Flash Flood Warning 64, NWS Flagstaff, AZ

979 
WGUS75 KFGZ 231723
FFSFGZ

Flash Flood Statement
National Weather Service Flagstaff AZ
1023 AM MST Mon Sep 23 2019

AZC025-231915-
/O.CON.KFGZ.FF.W.0064.000000T0000Z-190923T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Yavapai-
1023 AM MST Mon Sep 23 2019

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1215 PM MST FOR
YAVAPAI COUNTY...

At 1021 AM MST, Doppler radar and automated rain gauges indicated 
thunderstorms had produced very heavy rain over the warned area. 
Flash flooding is expected to continue.

Some locations that will experience flooding include...
Rock Springs, Black Canyon City and Lake Pleasant. 

This includes the following streams and drainages...Squaw Creek...
Larry Creek...Cottonwood Creek...Black Canyon Creek...Slate Creek...
Black Canyon...French Creek...Boulder Creek...Agua Fria River...
Humbug Creek...Castle Creek and Little Squaw Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now. Act quickly to protect your life.

&&

LAT...LON 3389 11232 3403 11233 3415 11197 3403 11198
      3405 11216 3404 11216 3403 11217 3401 11216
      3402 11218 3398 11219 3395 11224 3393 11223
      3391 11224 3390 11226 3388 11228

$$

KD

Area Forecast Discussion
National Weather Service Flagstaff AZ
429 AM MST Mon Sep 23 2019

.SYNOPSIS...Showers and thunderstorms are expected today through
Wednesday. A few stronger thunderstorms will be possible this
afternoon and evening. An unsettled pattern is forecast into next
weekend.

&&

.DISCUSSION...Showers and thunderstorms have initiated across
southern portions of the CWA early this morning. A low pressure
system continues to dig into the Southwest and is currently
situated in northwestern Nevada. The primary precipitation band
over northern Arizona currently stretches from south of Payson
and northeast towards Show Low, but will continue to expand in
coverage through this morning.

Dewpoint temperatures have gradually increased this morning,
especially along and south of the Mogollon Rim as a much more
moist airmass was drawn northward overnight. Mesoanalysis of the
850 mb pressure level displays this moist air well and will be a
primary ingredient for expanding coverage of thunderstorms
throughout today. CAPE values of around 500 - 1500 Joules per
kilogram are providing sufficient instability for current
thunderstorms and will likely be higher into the afternoon with
some diurnal heating.

The above described moisture and instability, aided by dynamics
associated with the closed low and trough, will create conditions
favorable for a slight chance of severe thunderstorms this
afternoon. The greatest chances within the Flagstaff CWA are for
Yavapai and Gila counties. These thunderstorms will be capable of
producing quarter size hail and wind gusts of around 60 mph,
besides heavy rainfall. The slight chance for severe thunderstorms
was added into the forecast for a portion of these two counties
this afternoon and early evening. Remember to have a way to
receive the latest weather information and warnings today.

Rainfall rates of up to 1 inch per hour are likely from some of
the stronger thunderstorms, while localized storm total rainfall
of around 3 inches is possible. These moist conditions, especially
seen across eastern Yavapai and western Gila counties, have
warranted a Flash Flood Watch to be issued. Never drive across a
flooded roadway or wash.

The center of the closed low will be over southern California by
this evening and continue to bring rainfall into the overnight
hours for many locations in the CWA. PoPs are similar to earlier
forecasts due to the contiued likely nature of thunderstorms
within this early overnight period. As the center of the closed
low continues to move south, a more east to northeasterly mid-
level flow will begin to cut off access to the deeper moisture
that will be over the region today. This will create decreased
chances for precipitation beginning early Tuesday morning and
through Wednesday for areas north of the Mogollon Rim. Scattered
thunderstorms and showers are still forecast within this period.

Current guidance is in strong agreement that more southeasterly
mid- level flow will bring another round of deeper moisture
late Wednesday evening. This is the result of a slight northward
shift in the center of the closed low (previously situated over
far southwestern Arizona). As the highest available moisture
is forecast to be southwest of the Four Corners region, chances
of precipitation on Thursday were decreased for that region.

The core of the low pressure system will move out of northern
Arizona by early Friday morning. This will bring a more west to
southwesterly flow for Friday and Saturday out ahead of another
advancing deep trough. Guidance continues to be in strong
agreement on the presence of this deep Pacific Northwest trough.
At least slight chances of precipitation will continue through
Sunday, mainly in western and southern portions of the CWA.

&&

.AVIATION...For the 12Z package...Areas of showers and thunderstorm
will spread from south to north through the morning with widespread
precipitation developing during the afternoon and evening hours.
Pockets of MVFR/IFR with the stronger and more persistent
precipitation areas. Surface winds remaining light outside of any
thunderstorm gusts. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Showers and thunderstorms will develop ahead of an
approaching low pressure system today and will continue through
tonight. Some of these storms may be strong and could produce heavy
rainfall. The most likely areas for wetting rains will be along and
south of a line from the Grand Canyon to Show Low. Shower and
thunderstorm chances decrease on Tuesday, with a wind shift to the
northeast.

.Wednesday through Friday...Unsettled weather will continue with
the best chance for additional rainfall from Wednesday night through
Thursday. Look for increasing southwest winds Friday, into next
weekend.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch from 11 AM
MST this morning until 5 AM MST Tuesday FOR AZZ008-018-037-038.

&&

PUBLIC...NL/ET
AVIATION...McCollum
FIRE WEATHER...McCollum

For Northern Arizona weather information visit
weather.gov/flagstaff

Special Weather Statement
National Weather Service Flagstaff AZ
823 AM MST Mon Sep 23 2019

AZZ037-231545-
Yavapai County Valleys and Basins-
823 AM MST Mon Sep 23 2019

...SIGNIFICANT WEATHER ADVISORY FOR YAVAPAI COUNTY UNTIL 845 AM
MST...

At 821 AM MST, Doppler radar was tracking a strong thunderstorm 17
miles northwest of Congress, or 26 miles east of Alamo Lake, moving
northeast at 25 mph.

Penny size hail and winds in excess of 40 mph will be possible with
this storm as it crosses Route 93.

This storm will remain over mainly rural areas of Yavapai County.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3413 11319 3432 11324 3450 11297 3420 11281
TIME...MOT...LOC 1521Z 247DEG 24KT 3427 11312

KD