Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/16/21
Area Forecast Discussion
National Weather Service Phoenix AZ
448 PM MST Fri Oct 15 2021
Updated 00Z Aviation discussion.
High pressure over the region will yield mostly clear skies and
quite seasonable temperatures through the weekend though
periodically breezy conditions will be common through south-central
Arizona. A weak cold front will result in somewhat cooler
temperatures Monday and Tuesday, however subtle warming will resume
Wednesday and Thursday. Dry weather is expected through the end of
A progressive pattern will continue through early next week with
modest ridging building into the SW Conus. Marked height and thermal
increases have already been evident per objective analysis and ACARS
in-situ sampling with better than 5C warming in the H7-H5 layer.
Correspondingly, surface temperatures have warmed and forecast
afternoon highs will push back very near the seasonal normal through
the weekend (and some 10F-15F warmer than the past several days).
However, the increased ridging pattern has resulted in stronger
surface pressure rises over the Great Basin; and combined with the
seasonally typical Gulf of California thermal low pressure, breezy
east to northeast boundary layer winds will be common through much
of central AZ. Nocturnal breezy conditions will be most evident over
ridge tops, however should readily descend into lower elevations
Saturday with mid/late morning mechanical mixing yielding gusts 20-
30 mph through much of region surrounding the Phoenix metro.
Early next week, a strong yet compact negative PV anomaly will
propagate from the northern CA coast into the Great Basin dragging a
weakening cold front inland. While mid and upper tropospheric winds
strengthen, moisture along the frontal boundary should be extremely
shallow and scoured along the California coast range leaving only
residual cirrus streaming into the forecast area. Little ensemble
spread has been exhibited with this system remaining well north of
the CWA and forecast confidence is excellent that notable impacts
from this system will primarily be limited to breezy conditions over
SW Imperial County. Wind anomalies associated with this system do
not appear to be resounding, so merely just some typical afternoon
breeziness for the majority of the area looks valid. Otherwise,
temperatures will cool only a few degrees behind the decaying front,
but quickly rebound during the second half of the week as the next
shortwave ridge moves over the region.
.AVIATION...Updated at 2348Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Strong surface high pressure centered over the 4-corners region will
keep winds from an easterly to northeasterly direction through the
TAF period. It now appears that light northeasterly winds (with a
bit of gustiness for the next couple of hours) will continue through
the afternoon/evening overnight hours at all of the PHX area
terminals. In addition, winds in the lower levels above the surface
will strengthen towards morning (as high as 40 kts at 020 AGL).
Thus, have now included LLWS in the TAFs during the early morning
hours. Breezy easterly surface winds develop by 16Z or so on
Saturday with gusts to 20kts (locally higher at times). These
easterly winds are expected to diminish somewhat by Sat afternoon as
low-level pressure gradients begin to relax. skies to remain CLR
through the TAF period.
Southeast California/Southwest Arizona including KIPL and KBLH:
Strong surface high pressure centered over eastern Utah will drive
northeasterly winds in the lower troposphere through the rest of the
afternoon, with a trend toward east tonight and southeast on
Saturday. Surface winds will favor a northwest-west direction at KIPL
and a northerly direction at KBLH through the TAF period. skies to
remain CLR through the TAF period.
Sunday through Thursday:
High pressure and dry conditions are likely to prevail across the
region through the period with temperatures near seasonal normals
on Sunday falling to slightly below normal by mid-week. Locally
breezy conditions will be possible on Sunday and morning in
southeast California and the lower Colorado River Valley as a dry
storm system moves across the Southwest. Min afternoon RH values
will mostly fall between 10-15% across the lower deserts to 20-25%
across the high terrain. Overnight recoveries will mostly reach
between 25-45% through the period.
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.