Area Forecast Discussion
Issued by NWS Tucson, AZ

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141
FXUS65 KTWC 300406
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
906 PM MST Wed Mar 29 2017

.SYNOPSIS...Warmer Thursday under high pressure aloft. The next
system will bring increasing winds Thursday afternoon and Thursday
night, with stronger winds Friday. We`ll also see another chance
of showers mainly northeast of Tucson Friday through Sunday with a
return to cooler temperatures Friday and Saturday. Temperatures
will then rebound to seasonal averages early next week.

&&

.DISCUSSION...Mostly clear in a dry northerly flow in between the
exiting trough and the shortwave ridge immediately upstream. Winds
will back around to the west and southwest over the next 18 hours
as a strong low digs quickly into the great basin and our
gradient is enhanced at all levels. We made a few minor
adjustments based on the latest HRRR and downscaled NAM trends,
which primarily went slightly stronger in the winds by late
Thursday afternoon. We also need to watch out for the surprise
shower activity advertised by the ECMWF early Friday morning. A
quick look at 00Z GFS trends are toward modestly increasing
moisture fields compared to previous runs. Please see the
previous discussion below for additional details.

&&

.AVIATION...Valid through 31/06Z.
Mainly SKC with few cirrus level clouds. Surface winds variable
less 12 kts overnight into Thursday morning, then gusty SW winds
in the forecast after 30/18z.

Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Warmer Thursday along with an increase in southwest
winds in advance of next Pacific weather system. There will be
isolated areas across southern portions of fire weather zones 150,
151 and 152 that could see a few hours of red flag conditions.

As the next Pacific weather system approaches the area on Friday,
strong southwest winds are forecast to develop late Thursday night
into Friday. Red flag conditions are possible Friday afternoon
across southern half of fire weather zone 152 and far southeast
portions of fire weather zone 151. This system will also bring a
chance of showers mainly northeast of Tucson Friday through
Sunday.

&&

.PREV DISCUSSION...Pressure gradient continues to tighten
Thursday night into Friday as upper low moves into SW Utah and
associated cold front sags SE across the state. There are timing
differences between the models on moving the cold front across the
area on Friday which will have an effect on how warm it could
get. In fact areas from Tucson west likely will see the high on
Thursday occurring right after midnight. I did trim a few degrees
on highs from Tucson west for Friday. On the precip side, the
ECMWF continues to show light QPF values in advance of the cold
front as it picks up some Gulf of California moisture, kinda
similar to what occurred early Tuesday morning. Not saying will
see a repeat but can`t rule out very light showers or sprinkles.
However the GFS, GFS ensembles and NAM not producing and QPF
across the area, except up in the whites. Will hedge on slight
chance PoPs in the mountains. Something the future shifts will
continue to monitor. Wind also a concern on Friday with the
favored areas S and SE of Tucson approaching wind advisory
criteria. Could start overnight across SW Cochise county as the
winds will be hollowing through the Huachuca mountains. Fire
weather concerns for Friday are addresses in the fire weather
section below.

Upper low moving slowly through the 4 corners and northern New
Mexico Saturday/Saturday night with disturbances on back side of
system moving across the area which will keep conditions unsettled
from area mainly east of Tucson. Could see a few thunderstorms
develop over the White mountains Saturday afternoon. Cool northerly
flow will keep below normal high temperatures across the area.

Warmer Sunday as short wave ridge builds over the area. Gusty
afternoon winds once again on Tuesday as weather system move through
Utah into Colorado.

&&

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

&&

$$

Meyer

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