Area Forecast Discussion
Issued by NWS Flagstaff, AZ
FXUS65 KFGZ 171002
Area Forecast Discussion
National Weather Service Flagstaff AZ
302 AM MST SUN JUL 17 2016
.SYNOPSIS...Monsoon moisture will return over the coming week with
the potential for showers and thunderstorms each day.
.DISCUSSION...High pressure aloft is in the process of shifting
to a position over the central United States. Models show the
high center then remaining in place into next weekend. The main
impact of this shift will be the development of southerly flow
with an increase in moisture and monsoon activity.
For Today...A large organized thunderstorms complex failed to
form over northwest Mexico over the past 24 hours with no
significant push of low level moisture anticipated. What northern
Arizona will see is an increase in mid to upper level moisture,
the remnants of weaker storms that have been forming over Mexico.
The moisture aloft and a lack of low level moisture will combine
for a weakly unstable environment. The best chance for showers and
storms will be over the eastern Mogollon Rim and White Mountains
region where the deepest moisture resides. Elsewhere, only a
slight chance of showers and storms. Cloud bases will be
relatively high so expect gusty winds of 30 to 45 mph in the
vicinity of any storms that do form.
The remainder of the week...Moisture will continue to creep in from
the south but the amount will be dependent on the level of
thunderstorm activity over northwest Mexico. At this time,
the overall pattern does not favor the development of a large
thunderstorm complex over Mexico which is critical for significant
moisture surges. In addition, models are consistently showing mid
to upper level cloudiness day and night early in the week which
normally puts a damper on instability and convective activity.
Later in the week, intrusions of drier low level air from the
west will become an issue. The net result will be generally low
grade monsoon activity with the best chance for wetter storms
extending from the White Mountains and eastern Mogollon Rim to the
.AVIATION...For the 12Z package...Expect VFR conditions over the
next 24 hours for most of the area. Btwn 17z Sun-02z Mon expect Sct-
nmrs showers and thunderstorms in and around the White mtns with
ocnl mvfr conditions. Elsewhere isolated high based storms are
possible with wind gusts to 40kt.
Surface winds SW 15-25 kts this afternoon. Aviation discussion not
updated for TAF amendments.
.FIRE WEATHER...Monsoon moisture is slowly increasing
from south to north this morning, the leading edge along a line from
Chinle to Valle at 3 am. North of this line the dry southwest flow
experienced by all the past several days is weakening. For this
afternoon, the White mountains area should see scattered
thunderstorms and the best chance for wetting rain amounts.
Elsewhere only isolated high based storm coverage is forecast,
though afternoon cloud cover should be greater than the past several
days. Gusty outflow winds are probable from any storms or showers
this afternoon and evening.
Monday through Thursday...Moisture to slowly increase across
northern Arizona, with shower and thunderstorm chances each day.
Winds may become erratic and gusty near thunderstorms.
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