this moment.

Next 72 hours - High res models Icon and Access R now have a SW turn commencing mid tomorrow morning 15th Feb from the last run of 1302 18Z and believe the sub tropical ridge is starting to weaken. Other main models like EC, GFS, HWRF keep WSW track towards the south east edge of New Caledonia. One would think the majority rules here and they can pick the ridge with more accuracy but if Icon and Access R are correct, the game is changing on an NZ impact zone.

Latest EC ensemble 1302 12Z has some impacts now on New Caledonia, beyond 96 hour though, it looks like a game of pin the tail on the donkey

Main black line is average of models, thick blue is the main EC model.

ScottyD · Unread post by **ScottyD** » Wed 14/02/2018 21:13

What has been the lowest central pressure for this storm? Must have surely peaked in intensity by now.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 14/02/2018 22:12

scottiedavies wrote: ↑Wed 14/02/2018 21:13 What has been the lowest central pressure for this storm? Must have surely peaked in intensity by now.

They use a variety of techniques to the measure the pressure from the Satellite shots. The one I look at is Advanced Dvorak Technique (ADT) and GITA is currently at her lowest as I write. 931.8 hPa. Another method 'SATCON' has also just dropped her to 928 hPa. GITA is peaking again for the moment....

Nev · Unread post by **Nev** » Thu 15/02/2018 06:42

scottiedavies wrote: ↑Wed 14/02/2018 21:13 What has been the lowest central pressure for this storm? Must have surely peaked in intensity by now.

The lowest pressure reported by Fiji Met was 927 hPa yesterday morning.
And I think US Navy's lowest was 929 hPa on Monday evening.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Thu 15/02/2018 10:51

GITA’s central pressure has now dropped back to 954 hPa on the ADT method and has an large eye of nearly 65 km wide, deep convection, slowing down now to 7 knots and interestingly has maintained a west direction for last 7 hours. Latitude 21.56 S 7 hours ago, now 21.53 S. No sign of a more SW poleward track yet. Fascinating and critical observations coming up over the next 48 hours.

(ADT method for the following)
- Current pressure 954 hPa
- Sustained winds 94 knots
- Central cloud top core temp 12.01c

Latest sat pic showing signs of vortex shedding in her wake off the south east quadrant

Cyclone Tracy · Unread post by **Cyclone Tracy** » Thu 15/02/2018 12:12

Latest EC ensemble 1402 12Z – Multiple members now showing eye crossing on New Caledonia but majority still has her as a clipper. Currently she is still heading west.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Thu 15/02/2018 14:17

She has commenced a slight WSW turn. Maintaining an annular tropical cyclone structure. New Caledonian government has just released a 4pm pre cyclone alert for the nation.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Thu 15/02/2018 20:51

She has just passed 22 degrees south. Definitely a shift to a WSW direction at the moment. A fraction earlier than the big models projected. Around 950 hPa, 95 to 100 knots. Some favourable shear coming up over the next 6 hours and still over 27 to 28c SST.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Fri 16/02/2018 08:29

GITA is currently wobbling between 22.5 and 22.7 S and tracked south of what the main models projected on the 12z and 18z runs. She deepened overnight with favourable wind shear to around 945 hPa and has since moved back to 953 hPa (ADT method). Convective cloud top average around -59c, much warmer than when she was peaking in the -70’s. Centre is 13c and still maintaining an annular cyclone status with sustained winds of 95 knots. She is moving at around 11 knots in a WSW direction. SST still above 26c for the next 24 hours.

Outer islands of New Caledonia now experiencing GITA's perimeter environment

Cyclone Tracy · Unread post by **Cyclone Tracy** » Fri 16/02/2018 09:57

1502 12Z U.S Hurricane High resolution model projecting first stage of TC to XT transition around 1pm 17th Feb NZT. The upper shredding machine will be around 30 knots and the SST bordering 26c. MetService responsibility kicks in based on 25 S cross over at this time if correct. Currently this model is spot on with eye placement unlike others. This model will still have flaws after 48 hours though IMO.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Fri 16/02/2018 14:29

12 hours on, fairly tight alignment by a selection of models on GITA's position for the 12Z run. She is about to start exiting the tropics holding at 955 hPa, sustained winds have dropped to 90 knots, average cloud top temp around -55c and centre is 2.6c.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Sat 17/02/2018 11:33

GITA is now 24.03 S 168.88 E and declining as moderate shear reduces her TC structure. Low level centre of circulation is still in good order. SST 26c and she has slowed to 7 knots heading in a WSW direction. Winds 63 knots and pressure 975 hPa.

Interesting on the position in 48 hours - latest 18Z model runs for UK, BoM and GFS all took her more east than the 12z runs. At 96 hours the size of her wing span makes model projections less certain..... the timing of the Interaction with the upper trough is now becoming the big player in the cold core development and steering into NZ.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Sat 17/02/2018 15:22

With GITA now a cat 2, weakening in TC status and closing in on 25S, NZ thread now seems more appropriate for observation and future model discussion.

viewtopic.php?f=2&p=173475#p173475

spwill · Unread post by **spwill** » Sat 17/02/2018 15:31

Thanks Cyclone Tracy for your excellent contribution to this thread.

