Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 270445

Area Forecast Discussion
National Weather Service Flagstaff AZ
945 PM MST TUE JUL 26 2016

.SYNOPSIS...The high pressure ridge is building westward into a
position that effectively blocks Monsoon moisture from moving up
into northern Arizona. Rather we will see a drier airmass move
into Arizona from the north heralding a low grade Monsoon weather
pattern with only a few thunderstorms developing along and north
of the Mogollon Rim country from Wednesday through Friday.
Another Monsoon moisture surge is forecast this weekend with
increasing chances for showers and thunderstorms through the
weekend with storm activity lasting into next week.


.DISCUSSION...The subtropical ridge will build westward blocking
our south to north Monsoon moisture tap and at the same time
advecting in drier air into Arizona from the north. Drier air
will cause higher cloud bases, lower chances for showers and
thunderstorms and increase the potential for gusty outflow winds
due to the dry boundary layer. This dry pattern will not last
long as the ridge shifts eastward and a low pressure system
moves across the mouth of the Gulf of California. The track of
this low will likely generate a pressure wave causing a moisture
surge northward up into Arizona.

Long range models continue to show this deep Monsoonal moisture
surge working its way into the state from south to north over the
weekend. Expect increasing chances and a higher coverage of
showers and thunderstorms pushing northward through the weekend.
Forecast guidance also shows climatologically excessive moisture
amounts on Monday and Tuesday as shown by precipitable water
totals in the 1.2 to 1.5 inch range. These exceedingly high
moisture totals may hinder convective development during the day
due to extensive cloud cover reducing the surface heating
convective trigger.


.AVIATION...Expect mostly VFR conditions with just isolated to
scattered showers and thunderstorms possible on Wednesday
afternoon mainly over the Mogollon Rim region. Storm activity
will diminish around sunset. Aviation discussion not updated for
TAF amendments.






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