Mesoscale Precipitation Discussion 0920
NWS Weather Prediction Center College Park MD
953 PM EDT Tue Oct 02 2018

Areas affected...Central and Southern AZ

Concerning...Heavy rainfall...Flash flooding likely

Valid 030153Z - 030753Z

Summary...Persistent showers and storms in a highly anomalous
moist environment will likely lead to localized flash flooding
this evening.

Discussion...Localized intense rainfall over portions of southern
into central Arizona will be likely through the evening hours.
Recent observations in the PHX metro (Deer Valley) area indicated
1" in around 30 minutes which lines up well with KIWA radar.

Much of this convection is occurring on the gradient of the high
PWATs (1.5 to 1.7") which is roughly 3-4 SD above normal. A
mesoanalysis shows there is still plenty of SBCAPE (1500-2000
J/kg) to support deeper convection. Hi-res models suggest that
convection will slowly drift north/northeast this evening over
highly sensitive urban areas of PHX and also low FFG areas due to
recent heavy rainfall the past 2-3 days. As a result, localized
flash flooding is likely.

Taylor

ATTN...WFO...FGZ...PSR...TWC...

ATTN...RFC...CBRFC...

LAT...LON   36051099 35831021 34201032 33051104 32231392
            32851440 34021333 35601192