290
FXUS65 KFGZ 131720
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1020 AM MST Thu Jun 13 2024

.SYNOPSIS...Expect another round of abnormally warm temperatures
today, even in the face of increasing cloud cover and some
isolated, light rain showers. From this evening through Friday, a
passing low pressure system will bring more scattered shower
activity, and a slight chance for thunderstorms. Dry, warm, and
breezy conditions return by the weekend, with a slight cooling
trend early next week.

&&

.UPDATE...Current forecasts through Friday are on track with no
morning updates planned. Increasing southerly flow aloft ahead of
the low off the northern Baja continues to pull moisture
northward, mainly in the mid levels. Radar is showing some shower
development (likely virga or sprinkles) in southwest Arizona and
this will move northward into our region this afternoon. Still
thinking this afternoon`s activity will be this virga/sprinkle
activity for the most part as CAPE is very low. As the low shifts
closer to our area later tonight/Friday, instability associated
with cooling mid-level temperatures will bring a bit better chance
for a few thunderstorms.

&&

.PREV DISCUSSION /351 AM MST/...Current satellite and upper-air
analysis shows a 500 mb low centered off the west coast of
northern Baja and a 500 mb ridge over northern Mexico. A southerly
flow between these features has transported moisture into
southern Arizona. For example, the dew point in Yuma, AZ is
currently sitting around 50 degrees, which is about 5-10 degrees
higher than this time yesterday morning.

Moist air will continue to spread northward across the state
today, bringing with it increasing cloud cover and chances
(10-30%) for light rain showers. While this moisture will keep
high temperatures a couple of degrees cooler than yesterday,
abnormally warm conditions will persist and an Excessive Heat
Warning remains in effect below 4000 feet within the Grand Canyon
and lower deserts of Yavapai County through 8 pm MST. Otherwise,
most locations will see a round of south-southwest winds, with
gusts in the 20-30 mph range during the afternoon hours.

From this evening through Friday, the aforementioned low will
move across the state resulting in higher chances (20-50%) for
showers, and a slight chance (10-15%) of thunderstorms and dry
lightning. While rainfall amounts are expected to be meager, a
few pockets of rainfall in the 0.2-0.4 inch range may occur,
especially across northeast Arizona. As you would expect with the
cloudy and unsettled weather forecast for Friday, daytime
temperatures will dip a few degrees resulting in an end to the
excessive heat.

On Saturday, dry weather returns to Arizona as the low pressure
system slides across the central United States. At the same time,
the general model consensus predicts a long wave trough over the
western United States will deepen keeping Arizona under the
influence of a dry southwest flow aloft through at least mid-
week. High temperatures may quickly rebound again on Saturday,
with temperatures approaching excessive heat levels once again.
This increase in temperature may be short-lived though, with a
slow but steady cooling trend likely after that.

Forecast uncertainty is high beyond Sunday. Model disagreements
hinge on the strength of the developing longwave trough, as well
as the timing of shortwaves traversing the general flow. Overall,
the main hazard in the extended forecast is for critical fire
weather. The majority of longer range models highlight Sunday and
Monday as the period with the best combination of low relative
humidity and strong surface winds.

&&

.AVIATION...Thursday 13/18Z through Friday 14/18Z...Mostly VFR
conditions will prevail under mid to high level cloud cover. Brief
MVFR conditions are possible throughout the TAF period in isolated
-SHRA, but mostly showers are excepted to be light. Look for SW
 winds 15-25 kts, gusting near 30 kts after 18Z. Light and
 variable winds should return after 06Z. Gusty/erratic winds will
 be possible near storm development, with greater chances for
 -TSRA after midnight.

OUTLOOK...Friday 14/18Z through Sunday 16/18Z...-SHRA/-TSRA will
continue along and NE of a KSJN-KPGA line between 18Z-00Z, with
drier conditions elsewhere. VFR conditions will prevail outside of
areas experience showers/thunderstorms. Winds look to be
generally out of the SW each afternoon, becoming gusty on Sunday.

&&

.FIRE WEATHER...Today and Friday...Hot temperatures will continue
today before slightly cooling off tomorrow. Chances for
rain/thunderstorms this afternoon across Yavapai & Coconino
Counties, becoming more focused across E Arizona on Friday. Dry
lightning and gusty/erratic winds possible near storms. Southwest
winds 15-25 mph today becoming more westerly 10-20 mph Friday.

Saturday through Monday...Above normal temperature will continue
through Sunday, with cooler conditions returning Monday. Mainly dry
conditions with gusty, southwest winds and afternoon RH values 5-15%
daily. Near critical fire weather conditions likely over the weekend
and continuing into next week.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning until 8 PM MST /9 PM MDT/ this evening
for AZZ005-006-037.

&&

$$

PUBLIC...JJ/RR
AVIATION...Konieczny
FIRE WEATHER...RR

For Northern Arizona weather information visit
weather.gov/flagstaff