Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 182129

Area Forecast Discussion
National Weather Service Tucson AZ
230 PM MST Fri May 18 2018

.SYNOPSIS...Warm conditions will persist over the next week, with
temperatures hovering near to just above normal through next week. A
dry storm system will dive down the West coast late this weekend
into early next week, resulting in breezy conditions across
Southeast Arizona Monday and Tuesday of next week.


.DISCUSSION...The upper pattern is defined by an upper ridge of high
pressure across Western Canada with a mean upper trough trapped
under this feature across the western states. The upper low
currently over the Salt Lake region this morning will drift to the
east today, allowing for a stronger vort lobe to dive down the West
Coast late this weekend into early next week. Southeast Arizona will
be on the dry southern periphery of this feature, but will be
impacted with a tightening of mid-level pressure gradients. This
will result in breezy conditions both Monday and Tuesday across the
forecast area.

Based on the evolution of the upper low, it is possible that the
timing is somewhat delayed, forcing the strongest winds to occur on
Tuesday. However, as of this forecast package, winds look equally
strong on Monday and Tuesday. In any event, these winds will be
borderline for critical fire weather conditions. Minimum afternoon
relative humidities will range in the single digits to lower teens.
Although widespread conditions do not appear to be present at this
time...the scenario will necessitate a closer monitoring for
critical fire weather concerns early next week.


.AVIATION...Valid through 20/00Z. Clear skies through the period.
Surface winds WLY-NWLY 10-15 kts with gusts to 25 kts today, with
slightly stronger winds in the SE corner of the state. Winds then
decrease below 10 kts after sunset. Light and variable winds
Saturday morning will increase around midday today WLY 10 kts with
gusts to 20 kts. Aviation discussion not updated for amended TAFs.


.FIRE WEATHER...Winds remain locally breezy this afternoon,
particularly across Cochise County, relaxing area-wide over the
weekend. A developing low pressure system then brings the return of
breezy winds Monday and Tuesday. Due to persistent dry humidities, a
portion of southeast Arizona could approach critical fire weather
conditions each of those days. High-based thunderstorms may develop
just across the border in New Mexico Monday, but our area appears
dry for the time being. Winds ease by Wednesday and beyond, with
occasional afternoon gusts typical for this time of year.





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