Flash Flooding in Arizona, July 1, 2016

Area Forecast Discussion
National Weather Service Tucson AZ
845 AM MST FRI JUL 1 2016

.SYNOPSIS...Abundant moisture and instability today will result in
plenty of showers and thunderstorms through this evening with below
normal temperatures. Then Saturday into the early part of next week a
gradual drying trend will limit convection to east of Tucson Saturday
and then only isolated convection over the mountains well east and
south of Tucson Sunday into Tuesday. Temperatures Sunday onward will
rise several degrees to normal levels.

&&

.UPDATE...No significant tweaks to the forecast necessary this
morning. Satellite imagery including NASA SPoRT LPW data indicates
that the Monsoon moisture plum has shifted over central and
eastern Arizona. A mid-level trough will swing through today
further nudging the moisture eastward with drier air filtering in
behind. Convection will likely get going early today, but be
limited later by the dry air. The transition in airmass will allow
for continued threat of heavy rainfall and strong gusty winds.

&&

.AVIATION...VALID THRU 02/18Z. Showers and thunderstorms will
continue to be scattered around southern Arizona through the
period including in the vicinity of the terminals. Ceilings
generally 8-10K ft with multiple cloud layers above. Gusty winds
and brief MVFR conditions in heavy rainfall are likely near storms
where wind gusts could exceed 35 kts. Otherwise surface winds
generally 10 kts or less. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Above average moisture continues to stream into
southern Arizona and combined with the instability in place will
yield plenty of showers and thunderstorms through tonight.
Stronger or slower moving storms will be heavy rainers with the
strongest storms also capable of winds in excess of 40 mph, mainly
during the afternoon and evening hours. If in the field, be
prepared for the potential for running washes that are normally
dry.

Moisture will begin to diminish across the region beginning Saturday
and continuing through Tuesday, resulting in a decrease in the
coverage of showers and thunderstorms and a slight bump up in
afternoon temperatures. Its beginning to look like moisture will
begin to return to the area Wednesday for a general increase in
showers and thunderstorms once again.

&&

.PREV DISCUSSION... /issued 217 AM MST FRI JUL 1 2016/

DISCUSSION...Plenty of moisture in place over the region this
morning with scattered showers east of Tucson where the best upper
level divergence is occurring in advance of a weak upper level
trough over the state. This feature will continue to slowly edge
to the east taking this upper level support with it which should
keep the focus of convection over eastern areas, at least until
the sun begins to do its work. With the influence of the sun would
expect storms to develop over central and western areas thanks to
the instability and moisture in place over the entire area so
maintained the reasonably high pops today. Will need to watch the
mid-level dry line area on the water vapor imagery as that can be
a nice convection focus. Overall good potential for today. With
the expected clouds and precipitation temperatures will remain
cooler than normal for another day.

Beginning Saturday significant mid-level drying takes place on
westerly flow developing with ridging over the area. This will
significantly limit convection across the area and once deep mixing
takes place in the afternoon the dewpoints will be noticeably lower
as well. This drop in pops already in the forecast so only minor
tweaks made to the down side. Afternoon temperatures will rebound
closer to normal with lack clouds and rain.

With an upper level ridge more directly overhead and the air aloft
remaining on the dry side, convection will be quite limited Sunday
into Tuesday although not entirely gone. Enough low level moisture
will be over southern and eastern areas to maintain a slight chance
of showers and storms those areas. Temperatures will continue to
warm to slightly warmer than normal levels.

Wednesday into Thursday some deeper moisture looks to return to the
area for an increase in convection overall across much of our area.
This trend started developing over the last couple of days in the
model world and have leaned a bit further that way in the forecast.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

Update...Cantin
Aviation/Fire Weather...Lader
Previous Discussion...Cerniglia/Mollere

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