Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 150952

Area Forecast Discussion
National Weather Service Flagstaff AZ
252 AM MST Sun Sep 15 2019

.SYNOPSIS...A passing low will deliver a round of showers and
thunderstorms to the area today, with the greatest activity
across eastern Arizona. Chances for storms continue on Monday,
along with increasing southwest wind speeds. Drier and breezier
conditions are forecast for Tuesday and Wednesday.


.DISCUSSION...Current satellite and radar imagery shows a closed
low centered over southeast Arizona. This low will move northward
across eastern Arizona today, before exiting into Colorado by
tomorrow morning. Lift associated with this passing low will
result in the greatest chances for showers and thunderstorms east
of line from Payson to the Four Corners, with the potential for
more scattered activity further westward. Cloud cover will limit
instability, but up to 1000 J/kg of CAPE along and south of the
Mogollon Rim is possible in areas that experience clearing.
Otherwise, deep layer bulk shear is expected to be light,
generally less that 20 kts. The primary hazards from today`s
storms will be lighting and flash flooding from heavy rainfall.

On Monday, the low exits as a deeper trough approaches from the
west. This trough will bring increasing wind speeds and greater
shear. Current model guidance shows between 20-30 kts of deep
layer bulk shear, which when combined with moderate instability,
may lead to greater storm organization and an enhanced severe
weather threat.

Breezy conditions continue on Tuesday, but chances for storms
decrease as the trough exits the area. However, another trough is
forecast to enter the western United States Wednesday. Uncertainty
is high with regards to how this second trough will impact
northern Arizona. Some model solutions predict this trough will
draw another round of moisture into the area later in the week,
but other model solutions remain dry.


.AVIATION...For the 12Z package...Numerous rain showers with
embedded thunderstorms to persist across Navajo and Apache counties
through 06z Mon. Elsewhere, expect scattered showers and storms to
develop after 18z, and diminish by 03z Mon. MVFR conditions and winds
gusts to 35 kts in the vicinity of storms. Aviation discussion not
updated for TAF amendments.


.FIRE WEATHER...Moisture will continue to move northward from
Mexico as a trough of low pressure approaches Arizona from the west.
Numerous showers and thunderstorms to continue through today across
Navajo and Apache counties, and scattered afternoon storm coverage
is forecast elsewhere. Moisture will remain in place through Monday
evening with the chance of showers and thunderstorms continuing.

Tuesday through Thursday...Tuesday is a transition day to a short
period of drier weather as a drying southwest flow returns. Look for
gusty southwest winds Tuesday and Wednesday afternoons. A slight
chance of precipitation returns Thursday.






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