Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Flagstaff Arizona
956 am MST Sat Aug 1 2015
Synopsis...deep moisture will remain in place across northern
Arizona today with scattered to numerous showers and
thunderstorms. There will be a slight decrease in activity on
Sunday as drier air begins to move in from the west. This dry air
will spread east across northern Arizona through Wednesday.
Update...abundant moisture resides over northern Arizona this
morning with extensive cloud cover north of a Payson to Window
Rock line. There are some light showers in this cloud shield. The
precipitable water off the 12z kfgz sounding was 0... average for this
time of year. Only partly cloudy conditions were seen over the
southeast portion of the County Warning Area. Will update this morning to decrease
probability of precipitation and cloud cover over the southeast portion of the County Warning Area. It
will not take long for the surface heating to start in this area.
Previous discussion /326 am MST/...an active Summer monsoon pattern
will continue across northern Arizona today. Moist southerly flow
continues to stream across the state as middle level high pressure
remains situated to our east over New Mexico and Texas. Light
shower activity has been developing this morning from central into
northern Arizona ahead of an inverted trough feature over
southwest Arizona. This trough lifts north today across western
portions of the state. Weak lift associated with the trough will
continue to fuel showers through the morning hours...favoring
western Arizona. Scattered showers and storms are then expected to
develop this afternoon through evening. Areas with less morning
cloud cover will see earlier development while clouded over areas
this morning will likely see later development. Storm motion today
will be from south to north at about 10-15 miles per hour. Locally heavy rain
will be the greatest threat from storms today.
The trough will rotate through northwest Arizona and into southern
Nevada tonight. This may prolong shower activity this evening and
overnight and have kept the chance for storms in the forecast
through the overnight hours.
A solid southwest flow develops on Monday and the westerly
component to the wind helps draw drier air into Arizona. A pretty
Stout break in monsoon thunderstorm activity is expected on Monday
through Wednesday for all except the White Mountains which will
continue to see a chance for storms. Moisture looks to make a
return by Thursday of next week when storm chances will increase
once again across northern Arizona.
Aviation...for the 18z package...expect rain showers and a few
thunderstorms to continue across portions of northern Arizona
through the morning hours and into the early afternoon. The greatest
shower and thunderstorm coverage will be along and west of a line
from kpga-kflg-kprc. Good chances for showers and thunderstorms will
develop across all of northern Arizona by later in the afternoon
into the evening. MVFR/IFR conditions will be possible in low
ceilings and visibility with the stronger storms. Aviation
discussion not updated for amendments.
Fire weather...an active monsoon pattern will continue across
northern Arizona into this weekend. Expect scattered afternoon and
evening showers and thunderstorms. Drier air will start to move into
western Arizona starting Sunday.
Monday through Wednesday...a drier southwest flow will continue to
move over northern Arizona with decreasing monsoon moisture and
chances of showers and thunderstorms. Fewer storms are expected each
day through Wednesday.
We will be discontinuing the fire weather section of our forecast
discussion until next year. Please see our fire weather zone
forecast product (fwffgz) for future fire weather discussions.
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