20200312

Discussion
Record high moisture values combined with a mid and upper-level low moving into Arizona will result in widespread thunderstorm activity over central and western Arizona today.   PW values are in the mid 30mm range over western Arizona and around 25mm in the Phoenix and Tucson area.

Day 1
Moisture continues to flow into Arizona due to a strong type 2 Atmospheric River event.  PW exceeds 50mm just of the southern coast of Baja!

At 850, there is a 30-40 knot jet present over southwestern Arizona.

By early afternoon 500-1000 J/kg are present over western Arizona.  These values are extremely high for this time of year.   There is quite a bit of difference between the 12Z WRFNAM and WRFRR with the WRFNAM being quite a bit higher.

There is a very impressive shear profile on the early afternoon Phoenix forecast Skew-T plot.  This will support organized strong to severe thunderstorms with hail and maybe even a tornado or two.  No wonder SPC has that area in a moderate risk. Edit: I thought I saw a moderate risk on Twitter.  SPC site has only Marginal.

Storms develop later this morning and into the early afternoon, moving rapidly to the north, over western Arizona.

There is a bit of a lull after the first wave passes, but by later in the afternoon, storms develop again.

The WRFNAM is more active than the WRFRR, but has the same general idea, increasing activity over central and western Arizona this evening.

Strong to severe storms continue into the late evening over parts of central and western Arizona.

The WRFNAM goes bonkers and is probably overdoing it.  It will be interesting to see what the 12Z WRFGFS and 15Z WRFRR look like.

Precipitation amounts are going to be very heavy, and in orographically favorable locations, extreme.  Here are a few of the recent model run precipitation amounts.