Area Forecast Discussion
Issued by NWS Flagstaff, AZ

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FXUS65 KFGZ 261700

Area Forecast Discussion
National Weather Service Flagstaff AZ
1000 AM MST FRI AUG 26 2016

.SYNOPSIS...Expect a chance of thunderstorms and cooler than
normal daytime temperatures through the weekend as a weak low
pressure system moves into Arizona. A drying and warming trend is
expected early next week, before increasing moisture and storm
chances return by mid week.

.DISCUSSION...The 12Z KFGZ sounding had more moisture than yesterday
morning (0.71 vs 0.56 inches). Other than the low level...the wind
was westerly all the way up. CAPE is lower than yesterday. There are
two inversions between 500 and 430 mb. There are three areas of
convection ongoing this morning: central Coconino County,
south-central Yavapai, and easter Gila/southern Navajo. There is a
cloud free area between the convection with will aid in surface
heating.  Will make a few minor adjustments to the forecast today
and tonight as more convection may continue through the night. An
active afternoon is expected across northern Arizona today.


.PREV DISCUSSION /428 AM MST/...At 4 AM...areas of rain with a few
thunderstorms were moving eastward across central and northern
Arizona producing widespread 0.20"-0.50" rainfall amounts since late
Thursday evening. Expecting this activity to shift into eastern
Arizona through mid morning and then dissipate. Otherwise, a weak
area of low pressure located to our west will move into western
Arizona Saturday then into central parts of the state for Sunday.
This low will provide for cooler than normal mid-level temperatures
(which increases instability) as well as some weak lift. Should see
enough sun by early afternoon to get some storm development over the
higher terrain of Coconino and Yavapai counties. Recent high res
model runs show a delayed start to additional convection for the
rest of the region, probably due to morning clouds and cool boundary
layer following this morning`s rain. Storm threats with today`s
activity will be locally heavy rainfall/flooding, and mostly small
hail. Saturday and Sunday, there will be some drying in the boundary
layer especially over central and northwest Arizona, though even
cooler mid-level temps near the weak low will offset this somewhat.
PoP values were increased a bit for the weekend in the latest

Drier and warmer weather is forecast Monday into Tuesday with the
best chance of storms near the AZ/NM line. Later Tuesday into
Thursday, a trough over the west coast could pull deeper moisture
back north into the area increasing our thunderstorm chances.


.AVIATION...For the 18z package...Expect increasing coverage of
shra/-tsra and increasing cloud cover by 18z-19z. Widespread cigs
bkn-ovc 6-8kft agl and sct-numrs shra/-tsra with isold +tsra. Brief
mvfr in the stronger storms. Slowly improving conditions aft 02z-04z
Sat, with pockets of low clouds and fog overnight. Aviation
discussion not updated for TAF amendments.






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