Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tucson Arizona
310 am MST Tuesday Sep 16 2014
Synopsis...periods of showers and thunderstorms can be expected
today and tonight...with heavy rainfall possible. The most
widespread and heaviest rain is expected Wednesday afternoon into
Thursday with potential flooding and flash flood issues.
Thereafter...lingering tropical moisture will keep scattered showers
and thunderstorms in the forecast Friday into the weekend.
Discussion...strong moisture increase over the past 12 hours with
precipitable water values now estimated around 1.7 to 1.8 inches
across Southeast Arizona as per current satellite estimates. Shower
and isolated thunderstorm activity increasing this morning on the
far northeast flank of Odile.
Odile has weakened to tropical storm strength as she pushes through
the central Baja California peninsula toward the northern Gulf of California.
Position as of 2am was about 25 miles west-northwest of Santa Rosalia Mexico
near 27.4n 112.7w. Long fetch of deep moisture being guided directly
into Southeast Arizona as Odile is even pulling up the remnants of
sixteen-east into the eastern periphery of the storm. Reinforcements so
to speak...as she successfully fends of the much drier air to her
west and northwest.
Widespread Flash Flood Watch in effect for most of the region. After
initial periods of shower and thunderstorm activity this morning
through today...the forecast track begins to bring the remnants of
Odile directly toward south central to Southeast Arizona Wednesday
morning with the bulk of the remaining circulation Wednesday night
into Thursday. We are anticipating storm total rainfall amounts over
the next 3 to 4 days in the 1.5 to 3 inch range in valleys and 2 to
5 inch range in mountains. On average we're expecting the heaviest
amounts near and just east of the track of Odile as she lifts
through as a low grade depression or remnant low. This would put our
areas of biggest threat for flash flood and flood activity in Santa
Cruz...southern and eastern Pima...Cochise...southern Graham...and
Greenlee counties. The Flash Flood Watch is in effect for Cochise
County today with coverage increasing to the rest of the area
tonight and Wednesday. It should be emphasized however that all of
Southeast Arizona is under significant threat for flash
flooding...not just the afore mentioned favored areas.
By Friday we should be pretty worked over but still have an
impressive amount of residual and boundary layer moisture to
recirculate into the weekend. Some medium range resolutions are also
keeping a favorable flow from the south and southeast over the
weekend into early next week that may keep thunderstorms in the
forecast into late September.
Hydrology...Tropical Storm Odile is expected to generate heavy
rainfall across much of Southeast Arizona through Thursday or
Friday. Storm total rainfall amounts ranging from 1.5 to 5 inches
are possible...with main Stem river flooding possible. This may
include the Gila...San Pedro and Santa Cruz rivers as well as washes
and creeks leading into them.
Aviation...valid through 17/10z
scattered showers and thunderstorms will continue this
morning...increasing in both coverage and frequency later today.
Areas of ceilings near 5k feet above ground level developing across southern part
of the region with multiple layers above and areas of showers and
thunderstorms. Showers will increase Wednesday with MVFR conditions
possible. Surface winds will generally be less than 10 kts except strong
gusts possible vicinity strong thunderstorms. Aviation discussion
not updated for taf amendments.
Fire weather...increasing tropical moisture with widespread shower
and thunderstorms activity through most of the week. Even after
Odile we expect to keep enough moisture around for a chance of
showers and thunderstorms Friday into the weekend.
Flash Flood Watch from Wednesday morning through Thursday
afternoon for azz501-505-506-509-510.
Flash Flood Watch through Thursday afternoon for
Flash Flood Watch from late Tuesday night through Thursday
afternoon for azz502>504-511-514-515.
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