Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Flagstaff Arizona
904 PM MST Wednesday Jul 29 2015
Synopsis...scattered showers will continue this evening across
areas generally south of a line from Prescott to Flagstaff to
Window Rock...with a slight chance elsewhere. From Thursday
through next Tuesday...expect daily chances for showers and
thunderstorms for all of northern Arizona.
light to moderate showers are continuing this evening...mainly
south of I-40 and east of I-17 with less activity elsewhere.
Forecast seems to handle expected short-term conditions well at
Previous discussion /336 PM MST/...model data suggests moisture will
continue to spread northward across northern Arizona tonight.
This is in part due to outflows from convective activity today and
tonight, as well as a moist southerly flow from a subtropical high
pressure cell centered over West Texas. By midday Thursday, there
will be enough moisture and instability in place for chances of
showers and thunderstorms across all of northern Arizona.
A moist monsoon flow will remain in place across northern Arizona
through Saturday. Thus precipitation chances are above climatology for
these days and some heavy rainers are possible. Precipitation chances
then drop to climatology values from Sunday through Tuesday.
Aviation...for the 06z package...isolated to scattered -shra may
persist overnight...mainly south of a line from kprc-kflg-krqe.
Another round of afternoon rain showers/thunderstorms and rain is forecast for
Thursday...spreading farther northwest to include most of northern
Arizona. Aviation discussion not updated for amendments.
Fire weather...monsoon moisture continues to increase tonight
leading to greater thunderstorm chances area-wide on Thursday
and Friday. Lightning...locally heavy rain...and small hail will
be the main hazards. Gusty outflow winds will also accompany some
of the storms.
Saturday through Monday...a more typical Summer monsoon pattern
will persist through the weekend and into early next week with
daily chances for showers and thunderstorms.
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