Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/26/22

Area Forecast Discussion

National Weather Service Phoenix AZ

 459 PM MST Fri Feb 25 2022

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Dry conditons will persist as high pressure builds over the region
through the middle of next next week resulting in a strong warming
trend. Weekend temperatures will rebound back near the seasonal
normals before warming to more than 10 degrees above average by the
middle of next week. While likely remaining below daily records,
readings during the middle of next week should be the warmest for
the region since November.

&&

.DISCUSSION...
Early this afternoon, general cyclonic flow persisted across the SW
Conus situated downstream of an East Pacific high amplitude ridge and
just ahead of a weakening, positively tilted trough moving through
the Great Basin. H5 heights have already rebounded to near 570dm,
and the overall pattern was dislodging the current cold airmass in
place (almost certainly the coldest weather impacting the forecast
area for the next 9+ months). In fact, ACARS soundings have sampled
5C-10C of warming in the H8-H7 layer already this morning which
will be translated through the lower troposphere this afternoon. The
western hemispheric pattern through the middle of next week will be
characterized by a stable high latitude omega block over
Alaska/western Canada, while quasi-zonal flow and dampened extension
of the ridge axis yields above normal heights/thermal profiles over
the SW Conus.

The aforementioned Great Basin will trough will slide through the
CWA over the next 36 hours with little fanfare other than enhancing
surface pressure rises across UT/CO, and resulting in somewhat
elevated winds across the lower Colorado River Valley Saturday.
Thereafter in the first part of next week, heights aloft will
gradually increase albeit with quasi-zonal flow emanating from the
Pacific. While this pattern will allow temperatures to moderate
back into a normal (or slightly above normal) range, periods of
thicker high clouds will be common which may conceivably hinder full
mixing and daytime heating. Nevertheless, spread among NBM members
is very narrow resulting in excellent forecast confidence into the
middle of next week.

More pronounced shortwave ridging will spread into the forecast area
at least briefly during the middle part of next week yielding the
warmest weather for the region in nearly 3 months. The greatest
forecast uncertainties hinge on the magnitude of the midtropospheric
ridge and residence time over the region. Recent EPS and CMC members
are trending towards the warmest ensembles with H5 heights peaking
around 582dm while the majority of GEFS membership paints a picture
of a more dampened ridge. Overall ensemble mean forecasts suggest
height/thermal fields only 1 normalized standard deviation above the
late February climatology (around 90th percentile which still
remains short of daily records); however historically, these spring
warming events more often than not end up well above the mean and
towards the upper end of the ensemble guidance envelop. Thus, there
is good confidence high temperatures will end up 10F-15F above
normal Wednesday and Thursday, with a very slim, but non-zero chance
of nearing record territory (in general, records are low 90s in the
beginning of March). At this time, NBM probabilities of hitting 90F
range from around 15% around Phoenix to a 30-50% range for the
warmer locations of SW AZ/SE CA.

Eventually, ensemble output generally agrees on larger pattern
realignment as the blocking pattern breaks down late in the week.
This should result in one or more dry shortwave troughs passing
through or near our region next weekend. Although NBM shows a much
higher spread in possible temperatures during this period, some form
of a cooling trend is probable depending on the depth of troughing
entering the western Conus.

&&

.AVIATION...Updated at 2355Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will remain light and mostly favor normal diurnal sequences.
Periods of light and variable conditions will also be seen. The
current increase in high cloud cover will culminate with SCT-BKN
decks this evening and then will clear out later tonight. Clear
skies to persist through Sat.

Southeast California/Southwest Arizona including KIPL and KBLH:
Light winds at KIPL will favor a W to NW component through much of
the period, while winds at KBLH favor a N to WNW component. Some
breezy N winds with gusts into the low 20s will begin at KBLH by
mid morning Sat. Otherwise, few to scattered mid and high clouds
this afternoon through the early evening and then clear skies
thereafter.

&&

.FIRE WEATHER...
Sunday through Thursday:
High pressure will begin building across the region over the weekend
and strengthen by the middle of next week. This will result in a
warming trend with temperatures at least 10F above normal. Dry
conditions will prevail through the period with minimum relative
humidity values around 10 to 15 percent. Overnight recovery maximum
values on the order of 30 to 50 percent across eastern districts and
lower values of 20 to 35 percent western sections can be
anticipated. Light winds will generally prevail through the period,
with the exception of the Lower Colorado River Valley where daytime
breeziness can be expected with gusts around 20 mph, especially on
Monday.

&&

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

$$

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DISCUSSION...18/Kuhlman
AVIATION...Sawtelle/Feldkircher
FIRE WEATHER...Kuhlman