Severe Thunderstorm Warning 5, NWS Flagstaff, AZ

Area Forecast Discussion
National Weather Service Flagstaff AZ
937 AM MST Sat Jul 14 2018

.SYNOPSIS...The monsoon weather pattern will persist over Arizona
through next week, with daily rounds of showers and thunderstorms.
The main threat with storms this weekend will be heavy rainfall
and localized flooding.

&&

.UPDATE...Most prominant feature this morning is the MCV currently
over Central Arizona - leftover from the MCS that dropped large
amounts of rain overnight across Eastern AZ. Satellite and radar
imagery show the feature is slowly moving to the west, and may
enhance convection over the forecast area today. Some convective
elements are already firing this morning, and expect this enhanced
activity to continue around and west of the MVC as it slowly
moves to the west and southwest. Convection will likely be delayed
over Eastern Arizona today given given the copious activity
across that area last night. Atmospheric moisture continues to be
high, with 0.99" PW measured (again) from the 12Z FGZ sounding.

In a nutshell, soils are saturated in many areas, and the
potential for flooding is increasing. We expect an active day
today, with generally slow moving storms and an enhanced risk of
flash flooding across the forecast area. Greatest flood threats
will be generally over, and southwest of the Mogollon Rim.

&&

.PREV DISCUSSION /450 AM MST/...A thunderstorm complex that
developed over eastern Arizona Friday evening has gradually
weakened as it moved westward overnight. At 430 AM, just a few
light showers are left from the Grand Canyon to near Flagstaff.
Elsewhere, some isolated showers and thunderstorms were
developing from Prescott to Black Canyon City. Deep moisture will
persist over our region for the next several days, at least
through Tuesday, before precipitable water values could gradually
decrease to more typical levels for monsoon season. For today, the
complicating factor in the forecast will be the lingering effects
of the overnight storm complex. It will likely start off cloudy
over much of Coconino and Yavapai counties which will at a minimum
delay the onset of new convection. Over eastern Arizona, rain
cooled air near the surface is also expected to delay storm
development until early afternoon. Once storms develop, they
should drift off toward the west-southwest at 5-10 mph. This slow
storm motion and abundant available moisture makes heavy rainfall
and localized flooding the main threat again today.

Expect the same general weather pattern to continue from Sunday
into Monday, with daily rounds of scattered to numerous showers
and thunderstorms. Steering flow toward the west will pick up a
bit though as the upper ridge builds to our north. There will be a
chance for overnight showers or storms, especially over eastern
Arizona as activity moves in from New Mexico.

Wednesday through Friday - models are in good agreement that the
mid and upper level ridge will strengthen and shift over or just
east of the four corners. Precipitable water values fall closer to
average values for this time of year. Daily storm coverage will
decrease compared to earlier in the week, but sufficient low level
moisture will remain for scattered activity in the mountains and
isolated at lower elevations. Temperatures will rise to near
normal Wednesday then several degrees above normal by Friday.

&&

.AVIATION...For the 18Z package...Expect scattered to numerous
SHRA/TSRA this afternoon and evening...most numerous along and
southwest of the Mogollon Rim. Local MVFR/IFR conditions with
gusty and erratic winds are possible near stronger thunderstorms.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect scattered to numerous showers and
thunderstorms through the forecast period especially in the
afternoon as deep moisture remains in place over Northern Arizona
Winds will generally be light, though gusty and erratic winds may
develop near storms.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.

&&

PUBLIC...BAK/JJ
AVIATION...BAK
FIRE WEATHER...ET

For Northern Arizona weather information visit
weather.gov/flagstaff

Special Weather Statement
National Weather Service Flagstaff AZ
1105 AM MST SAT JUL 14 2018

AZZ007-015-038-141830-
Coconino Plateau-Western Mogollon Rim-Oak Creek and Sycamore Canyons-
1105 AM MST SAT JUL 14 2018

...SIGNIFICANT WEATHER ADVISORY FOR COCONINO COUNTY UNTIL 1130 AM
MST...

At 1102 AM MST, Doppler radar was tracking several strong
thunderstorms along and south of Interstate 40 from Parks to
Williams. The storms were nearly stationary.

Very heavy rainfall, half inch hail and winds in excess of 40 mph
will be possible with these storms.

Locations impacted include...
Williams, Parks, White Horse Lake Campground, Raymond Boy Scout
Camp, Dogtown Lake Campground and Kaibab Lake Campground.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may also occurr with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3537 11181 3499 11181 3499 11230 3532 11228
TIME...MOT...LOC 1802Z 060DEG 1KT 3515 11201