Saturday, April 2, 2011


We have been desperate for lake-effect this spring and are looking for a few good cases to sample as part of our Sounding Observations of Lake-effect Precipitation EXperiment (SOLPEX).

As such, we are deploying teams to potentially take some upper-air soundings tomorrow and tomorrow night.  The GSL temperature is presently around 10C and the NAM forecasts very cold 700-mb air to be over us by 9am tomorrow (<12C).

NAM forecast valid 9 am MDT 3 Apr 2011.
That sounds good, but the cold air at 500-mb lags quite a ways behind, so there's still a capping inversion present that will probably keep a lid on lake-effect convection at that time.

NAM forecast sounding for KSLC valid 9 am MDT 3 Apr 2011.
Things look better later in the day (6 PM shown below), at least from a thermodynamic perspective, as the 500 mb trough and cold air move over northern Utah.

NAM forecast sounding for KSLC valid 6 pm MDT 3 Apr 2011.
Climatologically, however, there are very few lake-effect events that trigger and/or become intense during the afternoon.  As shown below, most events trigger after sunset or overnight.

Start time for GSL lake-efffect events relative to sunset
(Alcott et al. 2011, in prep)
As such, we're calling this the wait and see IOP and are hoping to either get lucky or to sample whatever may develop near or after sunset.  We may also take a couple of soundings in the afternoon even if nothing is happening as we are very interested in better understanding the diurnal modulation of lake-effect initiation and intensity.

Stay tuned and share your thoughts and ideas about the forecast and then observations tomorrow.

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