Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 192208

Area Forecast Discussion
National Weather Service Tucson AZ
305 PM MST Fri May 19 2017

.SYNOPSIS...Dry conditions will prevail across much of the area into
next week. A few thunderstorms may occur Sunday night and Monday
near the New Mexico border, and there is a slight chance of
thunderstorms Wednesday across the White Mountains. Much warmer
temperatures will also occur during the upcoming week.


.DISCUSSION...Strong high pressure aloft was centered this afternoon
off the West Coast near 33N/130W. The resultant northwest flow aloft
regime has produced clear skies across much of southeast Arizona
this afternoon, except for a few cumuloform clouds across the White
Mountains. Those clouds will dissipate this evening, then a paucity
of moisture will provide clear skies into Saturday night, and for
most locales Sunday morning as well.

The 19/12Z NAM/GFS/ECMWF remained consistent versus their respective
solutions regarding an increase in mainly mid-level moisture
especially across southwest New Mexico Sunday afternoon and
continuing into Monday. The NAM12 produced nearly one tenth of an
inch of rainfall by Sunday evening across the Chiricahua Mountains.
However, the Univ of AZ WRF-NAM depicted any measurable precip by
Sunday evening to remain farther east into southwest New Mexico. The
Univ of AZ WRF-NAM was thus more similar to the GFS/ECMWF/CMC in
this regard, and the NAM12 was discounted.

Thus, have maintained precip-free conditions across this forecast
area Sunday afternoon through Tuesday night with the belief that any
measurable rainfall will occur just east of the Arizona/New Mexico
border. However, any showers and thunderstorms that develop
especially late Sunday into Monday will be quite close to the border.

The deterministic GFS/ECMWF/CMC were very similar with depicting a
highly amplified ridge axis Wednesday to extend from the Pacific
Northwest southeastward into Chihuahua Mexico. These solutions have
increased the available mainly mid-level moisture, especially across
eastern sections of this forecast area. Thus, per coordination with
neighboring WFO`s, have opted for a slight chance of showers and
thunderstorms Wednesday across the White Mountains. Thereafter,
generally westerly flow aloft will shunt this moisture well east of
this forecast area by next Friday. The GFS/ECMWF were quite similar
with depicting a very dry surface-300 mb layer across southeast
Arizona, and this should translate into clear skies for next Friday.

The amplifying upper ridge near the West Coast this weekend, then
across the southwest CONUS during the upcoming week, will translate
into much warmer, or hotter, daytime temperatures. Using Tucson
International Airport as an example, high temperatures in the lower
90s Saturday are forecast to be followed by highs encroaching upon
the century mark perhaps as early as Sunday and Monday, but now more
likely Tuesday. The hottest day now appears to occur next Thursday,
then a very minor moderation in daytime temperatures next Friday.


.AVIATION...Valid thru 21/00Z.
Expect clear skies into Saturday afternoon. Surface wind terrain
driven mainly less than 12 kts, although occasional gusts to near 20
kts Saturday afternoon especially east of KTUS. Aviation discussion
not updated for TAF amendments.


.FIRE WEATHER...Dry conditions will occur across much of the area
through next Friday. However, a few thunderstorms may occur near the
New Mexico border Sunday night and Monday, and there is a slight
chance of thunderstorms Wednesday across the White Mountains. Winds
will generally remain below 15 mph although some afternoon gusts
will occur due to strong daytime heating.






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