910
FXUS65 KTWC 192150
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
250 PM MST Wed Jun 19 2024

.SYNOPSIS...Hot temperatures Thursday with an Excessive Heat
Warning in effect for portions of southeast Arizona. Moisture will
increase Thursday resulting in the potential for thunderstorms each
day into next week week. Windy conditions are also expected Thursday
into Friday. The added moisture will also result in temperatures
dropping back down to more seasonable levels.

&&

.DISCUSSION...Clear skies and warm conditions across southeast
Arizona this afternoon with high temperatures topping out a few
degrees above normal.

The weather pattern is going to be undergoing significant change
over the next couple of days as monsoonal moisture significantly
ramps up. This moisture will be brought in on strong east to
southeast winds. The leading edge of this push of moisture is now
moving west across southern New Mexico and will be on our doorstep
later this evening. Once this east push moves in tonight, the
surface pressure gradient will tighten with gusty easterly winds
after midnight for Graham/Greenlee/Cochise Counties. These winds
will then increase above advisory thresholds for the Upper Gila
River Valley and portions of eastern Cochise County where a Wind
Advisory remains in effect from Thursday morning into Friday
morning. As the day progresses Thursday, those easterly winds will
push west into east central Pima County, with sustained surface
winds (outside of the Wind Advisory area) of 15 to 25 mph with gusts
up to around 35 mph.

Meanwhile, moisture levels will increase Thursday as PWAT values
will be mostly in the 1 to 1.4 inch range. HREF/CAMS are now
consistent in showing a north to south line of showers/thunderstorms
developing Thursday afternoon from around Nogales northward through
Tucson into eastern Pinal County. This is along an area of lower
level convergence between the aforementioned east winds and lower
level west to southwest upslope flow that prevails over the western
deserts. Main concerns are strong gusty outflow winds and blowing
dust. Rainfall amounts will be light as thunderstorms will tend to
be a hybrid of dry and wet thunderstorms. Temperatures Thursday will
be the warmest of the period and an Excessive Heat Warning is in
effect from Tucson westward. There is greater than normal
uncertainty for high temperatures though as earlier convective
development could keep temperatures from reaching the full
potential.

For Friday, gusty east to southeast winds will prevail across the
entire forecast area. A few locales such as the Tucson area and
around Safford will have wind speeds near advisory thresholds on
Friday, before winds finally diminish Friday night. With moisture in
place Friday as PWAT values range from 1 to 1.5 inches, scattered
mainly afternoon and evening showers and thunderstorms are expected.
Temperatures still several degrees above normal out west Friday,
near normal for Tucson and several degrees below normal east of
Tucson.

For this weekend into next week, the monsoon moisture is here and
not going anywhere. This will mean that each day will have varying
levels of convective activity and will mostly be driven by the
mid/upper level high placement and flow pattern each day along with
smaller scale trends. Overall though, a low to mid grade monsoon
pattern during this time and certainly above normal for the last
week of June. There are some indications in the ensembles of the
high trying to strengthen a bit around the middle of next week which
could limit convection and increase temperatures but plenty of time
to see how that plays out.

&&

.AVIATION...Valid through 21/00Z.
SKC through 20/18Z, then SCT-BKN clouds 10-14k ft AGL developing,
especially from KTUS/KOLS eastward. Isolated to scattered SHRA/TSRA
are also expected Thursday afternoon with gusty outflow winds from
the storms in excess of 35-40 kts. SFC winds SWLY into this evening
at 10-15 kts with gusts to 25 kts. After 20/06Z, winds increase and
become SELY at 15-25 kts with gusts to 35 kts across much of the
forecast area and persist through the day Thursday. Even stronger
winds anticipated near KSAD and KDUG with gusts 35 to 40 kts in
these locales. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Temperatures are expected to peak Thursday from
Tucson westward, then more seasonable temperatures thereafter.
Starting late tonight, surface winds turn to the east to southeast
and become stronger, especially across Graham/Greenlee/Cochise
Counties where sustained 20-ft winds of 20 to 35 mph are expected
with stronger gusts. The strongest of these winds will be in the
Upper Gila River Valley near Safford as well as near Douglas along
the International and NM borders. With these east to southeast
winds, there will be increased moisture with min RH values in these
locales around 20 percent Thursday. So while the winds are at
critical levels, RH values will remain just above critical levels
but certainly still elevated fire weather conditions due to the
strong winds and dry fuels Thursday. Breezy to windy conditions
continue Friday, though increased moisture will have overspread more
of the forecast area. A mixture of dry/wet isolated to scattered are
expected starting Thursday afternoon from Tucson eastward and then
to include the remainder of southeast Arizona Friday. As moisture
remains this weekend, isolated to scattered thunderstorms will
continue each day through the weekend into early next week with a
low to mid grade monsoon pattern in place.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Warning from 10 AM to 8 PM MST Thursday for
AZZ501>506.

Wind Advisory from 5 AM Thursday to 5 AM MST Friday for AZZ508-
509.

&&

$$


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