656
FXUS65 KFGZ 190349
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
849 PM MST Thu Jul 18 2024

.SYNOPSIS...Scattered showers and thunderstorms are expected each
day through the next week. Temperatures will remain above average
through the weekend with typical afternoon winds.

&&

.UPDATE...Isolated thunderstorms and showers continue to taper
this evening, becoming tranquil overnight. Scattered to broken
cloud cover will remain over much of the region tonight, clearing
out by Friday morning. Overnight lows are forecast to be quite
similar to last night`s, a few degrees above average for this time
of year, given the moisture present. Went ahead and made some
minor adjustments to the low temperature forecast for tonight
using the obs from last night and a mix of some CONSMOS.

Expect another round of scattered afternoon and evening showers
and thunderstorms across northern Arizona with the greatest
chances along the high terrain. POPs have been decreased for
Friday (using a blend of the HRRR, WRF-ARW, SREF, HREF) due to
the NBM guidance being too high. Now, the forecast matches better
with the activity and coverage we have been seeing lately each
day. EPS guidance keeps PWATs in the 0.7-0.9" range for Friday and
into the weekend as high pressure remains in place over much of
the Intermountain West. Temperatures will remain roughly 5 degrees
above average each day with afternoon breezes from the west and
north. This typical monsoon pattern looks to stay put through the
weekend and for much of next week.

&&

.PREV DISCUSSION /451 PM MST/...High pressure aloft is centered over
the Arizona/New Mexico border this afternoon keeping us in a
moderate, yet warm, monsoon pattern. This high will gradually
retrograde westward over the coming days with little change
expected in the overall pattern.

For today, we remain on the western periphery of the high pressure
circulation which is keeping us in a very light southerly steering
flow. We will see a combination of light steering flow and outflow
driving storms today, so varying storm motion can be expected. So
far, storms have initiated over and just to the north of the high
terrain features and have been scattered in coverage. Expect these
to gradually make their way into the lower elevations by this
evening. Similar to the previous days this week, the best
instability and moisture are pooled south of the rim so this area
will see the best potential for any stronger storms or heavy rain
later today.

By tomorrow, the high center will be centered over northern
Arizona and we`ll start to see a shift to a more northerly flow
pattern for the next several days. The high will continue to
amplify through the Great Basin leaving us in a northerly flow.
This regime tends to see moisture remain south of the Mogollon
Rim with drier air beginning to filter in to far northern reaches
of Arizona. Daily thunderstorm chances will continue each day,
favoring areas along and south of the rim, with less coverage to
the north. Model consensus seems to favor a slight uptick in
moisture over the weekend which may lead to a bit higher storm
coverage. We have trended our precipitation chances slightly
lower than the NBM guidance which continues to show a high bias.
This overall pattern favoring the rim south for storm activity
will continue through next week.

As far as temperatures are concerned, they will continue to run
above average through the next week. The warmest day looks to be
Saturday and our heat risk starts to near warning criteria. Our
confidence is not high enough to issue any warnings with the
cloud cover/precipitation uncertainty, but we`ll continue to
monitor this potential.

&&

.AVIATION...Friday 19/00Z through Saturday 20/00Z...Mainly VFR
conditions persist through the period with SCT-BKN cloud cover
near 10,000 ft AGL. Scattered -TSRA/-SHRA continue through
03Z/04Z with greatest chances along and south of I-40, tapering
thereafter. Brief periods of MVFR VIS with mountain obscuration
due to lower cloud cover are likely in heavy storms. Widespread
VFR conditions return overnight followed by another round of
scattered -TSRA after 19Z. Outside of erratic/gusty outflow winds
of up to 30 kts, expect light winds overnight, becoming northwest
10-20 kts by 20Z.

OUTLOOK...Saturday 20/00Z through Monday 22/00Z...Scattered
showers and thunderstorms with brief periods of MVFR conditions
are anticipated each day from roughly 19Z-03Z. The greatest
chances for direct impacts from storms will be along and south of
a KGCN-KFLG-KSOW line. Besides for gusty/erratic outflows from
storms, expect north-northwest surface winds, 10-20 kts each
afternoon.

&&

.FIRE WEATHER...Tonight and Friday...Showers will continue to
diminish this evening with good humidity recovery overnight. Another
round of isolated to scattered showers and storms (most numerous
over the higher terrain) are expected on Friday. Gusty and erratic
outflow winds, small hail, and brief, heavy rainfall remain the main
hazards. Daytime winds generally southwest to northwest 5 to 15 mph
outside of storms, along with slightly above normal temperatures.

Saturday through Monday...Scattered showers and thunderstorms are
anticipated each afternoon and evening. Gusty and erratic outflow
winds, small hail, and heavy rainfall will be the main hazards.
Winds generally variable 5 to 15 mph outside of storms, along with
slightly above normal temperatures.

&&

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

&&

$$

PUBLIC...LaGuardia/MCT
AVIATION...LaGuardia
FIRE WEATHER...LaGuardia

For Northern Arizona weather information visit
weather.gov/flagstaff