Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 280939
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
240 AM MST Wed Jun 28 2017

.Update...Aviation and Fire Weather Discussions.

$$

.SYNOPSIS...
A dry airmass will remain over the region through the rest of the
week with temperatures moderating closer to average. Though high
temperatures will finally drop below 110 degrees, readings will
still end up in a slightly above normal range through early next
week. Skies will remain mostly clear as the monsoon wind pattern
has yet to be established and storm activity will stay well south
across Mexico.

&&

.DISCUSSION...
Large scale troughing edging southward across the Pacific
Northwest and the Great Basin has allowed for a significant drop
in 500mb heights from 592dm yesterday to around 588dm currently.
The slight cooling over the past couple days will continue today
with highs over most lower desert spots dropping below 110
degrees. The dry air that has already overtaken the region will
likely persist through the rest of the week resulting in good
nocturnal cooling and overnight lows mainly in the 70s except for
central parts of Phoenix.

Later this week, 500mb heights do begin to increase a bit as the
troughing to our north shifts over the central and eastern U.S.
After highs just below 110 through Friday, we should see a couple
degrees of warming on Saturday with the higher heights resulting
in highs around 110. Although 500mb heights stabilize this
weekend near 592dm and stay there into early next week, a slight
boost in low level moisture (afternoon surface dewpoints 35-40
degrees) should keep highs just below 110 Sunday through Tuesday.
This moisture uptick will however still be insufficient for any
monsoon activity to be seen across the area as both the GFS and
European are in good agreement keeping low level flow either out
of the west or north through next Wednesday. There are indications
we may manage to see a switch to southeasterly low level flow
late next week which could be enough to bring at least a low grade
monsoonal moisture flow out of northern Mexico.

&&

.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL:

A series of weak Pacific weather systems will move into the western
states north of AZ. Increasing winds aloft will mix down to the
surface resulting in gusty west to southwest winds during the
afternoon and evening hours. Through 20z Wed, light and variable
winds under 6 knots. Clear skies. From 20z Tue through 03z Wed,
increasing west to southwest winds 10 to 15 knots with gusts to 20.
Clear skies.


Southeast California/Southwest Arizona including KIPL and KBLH:

A series of weak Pacific weather systems will move into the western
states north of AZ. Increasing winds aloft will mix down to the
surface resulting in gusty west to southwest winds during the
afternoon and evening hours. Through 20z Tue, light and variable
winds under 6 knots. Clear skies. From 20z Tue to 03z Wed,
increasing southwest winds 10 to 15 knots. Clear skies.


Aviation discussion not updated for amended TAFs.

.FIRE WEATHER...

Friday through Sunday:

Dry westerly flow aloft over the region will result in clear skies.
Slightly above-normal temperatures are expected. Minimum relative
humidity will range from 5 to 8 percent. Good overnight recovery.
Afternoon southwest winds 10 to 20 mph each day.

Monday and Tuesday:

An increase in moisture from Mexico is expected over southeast AZ.
Minimum relative humidity will range from 8 to 12 percent. Afternoon
south to southwest winds 5 to 15 mph. There is a slight chance of
afternoon thunderstorm activity over the mountains of southern Gila
County Tuesday. Fair overnight recovery.

&&

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

&&

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

$$

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DISCUSSION...Kuhlman
AVIATION...Vasquez
FIRE WEATHER...Vasquez


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