Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 200317
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
817 PM MST Sat Aug 19 2017

.SYNOPSIS...Expect scattered thunderstorms during much of the
upcoming week. The greatest coverage of thunderstorms should occur
east to south of Tucson, but the lower deserts won`t be completely
left out. Daytime temperatures will be close to seasonal
averages.

&&

.DISCUSSION...Moisture is coming in as expected this evening,
particularly to the east and south of Tucson where we saw convective
activity earlier produce brief downpours and gusty winds of 40 to 50
mph across Eastern Cochise, Eastern Graham and Southern/Central
Greenlee County. Activity has settled out this evening, though some
residual showers continue across Cochise County. The remainder
of the forecast area is dry at this time and under considerable
cloudiness from Tucson eastward. With moisture increasing overnight,
inverted troughing aloft nearby across NE Sonora and and any
residual outflows, we can`t rule out a few showers or even
a thunderstorm overnight mainly east of Tucson. Increased shower and
thunderstorm coverage is expected Sunday, though cloud coverage
could inhibit coverage somewhat. Went ahead and made some minor
tweaks to slightly nudge down PoP coverage overnight. Otherwise, no
updates this evening. See previous forecast discussion below for
additional information.

&&

.AVIATION...Valid thru 21/06Z.
Isolated to scattered -TSRA/-SHRA mainly east to south of KTUS
tonight, with better chances on Sunday especially in the afternoon.
Otherwise, VFR conditions with surface wind variable in direction
mainly less than 12 kts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...As moisture increases once again from the south,
our chance of showers and thunderstorms will also increase.
Expect scattered mainly afternoon and evening thunderstorms most
of the coming week. A gradual reduction of thunderstorm coverage
may again occur by next weekend. Normal diurnal wind trends
outside of any gusty and erratic thunderstorm outflows.

&&

.PREV DISCUSSION...We should shake off the debris cloud a little
better tomorrow, and with deeper moisture and a degree or two of
cooling in mid levels should see better thunderstorm initiation in
the mountains. We still may not have a strong enough flow for a lot
of valley storms but some will stray off.

Beyond that, typical moisture for late August most of the coming
week with some up days and down days. An average chance of storms
to start the week with a general southerly flow open to whatever
cares to wrap around the high. Medium range model resolutions are
advertising one such mid level impulse from central Mexico through
Sonora and then us Wednesday and/or Thursday.

Another pattern change around the end of next week with a high
center reconsolidating west of our area. That would tend to tamp
down thunderstorm activity and start to once again limit moisture
across our area next weekend.

&&

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

&&

$$

Discussion...GL
Previous Discussion...Meyer

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