Tropical Storm Omais

[Somerset Squall]

Second tropical depression of the West Pacific 2010 season has formed from invest 98W:

From JTWC

TROPICAL DEPRESSION 02W (TWO) WARNING NR 001

01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC

MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE

WIND RADII VALID OVER OPEN WATER ONLY

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WARNING POSITION:

211800Z --- NEAR 6.6N 143.4E

MOVEMENT PAST SIX HOURS - 315 DEGREES AT 16 KTS

POSITION ACCURATE TO WITHIN 060 NM

POSITION BASED ON CENTER LOCATED BY SATELLITE

PRESENT WIND DISTRIBUTION:

MAX SUSTAINED WINDS - 025 KT, GUSTS 035 KT

WIND RADII VALID OVER OPEN WATER ONLY

REPEAT POSIT: 6.6N 143.4E

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FORECASTS:

12 HRS, VALID AT:

220600Z --- 7.9N 141.2E

MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT

WIND RADII VALID OVER OPEN WATER ONLY

VECTOR TO 24 HR POSIT: 295 DEG/ 11 KTS

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24 HRS, VALID AT:

221800Z --- 8.8N 139.1E

MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT

WIND RADII VALID OVER OPEN WATER ONLY

VECTOR TO 36 HR POSIT: 295 DEG/ 10 KTS

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36 HRS, VALID AT:

230600Z --- 9.7N 137.2E

MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT

WIND RADII VALID OVER OPEN WATER ONLY

VECTOR TO 48 HR POSIT: 295 DEG/ 11 KTS

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EXTENDED OUTLOOK:

48 HRS, VALID AT:

231800Z --- 10.6N 135.1E

MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT

WIND RADII VALID OVER OPEN WATER ONLY

RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT

030 NM SOUTHEAST QUADRANT

030 NM SOUTHWEST QUADRANT

035 NM NORTHWEST QUADRANT

VECTOR TO 72 HR POSIT: 300 DEG/ 08 KTS

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72 HRS, VALID AT:

241800Z --- 12.1N 132.2E

MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT

WIND RADII VALID OVER OPEN WATER ONLY

RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT

045 NM SOUTHEAST QUADRANT

045 NM SOUTHWEST QUADRANT

050 NM NORTHWEST QUADRANT

VECTOR TO 96 HR POSIT: 310 DEG/ 06 KTS

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LONG RANGE OUTLOOK:

NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM

ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY

NEAR 20 KT EACH DAY.

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96 HRS, VALID AT:

251800Z --- 13.7N 130.3E

MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT

WIND RADII VALID OVER OPEN WATER ONLY

VECTOR TO 120 HR POSIT: 330 DEG/ 07 KTS

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120 HRS, VALID AT:

261800Z --- 16.1N 128.8E

MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT

WIND RADII VALID OVER OPEN WATER ONLY

---

REMARKS:

212100Z POSITION NEAR 6.9N 142.9E.

TROPICAL DEPRESSION (TD) 02W, LOCATED APPROXIMATELY 355 NM EAST-

SOUTHEAST OF YAP, HAS TRACKED NORTHWEST AT 16 KNOTS OVER THE PAST 06

HOURS. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS DEEP CON-

VECTION CONTINUES TO BUILD OVER A WELL DEFINED LOW LEVEL CIRCULATION

CENTER (LLCC). A 211217Z ASCAT PASS REVEALED A SYMMETRIC LLCC WITH

WINDS BETWEEN 25 AND 30 KNOTS. UPPER LEVEL ANALYSIS INDICATES AN

ANTICYCLONE TO THE EAST OF THE LLCC IS CREATING AN AREA OF UPPER

LEVEL DIVERGENCE OVER THE LLCC, WHICH IS PROVIDING GOOD POLEWARD OUT-

FLOW ALOFT. IT IS ALSO CREATING MODERATE TO HIGH VERTICAL WIND SHEAR

(VWS), WHICH IS HAMPERING THE DEVELOPMENT OF TD 02W. THE SURFACE

ENVIRONMENT WILL REMAIN FAVORABLE THROUGHOUT THE FORECAST PERIOD. TD

02W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A MID-LEVEL SUBTROP-

ICAL RIDGE (STR). TD 02W WILL CONTINUE TO TRACK TO THE NORTHWEST

THROUGH TAU 72, WHEN A TRANSITORY MID-LATITUDE TROUGH WILL BREAK DOWN

THE STR AND ALLOW FOR TD 02W TO BEGIN MOVING MORE NORTHWARD. THE

TROUGH WILL ALSO CAUSE A SLOW DOWN IN TRACK SPEED AS THE STR WEAKENS.

