Bay of Bengal: Severe Cyclonic Storm AILA (02B)

[HURAKAN]

[HURAKAN]

Upgraded to a 35-knot tropical storm. http://rammb.cira.colostate.edu/product ... r=IO022009

[Derek Ortt]

so JT is also ignorning the QS? Not sure why when there are so many unflagged 45-55KT vectors

[Derek Ortt]

that forecast makes a lot of sense... start the TC 15KT too weak and have it strike with an intensity that is LESS than the GLOBAL MODELS ARE INDICATING

[HURAKAN]

if I were making a forecast on this, it owuld be something like the following (note... please don't pay close attention to the coordinates, as I am home and don't have good access to all the models or the initial position

Initial: 16.2N 86.8E 40KT
12 Hour: 16.8N 86.8E 45KT
24 Hour: 17.5N 86.8E 60KT
36 Hour: 19.5N 86.8E 80KT
42 Hour: 21.0N 86.5E 90KT (near land)

[Derek Ortt]

my mistake... I got my geography wrong... forgot that longitude increases in the eastern hemisphere (5k penalty run for me on Monday in the dead of day)

shift that last point to 87.1E

[HURAKAN]

SUBJ: TROPICAL CYCLONE 02B (TWO) WARNING NR 001
REF/A/NAVMARFCSTCEN PEARL HARBOR HI/230521Z MAY 09//
AMPN/TROPICAL CYCLONE FORMATION ALERT//
WTIO31 PGTW 240300
1. TROPICAL CYCLONE 02B (TWO) WARNING NR 001
01 ACTIVE TROPICAL CYCLONE IN NORTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
---
WARNING POSITION:
240000Z --- NEAR 18.1N 88.5E
MOVEMENT PAST SIX HOURS - 340 DEGREES AT 03 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
WIND RADII VALID OVER OPEN WATER ONLY
REPEAT POSIT: 18.1N 88.5E
---
FORECASTS:
12 HRS, VALID AT:
241200Z --- 18.7N 88.4E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
VECTOR TO 24 HR POSIT: 005 DEG/ 05 KTS
---
24 HRS, VALID AT:
250000Z --- 19.7N 88.5E
MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
040 NM SOUTHEAST QUADRANT
035 NM SOUTHWEST QUADRANT
045 NM NORTHWEST QUADRANT
VECTOR TO 36 HR POSIT: 010 DEG/ 07 KTS
---
36 HRS, VALID AT:
251200Z --- 21.0N 88.8E
MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 034 KT WINDS - 055 NM NORTHEAST QUADRANT
045 NM SOUTHEAST QUADRANT
040 NM SOUTHWEST QUADRANT
050 NM NORTHWEST QUADRANT
VECTOR TO 48 HR POSIT: 010 DEG/ 08 KTS
---
EXTENDED OUTLOOK:
48 HRS, VALID AT:
260000Z --- 22.5N 89.1E
MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 72 HR POSIT: 005 DEG/ 02 KTS
---
72 HRS, VALID AT:
270000Z --- 23.4N 89.2E
MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
240300Z POSITION NEAR 18.3N 88.5E.

THIS WARNING SUPERSEDES AND CANCELS REF A, NAVMARFCSTCEN 230521Z
MAY 09 TROPICAL CYCLONE FORMATION ALERT (WTIO21 PGTW 230530 )
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z IS 17 FEET.
NEXT WARNINGS AT 241500Z AND 250300Z.
//
BT
#0001
NNNN

[cycloneye]

Discussion of above warning:

REMARKS:
240300Z POSITION NEAR 18.3N 88.5E.
TROPICAL CYCLONE (TC) 02B (TWO), LOCATED APPROXIMATELY 260 NM SOUTH
OF KOLKATA, INDIA, HAS TRACKED NORTH-NORTHWESTWARD AT 03 KNOTS OVER
THE PAST SIX HOURS. ANIMATED WATER VAPOR SATELLITE IMAGERY INDICATES
A CONSOLIDATING SYSTEM WITH DEEP AND EXPANSIVE CONVECTIVE BANDING TO
THE SOUTH AND FORMATIVE BANDING TO THE NORTHEAST OF A VERY BROAD
LOW-LEVEL CIRCULATION CENTER (LLCC). THE CURRENT INTENSITY IS BASED
ON DVORAK ESTIMATES FROM PGTW AND KNES OF 35 KNOTS. THE CURRENT
POSITION IS BASED ON ANIMATED INFRARED SATELLITE IMAGERY AND A
232119Z TRMM MICROWAVE PASS. ENVIRONMENTAL ANALYSIS INDICATES
FAVORABLE CONDITIONS FOR FURTHER DEVELOPMENT WITH WEAK VERTICAL WIND
SHEAR AND EXCELLENT POLEWARD OUTFLOW ALOFT. ADDITIONALLY, THE
CYCLONE IS DRIFTING OVER WARM SEA SURFACE TEMPERATURES IN EXCESS OF
28 CELSIUS. THE SYSTEM, WHICH DEVELOPED WITHIN THE SOUTHWEST MONSOON
SURGE IN THE BAY OF BENGAL, IS DIRECTLY UNDER A SUBTROPICAL RIDGE
AXIS AND IS BEING STEERED BY A MID-LEVEL ANTICYCLONE TO THE EAST
OVER NORTHWESTERN MYANMAR. TC 02B IS EXPECTED TO FURTHER CONSOLIDATE
AND TRACK NORTHWARD THEN MAKE LANDFALL BY TAU 42 ALONG THE INDIA-
BANGLADESH BORDER. THE MAJORITY OF AVAILABLE NUMERIC TRACK GUIDANCE
SUPPORTS THIS SCENARIO. THIS WARNING SUPERSEDES AND CANCELS REF A,
NAVMARFCSTCEN 230521Z MAY 09 TROPICAL CYCLONE FORMATION ALERT
(WTIO21 PGTW 230530). MAXIMUM SIGNIFICANT WAVE HEIGHT AT 240000Z IS
17 FEET. NEXT WARNINGS AT 241500Z AND 250300Z.//
NNNN

