Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 250416
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
915 PM MST Fri Nov 24 2017

.SYNOPSIS...Daytime temperatures will continue at record levels
through the weekend. Cooler temperatures are expected next week
as a system passes north of our area, but dry conditions will
continue.

&&

.DISCUSSION...The upper waether pattern is defined and dominated by
a strong building ridge of high pressure centered off the Baja Spur.
This high was responsible for another record high temperature in
Tucson today with 88 degrees...breaking the old record of 86
degrees set in 1981, 1909 and 1904. This ridge will slowly track
east the next several days, resulting in a continuation of record to
near record heat through Monday.

The inherited forecast is on track, with no updates necessary.

&&

.PREV DISCUSSION...Another record afternoon underway. The ridge of
high pressure over Baja, southern California and Arizona is slowly
shifting eastward and weakening. As the ridge axis shifts
directly overhead around Sunday, we`ll probably max out at more
than 20 degrees above average for much of our area. Record
temperatures for SE AZ, with the latest 90 ever possible for
Tucson International Airport.

Otherwise dry, with surface dew points in the 20s and precipitable
water values around 1/3 of an inch.

We`re expecting a pattern change next week with high pressure
amplifying off the west coast, and much of the west open to a
series of storm systems off the Pacific. This means much cooler
temperatures (relatively) and gusty winds at times. The first
system should brush by north of our area Monday night into
Tuesday, with another later in the week around Wednesday night or
Thursday. Trajectories are problematic with the second system
with a wide variety of ensemble, mean and model blend resolutions.

Beyond that, we`re seeing some hints that December will start out
a little busier than the entire month of November was, with a
split developing under major Pacific features. It can`t stay dry
and warm forever.

&&

.AVIATION...Valid thru 26/06Z.
Expect a few clouds above 20k ft AGL and surface wind variable in
direction mainly less than 12 kts into Saturday evening. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Dry conditions will continue into next Friday.
20-foot winds will generally remain terrain driven less than 15 mph
during this forecast period. However, expect some gusty southwest to
northwest winds Monday afternoon into early Tuesday as a storm
system moves north of the area. Occasionally gusty easterly winds
may also occur next Thursday and Friday. Forecast confidence is
somewhat low regarding the timing of this easterly wind scenario,
however.

&&

.CLIMATE...The record high for Tucson on Saturday the 25th is 86
degrees set way back in 1894. This is currently the oldest daily
high temperature that has stood for 122 years. Current forecast high
on Saturday for Tucson is 88 degrees.

Rainfall at the Tucson airport has been pretty non-existent since
the start of September. With no rain likely to occur during the
remainder of November, the three month period (September 1 through
November 30th) will go into the record books as the DRIEST on
record with a measly 0.12".

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None.

&&

$$


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