Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 242115

Area Forecast Discussion
National Weather Service Tucson AZ
215 PM MST Sun May 24 2020

.SYNOPSIS...Temperatures will increase through Friday across much
of the area with the potential for much warmer than normal
conditions lingering into next weekend. A slight increase in
moisture from the east late in the week may allow for isolated
thunderstorms to develop Friday into Sunday east of Tucson.


.DISCUSSION...In the near term, we have the blessing of a cooler
than average day with high temperatures topping out 3-4 deg
cooler than average thanks to NW flow on the back side of a
passing trough. Monday we will remain in that NW flow however
heights will rise enough to allow for 3-4 degrees of warming under
sunny skies.

Tuesday into Friday heights will continue to increase as an omega
block develops and a mid-level ridge builds over AZ. As a result
temperatures will climb each day and at this point looking like
they should peak on Friday.

There is a bit of a question of Friday through the weekend thanks
to the potential for moisture to sneak in from the low on the
eastern side of the omega block. This moisture and the model
variance in the heights/thicknesses bring the thunderstorm and
temperature forecast details into some question Saturday and
Sunday. At this time we have a slight chance of thunderstorms near
the New Mexico border (as far west as Willcox) during the
afternoon and evening hours. This expands west a bit further
Saturday, but likely not quite as far as Tucson. Similar on Sunday
but maybe easing back east a bit.

The other concern is with temperatures. A trend is just beginning
to appear that the very hot temperatures could linger into
Saturday and possibly Sunday. Some uncertainty at this point so
have opted to leave the watch as is for today and I will likely
need to adjust the watch and/or warning on Monday if the night
shift hasn`t already done so. This matches up with other offices
not pushing further into the future at this time as well. The
moisture partially holds the key.


.AVIATION...Valid through 26/00Z.
Mainly SKC through the period. SFC wind WLY/NWLY at 10-15 kts and
gusts to around 20 or 25 kts, with the strongest speeds E of KTUS
and near KSAD. SFC wind decreasing to less than 10 kts this evening
and overnight into Monday morning. SFC wind NWLY much of Monday,
with speeds of 8-12 kts and gusts around 20 kts during the afternoon
hours. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions are expected through Thursday. There
will be a slight chance of thunderstorms in the White Mountains
during the afternoon/early evening hours Friday. The threat of
thunderstorms then expands westward next Saturday and Sunday and
will include areas mainly from Tucson eastward to the NM border.
High temperatures will be within a couple of degrees of normal
through Monday, increasing to above normal on Tuesday. Wednesday
into next weekend, expect well above normal high temperatures with
continued above normal temperatures overnight. Haines 6 conditions
will develop across eastern areas Wednesday, then spread westward on

Daytime humidity will fall below 10 percent across the lower
elevations much of this week, though a few degrees of improvement
may occur late this week as moisture tries to move into the region.
20-foot winds will generally remain less than 15 mph this week with
some afternoon gustiness due to daytime heating. However, strong,
gusty and erratic outflow winds may occur with any thunderstorms
that develop Friday into next weekend.


Excessive Heat Watch from Thursday afternoon through Friday
evening for AZZ501>507-509.



Fire Weather....Carpenter

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