FXUS65 KTWC 190950

Area Forecast Discussion
National Weather Service Tucson AZ
250 AM MST Fri Apr 19 2019

High pressure will continue to bring temperatures more suited to
May, including 90s from Tucson into the lower deserts. We`ll see
gusty winds Saturday and Sunday ahead of a Pacific system that
will lower temperatures back to around average early next week.


With a strong trough downstream through much of the country, a
strong ridge will bring temperatures around 15 degrees above
average today; well into the 90s for much of the area.

A weak low off the southern California coast will then begin to
pick up higher latitude support and kick eastward over the
weekend. HREF ensembles lift a weak 35-40kt 700mb jet enhancement
across northern Sonora and into Southeast Arizona ahead of this
feature Saturday afternoon. Combined with the dry conditions,
that should be plenty for fire weather concerns as outlined below.

Cool air advection in a still relatively dry westerly flow to
start the new week. we might see enough moisture for a couple of
afternoon buildups near the mountains the first half of the work
week, otherwise temperatures will fall back to within a couple of
degrees of seasonal normals (lower 80s around Tucson).

Ensembles and ensemble means support a weaker flow the second half
of the week. As the low fills and shifts downstream, a seasonable
retreat of the storm track should see us push temperatures back
to several degrees above average.


.AVIATION...Valid through 20/12Z.
Mainly SKC conditions with periods of passing cirrus above 25k ft
MSL. Variable SFC wind this morning less than 10 kts becoming
SLY/SELY this afternoon at 8-12 kts with a few gusts near 20 kts.
Winds relax and gusts decrease after sunset this evening into
Saturday morning. Aviation discussion not updated for TAF


.FIRE WEATHER...Dry conditions will continue with daytime
temperatures peaking this afternoon across the region. Minimum
relative humidity values will fall into the single digits with 20-ft
winds generally carrying an easterly component at less than 15 mph
into this evening. Gusty west to southwest winds return area-wide
over the weekend, with critical fire weather conditions possible
particularly on Saturday across Cochise and Santa Cruz Counties. A
Fire Weather Watch has been issued for portions of Fire Zones 151
and 152 from 12 pm to 7 pm Saturday. Minimum humidity on Sunday will
still range between 10 and 15 percent, but winds will not be as
strong as Saturday. Westerly winds will generally be less than 15
mph with a slight chance of a shower across the White Mountains each
afternoon for the first part of the new work week.


Fire Weather Watch from Saturday afternoon through Saturday
evening for AZZ151-152.




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NWS TWC Office Area Forecast Discussion