699
FXUS65 KFGZ 140412
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
912 PM MST Thu Jun 13 2024

.SYNOPSIS...A low pressure system will cross Arizona with scattered
shower activity, and a slight chance for thunderstorms through
Friday. Dry, warm, and breezy conditions return by the weekend,
with a slight cooling trend early next week.

&&

.UPDATE...The center of the low pressure center is south of Las
Vegas in California this evening. Scattered showers are moving
northward across eastern Arizona this evening. Several
thunderstorms have developed around the center of the low in far
western Arizona this evening as well. Very little precipitation is
expected with with many of the showers overnight. No updates need
for tonight.

&&

.PREV DISCUSSION /445 PM MST/...A well defined upper low was located
just off the coast of San Diego this afternoon, moving slowly
toward the northeast. Southerly flow ahead of this low has induced
a surge of mid level moisture into Arizona, and scattered shower
development is ongoing in southwest Arizona stretching up into
portions of Yavapai and Coconino counties. Most of this activity
through the afternoon should be in the form of virga and light
showers, though a couple lightning strikes have been observed
north of Yuma already. With the hot/dry boundary layer still in
place, a few of these showers could produce strong outflow winds
of 40+ mph. As the upper low moves closer to our area later
tonight, cooling temperatures aloft will steepen lapse rates and
allow for a few thunderstorms to develop and spread northward.
Precipitation amounts are forecast to be fairly minimal overnight,
less than 0.10" for most areas that see precipitation at all. By
Friday - the upper low shifts into northeast AZ and then NM/CO by
late afternoon. The chance for showers and thunderstorms continues
in the morning as far south/west as Flagstaff and then will be
focused in northeast Arizona by afternoon. With daytime heating,
scattered thunderstorms are forecast northeast of a Kayenta to St
Johns line. Temperatures Friday afternoon will be several degrees
cooler and well below Excessive Heat Warning criteria. Shower and
storm chances end by sunset Friday.

Saturday - Heat builds back in briefly as the low departs, and the
next larger western US trough begins to take shape. Ridging builds
between these two features and allows temperatures to rise to well
above normal levels once again. As of now, highs look to remain a
bit below warning criteria but this will need to be monitored.

Sunday through Tuesday - the major feature this period will be a
deep upper low (for mid June) centered over the NW US. Northern
Arizona will be on the dry and windy southern end of this feature,
with heights falling below normal and allowing for a cooling
trend. Southwest winds will increase, with sustained speeds of
15-25 mph and gusts greater than 30-35 mph likely each day. The
combination of gusty winds and low humidity brings the threat of
critical fire weather with the best chances Sun/Mon but Tuesday
will need to be watched too.

&&

.AVIATION...Friday 14/00Z through Saturday 15/00Z...Mainly VFR
expected. Brief MVFR conditions are possible in ISO SHRA. SW
winds 15-25 kts, gusting near 30-35 kts, becoming light and
variable after 06Z. Gusty/erratic winds will be possible near
storm development, with greater chances for TSRA after 06Z.

OUTLOOK...Saturday 15/00Z through Monday 17/00Z...Mainly VFR
conditions with SW winds. Winds become gusty on Sunday.

&&

.FIRE WEATHER...Tonight through Saturday...Isolated to scattered
showers and thunderstorms will continue tonight, becoming more
focused over E. AZ. on Friday. Gusty and erratic winds possible near
storm development along with dry lightning. W-SW winds 5-15 mph on
Friday, increasing to 10-20 mph on Saturday. Minimum RH values 10-
25% Friday afternoon dropping to 5-15% Saturday afternoon. Dry and
warm conditions forecast for Saturday.

Sunday through Tuesday...A slight cooling trend will occur Sunday
through the beginning of the week. Gusty SW winds Sunday, increasing
on Monday. Minimum RH values in the single digits to mid-teens each
afternoon. Near-critical fire weather concerns likely for the end of
the weekend through the beginning of next week.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

PUBLIC...MAS/JJ
AVIATION...Meola
FIRE WEATHER...Meola

For Northern Arizona weather information visit
weather.gov/flagstaff