FXUS65 KTWC 230922

Area Forecast Discussion
National Weather Service Tucson AZ
222 AM MST Tue Apr 23 2024

.SYNOPSIS...Dry with seasonable warm temperatures will continue
through the first of half of the week then turning cooler and
breezy during the latter half of the week.


.DISCUSSION...The sky was clear over southern Arizona this morning
with the ridge axis, which brought a warm late April day Monday,
has moved east of the area. Highs today remaining on the warm side
for late April but a few degrees cooler than Monday.

Southwest flow aloft increases this evening/tonight out ahead of
a shortwave trof, which this morning was about 1000 miles west of
San Diego. Expect an increase in high clouds after sunset across
the forecast area. This feature will tighten the pressure gradient
for breezes Wed and breezy to windy conditions Thu. See fire
weather section below for fire weather concerns on Thu. This
system is moisture starved for SE AZ. Highs Wednesday 1 to 4
degrees cooler than today and then 4 to 8 degrees cooler on
Thursday. Slightly warmer Friday with less wind.

A deeper Pacific trof moves into the state on Saturday bringing
another round of gusty winds and chance of precipitation (White
mountains) and cooler temperatures area wide. The uncertainty on
Saturday is with forecast highs with GEFS/EPS and NBM showing
large temperature spreads. At this time followed the NBM temps but
can easily see it be much cooler that forecast on Saturday.

Temperatures rebound Sunday/Monday with highs 6 to 8 degrees
above normal on Monday


.AVIATION...Valid through 24/12Z.
Clear skies/SKC conditions thru 24/03Z, then SCT-BKN clouds AOA 20k
ft AGL thru the end of the forecast period. SFC wind less than 12
kts and variable in direction thru 23/18Z and again aft 24/03Z.
SLY/SWLY SFC wind at 12-18 kts and gusts to 22-28 kts between 23/18Z
and 24/03Z. Aviation discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions and above normal temperatures are
expected through Wednesday. A weather system will move north of the
area on Thursday, dropping temperatures below normal and increasing
wind speeds. Wind speeds will be near critical levels over portions
of Cochise, Graham and Greenlee counties. Another weather system
will move across the area Friday night and Saturday, resulting in
even cooler temperatures and highs 5-10 degrees below normal, as
well as a continuation of the strong winds to the east of Tucson.
Min RH values in the valleys will be 7-14 percent through Wednesday,
increasing to 10-20 percent Thursday through Saturday. Min RH values
in the mountains will be 10-18 percent through Wednesday, increasing
to 20-30 percent Thursday through Saturday.





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NWS TWC Office Area Forecast Discussion