INTENSITY IS EXPECTED TO INCREASE SLOWLY AS VWS DECREASES, ALLOWING

FOR TD 02W TO ORGANIZE VERTICALLY IN LATER TAUS. THIS FORECAST IS

BASED ON THE CONSENSUS OF AVAILABLE MODEL GUIDANCE. THIS WARNING

SUPERSEDES AND CANCELS REF A, NAVMARFCSTCEN 202251Z MAR 10 TROPICAL

CYCLONE FORMATION ALERT (WTPN21 PGTW 202300) MAXIMUM SIGNIFICANT WAVE

HEIGHT AT 211800Z IS 10 FEET. NEXT WARNINGS AT 220300Z, 220900Z,

221500Z AND 222100Z.//

[Cookie]

thanks for the update

[Cookie]

being eaten quite a fair bit by shear.

[Somerset Squall]

Indeed, shear has really slowed development so far of TD 02W. However, 02W is looking a little more impressive in satellite imagery in the last few hours as it has pulled convection closer to the well defined LLC. 02W may finally be nearing tropical storm strength, though it is worth mentioning the depression won't be able to intensify significantly due to persistant shear. 02W is currently moving northwestwards along the southwestern periphery of a subtropical steering ridge to the northeast. This motion should continue for the next 72hrs, after which a trough pulling away from the east coast of China is expected to erode the ridge allowing 02W to swing to the north just short of the Philippines. At this stage, with shear remaining at moderate to high levels and waters begining to cool, 02W should begin to dissipate northeast of Luzon.

[Cookie]

the JTWC got bit over excited eariler

289

TPPN11 PGTW 230029

A. SUPER HURRICANE 02W (E OF YAP)

B. 22/2330Z

C. 9.3N

D. 139.4E

E. FOUR/MTSAT

F. T2.5/2.5/D1.0/24HRS STT: S0.0/06HRS

G. IR/EIR/VIS/MSI

H. REMARKS: 32A/PBO CDO/ANMTN. CVNCTN WRAPS .40 ON LOG10 SPIRAL

YIELDING 2.5 DT. MET AND PT AGREE. DBO DT.

I. ADDITIONAL POSITIONS:

22/1928Z 9.5N 139.9E AMSU

ROSS

Then corrected to:

901

TPPN11 PGTW 230029 COR

A. TROPICAL STORM 02W (E OF YAP)

[Somerset Squall]

LOL- I think someone was having a laugh there!

Shortly after I posted yesterday evening, 02W was upgraded to a tropical storm with intensity rising to 35kts. Today, 02W has failed to strengthen any further due to moderate shear and supressed outflow. 02W should intensify modestly over the next day or so as the compact circulation moves into an area of lower shear. However, by this stage, 02W will be nearing cooler waters which will then force weakening and ultimately dissipation east of Luzon.

[Cookie]

now named

TS OMAIS (PAGASA) TD AGATON

[Somerset Squall]

Indeed, we now have the first named storm of the eyar for the Western Pacific basin, TS Omais, with intensity rising more than expected to 50kts. Omais could strengthen a little more in an area of low shear and strong poleward outflow. However, beyond 12hrs, shear is set to increase and waters cool with northwards progression. This will cause rapid weakening and dissipation east of Luzon in around 48hrs time.

[Somerset Squall]

Very strong shear and cooling sea temps have caused a rapid decrease in convection over Omais' LLC today, and the system isn't far off dissipating as the shear is set to get stronger. Intensity has been reduced to 35kts. Omais is now swinging to the northeast as it becomes a shallower system and gets caught up in the mid-lattititude westerlies. Omais is likely to dissipate before it can become extratropical though.

[Cookie]

going down fast.

[Somerset Squall]

Convection has increased in association with Omais this morning, and intensity is back up to 35kts. It now appears that Omais will transition into an extratropical storm rather than dissipate. In fact, this process appears to already be underway, with convection outrunning the LLC to the northeast, and the LLC itself being cold cored at the surface. Omais is likely to complete extratropical transition within the next 18hrs.

[Cookie]

it made a brief fight back earlier but now on its way out.