Lots of thunder and bluster but only a trace in Catalina

Heard thunder for about 12 h it seemed yesterday, but little came of it.  Even the rainshafts looked anemic for the most part for the second day in a row.

Current 24 h rainfall totals from the Pima County ALERT gages here.  U of AZ network here.  “Coco” for Pima, here.

Got hopeful after a disappointing afternoon when an evening shelf of Stratocumulus with buildups spread westward from the northeast, shown in the first photo.  Rain shafts began to appear in the upwind direction as the sun set with occasional cloud to ground lightning strokes, ones that continued until after dark.  Those showers grew and then were almost dead by the time they passed over Catalina.  So another disappointment.  Seems you end up saying that a lot when you’re living in a desert and wanting some rain…

6:58 PM. Looking north
6:59 PM. Looking NE.
7:33 PM. OCNL LTGCG NE (weather texting example for “occasional lightning cloud-to- ground northeast”).
4:48 PM. Got hopeful here, too, looking at this dramatic sky toward Charoleau Gap.  But no;  instead it went down the Catalinas, didn’t spread southwestward.
5:27 PM. This is the same complex, now moving away into TUS.  Dumped nearly an inch on the wealthy Catalina Foothills district where they probably don’t even need it because they can afford so much irrigation.  It had missed us completely. I included this one with lightning because sometimes it seems like you are a people that enjoys fireworks more than a lecture about how graupel forms.

 

 

 

 

 

 

 

Canadian prediction mellowing.

That Enviro Can model isn’t going to win a Gold Medal, another clever play on the Olympic Games now underway in London, with its forecast track for Hector-Ernesto.  In our last episode, the Enviro Can mod had H-E drifting northward in a timely manner, and it had been that way in model run after run, so that portions of its remnant produced significant rains in southern Arizona.

The medalist in the H-E track forecast?  The USA! WRF-GFS model.  It had tropical storm Hector-Ernesto staying far away until it was dead, drifting glacially northward off Baja until it disappeared (as it is shown to do today) with only modest effects here.   That USA forecast was better forecast all along.

We just did not get that upper level trough along and off the West Coast, required to steer H-E rapidly northward before it faded over the cool waters off Baja.

The good news is that there is no real droughty days ahead either, which means a steady diet of scattered thunderblusters for another week or so, and if we can get the cloud bases down from 14,000 feet above seas level to 8000-9000 feet (at the top of Ms. Lemmon), we could be back in the 1-2 inch rains in those scattered intense rainshafts.  This morning’s sounding from TUS suggests they will be a couple of thousand feet lower than yesterday!  Yay!

Here is the hour by hour forecast from our weather friends at the U of AZ and their local model run from last night’s data.

A quite active day is forecast for us today, beginning in the early afternoon rather than mid to late afternoon as has been the case.  The first shower/Cumulonimbus cloud is forecast to form today on the Cat Mountains is by 1 PM, hours earlier than prior days.  That would go along with the 5 AM sounding just in which has is more moist than previous days.   Note that last night’s model run would not have had this new data.

So, chance of a hard rain in the afternoon if we’re lucky.  But what could be really nice is that rain (in the model) continues here off and on overnight at a moderate rate, pretty unusual.

Fingers crossed that the “initial conditions”, the starting point for lat night’s run, are accurate, one of the biggest bugaboos in our models.

The End.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.