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123
FXUS65 KPSR 191803
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1103 AM MST Thu Sep 19 2024

.UPDATE...
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Updated Aviation Discussion.
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&&

.SYNOPSIS...
Warming temperatures will continue today, prior to a brief cooling
trend going into the weekend. Temperatures will warm once again,
with lower desert highs exceeding 100 degrees, going into next
week. Dry conditions will persist, with some increased breeziness
developing across the region today and tomorrow. Otherwise, quiet
weather conditions continue through the middle of next week.

&&

.DISCUSSION...
Early morning satellite shows an enhanced mid-level moisture
plume cutting across southeastern Arizona, resulting in some
scattered clouds south and east of the forecast area. This
development is due to enhanced southwest flow as ridging across
central Mexico combines with the digging longwave trough currently
centered over the southern California coast. Negative height
anomalies will continue to persist over the Desert Southwest as
this trough continues to dig southeastward over the next couple of
days, resulting in temperatures at or below normal through
Saturday.

Winds will noticeably strengthen across the region over the next
couple of days, first across western Imperial County. As the
aforementioned trough continues to dig, stronger upper level winds
will traverse across southern California, with favored higher
terrain areas gusting 30-40 mph and portions of the Imperial
Valley gusting 20-30 mph this evening and tonight. Breezier winds
will then spread eastward tomorrow into southcentral Arizona, with
the most noticeable gustiness in the higher terrain areas of Gila
County of 20-30 mph. Wind impacts will be of lesser impact for
this system due to the deeper amplification of this trough,
pushing the strongest winds for this system into southern to
southeastern Arizona for tomorrow.

This trough will continue to progress eastward through Saturday,
with continued cooler temperatures. However, the mid-level weather
pattern will transition from troughing across the Desert Southwest
to a highly amplified ridging pattern, with the strongest height
anomalies setting up across the Pacific Northwest by early next
week. There remains discernible discrepancies on the progression
of the weakening trough and continued neutral to negative height
anomalies hanging on across the region going through early next
week. However, by mid-week, cluster analysis shows a pretty
consistent picture that the highly amplified ridge looks to be
more centered over the region. Thus, the main uncertainties in the
forecast at this point will be how quickly temperatures will warm
across the region, with latest forecast showing highs reaching
above 100 degrees once again no later than Monday, with continued
warming through mid-week, with lower desert highs of 100-105
degrees continuing into the latter portions of the week. Dry
conditions will persist, thus this warming trend will result in
above normal temperatures for most or all of next week.

&&

.AVIATION...
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Updated at 1803Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Persistence wind forecast is expected again for the next 24
hours. Southerly winds, with SW-SE variability, are expected to
develop by midday and persist through 00-01Z before a more
predominant west to southwest component develops. Diurnal
easterlies then return tonight. Daytime wind speeds will be around
7-10 kts with afternoon gusts occasionally up to 15-20 kts. FEW
to SCT cumulus will be common through the TAF period with varying
bases between 6-10K ft AGL (lowest overnight and highest in the
afternoon)

Southeast California/Southwest Arizona including KIPL and KBLH:
A period of variability this morning will be followed by SE winds
at KIPL and S at KBLH. Between 00-02Z, winds will shift W at KIPL,
with gusts up to 20-25 kt during the evening and into the
overnight hours. Speeds will mostly be in the 6-10 kt range at
KBLH. Skies will remain mostly clear. FEW cumulus are expected at
KBLH this afternoon, becoming FEW to SCT by late Friday morning.
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&&

.FIRE WEATHER...
A drier and cooler airmass encompassing the region will result in
below normal temperatures through Saturday. Stronger southerly to
southwesterly will develop this afternoon, with gusts to 20-25
mph expected today and tomorrow. MinRH`s will hover around 15-25%
region-wide over the next couple of days, with some slight drying
first across the western districts starting Saturday and spreading
eastward on Sunday, with MinRH`s more in the 10-20% range by the
beginning of next week. Overnight RH recoveries will be fair to
good across the region over the next couple of mornings, before
degrading to generally fair to poor in spots going into next week.
Warming temperatures to above normal are expected to develop late
this weekend and persist through most of next week.

&&

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

$$

DISCUSSION...Young
AVIATION...Benedict
FIRE WEATHER...Young