Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 180445
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
945 PM MST Sat Jun 17 2017

.SYNOPSIS...Very hot temperatures are expected this weekend through
much of next week, with several days of near or record breaking
temperatures likely. A modest increase in moisture next week will
bring a chance of dry thunderstorms, but the chance of
precipitation remains slim through late next week.

&&
.DISCUSSION...The upper pattern is defined and dominated by a strong
ridge of high pressure expanding and strengthening over the Desert
Southwest the next several days. The main impact with this pattern
will be the heat wave...with a week of intense afternoon heat
expected across all of Southeast Arizona then next week. This
situation has been well advertised with Excessive Heat Advisories/
Warnings. We will also continue to spread the word of this heat wave
thru social media and IDSS briefings. This is a very long period of
excessive heat that will have a significant impact on everyone, not
just those whom are typically vulnerable to the heat.

In any event, current forecast is well in hand and no updates will
be necessary this evening.

&&

.PREV DISCUSSION...Clear and dry today as high pressure shuffles
around a bit over the next 18 hours before strengthening right
overhead Sunday through most of the rest of the new week. Maybe all
of the week, with the only thing to mitigate the near record and
record heat being fluctuations in intensity of the high, and the
hope of limited moisture seeping in from the east and southeast
during the week. Of course that would bring it`s own problems with
dry high based thunderstorms that tend to generate more lightning
and strong erratic outflows than meaningful rainfall. Something to
watch for by Tuesday afternoon.

Our main story continues to be an extended heatwave that will
approach record levels in both length and intensity (including
consecutive days over 110 at Tucson International Airport as well
as near the all time record high).

Add in an early taste of the monsoon with moisture creeping in
from the east and it will be an interesting week. With high
pressure in a partial blocking position, the pattern will remain
unfavorable for an extended fetch of deep moisture. Until it
shifts a little further north it will remain below average until
Sonora becomes much more active with a couple of organized
thunderstorm complex days. The resulting outflows will help until
we can get a more favorable pattern established that will see more
direct influence from eastern waves and deeper surge activity.

&&

.AVIATION...Valid thru 19/06Z.
Clear skies. Light Surface winds overnight becoming W-NW 8-13 kts
with gusts to 20 kts in the afternoon and early evening hours
Sunday. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Extreme heat and very dry conditions will occur
into next week with Excessive Heat Warnings in effect this weekend
into next Thursday. Mid to high level moisture is expected to
increase early next week. This moisture combined with strong
surface heating could result in dry-lightning over the White
mountains Monday afternoon then near the International Border and
Sky Islands of zones 151,152 and 153 Tuesday and Wednesday
afternoons. Strong and erratic winds could be experienced near any
thunderstorms that develop.

A slightly enhanced gradient will result in an enhanced northwest
breeze down the Gila valley this afternoon with 15-20 mph winds,
which may impact the Frye fire similar to Friday. Otherwise,
20-ft winds will be typical for June, with light drainage
overnight and westerly to northwesterly 5-15 mph each afternoon.
Minimum RH values will be in the low single digits through the
weekend with slight improvement later on. The instability will
increase with Haines 6 conditions developing west across the area
through Sunday, and areawide Monday Through Thursday. Monday
through Wednesday afternoons, the atmosphere will be well mixed
and unstable up through 500 mb or 18,000 ft msl.

&&

.CLIMATE...
All time record highs across the region

                     RECORD_DATE AND YEAR
TUCSON INTL AIRPORT  117 6/26/1990
BISBEE-DOUGLAS ARPT  110 6/26/1994
AJO                  117 7/5/2007, 7/6 2007 and 7/31/1995
FORT THOMAS          115 6/26/1990
KITT PEAK             98 7/30/1995
ORGAN PIPE CACTUS    118 7/15/1998, 7/26/1995 and 6/26/1990
PICACHO PEAK         119 7/28/1995
SAFFORD AG STATION   114 6/30/1994
SIERRA VISTA FD      108 7/4/1989
TOMBSTONE            112 7/4/1989
WILLCOX              110 6/28 AND 6/29/1994, 6/26/1990 and 7/6/2005

Daily forecast highs and record highs Monday through Wednesday

                     Jun 19           Jun 20           Jun 21
                     FCST RCD/YR      FCST RCD/YR      FCST RCD/YR
TUCSON INTL AIRPORT  114 115/2016     115 112/2015     115 112/1990
BISBEE-DOUGLAS ARPT  106 108/1959     107 106/1960     108 105/1990
AJO                  115 114/1968     117 115/1968     115 115/1919
FORT THOMAS          112 115/1960     115 111/1960     116 109/2005
KITT PEAK             99  95/1989     100  93/1989     100  94/1979
ORGAN PIPE CACTUS    115 115/1960     117 115/1960     113 114/1989
PICACHO PEAK         115 111/2002     117 112/2008     117 116/2005
SAFFORD AG STATION   112 109/1989     114 111/1989     115 109/1960
SIERRA VISTA FD      106 106/1989     106 103/1989     107 103/1990
TOMBSTONE            107 108/1989     108 105/1980     109 106/1996
WILLCOX              105 108/1989     106 105/1990     107 106/1968

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM Monday to 7 PM MST Thursday for
AZZ510>514.

Excessive Heat Warning until 7 PM MST Thursday for AZZ501-502-
504>506-509.

Excessive Heat Warning from 11 AM Sunday to 7 PM MST Thursday
for AZZ503.

Excessive Heat Warning from 11 AM Monday to 7 PM MST Thursday
for AZZ507-508-515.

&&

$$

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