Flash Flood Watch 6, NWS Flagstaff, AZ

199 
WGUS65 KFGZ 180407
FFAFGZ

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Flagstaff AZ
907 PM MST Tue Aug 17 2021

AZZ018-181500-
/O.NEW.KFGZ.FF.A.0007.210818T0900Z-210818T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northern Gila County-
Including the cities of Payson, Strawberry, and Young
907 PM MST Tue Aug 17 2021

...FLASH FLOOD WATCH IN EFFECT FROM 2 AM TO 8 AM MST WEDNESDAY...

The National Weather Service in Flagstaff has issued a

* Flash Flood Watch for a portion of east central Arizona, including 
  the following area, Northern Gila County.

* From 2 AM to 8 AM MST Wednesday.

* A line of showers and thunderstorms will develop overnight across 
  portions of the low desert and Gila County and persist into the 
  early morning hours. Storms will be capable of producing very 
  heavy rainfall that could lead to flash flooding, especially in 
  slot canyons and burn scar areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

AZZ004>007-009-012-015-016-180600-
/O.CON.KFGZ.FF.A.0006.000000T0000Z-210818T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kaibab Plateau-Marble and Glen Canyons-Grand Canyon Country-Coconino
Plateau-Northeast Plateaus and Mesas Hwy 264 Northward-Little
Colorado River Valley in Coconino County-Western Mogollon Rim-
Eastern Mogollon Rim-
Including the cities of Jacob Lake, Flagstaff, Keams Canyon, Tuba 
City, Fredonia, Happy Jack, Valle, North Rim, Grand Canyon Village, 
Munds Park, Williams, Lees Ferry, Wupatki N.M., Heber, Supai, Page, 
Kaibito, and Forest Lakes
907 PM MST Tue Aug 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 11 PM MST THIS 
EVENING...

The Flash Flood Watch continues for

* Portions of north central Arizona, northeast Arizona and west 
  central Arizona, including the following areas, in north central 
  Arizona, Coconino Plateau, Eastern Mogollon Rim, Grand Canyon 
  Country, Kaibab Plateau, Little Colorado River Valley in Coconino 
  County and Marble and Glen Canyons. In northeast Arizona, 
  Northeast Plateaus and Mesas Hwy 264 Northward. In west central 
  Arizona, Western Mogollon Rim.

* Until 11 PM MST this evening.

* Showers and thunderstorms will continue to develop this
  evening over higher terrain with slow storm motions. This
  activity could persist into the evening. Storms will be capable
  of producing very heavy rainfall that could lead to flash
  flooding, especially in slot canyons and burn scar areas.


$$

ET

504 
WGUS65 KFGZ 180547
FFAFGZ

Flood Watch
National Weather Service Flagstaff AZ
1047 PM MST Tue Aug 17 2021

AZZ004>007-009-012-015-016-180700-
/O.EXP.KFGZ.FF.A.0006.000000T0000Z-210818T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Kaibab Plateau-Marble and Glen Canyons-Grand Canyon Country-Coconino
Plateau-Northeast Plateaus and Mesas Hwy 264 Northward-Little
Colorado River Valley in Coconino County-Western Mogollon Rim-
Eastern Mogollon Rim-
Including the cities of Jacob Lake, Flagstaff, Keams Canyon, Tuba 
City, Fredonia, Happy Jack, Valle, North Rim, Grand Canyon Village, 
Munds Park, Williams, Lees Ferry, Wupatki N.M., Heber, Supai, Page, 
Kaibito, and Forest Lakes
1047 PM MST Tue Aug 17 2021

...FLASH FLOOD WATCH WILL EXPIRE AT 11 PM MST THIS EVENING...

The Flash Flood Watch for portions of north central Arizona, 
northeast Arizona and west central Arizona, including the following 
areas, in north central Arizona, Coconino Plateau, Eastern Mogollon 
Rim, Grand Canyon Country, Kaibab Plateau, Little Colorado River 
Valley in Coconino County and Marble and Glen Canyons. In northeast 
Arizona, Northeast Plateaus and Mesas Hwy 264 Northward. In west 
central Arizona, Western Mogollon Rim will expire at 11 PM MST this 
evening. Heavy rainfall has ended across the watch area this evening.

