093
FXUS65 KPSR 210515
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1015 PM MST Wed Nov 20 2024

.SYNOPSIS...
High pressure will continue to build over the region through
tomorrow leading to a quick warmup and above normal temperatures
Thursday and into this weekend. Dry conditions are expected to
continue into the weekend with periods of higher level clouds,
especially by Sunday. Mostly cloudy skies, cooler temperatures, and
chances for light higher terrain precipitation are then forecast
early next week.

&&

.DISCUSSION...
The latest objective analysis showed an upper level ridge in place
over the Desert Southwest promoting dry, tranquil conditions with
mostly clear skies across the region. This ridge will continue to
build over the region through tomorrow as a deep upper level low
continues spin off the Pacific Northwest coast. Heights will
continue to rise over the region through tomorrow with ensemble
guidance showing 500 mb heights increasing to around 585-587 dm,
which is in excess of the 90th climatological percentile for this
time of year. Temperatures will respond with daytime highs warming
into the upper 70s to low 80s across the lower deserts for Thursday
and Friday, which is around 4-9 degrees above seasonal normals. The
deep trough to our northwest is expected to sag a bit farther to the
southeast into the weekend, gradually nudging the upper level ridge
over our region back to the south. Temperatures Saturday are still
expected to be several degrees above normal, but by Sunday we will
begin a cooling trend.

Guidance continue to indicate an AR event for the West Coast before
extending further inland this weekend into the beginning of next
week. This AR will weaken as it approaches the southwest CONUS with
ensemble guidance showing inland IVT values around 200-300 kg/ms,
which is in excess of the 90th percentile. Forecast soundings show
the best moisture remaining confined to the mid to upper levels of
the troposphere with a lack of good boundary layer moisture. The
increase in moisture is evident in both the EPS and GEFS, which show
PWAT anomalies increasing to upwards of 150-200% over our area
starting Sunday. Despite the increase in moisture over the region,
the lack of good boundary layer moisture along with the lack of
forcing, aside from some upslope/orographic influences, will hinder
rainfall potential across the area with NBM PoPs less than 10%
across the CWA. Unless something changes to provide some sort of
decent lifting mechanism, all we will likely see early next week is
cloudy skies and temperatures returning to around normal.

&&

.AVIATION...Updated at 0515Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No major weather concerns will exist through Thursday night under
some occasional passing high cirrus decks. Trends in wind directions
and speeds will be very similar to the past 24 hours with prolonged
periods of nearly calm conditions common.

&&

.FIRE WEATHER...
High pressure will build across the region over the next couple of
days leading to a decent warmup and temperatures slightly above
normal by Thursday. Even drier conditions are expected with MinRHs
dropping to around 10% across the lower deserts to 15% in higher
terrain areas. Light winds are expected over the next several days
with only some periodic light breezes mainly during the morning
hours and focused along ridgetops. Over the weekend into early next
week, moisture levels will increase as high pressure weakens and
temperatures gradually cool back into the normal range.

&&

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

&&

$$

DISCUSSION...Smith/Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman