Blythe, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

513
FXUS65 KPSR 150811
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
110 AM MST Tue Apr 15 2025

.SYNOPSIS...
Weakening high pressure will continue to yield above normal
temperatures the next couple days, however a weather disturbance
will move across the region during the latter half of the week
causing readings to briefly fall into a below normal range. This
system will also result in slight chances for light rainfall Friday
and Saturday. As this system exits the region by early next week,
temperatures will quickly rebound back towards the seasonal normal.

&&

.DISCUSSION...
Early morning WV imagery and objective analysis depicts an expansive
cutoff low spinning off the California coast forming a quasi-Rex
block across the eastern Pacific. In advance of this feature,
individual vorticity centers within a subtropical jet have entrained
midtropospheric moisture and steep lapse rates spreading into the SW
Conus while also producing widespread virga. Models are in good
agreement showing a period of shortwave ridging enveloping the
forecast area today yielding a reprieve from more extensive cloud
cover and virga. However, there remains very good confidence that
the northern stream blocking ridge will retrograde towards the
central Pacific over the next 48-60 hours while the cutoff feature
phases with a deep negative PV anomaly digging south from the
northern Rockies to form a mean longwave troughing over the western
Conus during the latter half of the week.

Although there is excellent ensemble agreement with respect to this
trough development, there remains sufficient uncertainty among model
suites to the degree of phasing and magnitude of PV and midlevel
cold core that descends into the forecast area. CMC membership
remains the least aggressive modeling suite in pulling deeper PV
into the SW Conus and maintaining an elongated weaker trough. A
large preponderance of GEFS members pull much stronger vorticity
equatorward with a more intense cold core at least propagating into
northern Arizona. EPS members are more dispersive, but generally
favoring a GEFS flavor of more readily tapping northern stream PV.
At this time, the forecast favors a GEFS/EPS blend which is not too
dissimilar from their respective deterministic output.

While height falls should only gradually spread into the CWA,
seasonally deep mixing depths juxtaposed with the approaching
shortwaves will encourage breezy afternoon conditions during the
middle and latter half of the week supporting a somewhat elevated
fire danger. However, cooling temperatures and increased moisture
intrusion should limit this threat in time and space. Otherwise,
recent models indicate only modest moisture advection into this
system with low level mixing ratios reaching near 5-6 g/kg.
Depending on the depth of the cold core and presence of any
vorticity lobes rotating south through the larger circulation
center, a few showers may affect some portions of the CWA Friday and
Saturday. Based on pattern recognition, showers would be preferred
in orographic upslope areas north of Phoenix Friday afternoon ahead
of the incoming PV anomaly and along a decaying cold front where
dynamic ascent is maximized. Lower elevation showers would be likely
Saturday afternoon as a notable vorticity lobe rotating on the
western periphery of the trough taps the colder midlevel
temperatures and squeezes out modest moisture in a marginally
unstable environment. Based on the overall scenario, feel the
mandated NBM POPs Friday were too high and too expansive while
Saturday POPs were too restrictive; and made some modest adjustment
to grids to account for this model analysis.

By the end of the weekend, the entire trough structure will have
moved into the southern Rockies/plains with a quasi-zonal flow/flat
ridging regime in its wake over the forecast area. H5 heights should
quickly rebound, however likely stagnating around 572dm through the
first half of next week. As such, confidence is very good that
temperatures 5F-10F below normal during the end of this week will
warm much closer to the seasonal normal early next week under dry,
tranquil conditions.

&&

.AVIATION...Updated at 0540Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds have been generally light and variable or E for the last few
hours, but Hi-Res guidance and TDWR radial velocities indicate a
boundary moving across the Phoenix Area late this evening, which
will tend to shift/increase winds out of the SW/W. Between 08-10Z,
after the last of the scattered virga showers move north of the
area, winds should settle out of the E/SE, and skies will clear. For
Tuesday, winds return to a more typical diurnal pattern, with a
period of a southerly cross-runway component at KPHX and KDVT late
morning into the afternoon before shifting SW. Wind speeds should
remain mostly AOB 10 kts through the TAF period, though afternoon
and early evening gusts into the mid to upper teens will likely
develop Tuesday.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Tuesday evening under
mostly clear skies. Winds will relax to AOB 5 kts during the
overnight hours and remain light with periods of variability through
much of Tuesday morning. Directions will favor S/SE during the
daytime and shift SSW/SW Tuesday evening at both terminals.

&&

.FIRE WEATHER...
Above normal temperatures the next couple days will cool to below
normal levels during the latter half of the week as a weather system
moves through the region.  This system will yield gusty afternoon
winds coincident with seasonally low humidity values resulting in an
elevated fire danger during the middle of the week. However, cooling
temperatures and a modest increase in moisture associated with this
system will allow humidity levels to gradually increase throughout
the week precluding widespread critical thresholds. In general,
minimum afternoon humidity levels in the teens will be common
through Wednesday with values increasing closer to a 20-30% range
during the latter half of the week. By early next week, warming
temperatures and lowering RH values will return to the districts.

&&

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

&&

$$

DISCUSSION...18
AVIATION...Whittock
FIRE WEATHER...18