Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/16/23
Area Forecast Discussion
National Weather Service Phoenix AZ
417 PM MST Sun Oct 15 2023
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
Well above normal and near record high temperatures are the primary
weather impacts this week as dry conditions persist. Little relief
from these abnormally warm readings will occur until late in
the weekend or early next week at the earliest.
&&
.DISCUSSION...
High pressure ridging has grown in magnitude and amplitude over the
SW Conus in the past 24 hours with objective analysis indicating H5
heights near 590dm centered directly over south-central AZ this
afternoon. In situ ACARS sounding data has sampled substantial
warming through the majority of the troposphere resulting in
afternoon highs some 3F-6F warmer than yesterday and 5F-10F above
the daily normal. In fact, many communities around the Phoenix metro
will once again be flirting with 100F today. Ridging will continue
to strengthen Monday with excellent ensemble agreement that
widespread lower elevation 100F+ readings will be attained and at
least a 75% chance of KPHX reaching or exceeding the daily record.
During the middle of the week, a weak trough will progress from the
Pacific NW through the Intermountain West before digging into the
mean longwave trough position across the eastern Conus. Ensemble
trends continue to indicate this trough considerably weaker as
compared to previous iterations with more resolute ridging holding
in place over the Southwest. In fact, now the preponderance of
evidence suggests H5 heights barely falling below 588dm, then
quickly rebounding above 590dm during the latter half of the week
under another very strong high pressure system. Consequently, it
should come as no surprise seeing temperature trends for this period
remaining warmer with very little cooling through the remainder of
the week. Thus, numerical guidance spreads have narrowed with many
lower desert communities still nearing the 100F threshold heading
into the weekend.
This strong ridging with heights in excess of 590dm will persist
into the weekend with a Pacific trough beginning to impinge on
the ridge axis causing a gradual erosion of higher heights.
Temperatures should make a more noticeable downtrend into next week,
however there is rather substantial ensemble spread with respect to
the timing and magnitude of height falls into the Southwest. With
the hemispheric pattern in a retrogressive phase and pointing
towards blocking becoming repositioned over the north-central
Pacific, some form of East Pacific/western Conus longwave troughing
should be established. However, the orientation of these features is
highly uncertain, and while favoring much cooler temperatures beyond
the official 7-day forecast, the chances to enter a wetter period
are not necessarily guaranteed.
&&
.AVIATION...Updated at 2317Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns are expected through the TAF period
as dry, tranquil conditions persist. Winds will generally follow
light, diurnal tendencies with variable winds expected at times
throughout the period. Easterly winds will increase Monday morning
around 16Z at the terminals with a few gusts upwards of around 15
kts possible before weakening by around noon. Confidence is
currently low in a westerly shift tomorrow afternoon with
directions potentially remaining variable in nature. Otherwise,
clear skies will continue.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected through the next 24
hours as dry, tranquil conditions continue. Light winds will favor
the W to NNW at KIPL and N at KBLH through the period. Otherwise,
clear skies will continue.
&&
.FIRE WEATHER...
Dry conditions will persist through the week as wetting rainfall
chances continue to be absent from the forecast. Temperatures will
hover in a much above normal category this week with readings around
10F greater than the seasonal average. Minimum afternoon humidity
values will generally range between 15-25% across the high terrain
of far eastern districts, but only 10-15% elsewhere with periods of
single digit humidities likely. Overnight recoveries will mostly be
poor to fair at only 20-40%. Winds will mostly remain light with
only limited afternoon upslope gusts.
&&
.CLIMATE...
Record high temperatures early this week:
Date Phoenix Yuma El Centro
---- ------- ---- ---------
Oct 15 103 in 1991 105 in 1958 103 in 1991
Oct 16 102 in 2020 106 in 1958 103 in 1958
Oct 17 102 in 2009 104 in 1959 102 in 2009
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...18/Young
AVIATION...Smith
FIRE WEATHER...18/Young
CLIMATE...18