Nev · Unread post by **Nev** » Sat 17/02/2018 20:20

Cyclone Tracy wrote: ↑Sat 17/02/2018 15:22 With GITA now a cat 2, weakening in TC status and closing in on 25S, NZ thread now seems more appropriate for observation and future model discussion.

Umm… Just for the record, TC Gita is still officially a Cat 3 this evening (albeit barely) according to MetService…

TCWC Wellington Hurricane Warning

WHNZ41 NZKL 170613
HURRICANE WARNING 279
THIS AFFECTS OCEAN AREA: SUBTROPIC
TROPICAL CYCLONE GITA 970HPA] CENTRE WAS LOCATED NEAR 25.0 SOUTH
165.5 EAST AT 170600 UTC.
POSITION 60.
REPEAT POSITION 25.0S 165.5E AT 170600 UTC.
CYCLONE IS MOVING WESTSOUTHWEST 10 KNOTS.
EXPECT SUSTAINED WINDS OF 65 KNOTS CLOSE TO THE CENTRE WITH
PHENOMENAL SEA.
EXPECT WINDS OVER 63 KNOTS WITHIN 40 NAUTICAL MILES OF CENTRE.
EXPECT WINDS OVER 47 KNOTS WITHIN 60 NAUTICAL MILES OF CENTRE WITH
HIGH TO VERY HIGH SEA AND MODERATE TO HEAVY SWELL.
EXPECT WINDS OVER 33 KNOTS WITHIN 170 NAUTICAL MILES OF CENTRE IN
THE SECTOR FROM EAST THROUGH SOUTH TO NORTHWEST AND WITHIN 120
NAUTICAL MILES OF CENTRE IN THE SECTOR FROM NORTHWEST THROUGH
NORTHEAST TO EAST WITH VERY ROUGH SEA AND MODERATE TO HEAVY SWELL.
FORECAST POSITION NEAR 25.7S 164.5E AT 171800 UTC
AND NEAR 26.6S 163.5E AT 180600 UTC.
THIS WARNING CANCELS AND REPLACES WARNING 276.

Also, here's RSMC Nadi's final Advisory and Track-map from earlier today…

TROPICAL DISTURBANCE ADVISORY NUMBER A35 ISSUED FROM RSMC NADI
Feb 170107 UTC.

SEVERE TROPICAL CYCLONE GITA CENTRE 970HPA WAS LOCATED NEAR 24.5S
166.6E AT 170000 UTC. POSITION GOOD BASED ON HR HIMAWARI-8 VIS/EIR
IMAGERY AND PERIPHERAL SURFACE REPORTS. GITA MOVING WEST SOUTHWEST AT
ABOUT 4 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE
ESTIMATED AT ABOUT 65 KNOTS.

EXPECT WINDS OVER 63 KNOTS WITHIN 40 NAUTICAL MILES OF CENTRE
EXPECT WINDS OVER 47 KNOTS WITHIN 65 NAUTICAL MILES OF CENTRE
EXPECT WINDS OVER 33 KNOTS WITHIN 120 NAUTICAL MILES IN NORTHERN
SEMICIRCLE
AND WITHIN 170 NAUTICAL MILES IN SOUTHERN
SEMICIRCLE.

CONVECTION HAS DECREASE IN AERIAL EXTENT WITH CLOUD TOP WARMING.
OVERALL ORGANISATION REMAINS GOOD BUT DRY AIR INTRUSION IS GRADUALLY
WEAKENING THE EYE STRUCTURE IN THE LAST 12 HOURS.SYSTEM LIES IN A
MODERATE SHEARED ENVIRONMENT WITH GOOD POLEWARD OUTFLOW. SST AROUND
26 DEGREES. GITA CONTINUES TRACKING SOUTHWEST ALONG THE NORTHWESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE LOCATED TO THE SOUTHEAST.

DVORAK ANALYSIS BASED ON CURVED BAND PATTERN WITH 1.30 WRAP ON VIS
IMAGERY. THUS DT=4.0, MET AND PAT AGREE. FT BASED ON DT. THUS,
YIELDING T4.0/4.5/W0.5/24HRS.

FORECASTS :
AT 12 HRS VALID AT 171200 UTC 25.5S 165.1E MOV SW AT 09 KT WITH 65
KT CLOSE TO CENTRE
AT 24 HRS VALID AT 180000 UTC 26.9S 163.7E MOV SW AT 09 KT WITH 55
KT CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 181200 UTC 28.7S 162.8E MOV SW AT 09 KT WITH 45
KT CLOSE TO CENTRE
AT 48 HRS VALID AT 190000 UTC 31.1S 163.0E MOV SSW AT 09 KT WITH 30
KT CLOSE TO CENTRE

THIS WILL BE THE FINAL TROPICAL DISTURBANCE ADVISORY ON TROPICAL
CYCLONE GITA.

TC Gita - Nadi Track-map - Feb 17, 0126z.png

Thunder081 · Unread post by **Thunder081** » Sun 18/02/2018 23:36

Yeah thanks Mr Tracy good job

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