Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 262245
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
345 PM MST MON SEP 26 2016

.SYNOPSIS...A low pressure system over central Baja California will
move north into southern California late Tuesday. This system will
bring scattered showers and thunderstorms Tuesday afternoon and
evening. Moisture will remain sufficient for a chance of showers and
thunderstorms especially east of Tucson Wednesday and Thursday. Dry
conditions will return area wide late this weekend.

&&

.DISCUSSION...A few showers continued across portions of Graham/nrn
Cochise Counties at this time. Most rainfall amounts from earlier
today were under one quarter of an inch, though a few locales
especially near mountains had heavier amounts. Showers will continue
to decrease in coverage during the next several hours. However,
various hi-res models suggest that additional showers may develop
later tonight or toward daybreak Tuesday. Thus, have maintained at
least a slight chance of showers area-wide into Tuesday morning.

The upper low centered near the Baja California Spur this afternoon
continues to be progged to lift northward into the northern Gulf of
California/southern California region by Tuesday evening. 26/12Z
Univ of AZ WRF-NAM and GFS remained very consistent versus their
respective previous solutions with developing showers/thunderstorms
southwest of Tucson by Tuesday afternoon.

Showers and thunderstorms should increase in coverage and move
northward across a fairly substantial portion of this forecast area
Tuesday afternoon and evening. Some strong thunderstorms may occur,
although the latest SPC Day 2 Convective Outlook has tempered this
potential somewhat versus the previous Convective Outlook. At any
rate, the bulk of any showers/tstms should occur across eastern
sections Tue night with dry conditions elsewhere.

A chance of showers/tstms exists mainly east of Tucson Wednesday as
deep sly flow continues ahead of the weakening upper low west of the
area. Per coord with neighboring WFO`s, PoPs were raised slightly
Thur mainly in response to moisture from remnant tropical system
Roslyn to be entrained northeastward across the area. A slight
chance of showers/tstms continues Friday across western sections
with precip-free conditions elsewhere. Thereafter, have opted for
dry conditions area-wide this weekend as increasing swly flow aloft
shunts deeper moisture well northeast of the area.

A warming trend will occur Tue-Thur followed by no significant change
in daytime temps Fri-Mon. The upshot is that high temps Thursday
into early next week will trend closer to seasonal normals for late
Sep/early Oct.

&&

.AVIATION...Valid through 28/00Z.
Isol`d to Sct -SHRA thru Tuesday, with a slight chance of -TSRA
Tuesday afternoon. Generally SCT-BKN clouds at 8-12k ft AGL thru the
period, however brief MVFR conditions and higher terrain
obscurations may occur into this evening. ELY/SELY sfc winds around
15-20 kts with gusts to 30 kts decreasing to around 8-12 kts late
this evening. ELY/SELY sfc winds increase again Tuesday afternoon to
around 12-16 kts, with the strongest speeds near the KSAD/KDUG
terminals. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Scattered showers will continue into this evening
with coverage gradually decreasing from south to north. Showers and
thunderstorms will develop again on Tuesday. Thereafter, a chance of
showers and thunderstorms will continue Wednesday through Friday,
mainly near the New Mexico border. Gusty easterly 20-ft winds around
15-25 mph will decrease this evening. Easterly winds continue
Tuesday through Thursday, although speeds will be somewhat weaker.
Expect normal diurnal wind patterns to resume late this week into
the upcoming weekend.

&&


.TWC WATCHES/WARNINGS/ADVISORIES...
    Wind Advisory until 8 PM MST this evening for AZZ511>515.

&&

$$

DISCUSSION...Francis
AVIATION/FIRE WEATHER...French

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