Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 121700
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1000 AM MST Mon Apr 12 2021

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Dry conditions will remain across the region this week, but the
influence of a weather disturbance north of the area will result in
a slow decline in temperatures through Thursday. Breezy to locally
windy conditions are forecast for Tuesday with locally daytime
breezy conditions through the rest of the week. Increasing high
pressure should then turn temperatures gradually warmer heading into
the weekend, likely topping 90 degrees again as early as Saturday.

&&

.DISCUSSION...
A weak shortwave trough currently tracking eastward across Arizona
will exit to the east by this afternoon allowing skies to clear from
west to east throughout the rest of the morning. Additionally, a
pattern shift will begin today as a shortwave trough is seen digging
southward into the Pacific NW later today. This will allow for a
westward expansion of a large scale trough currently seen across
much of the North-Central U.S. into the Great Lakes.

As the trough to our north slowly shifts southward into the Great
Basin during the middle part of the week, heights aloft across the
Desert Southwest will gradually lower resulting in modestly cooler
conditions. Highs are forecast to drop into the mid to upper 80s
starting Wednesday, likely lasting through Friday. The approaching
trough will also cause an increase in height packing across our
region, thus leading to stronger winds for Tuesday into Wednesday.
Winds Tuesday look to be the strongest with widespread gusts into a
20-30 mph range with locally higher gusts across southeast
California. Winds Wednesday do look to fall off somewhat with gusts
mostly ranging between 20-25 mph.

Model ensembles remain in good agreement showing the quasi-
stationary trough north of our region weakening and likely ejecting
some of its energy eastward on Friday. Another piece is likely to
hang out across the Great Basin before potentially tracking
southeastward through Arizona this weekend. Dry conditions are still
heavily favored during this period, while temperatures are more than
likely going to be trending warmer Friday into the weekend. The
lingering trough should keep temperatures from rising much, but
eventually an upper level ridge is likely to overtake the region at
some point early next week. This transition to higher heights is
likely to push daytime highs back into the lower 90s by Sunday and
potentially into the mid to upper 90s later next week if the ridge
does end up settling over our region.

&&

.AVIATION...Updated at 1700Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No notable weather issues should exist through Tuesday afternoon
under mostly clear skies. A period of light southerly cross runway
winds are likely early this afternoon as a slow shift to the
traditional westerly component occurs. Any gusts should be limited
in time and magnitude. West winds may hold on slightly longer
tonight, and the morning easterly direction may short lived only
into mid/late Tuesday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather impacts should occur through Tuesday afternoon
under mostly clear skies. Light and variable winds early this
afternoon should become southerly, then SW by late afternoon and
evening. A brief period of sundowner wind gusts may be possible at
KIPL though confidence is low.

&&

.FIRE WEATHER...
Wednesday through Sunday:
Near normal temperatures are expected during the middle of the week,
but should gradually warm back up to the low 90s area wide by
Sunday. Afternoon breeziness will be common with the typical upslope
favored areas experiencing the strongest gusts. Stronger winds will
be likely during the middle of the week yielding a period of
elevated fire danger, primarily Wednesday. Dry conditions will also
prevail through the week with afternoon minimum humidity values
falling to near 10% while overnight recovery will be poor only
bouncing back to a 25-40% range.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

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

&&

$$

DISCUSSION...Kuhlman
AVIATION...MO
FIRE WEATHER...Benedict/Kuhlman


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