Thursday, August 29, 2013

PW Very High Today

This morning's Tucson sounding (above) is soaking wet, with almost 2 inches of precipitable water (PW). The sounding has some CAPE, given even small amounts of solar heating. Wind profile is not great with part of the inverted trough nearly overhead. Notice that the K-index is 42 - also very high.

Both versions of the early runs of the WRF model appear to forecast too much solar radiation, given the heavy cloud cover this morning. GFS forecast solar radiation above is w/m**2 at 11 am MST and below is NAM forecast valid at noon. Both versions forecast widespread rain across southern Arizona but with mostly light amounts. I didn't dig deeply into the forecasts, so I'm not sure why the convection is fairly mundane in the WRF forecasts.

However, this morning's run of the NWS NAM goes the other direction and forecasts a very big precipitation event for today - above is NAM forecast of rainfall through 8 pm MST this evening. Likely outcome probably will be somewhere in between these model forecasts.

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