Area Forecast Discussion
Issued by NWS Tucson, AZ

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FXUS65 KTWC 221020

Area Forecast Discussion
National Weather Service Tucson AZ
320 AM MST Thur Jun 22 2017

.SYNOPSIS...Expect very hot and near record temperatures into this
weekend. Dry conditions will prevail Thursday into Friday, then a
more favorable pattern will provide scattered afternoon and evening
thunderstorms especially by Sunday and continuing into the middle of
next week.


.DISCUSSION...IR satellite imagery indicated scattered debris
cloudiness across southeast Arizona this morning. As such, surface
temperatures were still quite warm, as much as 5 degrees warmer than
24 hours ago in some locations.

Drier air aloft moves in today through Saturday along with a slight
moderation in daytime high temperatures. Even so, highs will be
above normal and dangerously hot, with the Excessive Heat headlines
remaining in place through Sunday evening. Another concern for this
afternoon will be gusty NW winds in the Upper Gila River Valley
including Safford. MOS guidances over the last 24 hours have trended
upward with regard to wind speeds, but the inclination is that the
numbers are a bit overdone. However, wind speeds may cross the
threshold to create critical fire weather conditions. Even so,
decided against issuing a Red Flag Warning as conditions will be
likely be very localized and short-lived. Please see the Fire
Weather section below for more details.

Dry conditions continue Friday into Saturday morning, with some
isolated showers and thunderstorms possible over the mountains along
the AZ/NM border on Saturday afternoon. Sunday into next week, high
pressure migrates to a much more favorable location to draw deeper
moisture into the region from the south. With that, we`ll see a
decrease in chances for dry lightning and an increase in convection
producing measurable rainfall, especially as we get into Monday and
Tuesday. The official forecast calls for isolated to scattered
showers and storms mainly from Tucson eastward to the AZ/NM border
starting Sunday and continuing each day next week through Thursday.
As per usual, the best precip chances will be across the higher
elevations including the White and the Chiricahua Mountains.

As expected, it usually takes a long stretch of very hot
temperatures to kick-start the monsoon, and we should see exactly
that happen over the week. Additionally, we`ll get a well-deserved
break from the extreme heat, with highs dipping below warning and
advisory criteria on Monday/Tuesday and dropping even further to
near-normal by next Wednesday/Thursday.


.AVIATION...Valid thru 23/12Z.
SCT 10k-15k ft AGL thru pd. Surface wind less than 10 kts thru
23/18z then bcmg nwly 10-25 kts with gusts 25-35 kts. The strongest
speeds will be northeast of KTUS and especially near KSAD. Aviation
discussion not updated for TAF amendments.


.FIRE WEATHER...Dry conditions will prevail today and Friday and
across much of the area Saturday. The exception is near the New
Mexico border where a slight chance of thunderstorms may occur.

Thereafter, a favorable pattern for thunderstorm development will
return Sunday and continue into the middle of next week. Scattered
afternoon and evening thunderstorms should prevail, especially east
to south of Tucson. However, the coverage of thunderstorms Monday
into Tuesday should expand further west to also encompass Fire Zone
150 west of Tucson.

Otherwise, 20-foot winds will generally be terrain driven less than
15 mph. The exception is this afternoon and evening, when gusty
northwest winds should occur, especially northeast of Tucson and
across the Upper Gila River Valley including Safford. The
combination of the gusty winds and minimum relative humidity of 5 to
10 percent may create critical fire weather conditions in the
northern portion of Fire Zone 152 late this afternoon. However,
these conditions are not expected at this time to be long-lived.



Daily record highs Thursday

                         June 22

AJO                      115/1960
FORT THOMAS              112/1961
KITT PEAK                 92/1988
ORGAN PIPE CACTUS        113/1955
PICACHO PEAK             113/1988
SAFFORD AG STATION       108/1960
SIERRA VISTA FD          104/2012
TOMBSTONE                109/1929
WILLCOX                  106/1990


 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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