Area Forecast Discussion
Issued by NWS Tucson, AZ

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000
FXUS65 KTWC 191627
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
927 AM MST Mon Jun 19 2017

.SYNOPSIS...Very hot temperatures are expected this week, with
several days of near or record breaking temperatures likely. A
modest increase in moisture will bring a chance of thunderstorms,
but they will be more likely to generate gusty outflow winds and
lightning than significant rain.

&&

.DISCUSSION...Very hot with mainly dry thunderstorms northeast of
Tucson today. The morning KTWC sounding showed our precipitable
water up to 1/2 inch, with a decent increase around mid levels.
GOES Total PW estimates show deeper values in excess of 1 inch
just over the state line across southern New Mexico. An easterly
flow immediately south of the developing high center will continue
to import some of that into eastern areas this afternoon, with
mainly dry thunderstorm development over east central mountains. A
perfect scenario for strong thunderstorm outflow pushing south
through portions of Graham and Cochise counties. Plenty of dry
lightning with limited actual shower activity. Most of the
favorable thermodynamics is also in New Mexico (even with
excessive solar insolation), but multiple outflows will help. Our
current forecast looks solid. Please see the previous discussion
below for details.

&&

.AVIATION....Valid thru 20/18Z.
Patchy mainly thin cirrus this morning, then after 19/20Z SCT-
BKN 120 mainly east of KTUS with ISOLD TSRA NE of KTUS. Light
surface winds becoming W-NW 6-12 kts with gusts to 20 kts in the
afternoon mainly KTUS west. Otherwise, very strong and gusty
outflow winds possible in the afternoon and early evening NE and
E of KTUS, especially in the Gila River Valley near KSAD.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expecting another critically unstable day with
near record heat, single digit humidity levels and ERCs pushing the
97 percentile today.  It will be as unstable as yesterday with a
solid Haines 6 and mixing heights pushing 20,000 feet nearly area
wide for good plume development potential as we saw on the Frye Fire
yesterday.  Also, thunderstorms are expected to develop this
afternoon over the Rim and White mountains with a good potential for
strong outflow winds dropping into the Gila Valley late today. It
will be a critical, heads up, day especially for the Frye Fire with
the instability and potential strong NE outflow winds late in the
day.  Good chance the Freeze 2 will be impacted by storms this
afternoon with lightning and gusty winds.  Rain will be very
limited.

Tuesday will be another critical day.  It will remain unstable and
with the expected westward push of moisture, mostly dry
thunderstorms as far west as Tucson are expected during the
afternoon and evening.  With the very dry air in the low levels the
storms will be mostly dry with the potential for very strong outflow
winds.  We are continuing to go with the LAL of 6 as a result . with
the possibility of plenty of fire starts.  Less clear, but we could
get another significant outflow off the Rim late in the day.

Enough moisture may linger into Wednesday for a few more
thunderstorms, mainly east of Tucson over the mountains.  Beyond
that the upper high pressure center will settle down the convection
the remainder of the week with a decent NW breeze on Friday. Monsoon
moisture may try to return again late next weekend. Cerniglia

&&

.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     113 112/1990
BISBEE-DOUGLAS ARPT  107 108/1959     107 106/1960     106 105/1990
AJO                  117 114/1968     119 115/1968     116 115/1919
FORT THOMAS          113 115/1960     114 111/1960     112 109/2005
KITT PEAK             99  95/1989     100  93/1989      98  94/1979
ORGAN PIPE CACTUS    115 115/1960     117 115/1960     115 114/1989
PICACHO PEAK         115 111/2002     117 112/2008     115 116/2005
SAFFORD AG STATION   112 109/1989     113 111/1989     111 109/1960
SIERRA VISTA FD      106 106/1989     107 103/1989     105 103/1990
TOMBSTONE            107 108/1989     108 105/1980     107 106/1996
WILLCOX              105 108/1989     106 105/1990     105 106/1968

&&

.PREV DISCUSSION...Very hot temperatures across the region this
week into next weekend. Thus have extended both the Excessive Heat
Warning and Heat Advisory out into Saturday. Made some slight
adjustments to daily highs as the increase in limited moisture and
cloud cover may keep some areas from reaching previous forecast
highs. MOS/thickness values slightly cooler/lower.

Satellite imagery this morning showed debris cloudiness north of
Tucson from last nights convection across west central New Mexico.
An additional area of debris cloud was moving northwest out of
Chihuahua MX into eastern Cochise county. Precipitable water values
continue to slowly rise as moisture pushes in from the east. Values
this morning were mostly in the 0.40" to 0.60" range with values up
to 0.80" across SW New Mexico. Expect the values in SW NM to slowly
push west into far eastern areas later today and combined with the
daytime heat, isolated high based mostly dry thunderstorms will be
forming mainly across central and northern Greenlee county. Main
concern with these storms is dry lightning and strong gusty and
erratic outflow winds. High resolution models bring gusts over 40
mph into the Fry Wildfire on Mt. Graham after 4 pm.

Models suggesting that precipitable water values could get as high
as 1" from Tucson east on Tuesday. This will bring a mix of high
based dry and wet storms with main concern once again being strong
gusty erratic outflow winds and with coverage further west, blowing
dust becomes a concern between Tucson and Phoenix. Can`t rule out a
storm or two getting close to severe limits Tuesday afternoon.

Moisture retreats a bit Wednesday into Friday with slight chance of
storms in the White mountains. Moisture starts working back into the
area from the east southeast for a slight chance of afternoon and
early evening thunderstorms from Tucson east and south.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM MST Saturday for AZZ510>514.

Excessive Heat Warning until 7 PM MST Saturday for AZZ501>506-
509.

Excessive Heat Warning until 7 PM MST Saturday for AZZ507-508-
515.

&&

$$

Meyer

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