Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 061710

Area Forecast Discussion
National Weather Service Tucson AZ
1010 AM MST Tue Dec 6 2016

.SYNOPSIS...A few rain and snow showers may occur across the White
Mountains tonight into Wednesday. Otherwise, dry conditions will
prevail into early next week. Some minor cooling will occur
Wednesday, then above normal daytime temperatures will return Friday
into next Monday.


.DISCUSSION...IR/visible satellite imagery and surface observations
depict broken to overcast mid and high-level clouds across southeast
Arizona at this time. Colder topped clouds were in a band from
southeast California eastward toward the White Mountains. IR imagery
depicted these cloud tops to be warming during the past 1-2 hours.

06/12Z KTWC sounding total precip water value of 0.49 inch was
nearly 0.15 inch higher versus 24 hours ago. The bulk of the
moistening was in the 500-200 mb layer, indicative of the increased
mid and high-level clouds observed. 06/12Z upper air plots depicted
a broad trough over Canada and much of the CONUS, a 515 dm low was
over northern Minnesota, and a shortwave trough was over the Great
Basin. Moderate to fast wly flow above 700 mb prevailed across
southeast Arizona.

The aforementioned shortwave trough will move eastward toward the
Four Corners tonight, then continue to move eastward into the
central CONUS plains Wednesday. Synoptic scale ascent associated
with this shortwave trough may be sufficient to generate a few
rain/snow showers across the White Mountains tonight into Wednesday.

Otherwise, dry conditions will prevail into early next week as the
upper level pattern will generally be characterized with a trough
over Canada extending south into the central/eastern CONUS.
Meanwhile, a ridge will prevail near the West Coast. This pattern is
expected to maintain precip-free conditions, although variable
amounts of mainly high-level clouds will move across the area.

High temps this afternoon will be quite similar to temps achieved
Monday, and thus will average about 5 degs or so warmer than normal
from Tucson westward, but will be fairly close to seasonal normals
elsewhere. Cooler temps will occur Wednesday as the shortwave trough
passes northeast of the area. A warming trend will then prevail Thur-
Fri, then only very minor daytime temp changes are forecast to occur
this weekend and early next week. High temps Fri-Mon will average
about 2-5 degs or so above normal depending upon location.


.AVIATION...Valid through 07/18Z.
Isolated -SHRA/-SHSN may occur across the White Mountains tonight
into Wednesday. Otherwise, SCT clouds around 12k-15k ft AGL and BKN-
OVC clouds above 20k ft AGL through the period. Surface wind this
afternoon swly-nwly at 10-18 kts with gusts to 25 kts. Surface wind
variable in direction less than 12 kts this evening into Wednesday
morning. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...There is a slight chance of rain and snow showers
across the White Mountains tonight and Wednesday. Otherwise, dry
conditions will continue into early next week. 20-ft winds will be
gusty to near 20 mph from the southwest to northwest this afternoon,
with winds becoming easterly or southeasterly on Thursday and
Friday. 20-foot winds will mainly follow terrain at less than 15 mph
at other times.






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