Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 181611

Area Forecast Discussion
National Weather Service Tucson AZ
Issued by National Weather Service Flagstaff AZ
911 AM MST Tue Oct 18 2016

.SYNOPSIS...A rather static weather pattern across the Southwest
will maintain the mostly clear and dry weather conditions through
the week. A weak frontal boundary sagging into our corner of the
state from New Mexico may bring gusty east to southeast winds
Thursday into Friday.


.DISCUSSION...Clear skies and relatively light winds prevailed
across most of southeast Arizona this morning. High temperatures
will continue to be several degrees above normal today. Additional
details can be found in the previous discussion section below.


.AVIATION...Valid through 19/15Z.
VFR conditions are expected to persist through Wednesday morning.
SCT cirrus clouds may drift across the area at times. Surface
winds generally less than 12 kts. Aviation discussion not updated
for TAF amendments.


.FIRE WEATHER...Dry and warmer than normal conditions will continue
this week. Through Wednesday, expect light drainage winds during the
overnight hours and 20-foot winds less than 15 mph with occasional
higher gusts during the afternoon and early evening hours. Gusty
east winds will then develop late Wednesday night and linger into
early Friday as a backdoor front pushes into the area.


.PREV DISCUSSION...Water vapor imagery and the latest models
indicate a ridge centered just west of the northern Baja
peninsula, and another over the Dixie states, with a deformation
zone between the two over southern New Mexico and west Texas.
Meanwhile, a Pacific system continues to affect the Pacific
Northwest with the associated trough axis dipping down into
northern and central California. Arizona still affected by zonal
flow aloft. IR satellite imagery shows mostly clear skies across
much of the Desert Southwest with the closest cloudiness being a
thin band that extends across Utah, southern Nevada and south
central California, with mostly scattered high clouds to our east
over parts of New Mexico.

Models indicate that the vort max associated with the Pacific trough
will move across the Great Basin today, perhaps knocking a degree or
two off of high temperatures compared to Monday. By Wednesday this
feature will be over the central Rockies/plains with the weak
troughiness extending into New Mexico. As this occurs, a back door
front will be just to our east late in the week, with breezy east to
southeast winds developing early Thursday and perhaps lingering
through early Friday. Meanwhile, a high pressure system off the west
coast will begin to move slowly east, reaching the eastern Pacific
waters, southern California and Arizona by Thursday. The high will
continue to progress eastward, becoming nearly overhead by late
Thursday into Friday. As this occurs we should see our warmest days
during the Thursday through Saturday time frame, but only a few
degrees warmer than what is expected for today and Wednesday.

THe high will continue to move east through the weekend as another
Pacific trough approaches the Pacific Northwest. The models suggest
a slight return of moisture from the south and southwest as the
trough approaches early next week, but for now I just have single
digit `silent` POPs in the forecast grids. So stay tuned.

For Tucson, high temperatures will be well above normal each day,
but the warmest days will likely occur Friday and Saturday when they
will be around 10 degs above normal. Low temps will be near normal
Wednesday morning, then 5 to 7 degs above normal thereafter.





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