Heat in Arizona, August 2 to 3, 2018

Area Forecast Discussion
National Weather Service Tucson AZ
210 AM MST Thu Aug 2 2018

.SYNOPSIS...A low to mid grade monsoon pattern will continue into
next week with continued rain chances each day. Temperatures will
remain within slightly above normal for early August.

&&

.DISCUSSION...Latest WV imagery shows the mid level high centered
just NW of our forecast area this morning with leftover convection
from last night fading away leaving us with just some debris
cloudiness early this morning. Plenty of moisture across our area
with latest GPS PW values ranging from 1.25 inches across eastern
areas to 1.75 inches across the western deserts. Once residual cloud
cover diminishes later today, the stage should be set for another
typical early August monsoon day with perhaps a little bit of a
later start as the atmosphere is partially worked over from
convection last night. Storm motions today into this evening will be
rather slow with initial development likely favoring the mountains
with valleys more dependent on outflows. Given the slow storm
motions, the main concern would appear to be flash flooding. Some of
the convective allowing models are trying to hint at enough gusty
outflow areas of dust in Pinal County this evening but confidence is
too low to include in the forecast at this point. Otherwise, with
the mid/upper high nearby temperatures will be about 5 degrees above
normal for early August.

As the mid/upper level high reorients itself Friday just south and
west of our area, that will tend to favor areas from Tucson eastward
for convection. By this weekend, a more typical east to
northeasterly steering flow should resume as the mid/upper high
shifts to our north from central Arizona into central New Mexico.
Ample moisture will continue this weekend for isolated to scattered
mainly afternoon and evening showers and thunderstorms. The easterly
flow will become more pronounced early next week with perhaps an
interlude of slightly drier air around Tuesday moving in from the
east to slightly lower our thunderstorm chances. Otherwise, its just
a typical low to mid grade monsoon pattern through the forecast
period with day to day variation in storm coverage. Temperatures
will remain slightly above normal through the forecast period.

&&

.AVIATION...Valid through 03/12Z.
Lingering BKN-OVC150 cloud cover expected through the pre-dawn hours
but storms should be over for the night. Expect another round of
storms at all 3 TAF sites later this afternoon with brief periods of
MVFR conditions possible. Typical diurnal wind trends continue
outside of potential gusty and erratic thunderstorm outflow.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Sufficient moisture typical of early August remains
in place through the forecast, with daily afternoon/evening
thunderstorms continuing. Humidities will recover well each night
and only drop to around 20-30 percent each afternoon. Outside of
thunderstorm induced gusts, expect diurnal trends with speeds of 15
mph or less.

&&

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

&&

Lader

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