Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 131829
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
Issued by National Weather Service Phoenix AZ
1129 AM MST Tue Nov 13 2018

.UPDATE...
Updated 18Z aviation discussion.

&&

.SYNOPSIS...Expect gusty winds at times with unseasonably cool
daytime temperatures as well into Wednesday. Thereafter, a warming
trend with less wind as dry conditions continue later in the week
and into this weekend.

&&

.DISCUSSION...
With ridging amplifying along the west coast of North America,
strong sfc pressure rises over the Great Basin have forced the
coldest airmass of the season to spill into SE Arizona. Despite
unusually low dewpoints, the saving grace against even colder
morning temperatures has been partial mixing of a 30-45kt LLJ axis
associated with the tightest baroclinicity centered squarely over
the forecast area. Given observational and objective analysis data,
have increased winds along ridge tops this morning along with small
adjustments to diurnal temperature and dewpoint trends. Otherwise,
have allowed Hard Freeze Warnings to expire this morning with
widespread mid 20s observed.

&&

.PREVIOUS DISCUSSION...
A ridge of high pressure aloft extended along the west coast and
will moderate daytime temperatures the next few days. That said,
high temperatures will warm back to near seasonable readings by
Friday with dry conditions prevailing. Models showed the ridge of
high pressure aloft weakening by Saturday, with the possibility of a
weather system approaching the region early next week.

&&

.AVIATION...Valid through 15/00Z.
Gusty easterly winds will affect all TAF sites this afternoon in
response to a strong pressure gradient behind a backdoor front.
Winds at KTUS will remain sustained at 20-25 knots with gusts of
30-35 knots, whereas sustained winds and gusts will be about 5-10
knots weaker at KOLS and KDUG. Wind gusts should fall below 15-20
knots around 00-01Z at all sites, but this will be brief at KTUS
as enhanced downsloping effects will allow for gusts up to 25
knots to return after 04Z and persist into tomorrow morning. Winds
will finally weaken below 10 knots at KTUS late tomorrow
afternoon. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Very low humidity levels and gusty northeast to
east winds of 15-25 mph will today. While the overall fire danger is
low, the wind and very low RH conditions could result in challenging
dead grass fires during the afternoon hours. Easterly winds will
persist on Wednesday, but at lesser speeds. Cool temperatures
expected through Wednesday with a moderating trend into the weekend
with humidity levels remaining low. The next chance of wetting rains
won`t be till at least the middle of next week.

&&

&&

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

$$

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