737
FXUS65 KFGZ 060502
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
1002 PM MST Wed Jun 5 2024

.SYNOPSIS...Much warmer temperatures and mainly dry conditions
are expected through Friday as high pressure builds over the
Southwest. There remains a slight chance for thunderstorms
developing Thursday afternoon. Temperatures begin to cool
gradually for this weekend with the potential for additional
showers and thunderstorms.

&&

.UPDATE...Look for milder temperatures overnight as a bit of
moisture and its heat trapping qualities has crept across
northern Arizona. Otherwise, dry conditions, light winds and
mainly clear skies are in store. The remainder of the forecast is
on track with the hottest daytime temperatures of the year in
store for Thursday. A good day to take those heat precautions and
protections seriously.

&&

.PREV DISCUSSION /422 PM MST/...Tranquil weather conditions are taking
place across northern Arizona as a high pressure ridge strengthens
over much of the western half of the country. High temperatures
this afternoon are forecast to be around 10 degrees above average,
followed by roughly 15 degrees above average for Thursday and
Friday. This is shaping up to be the warmest temperatures of the
year so far and taking place quite early in the summer season.
Excessive Heat Warnings remain in effect for Thursday and Friday
for lower valleys and canyons below 4000 feet. Much, if not all,
of northern Arizona will experience uncomfortable heat for the
next two days. Be prepared.

Global models show the ridge axis migrating eastward on Thursday,
resulting in a switch to light south to southeast flow. This flow
should allow for a slight increase in moisture advection in the
mid-levels with PWAT values near average (~0.50"-0.60") for this
time of year. Slight chances (15-20%) for isolated showers and
high-based thunderstorms remain in the forecast for Thursday
afternoon and evening, mainly confined to the Kaibab Plateau, San
Francisco Peaks, Mogollon Rim, and the White Mountains. Due to the
sufficient surface heating expected and lack of surface moisture,
any showers and/or thunderstorms that do develop over the high
terrain will likely be on the dry side with lightning and gusty
outflow winds (30-40 mph) being the main threats. The classic
"inverted-V" signature in various model soundings suggest this
potential for Thursday afternoon. With this in mind, new fire
starts will be possible. The good news is that outside of any
erratic outflows from storms, winds should generally be light,
10-20 mph, from the south and west on Thursday. Afternoon winds
thereafter are forecast to remain in the 10-20 mph range with
occasional gusts of up to 25 mph from the southwest. According to
both GEFS and EPS guidances, there are no strong wind events on
the horizon, which is good just in case there is an undetected
lighting fire start. Flow becomes more southwesterly on Friday
with moisture advection confined to the White Mountains and along
the AZ/NM border.

A slight cooling trend develops on Saturday with daytime highs
forecast 5-10 degrees above average, returning to near average
(within 5 degrees) on Sunday as geopotential heights decrease in
response to weakening high pressure and the potential for a low
pressure trough to move inland from the Baja coast. Isolated
showers and dry storms are forecast (15-30% chances) on Sunday as
the weak trough moves overhead from the southwest. Additional
chances are anticipated on Monday before drying out by mid-next
week. With that said, confidence continues to increase in another
warming and drying trend for the 8-14 day period. No indications
of any significant moisture to the region on the horizon at this
time.

&&

.AVIATION...Thursday 06/06Z through Friday 07/06Z...Mainly VFR
conditions expected. Slight chance for MVFR and gusty, erratic
winds near ISO SHRA/TSRA near a KGCN-KFLG-KJTC line after 18Z.
Light and variable winds, becoming W/SW around 10 kts after 18Z.

OUTLOOK...Friday 07/06Z through Sunday 09/06Z...Mainly VFR conditions.
ISO chance for MVFR and gusty, erratic winds in vicinity of KSOW/KJTC
each afternoon. Winds W/SW 10-15 kts each day, becoming light and
variable overnight.

&&

.FIRE WEATHER...Thursday and Friday...Hot temperatures, with a
slight chance for very light showers and thunderstorms in the high
terrain. Dry lightning and gusty, erratic winds will be the main
threat from any stronger storm. West/southwest winds around 10-20
mph with minimum afternoon RH 5-15% each day.

Saturday through Monday...Cooler temperatures. Slight chance for
light showers and thunderstorms over the Mogollon Rim and White
Mountains, otherwise dry conditions. Winds southwest 10-20 mph with
minimum afternoon RH 10-20% each day.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM MST /11 AM MDT/ Thursday to 8
PM MST /9 PM MDT/ Friday for AZZ005-006-037.

&&

$$

PUBLIC...McCollum/LaGuardia
AVIATION...Humphreys
FIRE WEATHER...Humphreys

For Northern Arizona weather information visit
weather.gov/flagstaff