Warm temperatures aloft in middle-levels continued to keep thunderstorm activity confined to higher elevations over southeastern Arizona again yesterday. Slowly diminishing moisture in the lower half of the troposphere also led to a marked down-turn in the amount of storm activity and this looks like the situation again for today.
Mike Leuthold has added 500 mb forecasts to the product list for the WRF forecasts at Atmo, and I am happy to see this addition. I noticed that the early WRF-NAM run from last night begins to increase thunderstorm activity over southeastern Arizona tomorrow and especially on Thursday. The two 500 mb forecasts (above valid 5 am today and below valid at 11 pm MST on Thursday the 25th) indicate why the model forecasts are increasing deep convection. This morning 500 mb temperatures are around -5 C or a bit warmer over Arizona and western New Mexico. However, as the anticyclone currently to our southwest builds northeastward, the flow around the top and east side of the anticyclone begins to advect cooler air our way. The 500 mb forecast below brings temperatures of -7 to -10 C southward and westward over eastern Arizona and western New Mexico, resulting in increased CAPE, even though PW is down considerably from values of the past week or so. This forecast cooling in middle-levels would be a welcome change.
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