[Derek Ortt]

that's how you ignore the data that suggests a more intense cyclone and instead use an estimate that is prone to error

[HURAKAN]

my mistake... I got my geography wrong... forgot that longitude increases in the eastern hemisphere (5k penalty run for me on Monday in the dead of day)

shift that last point to 87.1E

[Derek Ortt]

worth noting that my center is SW of JTWC's center position. However, mine matches up better with the earlier QS pass. JT seems to be tracking something else

[HURAKAN]

The NRL is behind updating the site.

[HURAKAN]

[Derek Ortt]

IMD STILL has this at 25KT

no eye means no upgrade to deep depression for them

[HURAKAN]

DEMS–RSMC TROPICAL CYCLONES NEW DELHI 24-05-2009

Tropical weather outlook for north Indian ocean (The bay of Bengal and Arabian sea) valid for next 24 hours issued at 0300 utc OF 24 MAY, 2009 based on 0000 UTC of 24 MAY, 2009 (.)

THE DEPRESSION OVER WEST CENTRAL & ADJOINING EAST CENTRAL BAY OF BENGAL REMAINED PRACTICALLY STATIONARY AND LAY CENTRED AT 0000 UTC OF TODAY, THE 24TH MAY 2009 NEAR LAT. 17.00 N AND LONG. 88.50 E, ABOUT 430 KM SOUTHEAST OF PARADIP (42976), 530 KM SOUTH SOUTHEAST OF SAGAR ISLAND (42903) AND 590 KM SOUTH-SOUTHWEST OF KHEPUPARA (41984).

SATELLITE IMAGeRY INDICATES PERSISTANT ORGANISED CONVECTION. THE INTENSITY OF THE SYSTEM IS T1.5. ASSOCIATED BROKEN INTENSE TO VERY INTENSE CONVECTION OBSERVED OVER AREA BETWEEN LAT. 10.00 N AND 21.50 N AND WEST OF LONG. 89.00 E. THE LOWEST CLOUD TOP TEMPERATURE (CTT) DUE TO CONVECTION IS ABOUT -800C AROUND THE SYSTEM.

sustained maximum SURFACE wind speed is estimated to be about 25 KNOTS. the state of the sea is rough to VERY rough around the system centre. the estimated CENTRAL pressure is about 996 hpa.

VERTICAL WIND SHEAR OF HORIZONTAL WIND OVER THE REGION IS AROUND 15-20 KNOTS. THE SYSTEM LIES VERY CLOSE TO THE UPPER TROPOSPHERIC RIDGE, WHICH ROUGHLY RUNS ALONG 170N IN ASSOCIATION WITH THE ANTICYCLONIC CIRCULATION OVER EAST CENTRAL BAY LOCATED TO THE EAST-NORTHEAST OF THE SYSTEM CENTRE. THERE IS A FEEBLE UPPER TROPOSPHERIC TROUGH IN WESTERLIES ROUGHLY RUNNING ALONG 800 E TO THE NORTH OF 200 N. SEA SURFACE TEMPRATURES ARE ALSO FAVOURABLE FOR INTENSIFICATION AS IT IS 0.50 TO 1.00 C ABOVE NORMAL. MAJORITY OF NWP MODELS ALSO SUGGEST INTENSIFICATION OF THE SYSTEM AND LANDFALL OVER WEST BENGAL AND ADJOINING BANGLADESH COAST.

CONSIDERING ALL THE ABOVE, THE SYSTEM IS LIKELY TO INTENSIFY FURTHER AND MOVE IN A NEAR NORTHERLY DIRECTION AND CROSS WEST BENGAL-BANGLADESH COAST NEAR LATITUDE 890 E (ABOUT 100 KM EAST OF SAGAR ISLAND) BETWEEN 1200 AND 1500 UTC OF 25TH MAY 2009.

[ugaap]

Suggestion... It would be great if the map is oriented correctly to show North side at the top of the map.

[HURAKAN]

Suggestion... It would be great if the map is oriented correctly to show North side at the top of the map.

Here you go!

