FXUS65 KTWC 232205
Area Forecast Discussion
National Weather Service Tucson AZ
305 PM MST Thu May 23 2019
.SYNOPSIS...Expect dry conditions into the middle of next week.
Although a warming trend will occur into Saturday, below normal
temperatures will still prevail. Even cooler temperatures and a
return of gusty winds on Sunday as a storm system develops northwest
of the area. This system will weaken followed by much warmer
temperatures by the middle of the upcoming week.
.DISCUSSION...The cumuloform clouds that prevailed across much of
southeast Arizona early this morning have mostly dissipated as of
mid-afternoon. Thus, clear skies except for a few cumulus clouds
mostly confined to the White Mountains. After the loss of daytime
heating, expect the remaining clouds to dissipate later this evening
with clear skies area-wide later tonight.
Various 23/12Z numerical weather prediction models continue with the
depiction of a broad longwave trough over the western CONUS through
this forecast period, or most likely into the middle of next week.
Southwesterly flow aloft will continue Friday albeit with relatively
light surface winds due to a fairly relaxed mid-level pressure
gradient. Winds should increase somewhat on Saturday as the mid-
level gradient tightens ahead of the next upper low pressure system
progged to deepen over northern or central California by midday
Various models suggest precip-free conditions will continue across
southeast Arizona on Sunday ahead of this deepening upper low.
However, the main impact will be breezy to windy conditions
especially during the afternoon and early evening hours. This
scenario should produce potential patchy blowing dust and critical
fire conditions. Please refer to the Fire Weather section in this
product for additional information.
The upper low is progged to weaken on Monday while moving eastward
across southern Utah or northern Arizona. Any measurable precip
associated with this system is progged to remain north-to-east of
this forecast area, and this scenario seems reasonable. There should
still be some gusty winds on Monday, but wind speeds should be lower
than Sunday. Thereafter, upper trough to prevail over the western
CONUS Tuesday into Thursday. This pattern should translate into
continued dry conditions with some gustiness at times, especially
during the afternoon hours.
Although warmer temps are forecast to occur Friday into Saturday,
daytime highs will average at least several degrees below normal. A
cooling trend is on tap Sunday and especially Monday before the next
warming trend Tuesday through Thursday.
.AVIATION...Valid through 25/00Z.
FEW clouds at 5k-8k ft AGL becoming SKC (clear conditions) by 24/03Z
and then continuing thru the remainder of this forecast cycle. SFC
wind generally less than 12 kts thru the valid period, favoring a
WLY/NWLY direction Friday afternoon. Aviation discussion not updated
for TAF amendments.
.FIRE WEATHER...Dry conditions are expected into at least the middle
of next week. Light 20-foot winds are expected Friday, less than 15
mph with some afternoon gustiness. 20-foot winds will then increase
this weekend in advance of another storm system passing by to the
north Sunday night into Monday. Critical Fire Weather conditions
will be possible Sunday afternoon and evening across portions of the
area. Below normal temperatures are expected to continue through the
middle of next week.
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