Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 181039

Area Forecast Discussion
National Weather Service Tucson AZ
339 AM MST Sat Jan 18 2020

.SYNOPSIS...Dry conditions and above normal daytime temperatures
will prevail into early next week. A chance of showers will return
Tuesday and Wednesday as a weak storm system brushes the region.
This will also moderate temperatures down a few degrees to near
average for the second half of next week.


.DISCUSSION...Mostly clear skies over much of the southwest this
morning as a deep trough pushes eastward across the central CONUS.
Weak ridging positioned near the west coast will amplify over the
next 48 hours allowing temperatures to warm up to above normal
values. With the ridge axis passing overhead Sunday into Monday,
expect temperatures to peak at 4-8 degrees above average for mid-
January. Mid-level moisture passing under the ridge will result in
passing cirrus from time to time through the weekend.

With the ridge moving off to the east Monday night, a weak shortwave
will bring thicker cloud cover and a slight chance of valley rain
and high elevation snow showers to southeast Arizona starting
Tuesday morning. Any measurable precip will likely be confined to
areas east of Tucson with very light QPFs due to the progressive
nature of the upper pattern.

After a short break between systems, another shortwave will approach
the Four Corners area Wednesday, resulting in another chance for
rain and snow showers. There remains fairly significant differences
in the timing and depth of this system between the GFS/ECMWF and
their respective ensembles, so the inherited forecast was changed
very little. Model solutions continue to diverge late next week in
terms of the upper air pattern, but it looks like dry conditions
will return at least for Thursday. We`ll watch for another potential
system Friday into Saturday with subsequent model runs.


.AVIATION...Valid through 19/12Z.
SKC to SCT clouds AOA 20k ft MSL through the period. SFC wind
variable in direction this morning becoming ELY/SELY this afternoon
at 8-12 kts. Variable winds return this evening into Sunday morning.
Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions will prevail into Monday. A slight
chance of valley rain and mountain snow showers returns to areas
east to northeast of Tucson Tuesday and again Wednesday. Elevated
easterly 20-ft winds Sunday and Monday with some gusts to 25 mph.
Otherwise, 20-ft winds mainly terrain driven at less than 15 mph.





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