CIMSS TPARC Support Blog

Attached is an IR animation for TCS043:

Taking a look at a two day animation (focus on TCS043 at about 15N 142E) you can see dirunal variation, as TCS043 strengthens around 12Z (22:00 Guam time) and weakens around 00Z (10 am Guam time). The short animation above is from 10Z - 15Z: near the convective maximum.

At this point, however, shear is the primary factor influencing TCS043:

The above plots show the shear (top) and divergence (bottom) over TCS043. The shear is consitently pushing the convection south. You can see this with the IR images, and with the location of maximum divergence. It’s unlikely to develop while under such strong shear.

The models are in two camps with this invest. The NOGAPS and GFS model have TCS043 developing and then recurving around (NOGAPS) and past (GFS) 140 E longitude. The 12Z ECWMF still has TCS043 moving west and interacting with the monsoon near the Philippians. Unlike the previous run, this run suggest hints of recurvature towards the end of the forecast period. The Met Office model, always the most reluctant developer, brings TCS043 westward and has a weaker interaction with that Phillipean convection.

The key to the recurve/no recurve difference seems to stem from a trough coming off of the China coast from the 20th-21st. The models with a deeper trough seem to be recurving the storm. The models without it seem to allow TCS043 to progress westward. We’ll have to keep an eye on this track difference in future runs.

TCS025 is strenghthening. 18Z is 4am local in Guam, early in the morning. As cloud tops radiate to space, they cool, lowering temperatures aloft more than at the surface. This increases convection. In the IR animation below you can see the convection pick up once again. TCS025 is still fairly elongated, and expected to move off quickly to the northwest, but for now it’s strengthening.

IR Animation showing a diurnal increase in convection.

This small unorganized system has continued to develop. Attached below is the animated IR image with AMVs and analyzed divergence overlayed:

MTSAT-IR image, upper level AMVs and analyzed divergence of TCS025. Valid 13Z 28 August, 2008.

As seen in the animation, TCS025 has decent outflow to it’s north. The convection isn’t organized or symmetric, but it’s fairly wide-spread. It seems to be interacting with a fairly strong upper-level low to it’s north and northwest. This low may be the key to it’s forward motion.

What about surface circulation?

Here is the same IR with a quickscat analysis valid on 07 Z on the 28th of August along with low-level AMVs.

MTSAT-IR image with low-level AMVs and recent quickscatt analysis. Image and AMVs valid 13Z, 28 August, 2008. Quickscat Valid 07Z.

From the image, you can see an almost complete low-level circulation, missing a northerly component on the system’s west side. There is however, one ship report at 20 N, 145E of a fairly weak northwesterly wind.

The water underneath is fairly warm (around 30C). It’s survival is most likely related to the interaction with that trough to it’s northwest.

We’re looking at some clusters of convection, roughly centered on TCS025 right now.

You can see the system in the animation below:

IR image, upper-level AMVs and analyzed divergence. Valid 19z 26 August, 2008.

This system is on the southside of an upper level low with underneath a fairly good region of upper level divergence. In the GFS, this system develops over the next 24 hours or so (12z on the 27th) as seen in this vorticity loop. The system moves up towards Japan and weakens over the next few days according to the model. It will be worth looking at this structure as it develops over the next 24 hours.

Deep-layer wind shear and MTSAT Water Vapor Image. TCS026, located at about 18N 155E is just south of a region of fairly low shear.

If the GFS is correct in it’s motion, the shear analysis shown above has it moving into a region of relatively low shear.

This system is worth keeping an eye on for the next few days.

The 12z run on August 20, 2008 is doing different things with this invest.

The GFS model seen here seems to split up the disturbance. It develops something fairly far to the north at 144 hours, and has a weak disturbance that heads toward the China coast, but it doesn’t seem particularly coherent.

The NOGAPS model seen here pretty much kills off 17C. It also seems to develop a weaker mid-latitude system by the 26th.

The Met Office Model here develops a weak disturbance that heads off toward the Philipeans. Previous model runs have been a bit more aggressive with development so will see what happens.

As the West Pacific is fairly quiet, it is worth looking and some smaller features and at least examine connections between the surface and the atmosphere aloft.

Here is an IR image with upper-level AMVs and divergence contoured above it from 13z on 13 August, 2008 of TCS invest 014.

IR image, upper-level AMVs and upper-level divergence for TCS invest 014. The strongest convection and divergence lie on the eastern side of the invest.

The strongest convection, outflow and divergence seem to be to the east. What’s causing this asymmetry? One possibility is to look at the Ocean Heat Content product:

Ocean Heat Content for TCS invest 014, valid 12Z 2008, August 13th. As seen in the image, the ocean surface may be fueling this asymmetry.

A more difficult question to answer is whether the divergence is a reaction to the intensification from the ocean surface, or whether the divergence helps intensify the storm. It’s a question that will hopefully be addressed with some research from this experiment.

Here’s a quick animation (click on the image) of 98W over the Philippines. You can see some outflow from the AMVs to its northeast.

You can also see some of the trade wind flow to its south.

This storm is being monitored for development over the next few days.

The TPARC group is investigating several areas of interest: ex-Invests 98W, Invest 09W and TCS002 and TCS005.

You can see an anotated 18z 31th July satellite summary here.

An image, at the same time with AMVs included is shown below:

Upper-level AMVs and associated Satellite Image valid 18UTC on 31 July, 2008

Several of the features on the annotated image can be seen clearly. The TUTT, or Tropical upper-tropospheric trough can be seen around 20N 158E.  This trough is fairly robust and hangs around through at least the next 18 hours.

One can also see some of the upper level divergence around TCS004 as well, the invest area that seems to be the primary focus of the TPARC group.

This system appears to be in fairly good shape as seen in the image below:

Upper-level AMVs and divergence for TCS004

This divergence centered over the system has also been fairly robust over the past several hours. Definitely a system worth watching.

The forecast:

By 00z on the 3 of August, the NOGAPS begins to spin up this system. We’ll have to monitor the shear product at this time to see if it weakens. Currently the shear is fairly strong. They are considering a targeted flight over this region to evaluate the model.

The 00z run on August 1st continues to develop a system here according to the NOGAPS. The Met Office Global model develops a smaller and weaker system (00z, August 1st). We’ll keep an eye on these forecasts and hope to use some of the satellite products to validate.

Hello, and welcome to the CIMSS TPARC blog. CIMSS is providing satellite support for the THORPEX Pacific Asian Regional Campaign (TPARC). The campaign is examining Typhoon genesis and extra-tropical transition. This blog is primarily designed to monitor and analyze some of the satellite products that CIMSS is producing as part of TPARC. We’ll examine the meteorology from a satellite perspective and take note of cases of interest where the satellite data may be particularly useful. These notes will be useful for after the field campaign when we are considering case studies to examine.

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