Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 181018

Area Forecast Discussion
National Weather Service Tucson AZ
317 AM MST Sat Feb 18 2017

.SYNOPSIS...A strong Pacific storm system will bring valley rain,
mountain snow and cooler temperatures this weekend. Expect gusty
winds into today before winds diminish Sunday. Dry conditions
with a strong warming trend will then prevail Monday into the middle
of next week. Cooler temperatures will occur next Thursday and
Friday with dry conditions continuing.


.DISCUSSION...A storm system continued to move into California early
this morning with showers increasing across western and central
Arizona. Regional radars were showing an extensive band of showers
along the Colorado River with more development farther east across
central and northern portions of this state. Isolated to scattered
light showers had already moved into western and central Pima county
as of 245 AM MST. Models were still advertising a rather wet system
moving through the area today into Sunday. Strong winds will develop
this morning in advance of the main system. A Windy Advisory has
been post for portions of southeast Arizona through 4 PM MST today.
The snow level ahead of the system was still rather high, above 8000
feet, early this morning but will gradually lower throughout the day
and tonight. A Winter Storm Warning for above 7500 feet remains in
effect from 3 PM MST today until 5 PM MST Sunday. Models showed the
system exiting the area late Sunday with improving weather from west
to east Sunday night. A ridge of high pressure aloft will build over
the region Monday into Tuesday with daytime temperatures rebounding.
Thereafter, another system was progged to track through the Rockies
brushing southern Arizona on Wednesday into Thursday. At this time,
the bulk of the precipitation chances associated with this system
will be north of the area.


.AVIATION...Valid through 19/12Z.
ISOLD-SCT -SHRA mainly west of KTUS early this morning, then
numerous valley -SHRA and higher terrain SHSN by late morning/early
afternoon areawide. ISOLD -TSRA may also occur this afternoon,
mainly from KTUS south and west. MVFR and occasional IFR conditions
are expected particularly near mountains. Otherwise, cloud decks
will be at 4k-8k ft AGL. Surface wind sely/sly at 10-18 kts thru
18/15Z, increasing to 18-26 kts with gusts to near 40 kts between
18/15Z-19/00Z, then diminishing tonight. Aviation discussion not
updated for TAF amendments.


.FIRE WEATHER...A strong Pacific storm system will bring widespread
valley rain and mountain snow this weekend. Gusty southeast/south 20-
foot winds will occur today, with the winds diminishing tonight, but
remaining on the breezy/gusty side through Sunday. Dry conditions
with a strong warming trend will occur Monday into the middle of
next week.


    Winter Storm Warning from 3 PM today to 5 PM MST Sunday for
      AZZ510-511-513-514 above 7500 feet.

    Winter Weather Advisory from 3 PM today to 5 PM MST Sunday
      for AZZ512 above 7500 feet.

    Wind Advisory from 7 AM this morning to 4 PM this afternoon for



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