The Flood Watch is cancelled. Flooding is no longer expected to pose 
a threat. Please continue to heed remaining road closures.

$$

AZZ018-181500-
/O.CON.KFGZ.FF.A.0007.210818T0900Z-210818T1500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Northern Gila County-
Including the cities of Payson, Strawberry, and Young
1047 PM MST Tue Aug 17 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT FROM 2 AM TO 8 AM MST 
WEDNESDAY...

The Flash Flood Watch continues for

* A portion of east central Arizona, including the following area, 
  Northern Gila County.

* From 2 AM to 8 AM MST Wednesday.

* A line of showers and thunderstorms will develop overnight across 
  portions of the low desert and Gila County and persist into the 
  early morning hours. Storms will be capable of producing very 
  heavy rainfall that could lead to flash flooding, especially in 
  slot canyons and burn scar areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

ET

Area Forecast Discussion
National Weather Service Flagstaff AZ
1009 AM MST Tue Aug 17 2021

.SYNOPSIS...Widespread showers and storms will develop today and
then again on Wednesday. Dryer conditions are then expected for
later in the week and into the weekend. Cooler temperatures are
also expected through the rest of the week.

&&

.UPDATE...A high pressure ridge axis is currently positioned over
northern Arizona. Generally weak winds aloft will lead to
generally slow storm motions. Slow storm motions could lead to
isolated flash flooding. However, given the weak wind shear
aloft, do not expect widespread storm organization or widespread
flash flooding. Will hold off on a flash flood watch for now.

The HREF progs most unstable CAPE (1500-2000 J/KG) will develop
over Coconino and Yavapai counties this afternoon. Sufficient
instability exists for a few storm to produce large hail this
afternoon. However, weak wind shear should prevent widespread
severe weather from occurring. Pulse severe storms are primarily
expected.

No major changes were made to the ongoing forecast. Only
introduced hourly POPs to try and better capture the temporal
evolution of precipitation chances through Wednesday night. The
updated grids have been sent.

&&

.PREV DISCUSSION /222 AM MST/...MCS from this evening has largely
moved out of the area tonight, with only a few lingering showers
through the overnight possible in souther Gila and southern
Yavapai counties. Showers and thunderstorms are expected to
develop once again during the afternoon today. Storms are expected
to initiate mainly over the high terrain during the first half of
the afternoon, before increasing in coverage later in the
afternoon and evening particularly south and west of Flagstaff.
Flash flooding from heavy rainfall will continue be the primary
threat, however a few severe storms with damaging winds and large
hail will be possible as storms become more organized during the
late afternoon and evening.

Wednesday heights begin to fall as a longwave trough begins to dig
into the western United States. Monsoonal moisture surges
northward across much of Arizona as a result. Widespread showers
and thunderstorms expected during the day again on Wednesday,
particularly over northern and eastern Arizona. Additionally,
with an increasing pressure gradient as the trough approaches,
breezy winds are expected as well on Wednesday over much of
northern Arizona, and to a lesser extent again on Thursday.
Cooler temperatures are also expected to continue through at
least the first part of the weekend as the trough passes and in
its wake.

As the trough passes to the north on Thursday, moisture gets
swept away and dryer conditions are expected thereafter in the
wake. Greatest chance for precipitation at this time, looks to be
in the higher terrain over far northern Arizona on Thursday and
Friday. Both GEFS and EPS ensemble guidance indicate that drier
conditions are expected to remain in place through the weekend.
Ensemble guidance only begins to signal a possible return of
monsoonal moisture and warmer temperatures during the first half
of next week.

&&

.AVIATION...For the 18Z package...Another round of scattered to
numerous thunderstorms will develop after 18Z today. A few storms
may be severe producing brief IFR conditions, strong outflow
winds, and hail. Storms will likely continue into the evening
hours, especially across central Arizona. Outside of storm
activity, mainly VFR conditions and southwest winds around 10-15
kts or less. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered to numerous showers and thunderstorms are
expected through Wednesday. Large hail, localized flash flooding and
very gusty outflow winds are the main hazards. Winds outside storms
will be light today, but become breezy out of the southwest
Wednesday. Cooler temperatures today and especially on Wednesday.

Thursday through Saturday...Drier weather is expected Thursday
through Saturday, with below normal temperatures and breezy
southwest winds.

&&

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

&&

PUBLIC...TM/Humphreys
AVIATION...TM
FIRE WEATHER...MCT

For Northern Arizona weather information visit
weather.gov/flagstaff