Tempe, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

179
FXUS65 KPSR 141758
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1058 AM MST Thu Aug 14 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Increased moisture will result in better shower and thunderstorm
  chances through at least Friday with gusty winds, blowing dust,
  and lightning the greatest threats.

- Rainfall chances decrease substantially over the weekend with
  storms primarily relegated to higher terrain areas of central
  and eastern Arizona.

- Temperatures will drop into the seasonal normal range by Friday
  and stay there through the weekend before readings rebound back
  above normal by the middle of next week.

&&

.SHORT TERM /Today through Friday/...
Radar imagery early this morning shows diminishing shower activity
with some light showers over the high country and showers
associated with an newly formed MCV near Tucson. Moisture has
improved over the past 24 hours with PWATs now mostly between
1.0-1.2" with better quality moisture situated just to our south
across Sonora Mexico. For the rest of tonight, we may still see
some isolated showers, but overall activity should be minimal.
The MCV may help to kick off some additional activity mainly
across Pinal County by sunrise, but the latest CAMs are barely
picking up on this potential.

Even with the improving moisture today, the convection that
affected portions of the region yesterday may somewhat hinder
development this afternoon and evening. NBM PoPs continue to run
hot, especially given the lack of expansive convection shown by
the CAMs for today. We have again dialed back PoPs from the NBM
showing the best chances this evening with PoPs around 30% across
the south-central Arizona lower deserts to upwards of 50-60% over
the high terrain east of Phoenix. Model soundings do show less
convective inhibition today compared to yesterday, largely due to
the improved moisture profile. However, the steering flow will be
switching to a light southwesterly by this afternoon which makes
it more difficult for convection to reach the lower deserts. The
best time frame for showers and storms today will likely be during
the late afternoon/early evening for the higher terrain and more
into the mid evening hours for the south-central Arizona lower
deserts. The potential for strong winds later today is expected to
be less than what we saw yesterday due to a marginal reduction in
DCAPE, but there should still be an overall 20-40% probability of
seeing 35+ mph winds.

Moisture advection will then continue tonight into Friday with
guidance now showing peak PWATs between 1.4-1.6" over south-
central Arizona on Friday. Low level mixing ratios are also shown
to increase to a more respectable 11 g/kg on Friday as
southwesterly flow increases due to the Pacific trough moving into
southern California. Despite the less than ideal southwesterly
steering flow on Friday, weak upper level difluence and
potentially some vorticity forced ascent associated with the
trough should aid in shower and thunderstorm development by Friday
afternoon. Forecast soundings also look quite good for Friday
afternoon with little to no convective inhibition and MUCAPE
of 1000-1500 J/kg. NBM PoPs for Friday seem a bit more reasonable,
but still too high as we have cut them back to 40-60% across the
south-central Arizona lower deserts to 60-75% over the higher
terrain. Friday should also see a better shot at a few strong to
severe storms given the higher expected instability and at least
some marginal shear. Localized rainfall amounts upwards of an inch
will also be possible, but given the 10-15 kts of southwesterly
steering flow the potential for flooding should again be very
minimal.

Temperatures over the next couple of days will also be trending
lower, but highs today may still reach to around 110 degrees
across the western deserts to more like 104-108 degrees in the
Phoenix area. Even more improvement is expected on Friday with
highs falling back into the normal range, or between 103-106
degrees.

&&

.LONG TERM /Saturday through Wednesday/...
By Saturday the Pacific trough, which is expected to remain
fairly stationary just to our northwest, will usher in drier air
into our area from west to east. This dry air will first move in
aloft early Saturday and then mix down into the boundary layer
Saturday afternoon. The lingering boundary layer moisture should
be enough to spark off some afternoon convection over higher
terrain areas (20-40% PoPs), but for the south-central Arizona
lower deserts chances will be at most 10-15%. The dry air
advection will persist through the rest of the weekend with PWATs
dropping to below 1.0" again on Sunday. This will end any rain
chances across the lower deserts leaving only very minimal chances
of 10-20% over the far eastern high terrain through Monday.

The influence of the Pacific trough will help to keep temperatures
near normal through the weekend with highs mostly between 102-105
degrees across the lower deserts. We will also see noticeably
cooler overnight temperatures as lows fall back into the 70s
across the western deserts to around 80 or the lower 80s in the
Phoenix area for Sunday and Monday mornings.

The weather pattern will begin to shift again beginning early next
week as the subtropical highs shifts westward into our region by
next Tuesday. Ensemble guidance shows the ridge center
strengthening during this time before reaching its peak at some
point mid to late next week. This will likely bring H5 heights of
595-597dm back into our area by the middle of next week resulting
in highs warming back to around 110 degrees by next Tuesday or
Wednesday. Overnight lows will also begin to warm, but with low
level moisture remaining on the lower side readings should stay
near or just above normal into mid week. Depending on the eventual
strength of the ridge, we may end up seeing some localized Major
HeatRisk again later next week. Although still fairly uncertain,
models do show some moisture beginning to return back into the
region late next week into the following weekend.

&&

.AVIATION...Updated at 1758Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The greatest weather concern will be the chance of returning
thunderstorms late this evening from outflows. The outflows may
also interfere with routine wind shifts late tonight. There is a
low probability (~30%) of thunderstorms redeveloping across the
terminals that could see gusts near 15-25 kts starting late this
evening. Confidence is low, but expect initial VCSH around 01Z
with winds 10-15kts (with higher gusts) out of the west-
southwest. Around the 06Z timeframe winds are expected to shift
out of the east-southeast with BKN ceilings at around 12kft with
periods of VCTS (06-09Z).


Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through the forecast period
with mostly clear skies expected. Winds will follow a near
persistence forecast with directions varying between SE and SW and
gusts around 25kt common at KBLH.

&&

.FIRE WEATHER...
Thunderstorm chances will remain elevated over the eastern
districts through Friday with moderate chances of wetting
rainfall, particularly over higher terrain of Gila County. Abrupt
wind shifts with gusty outflows will be common with any storms.
Temperatures will slowly cool closer to the seasonal normal
through Friday, and in combination with better moisture profiles,
afternoon humidity levels should improve closer to a 20-30% range
in eastern districts, but remain 10-20% in western areas.
Overnight recovery will vary widely across the area from 30% to
80%. Drier air will usher back into the area over the weekend
mostly ending rain chances except for far eastern Arizona. MinRHs
will eventually lower to closer to 10-15% by next Monday.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Ryan/95
FIRE WEATHER...Kuhlman