[theavocado]

so JT is also ignorning the QS? Not sure why when there are so many unflagged 45-55KT vectors

The nature of the BoB leads to Monsoon Depressions being formed from the SW monsoon flow around Indochina. Often times this flow is rather strong and it will induce a warm-core cyclone in the region on the poleward side of the flow. When the high winds are still only on one side of the system, the winds are generally a result of the monsoon and the system isn't self sufficient. Once you see higher winds wrapping all the way around the LLCC then you know it's an independent system and not an eddy vortex.

I'm almost positive that's what the delay has been. Yes, India is known to be late on systems that are not hitting India, but for both JTWC and DEMS to be "slow" tells me that even though there are high monsoonal winds, the system isn't (wasn't) fully developed. If that is the case, it's probably not going to have the extreme low pressures and convection (hence low Dvorak values) that you would expect.

[HURAKAN]

[Grifforzer]

DEMS–RSMC TROPICAL CYCLONES NEW DELHI (24-05-2009). Tropical weather outlook for north Indian ocean (The bay of Bengal and Arabian sea) valid for next 24 hours issued at 0600 utc OF 24 MAY, 2009 based on 0300 UTC of 24 MAY, 2009 (.)

THE DEPRESSION OVER WEST CENTRAL & ADJOINING EAST CENTRAL BAY OF BENGAL INTENSIFIED INTO A DEEP DEPRESSION, MOVED NORTHWARDS AND LAY CENTRED AT 0300 UTC OF TODAY, THE 24TH MAY 2009 OVER WESTCENTRAL AND ADJOINING EASTCENTRAL AND NORTHWEST BAY OF BENGAL NEAR LAT. 18.00 N AND LONG. 88.50 E, ABOUT 350 KM SOUTHEAST OF PARADIP (42976), 400 KM SOUTH SOUTHEAST OF SAGAR ISLAND (42903) AND 470 KM SOUTH-SOUTHWEST OF KHEPUPARA (41984).

SATELLITE IMAGE RY INDICATES FURTHER ORGANISATION OF THE SYSTEM. THE INTENSITY OF THE SYSTEM IS T2.0 ASSOCIATED BROKEN INTENSE TO VERY INTENSE CONVECTION OBSERVED OVER THE BAY OF BENGAL NORTH OF LAT. 10.0 N AND WEST OF LONG. 91.0 E. THE LOWEST CLOUD TOP TEMPERATURE (CTT) DUE TO CONVECTION IS ABOUT -80C TO THE SOUTHWEST OF THE SYSTEM CENTRE.

SUSTAINED MAXIMUM SURFACE WIND SPEED IS ESTIMATED TO BE ABOUT 30 KNOTS GUSTING TO 40 KNOTS. STATE OF THE SEA IS VERY ROUGH AROUND THE SYSTEM CENTRE. ESTIMATED CENTRAL PRESSURE IS ABOUT 992 HPA.

VERTICAL WIND SHEAR OF HORIZONTAL WIND OVER THE REGION IS AROUND 20 KNOTS. THE SYSTEM LIES VERY CLOSE TO THE UPPER TROPOSPHERIC RIDGE, WHICH ROUGHLY RUNS ALONG 190N IN ASSOCIATION WITH THE ANTICYCLONIC CIRCULATION OVER MYANMAR AND ADJOINING EAST CENTRAL BAY LOCATED TO THE EAST-NORTHEAST OF THE SYSTEM CENTRE. THERE IS AN UPPER TROPOSPHERIC TROUGH IN WESTERLIES ROUGHLY RUNNING ALONG 79E TO THE NORTH OF 20N. SEA SURFACE TEMPRATURES ARE WARMER OVER NORTH & CENTRAL BAY OF BENGAL. MAJORITY OF NWP MODELS ALSO SUGGEST INTENSIFICATION OF THE SYSTEM AND LANDFALL OVER WEST BENGAL AND ADJOINING BANGLADESH COAST NEAR 89.0E.

CONSIDERING ALL THE ABOVE, THE SYSTEM IS LIKELY TO INTENSIFY FURTHER AND MOVE IN A NEAR NORTHERLY DIRECTION AND CROSS WEST BENGAL-BANGLADESH COAST NEAR LATITUDE 890 E (ABOUT 100 KM EAST OF SAGAR ISLAND) BETWEEN 1200 AND 1500 UTC OF 25TH MAY 2009.

---
can't get the forecast track and intensity

24.05.2009/0300 18.0/88.5 30 knots GUSTING TO 40 knots
24.05.2009/0600 18.5/88.5 30 knots GUSTING TO 40 knots
24.05.2009/1200 19.0/88.5 35 knots GUSTING TO 45 knots
24.05.2009/1800 19.5/88.5 40 knots GUSTING TO 50 knots
25.05.2009/0000 20.0/88.5 40 knots GUSTING TO 50 knots
25.05.2009/1200 21.5/89.0 40 knots GUSTING TO 50 knots
26.05.2009/0000 22.5/89.0 35 knots GUSTING TO 45 knots
26.05.2009/1200 23.5/89.0 25 knots GUSTING TO 35 knots

Bold font means overland system