Flash Flood Warning 41, NWS Tucson, AZ

187 
WGUS55 KTWC 042303
FFWTWC
AZC019-052015-
/O.EXT.KTWC.FF.W.0041.000000T0000Z-181005T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
403 PM MST THU OCT 4 2018

The National Weather Service in Tucson has extended the

* Flash Flood Warning for...
  Excessive Rain in...
  Central Pima County in southeastern Arizona...

* Until 115 PM MST Friday.

* At 402 PM MST, there are continued concerns related to the 
  structural integrity of Menagers Dam in southwest Tohono O'Odham 
  Nation near the International border. The potential for it to fail 
  is expected to continue, thus the Flash Flood Warning has been 
  extended into Friday afternoon. No additional rain is expected the 
  rest of the week, but more rain is possible Sunday and Monday.

* Locations impacted include...
  Ali Chuk.

This includes the following streams and drainages...Ali Chuk Wash...
Pia Oik Wash and Siovi Shuatak Wash.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Stay away or be swept away. River banks and culverts can become
unstable and unsafe.

&&

LAT...LON 3183 11265 3189 11252 3177 11244

$$

Meyer

094 
WGUS75 KTWC 052018
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
118 PM MST FRI OCT 5 2018

AZC019-052023-
/O.EXP.KTWC.FF.W.0041.000000T0000Z-181005T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima-
118 PM MST FRI OCT 5 2018

...THE FLASH FLOOD WARNING FOR CENTRAL PIMA COUNTY WILL EXPIRE AT 115
PM MST FRIDAY...

With no additional rainfall expected through Sunday morning, and 
waters slowly receding, the Flash Flood Warning for potential 
failure of the Menegers Dam is being allowed to expire. Additional 
rainfall is expected in the area Sunday and Monday, however it is 
not expected to be enough to have much influence on the still 
excessive water level of the dam. There is also the potential of 
another tropical system impacting the area late next week. The 
situation will continue to be closely monitored.

LAT...LON 3183 11265 3189 11252 3177 11244

$$

Meyer

Area Forecast Discussion
National Weather Service Tucson AZ
954 AM MST Thu Oct 4 2018

.SYNOPSIS...We'll dry out the second half of the week with
temperatures about average for early October. An early Fall
weather system is expected to push in from the northwest early
next week, bringing with it a chance of showers and thunderstorms
along with strong gusty winds and cooler temperatures.

&&

.DISCUSSION...Plenty of drying over the past 24 hours with
precipitable water down to 1 inch on the 12Z KTWC sounding, and
latest satellite estimates dropping toward 3/4 of an inch.
Surface dewpoints are still elevated with all of the residual
boundary layer moisture, only dropping 2 to 5 degrees over the
past 24 hours. However with the moisture erosion in the air column
we will likely see some cratering of values this afternoon.

No precip the rest of the week as we continue to watch the early
Fall storm system taking shape for our area early next week.
Please see the previous discussion below for details.

&&

AVIATION...Valid through 05/18Z.
Clear skies to SCT clouds at 7k-9k ft AGL. SFC wind generally
less than 12 kts with normal diurnal trends. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions are expected through Saturday. A
storm system will then result in cool temperatures and a chance of
showers late Saturday into early Monday primarily from Tucson
eastward. Increasing southwest winds will occur over the weekend,
with wind speeds of 10-25 mph. A slow warming and drying trend will
then take place next week behind the system, with wind speeds less
than 15 mph.

&&

.HYDROLOGY...The Vamori Wash in the Tohono O'odham Nation is now
falling, with the latest stage down to 9.1 feet. The areal flood
warning has expired.

As of late Wednesday afternoon, the Menager Lake Dam was holding
and water levels were no longer increasing. At some point during
the event, the dam was overtopped and suffered some erosional
damage. With uncertainty about the structural status of the dam at
this time and the high water level, we and the emergency
management officials have elected to continue the Flash Flood
Warning for a potential dam break through today.

&&

.PREV DISCUSSION...Outside of a brief isolated shower across far
eastern Pinal county this morning, it will be dry today as
negatively tilted upper level trof lifts across NW Arizona.
Follow-up trof will move across the state on Friday but will be
dry for our area. Highs a few degrees shy of normal values today
then a few degrees cooler on Friday. The wind will kick up on
Saturday as the pressure gradient tightens in advance of
approaching stronger weather system. This system will bring a
chance of valley rain and high elevation snow showers, gusty winds
and much cooler temperatures Sunday and Monday. Could see a few
inches of snow in the Whites by Monday. Dry Tuesday through
Wednesday with warming temperatures.

Hurricane Sergio is currently churning west across the eastern
Pacific south of 20N. Latest model runs keep moving Sergio west to
about 130W by Monday and then start to move Sergio back east
toward Baja Peninsula by the end of next week into next weekend.
Way to early to know if the area will see any moisture from Sergio
late next week but something to keep an eye on. Definitely a most
interesting forecast track for sure.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

Meyer/G

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