Monday, April 13, 2015

Quick Summary Of Yesterday's Near Miss

Yesterday's rain/no rain dividing line was very sharp across the ALERT network - as sjown by the plots of rainfall for 24-h ending at midnight last night - SW sector above and SE sector below. The rain and showers inched as far north as Sahuarita and the north end of the Santa Rita/Empire Mountains but basically missed the Tucson metro area. Not a drop here at the house, although there was a nice smell of moisture in the air several times. 

A broader view is provided by the MesoWest plot of 24-h rainfall through 6:00 am MST this morning (above). The model forecasts continued to waffle somewhat on the northern extent of the rain right through the 12 UTC forecasts yesterday morning. During the 24-hours leading up to the event Mike Leuthold's version of the WRF-NAM was the most accurate of the models with the northern extent of the rain forecast. The NWS GFS operational was the least accurate through the period keeping the rain along the border and into just the southeast corner of Arizona. The WFR-NAM forecast from Atmo at 12 UTC yesterday morning was quite accurate for the event's evolution - below is the model's forecast of rainfall through 5:00 am this morning.

Apparently convective cloud tops did not grow into cold enough temperatures aloft to produce lightning and thunderstorms. The CG flash plots show that closest thunderstorms were far south of the border in north-central Sonora. The WRF-NAM was also quite good wrt to thunderstorms.

Weather attention will now turn to an end of the week system that is forecast to dig into the Southwest - question will be whether it will come far enough south to bring us anything more than April winds.

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