992
FXUS65 KFGZ 302338
AFDFGZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
438 PM MST Sun Jun 30 2024

.SYNOPSIS...The active monsoonal pattern continues through
Wednesday with scattered showers and thunderstorms, light winds,
and seasonable temperatures expected each day. Then, a warming
and drying trend develops for the holiday weekend as high pressure
strengthens towards the west.

&&

.DISCUSSION...As predicted, thunderstorms have developed early
this afternoon across the White Mountains and portions of
southern Coconino County, moving northward at about 10-20 mph. No
indications of any severe storms at this time, however, the main
concern continues to be the threat of heavy rain and flash
flooding. Current dewpoints are in the 50-60F range along and
south of I-40 and should continue to increase northward as the
afternoon progresses. Shower and storm coverage is forecast to
increase during this time and persist into early this evening.

Then, things get interesting tonight as a subtle shortwave comes
up from the south and tracks across northern Arizona, southwest
to northeast. This disturbance will likely result in increased
shower activity overnight with greatest chances across Yavapai and
southern Coconino counties. Overcast skies with moderate to heavy
rainfall at times is anticipated along with areas of steady,
stratiform rain. With a longwave trough draped over the
Intermountain West, dry southwesterly flow should inhibit this
moisture advection, from the south, from reaching farther north
than the Grand Canyon. POPs have been adjusted this afternoon for
tonight, using the latest hi-res guidance, with the greatest
chances extending from Prescott to Polacca on the Navajo Nation.

By sunrise Monday morning, shower coverage should decrease
becoming more isolated with scattered activity continuing near the
Four Corners. Southwesterly flow increases a bit for Monday
afternoon as a trough passes by towards the north. Another round
of shower and storm activity remains in the forecast for Monday
afternoon, however, confidence is on the lower side at this time
in regards to overall coverage as cooler, overcast conditions
could lead to limited convection.

Cloud cover clears Monday night and into Tuesday as surface to
mid-level moisture remains in place. Weak westerly flow develops
by the afternoon, but given the moisture and anticipated clear
skies Tuesday morning, thunderstorm activity could be more
abundant compared to Monday with a few hi-res model solutions
showing signs of this potential scenario. As of now, chances are
confined to locations mainly along and south of I-40, however,
this could increase in coverage northward with even greater
chances towards the south for Tuesday. Something to keep our eye
on.

One more day of isolated to scattered showers and thunderstorms
is likely on Wednesday before a drying and warming trend develops
for Thursday and Friday as high pressure strengthens towards the
west. Confidence continues to increase in 5-10 degree above
average temperatures returning for the 4th of July and into the
holiday weekend with little to no chances for precipitation thanks
to dry, northwest flow. Ensemble guidance continues to show a
strong, high pressure ridge developing over much of the West Coast
for next weekend and into early next week. This is not a favorable
position for a ridge in regards to monsoonal activity as being on
the eastern side of this high pressure system results in much
drier northerly flow. However, depending on the overall strength
of this high and potential convective activity in Mexico, moisture
could try to sneak northward into Arizona.

&&

.AVIATION...Monday 01/00Z through Tuesday 02/00Z...Isolated to
scattered showers and thunderstorms through the night with heavier
showers along and near a KPRC-KSEZ-KFLG line until 14Z. Gusty and
erratic outflow winds and MVFR conditions possible in the
vicinity of any storms. Otherwise, south to southwest winds at
10-20 kts Monday afternoon.

OUTLOOK...Tuesday 02/00Z through Thursday 04/00Z...The active
pattern continues with showers and storms expected each day,
tapering off each night. West-northwest winds at 10-20 kts for
Tuesday and Wednesday.

&&

.FIRE WEATHER...This Evening through Tuesday...The active
monsoonal pattern continues through Tuesday with scattered showers
and thunderstorms each afternoon. Activity looks to increase this
evening and persist overnight, with greatest chances and coverage
across Yavapai, northern Gila, and southern Coconino counties.
Main threats include brief, heavy rainfall rates of 1-2 inches per
hour and gusty outflows. Outside of any outflow winds, anticipate
southwest winds, 15 to 20 mph, becoming west on Tuesday.

Wednesday through Friday...One more day of isolated to scattered
showers and thunderstorms is likely on Wednesday before a drying and
warming trend develops for Thursday and Friday as high pressure
strengthens towards the west. Daytime temperatures of 5-10 degrees
above average return for both Thursday and Friday with afternoon
humidity near 15%. West-northwest winds, 15 to 20 mph, are forecast
on Wednesday, followed by north-northwest winds on Thursday and
Friday.

&&

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

&&

$$

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

For Northern Arizona weather information visit
weather.gov/flagstaff