Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 181606
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
906 AM MST Sun Jun 18 2017

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

&&

.DISCUSSION...The 12Z KTWC sounding holds no surprises, with about
4 degrees of warming ready to push temperatures up accordingly
this afternoon. The modest moisture increase is also evident, with
precipitable water at .42 inches (which we haven`t even come close
to in the past 5 or 6 days). Surface dew points again in the 20s
this morning with room to mix into the teens.

Today the ridge starts to get serious for the desert southwest,
with the ridge amplifying through the region, followed by the
high center slowly consolidating over Arizona in the next 48
hours. As the max heat hits us early to mid week, we will also
have to deal with just enough moisture for high based convection
that will bring more wind and lightning than rain. Please see the
previous discussion below for additional details.

&&

.AVIATION...Valid thru 19/18Z.
Clear skies. Occasional smoke layers above 10k ft AGL. Light
Surface winds becoming W-NW 8-13 kts with gusts to 20 kts in the
afternoon and early evening hours. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Extreme heat and very dry conditions will occur
to start the week with Excessive Heat Warnings in effect into
next Thursday. Mainly mid to high level moisture is expected to
increase, however. 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

&&

.PREV DISCUSSION...High pressure aloft will be strengthening over
the desert southwest thru Monday and will remain over the area
through the week. Daily record high temperature likely in this
extreme heat wave with all-time record high temperature being
approached. Daily record high minimum temperatures are also
likely.

Limited moisture seeping in the from the east will bring a slight
chance of high based dry thunderstorms over the White mountains this
afternoon. Moisture continues to slowly increase from the east
Monday resulting in high based, mainly dry, thunderstorms over the
mountains east of Tucson on Monday. Tuesday could be a very
interesting day as the models are suggesting a bit more thunderstorm
activity, with a better mix of dry and wet storms. Strong outflow
winds may also produce areas of blowing dust. Slight chance of
afternoon/evening thunderstorms mainly over the mountains will be
around Wednesday through Saturday. Stay cool this week.

&&

.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 until 7 PM MST Thursday for AZZ503.

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

&&

$$

Meyer

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