Area forecast discussion 
National Weather Service Tucson Arizona 
224 PM MST Wednesday Sep 17 2014 


Synopsis...the most widespread and heaviest rainfall is expected 
into this evening...overnight and through much of the day on 
Thursday with flooding and flash flooding problems expected. 
Thereafter...lingering tropical moisture will keep scattered showers 
and thunderstorms in the forecast Friday through the weekend. 


&& 


Discussion...as of 2 PM PDT/MST...Tropical Depression Odile has 
weakened to just a remnant low over northwest Mexico. As of 2 PM the 
position of the center of circulation was located at latitude 31.1 
n; longitude 112.7 west...which is about 20 miles west northwest of 
caborca Mexico and was moving to the northeast at 7 miles per hour. This motion 
is expected to continue this afternoon and evening with the center 
of circulation expected to continue moving over northwest portions 
of northwest Sonora through this afternoon and into southern Arizona 
this evening. 


Radar mosaic shows a band of showers currently moving through much 
of our central and eastern portions of the forecast area...which 
includes the Tucson metropolitan...the east side of the catalinas and 
rincons and into northern portions of Cochise County where a couple 
of small stream flood advisories are in effect...but will expire 
shortly. A large area of showers south of the border will continue 
to stream northward into Santa Cruz and Cochise counties and 
continue the journey northward this afternoon and into this evening. 
An Urban and Small Stream Flood Advisory has thus been issued for 
much of Santa Cruz County and southwestern Cochise County through 5 
PM MST as these showers move north into Arizona. 


A Flash Flood Warning was extended for central portions of Graham 
County...just west of the Safford area...which includes the town of 
Pima. Reports from law enforcement officials and spotters indicated 
that heavy rain was impacting Ash Creek resulting in Road 
closures...with a few homes impacted by the heavy rain as well. This 
high water and resulting flash flooding was due to over 3 inches of 
rain within the past 24 hours...but the bulk of that fell within the 
past 12 hours or so. The warning will continue through 530 PM MST 
this afternoon...unless the need arises for US to extend the warning 
even further. 


The latest official forecast from the hurricane center indicates 
that the center of circulation will move generally west of the 
Tucson area near Sells by late this evening...with the bulk of the 
precipitation impacting areas east of this circulation...including 
Tucson...Nogales and areas to the east toward New Mexico...with 
lesser amounts to the west of this circulation center. The models 
are continuing the indicate that rainfall amounts will continue to 
be heavy with storm total amounts ranging from 2 to over 4 inches 
for Tucson...depending on the model of choice. The 12z nam12 was the 
outlier with a bullseye of 4.5 inches...whereas the GFS and European model (ecmwf) 
showed values ranging from 2.0-3.0 inches. Our official quantitative precipitation forecast forecast 
falls within this more conservative range. The heaviest swath of 
precipitation expected to extend from Santa Cruz County through 
southeastern Pima and into Cochise...Graham and Greenlee counties 
with storm total values ranging from perhaps 3 to 5 inches and near 
6 to 8 inches for some of the mountain tops. Expect to see the bulk 
of the heavy rains to continue into this evening and increase in 
intensity overnight and into Thursday. 


By late Thursday/early Friday the circulation should be somewhere 
over New Mexico with a marked decrease in shower activity starting 
overnight Thursday and especially into Friday. By that 
time...lingering moisture as well as an approaching Pacific trough 
will keep isolated to scattered showers and thunderstorms in the 
forecast for Friday. This general theme will continue through at 
least the weekend...until high pressure builds in from the south 
early next week...resulting in a decrease of showers and 
thunderstorms to just isolated in nature. 


&& 


Hydrology...remnants of Tropical Depression Odile is expected to 
generate heavy rainfall across much of Southeast Arizona through 
Thursday with storm total rainfall amounts ranging from 2 to 5 
inches with amounts of 6 to 8 inches in some mountain locations. 
Flooding on creeks and washes is likely tonight and Thursday with 
main Stem river flooding possible through the weekend. The main Stem 
rivers of concern are the Gila...San Pedro and Santa Cruz and their 
tributaries. Based on the latest river forecasts the Gila River and 
its tributaries are forecasted to reach bankfull or even flood 
stage. For individual river forecasts please refer to the Colorado 
basin river forecast center Wednesday site at www.Cbrfc.NOAA.Gov 


&& 


Aviation...valid through 19/00z 
numerous showers and isolated thunderstorms will continue through 
tonight and taper off Thursday as the remains of Odile push through 
Southeast Arizona. Expect lower ceilings today with areas of MVFR 
conditions areawide by this evening and continuing through by middle 
morning Thursday before improving. Surface winds increasing out of 
the southeast today with sustained values around 12 to 20 kts this 
afternoon into the evening then easing and becoming more southerly 
overnight. Stronger gusts possible near the strongest showers or 
thunderstorms. Aviation discussion not updated for taf amendments. 


&& 


Fire weather...plentiful tropical moisture with widespread shower 
and thunderstorm activity expected through Thursday...primarily near 
and east of Tucson. Expect local flooding issues through Thursday. 
Enough residual moisture will be in place for a chance of showers 
and thunderstorms Friday through the weekend. 


&& 


Twc watches/warnings/advisories...Flash Flood Watch through 
Thursday afternoon for azz501>515. 


&& 


$$ 


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Public...mollere 
aviation/fire weather...cerniglia 
hydrology...Boyle 












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