Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 211601
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
902 AM MST Wed Jun 21 2017

.SYNOPSIS...Very hot temperatures will continue across the area
through this weekend with near or record breaking temperatures
forecast. Moisture around the area will bring a chance of
thunderstorms again today east and south of Tucson, but they will be
more likely to generate gusty outflow winds and lightning than
significant rain. A return to dry weather is forecast Thursday and
Friday although moisture and a chance of thunderstorms looks
increasingly likely early next week.

&&

.DISCUSSION...Another hot day in store for the region as very strong
high pressure remains anchored over the area. 12Z KTUS sounding came
in with a very similar profile compared to yesterday with only
subtle differences through 500mb. Biggest differences were thanks to
mostly clear skies across the area vs. the thick overcast we started
out with on Tuesday. Temperatures at various levels are near
climatological extremes per SPC sounding climo page and it`s not
much of a stretch to envision today`s highs being very close to
those observed yesterday. Inherited forecast of 114 at Tucson seems
more than reasonable and no major changes appear necessary at this
point. Temperatures through 16Z are lagging by a few degrees
compared to yesterday but either way the dangerously hot temps will
remain in place.

Taking a look at the 00Z NCAR ensemble and SPC SSEO datasets, both
indicate another round of showers and thunderstorm (mainly dry in
nature but could see a few hundredths of an inch from the stronger
storms) across the eastern half of the forecast area later this
afternoon. Guidance suggests that storms may not make it as far west
as what was seen yesterday but still with decent areal coverage.
Made some slight upward adjustments to PoPs this afternoon into
early evening. Biggest concern will be with the potential for
strong/gusty winds in an area littered with wildfires. HRRR-TLE is
suggesting a decent potential for 50kt gusts with any storms that
form and given the extreme dewpoint depressions that will be in
place later today, this seems more than reasonable.

&&

.AVIATION...Valid thru 22/18Z.
FEW-SCT clouds 8-15k ft AGL with isolated to scattered
-TSRA/-SHRA developing mainly east-to-south of KTUS this afternoon.
SFC wind mainly less than 12 kts, though brief gusts to 45 kts are
possible in/near the stronger TSRA. Precip chances will diminish
this evening. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Isolated to scattered thunderstorms will occur
this afternoon, mainly east to south of Tucson. Thunderstorm
outflows will produce brief strong, gusty and erratic winds. Dry
conditions will return area-wide Thursday and Friday. A more typical
monsoonal pattern will develop this weekend, with a few showers and
storms on Saturday, followed by better coverage Sunday and Monday
afternoon and evening. The greatest coverage of thunderstorms will
be mainly east to south of Tucson. In general, 20-foot winds will be
terrain driven at less than 15 mph. The exception will likely be
Thursday afternoon, when gusty northwest winds should prevail,
especially northeast of Tucson and across the Upper Gila River
Valley including Safford.

&&

.PREV DISCUSSION...
Debris cloud cover continues to thin across the area as of 3 am.
Temperatures were as warm as 24 hours but they will still bottom out
well above June normals. Surface dewpoints were mostly in the 40s
with precipitable water values in the 0.75" to 1" range. A little
less convective activity today versus Tuesday with main threat once
again being strong gusty outflow winds which may cause havoc with
ongoing wildfires along with developing areas of blowing dust. Highs
today will be at or slightly cooler than Tuesday.

Atmosphere dries out Thursday and Friday as upper high center
settles right over the area. Further south it will become more
active both days over the Sierra Madres. Thats good thing.

Very hot temperatures will continue thru the weekend where both the
Excessive Heat Warning and Heat Advisory were extended into Sunday.

Models indicating a return of moisture from the east on Sunday as
back door cool front approaches the area. Thus a slight chance of
afternoon and evening showers and thunderstorms mainly east of
Tucson Sunday and Monday. Will see some minor moisture seepage north
from Sonoran storms early next week with deeper moisture possible as
the week progress with the upper high shifting to a position east of
the. High temperatures early next week will gradually cool.

&&

.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 record highs today and Thursday

DATE                      Jun 21     Jun 22
                          RCD/YR     RCD/YR
TUCSON INTL AIRPORT      112/1990   114/1988
BISBEE-DOUGLAS AIRPORT   105/1990   106/1990
AJO                      115/1919   115/1960
FORT THOMAS              109/2005   112/1961
KITT PEAK                 94/1979    92/1988
ORGAN PIPE CACTUS        114/1968   113/1955
PICACHO PEAK             116/2005   113/1988
SAFFORD AG STATION       109/1960   108/1960
SIERRA VISTA FD          103/1990   104/2012
TOMBSTONE                106/1996   109/1929
WILLCOX                  106/1968   106/1990

&&

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

 Excessive Heat Warning until 7 PM MST Sunday for AZZ501>509-515.

&&

$$

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