Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 170359
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
859 PM MST Fri Jun 16 2017

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

&&

.DISCUSSION...The main story continues to be the building heat.
The pre-game warm up has been the strong high pressure through
northern and northwest Mexico. A brief pause as this feature
continues to build westward and then northward as it merges into
a larger scale ridge feature through the far eastern Pacific. The
main event will be the stronger ridge of high pressure building
through the desert southwest with a new high center
reconsolidating near and over our area most of next week.

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). Please see the previous discussion below for additional
details.

&&

.AVIATION...Valid thru 18/06Z.
Clear skies with strong high pressure overhead. Surface winds
westerly 8-13 kts with gusts to 20 kts in the afternoon and early
evening hours. Otherwise, light surface winds. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...Extreme heat and very dry conditions can be
anticipated into next week. Excessive Heat Warnings have been
posted for most of southeast Arizona this weekend into next
Thursday. Models continued to show some increase in mid-level
moisture early next week. This moisture combined with strong
surface heating could result in dry-lightning near the
International Border and Sky Islands around Tuesday and Wednesday
afternoons. Erratic winds could be experienced near any
thunderstorms that manage to develop. 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 into the weekend with slight improvement
later on. The instability will increase with Haines 6 conditions
slowly developing across the area through Sunday, and areawide
Monday Through Thursday.

&&

.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     114 112/1990
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      99  94/1979
ORGAN PIPE CACTUS    115 115/1960     117 115/1960     113 114/1989
PICACHO PEAK         115 111/2002     117 112/2008     116 116/2005
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...Another very unusually dry mid June afternoon
across southeast Arizona with surface dewpoints ranging from the
negative single digits south and east of Tucson to the teens from
Tucson westward. WV imagery clearly depicts the anomalously dry
air as well with westerly flow across the region as the
subtropical high remains to our south. The main story through this
forecast period is going to be the extreme heat. As the
subtropical high builds northward and strengthens, temperatures
over the next couple of days and especially heading into next work
week will rise accordingly. While Saturday is quite marginal for
excessive heat criteria, for the sake of simplicity and to keep
the awareness up, have decided to maintain the excessive heat
warnings previously in effect for Saturday. The hottest
temperatures in this potentially deadly heat wave will peak Monday
through Wednesday with numerous daily record highs expected to be
broken and several all time record highs in jeopardy. See climate
section below for additional specifics.

As the lower level flow becomes a bit more easterly by Monday
through Wednesday, some increased moisture is expected mainly over
the higher terrain east of Tucson and especially close to the New
Mexico border. This will likely be enough for some build-ups and dry
lightning concerns, raising the threat for new wildfires. Given the
high placement and orientation for much of next week, it will be
difficult to transport deeper moisture into the area so will have to
keep an eye on the dry lightning and gusty wind threat with any
thunderstorms that are able to form over the higher terrain into
the end of next week as well.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 11 AM Saturday to 7 PM MST Thursday
for AZZ501-502-504>506-509.

Heat Advisory from 11 AM Monday to 7 PM MST Thursday for
AZZ511>514.

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.

&&

$$

Meyer/GL

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