Area Forecast Discussion
Issued by NWS Tucson, AZ
FXUS65 KTWC 201602
Area Forecast Discussion
National Weather Service Tucson AZ
900 AM MST WED JUL 20 2016
.SYNOPSIS...Today will see another round of isolated to scattered
afternoon and evening showers and thunderstorms. A decrease in
coverage of showers and thunderstorms will then prevail Thursday into
this weekend. Expect hotter daytime temperatures Thursday through
Saturday followed by a minor moderation in temperatures early next
.DISCUSSION...Mostly clear skies this morning with a few debris
clouds around but not enough to significantly affect heating today.
Morning sounding still showing around 1.45" PW with local PW sensors
showing a slight downtrend this morning. Sat imagery and model data
suggest a weak feature over SE AZ this morning that will drift NNW
which could be what the HRRR is picking up on which for 3 runs in a
row has convection developing and moving across Tucson around 20z.
That said I haven`t been impressed with the HRRR lately but even the
latest UA NAM has convection moving through the metro area 20-21z.
We will see soon enough.
Overall today would expect storms to fire up vicinity Santa Cruz
county/western Cochise county first then drift to the N followed by
convection bubbling up further N and E. Before we start getting
outflow interactions, storms should be moving more to the N rather
than NW today.
Without a significant forcing mechanism this evening and tonight
would expect the convection to begin to wind down a bit earlier this
evening compared to the previous few evenings. I made some minor
adjustments to the first 12-18 hours to tweak pops and convection
wording otherwise it all looks good at this point. Cerniglia
Remainder from previous discussion...Sub-tropical upper ridge to
expand west across the desert southwest starting Thursday and
continuing into the upcoming weekend. The will bring hotter daytime
temperatures to the area with near record highs possible starting
Thursday and continuing into the weekend. See climate section below.
Expect a slow drying trend Thu thru Sat resulting in a gradual
decrease in the areal coverage of afternoon and evening storms, but
not a complete shutdown like earlier this month. Will have to keep
an eye for any inverted trofs that may pass by to our south that
could enhance storm activity. Timing of these features usually
tough. Will be interesting to see if the inverted trof that is
currently moving through the Gulf of Mexico will have any impact
here, if it holds together, either Friday or Saturday.
Early next week could see a renewed influx of tropical moisture into
northern Mexico that may eventually end up across our area.
.AVIATION...VALID THRU 21/18Z.
Sct-bkn clouds developing at 6-9k ft agl and bkn-ovc clouds at 10-
15k ft agl with isolated to scattered showers and thunderstorms
developing during the early afternoon, persisting through the mid
evening hours tonight. Brief wind gusts to 45 kts and MVFR
conditions will occur with the stronger TSRA. Outside of
thunderstorm outflows, sfc wind will generally be less than 12 kts
thru the forecast cycle. Aviation discussion not updated for TAF
.FIRE WEATHER...Moisture in place will lead to the daily cycle of
mainly afternoon and evening isolated to scattered showers and
thunderstorms through Thursday. Thunderstorms that develop will
generally move to the north today rather than W to NW like previous
A drying trend will then lead to reduced coverage of showers and
thunderstorms Friday into this weekend. Moisture will remain
adequate for isolated to scattered thunderstorms early next week.
Outside of gusty thunderstorm outflows, 20-foot winds will be
terrain driven and mostly less than 15 mph.
.CLIMATE...Record high temperatures will be approached at a few spots
on Thursday then most of the area will be at or near record highs
Friday and Saturday.
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