20160810

Previous Day
As expected due to the poor initialization of cloud, showers, and storms, model performance wasn't very good.  The WRFNAM had the best forecast as it had the morning convection around Tucson which produced a moderate outflow that moved near Phoenix and caused additional storms.  The WRFNAM was about 75 miles too far to the west, a few hours too late, and produced too much precipitation.  That doesn't sound like a good forecast, but it was much better than any of the other models, including the 15Z WRFRRx.

12Z WRFNAM

 
Initializations
I'm writing this discussion early as I have a commitment later this morning thus will mainly be using the 6Z runs and only the 12Z RR.  Morning clouds and some showers are present around Phoenix and over much of the eastern 1/3 of the state.  Both 6Z runs were OK with the WRFGFS having the edge as it did have the activity around the Phoenix area.  The remnants of Javier continue to slowly spin off of central Baja California Sur.  The WRFGFS barely has this feature present while the WRFNAM still had 20-25 knot winds.  Reality looks somewhere in the middle.  A quick look at the 0Z runs shows that the 0Z WRFNAM is doing a pretty good job as it has some moderate to strong deep convection developing in Pinal county this morning.

The upper air pattern has a strong trough from northern ID to southern CA.  Upper winds are very strong with a 250mb 75knot wind at Las Vegas and 60 knots at Flagstaff.   The 500mb ridge is located from north central Mexico to southern TX and a weak 700mb IT is still seen in the upper air data south of Tucson.  Yesterday, this feature appeared to lift to the NE, but the upper air data says differently.  This feature could again act as a focus for convection over SE Arizona.  The 6Z WRFNAM has this feature over the bootheel of NM and very weak while the WRFGFS has it a bit to the west and also very weak.  The rest of the model upper air pattern looks fine.

IPW initialization was good in both of the 6Z models.  Like in Tucson, the morning convection has the potential to become quite strong and 6Z WRFGFS increase the coverage throughout the morning. However, it may be overdoing it as model IPW is running about 3-5mm higher than observed.  Afternoon and evening forecasts depend very much on what happens in and around Phoenix this morning.  As that is uncertain, model confidence is again low.  The 0Z WRFNAM seems to be the best of the overnight runs.

Day 1
Both 12Z soundings have a moderate amount of CAPE present with low LFCs so no wonder that some deep convection is breaking out.  Moisture convergence is seen on the Phoenix IPW trace too, much like Tucson yesterday, thus another positive for morning storms in the area.  The 0Z WRFNAM keeps the morning convection somewhat limited while the 6Z WRFGFS develops activity on the outflows into the Phoenix area later this morning.  I'm leaning towards the lesser activity, but the potential is there for more.  No run has picked up on the SE Arizona activity.

Southerly flow continues to import moisture into Arizona, which is a bit different than yesterday's forecasts as they had moisture decreasing today.  Goes to show you how unreliable day ahead forecasts can be.  Of interest is the strong southerly flow up the Colorado river valley which brings wet air into NW Arizona, ahead of the trough.

CAPE is very high throughout that area.  Looks like some strong storms are in store for the NW part of the inner domain.

Both the Tucson and Phoenix afternoon vertical profiles have moderate to high CAPE and a capping inversion present.  Winds are mainly unidirectional with height with only about 15 knots at 500mb. Some lifting mechanism is going to be needed for deep convection for those locations to trigger deep convection.

The 0Z runs have much less activity over southern Arizona than the 6Z runs for some reason.  The 0Z WRFNAM has only isolated weak storms.

The 6Z WRFNAM has some very strong storms scattered over SE Arizona during the late afternoon and mainly stay out of the Tucson area.

Some storms continue into the evening in the vicinity of the trough with some development possible in the Phoenix area too.  (that is dependent on what happen there this morning)

12Z WRFRR is now available but looks bad as it's missing all the clouds and morning activity.

Day 2 will follow later this morning.