Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 151537
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
837 AM MST Tue Aug 15 2017

.SYNOPSIS...A slight chance of thunderstorms near the New Mexico
border this afternoon followed by dry conditions Wednesday into
Friday. Expect scattered thunderstorms to return this weekend into
early next week. Daytime temperatures quite close to seasonal
normals except a few degrees above normal Thursday into Saturday.

&&

.DISCUSSION...WV satellite imagery shows westerly flow aloft across
southeast Arizona in response to troughing extending from the Great
Basin into NW Arizona. All three channels of GOES 16 WV imagery are
showing very dry air over our forecast area this morning and that is
seen on the 12Z KTWC sounding with a PWAT down to 1.13 inches with a
very dry atmosphere above the boundary layer. The drier air working
its way in will more or less shut the monsoon down starting today
for most areas. We still can`t rule out a stray shower or
thunderstorm mainly near the New Mexico border this afternoon but
certainly nothing of great consequence. From Wednesday through
Friday, it will remain dry area-wide before monsoonal moisture works
its way back in from the south this weekend. This moisture will lead
to a return of isolated to scattered showers and thunderstorms
starting Saturday and continuing into early next week. Given the
troughiness and slightly lower heights the next couple of days, that
will prevent the temperatures from getting too warm even with the
drying taking place. High temperatures will be near to just a few
degrees above normal through Saturday, then near normal temperatures
early next week with greater moisture in place.

&&

.AVIATION...Valid thru 16/18Z.
FEW-SCT clouds at 8k-12k ft AGL mainly east of a KOLS to KTUS to
KPAN line. Isolated -TSRA/-SHRA east of KTUS this afternoon and
early evening. Clear skies west of KTUS. Surface wind variable in
direction and less than 12 kts thru 15/17Z. Surface wind sly/swly at
8-16 kts with gusts to near 25 kts between 15/17Z and 16/03Z, with
the strongest speeds east of KTUS. Surface wind less than 12 kts aft
16/03Z. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A few showers and thunderstorms will occur near the
New Mexico border this afternoon followed by dry conditions
Wednesday into Friday. Isolated to scattered showers and
thunderstorms will then return this coming weekend. 20-foot winds
will be a little elevated today, with afternoon/early evening south
to southwest winds of 13-18 mph. Otherwise, 20-foot winds will
generally be terrain driven and less than 15 mph apart from any
thunderstorms outflows.

&&

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

&&

$$

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