Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 240448

Area Forecast Discussion
National Weather Service Tucson AZ
948 PM MST Sun Jul 23 2017

.SYNOPSIS...Scattered to numerous showers and thunderstorms
possible through Monday night. Conditions for thunderstorms will
become less favorable by mid week, before another upswing in
activity develops late in the week into next weekend.


.DISCUSSION...Near record amounts of available moisture with the
00Z KTWC sounding coming in with 2.02 inches precipitable water.
This is the 4th highest amount ever measured in July, short of the
record of 2.12 inches from 2010. Once again easily accessible
conditional instability was available along with the copious
amounts of moisture. The Flash Flood Watch yielded 6 Flash Flood
Warnings and numerous reports. A few areas of light to moderate
showers possible in debris flow as it continues to push across the
area from the east, otherwise no significant threat of flash
flooding across the area. We`ll continue to see heavy flow in
streams and washes overnight though.

We`ll still be loaded for bear tomorrow, but start to see a
diminishing trend in western areas as we transition to a brief
break in the heavy monsoon activity by mid week. Please see the
previous discussion below for details.


.AVIATION...Valid thru 25/06Z.
Isolated to scattered -TSRA/-SHRA late tonight into early Monday
morning. Scattered to numerous TSRA/SHRA developing again late
Monday morning and afternoon. Otherwise, VFR conditions with cloud
decks generally 5k-10k ft AGL. Surface wind variable in direction
mainly less than 12 kts, except in the vicinity of TSRA where
gusts may exceed 45 kts. Aviation discussion not updated for TAF


.FIRE WEATHER...Scattered to numerous mainly afternoon and evening
thunderstorms will continue into Monday with locally heavy rain and
strong winds. Isolated to scattered showers and thunderstorms are
then expected Tuesday into next weekend. Temperatures will remain
below normal through Tuesday, with near normal readings the rest of
the week. 20-foot winds will remain below 15 mph with the exception
of strong outflow winds in the vicinity of thunderstorms.


.PREV DISCUSSION...Scattered showers and thunderstorms were
occurring across southeast Arizona this afternoon. Some of these
storms have been efficient rain producers as they move generally
to the west. Expect a continuation of storms into the late evening
hours where some will be capable of producing very heavy rain
with a daily record precipitable water value of 1.92" on the
Tucson morning sounding. After coordinating with the neighboring
offices and WPC this morning, a flash flood watch was posted
across Arizona, which includes the eastern two-thirds of the
forecast area, or basically east of a Casa Grande to Sasabe line
through midnight tonight. Based on latest high resolution model
runs and 18z NAM, this watch may need to be extended for portions
the area into Monday, like from Tucson northwest, as an inverted
trof moves north out of Sonora MX and produces localized heavy
rainers. Not clear cut but something to watch out for.

The monsoon train will continue through the upcoming week, although
it will slow down a bit on Tuesday thru Thursday before ramping back
up again next weekend. High temperatures will also warm to at or
slightly above normal values by mid-week with triple digits
returning to the lower deserts from Tucson west.


Flash Flood Watch until midnight MST tonight for AZZ502>515.




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