Tuesday, October 18, 2011

Not Yet Sure if MJO Precipitation is Coming

It was an interesting weather day today, as you can tell from the happy faces in Container 9….although we are still not sure if the MJO is coming.

The day started out with an interesting sky containing towering and building clouds off in the distance. One such complex of heavy precipitating clouds to the west of us set off an equatorial surge of west winds that blew through the Addu Atoll during the late morning/early afternoon and provided about a 20-25 mph flow from the west near the surface that decreased gradually through day. The layer of west winds was initially extremely shallow as noted by Doppler radar measurements from the S-Pol with a vertical wind shear of about 15 m/s or greater over the lowest 4 kilometers of the atmosphere. The shear could be clearly seen in the tilting of low-level clouds, as shown in the picture below.

A new area of convection developed to the east of us (likely initiated by this gust front) that provided much excitement and excellent photo opportunities, which Daehyun is taking advantage of in this picture.

Doppler radar showed that the layer of westerly winds mixed upward and deepened during the day, eventually weakening the westerly surface wind and turning the winds eastward near 4 km. The net result of the newly developed precipitation complex likely spawned by the gust front was an amorphous “stratiform” layer of clouds near sundown that lightly precipitated over the radar site, but also produced this nice rainbow as the sun set.

We are still not sure whether a new blowup of precipitation associated with the MJO is upon us. Although interesting tropical meteorology has been occurring in the Indian Ocean the last couple of days, the large organization of precipitation may be slightly less impressive today than yesterday. And dry air seems to be knocking on the door in the Southern Hemisphere. Are the hopes of an MJO precipitation event waning? Stay tuned I guess.

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