Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 200509

Area Forecast Discussion
National Weather Service Phoenix AZ
1009 PM MST Wed Jun 19 2019

.UPDATE...aviation discussion.


The weather will remain uneventful through Thursday before a
weather disturbance passing to our north will bring breezy
conditions and below normal temperatures. Breezy conditions will
impact the area primarily on Friday and Saturday. High
temperatures this Saturday and Sunday are likely to stay below 100
degrees for most locations.


There is very little change to the sensible weather today with
abundant sunshine and daytime temperatures reaching near seasonal
normal values. Currently, temperatures across the forecast area
are around the century mark and will bump up a few degrees by this

The overall pattern does not change much through tomorrow as dry
west to northwesterly flow aloft remains in place giving the edge
to a persistence forecast for tomorrow. Very early Friday, a
seasonably strong upper level low will penetrate the Intermountain
West with the trough axis dissecting Arizona by early Saturday
morning. As a result, the pressure gradient will tighten leading
to breezy conditions beginning late Thursday and peaking Friday
afternoon. Wind gusts upwards of 35 mph are likely across portions
of Southeast California, especially along the Interstate-8
corridor, and across the higher terrain areas across central
Arizona. These winds will may exacerbate the already elevated fire
weather concerns. On the flip side, the NAEFS climatological
percentiles for atmospheric heights at all of the standard levels
indicate trough heights are near the 10th percentile. As such,
forecast high temperatures for Phoenix remain below 100 degrees on
Saturday and Sunday.

Trofy conditions will linger over the region, eventually giving
way to a steady warmup towards seasonal normal values next week.
The fantastic news is that the extreme heat that often
accompanies June will remain out of sight for at least the time
being. Long range ensembles do hint at the subtropical ridge
building into the Southwest in the extended 10 day range...leaving
plenty of uncertainty as to exactly when that will happen.


.AVIATION...Updated at 0500 UTC.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT;

Dry southwest flow will keep skies clear at the TAF sites through
the TAF period. Overnight winds are expected to shift to the
southeast with speeds under 10 kts. Low pressure strengthening to
the north of Arizona will lead to slightly stronger winds Thursday
afternoon and evening; there may be a few hours of mainly
southerly winds up to 10kt late morning into early afternoon but
by around 21z we should see winds mostly from the southwest at the
TAF sites. Look for occasional gusts to near 20kt at times into
the middle of the evening tomorrow.

Southeast California/Southwest Arizona including KIPL and KBLH:

Dry southwest flow will keep skies clear across the western deserts
through the TAF period. Winds will be only weather impact for the
TAF sites. At KIPL, winds favor the southeast much of the time
but should turn to the west/southwest by mid afternoon Thursday.
Look for some gusts over 20kt after 22z continuing into the
evening hours. Winds favor the south at KBLH next 24 hours, with
winds becoming stronger Thursday afternoon. Look for sustained
winds to near 20kt after 18z Thursday with higher gusts likely.

Aviation Discussion not updated for amended TAFs.


Saturday through Wednesday:
Cooler temperatures through this weekend will eventually give way
to a steady warmup to near seasonal temperatures next week.
Daytime humidity values will still remain near 10% each afternoon
with overnight recovery into the 20-30% range. Gusty winds will
remain a concern through Sunday, especially across the Tonto NF
and Rim area, with gusts upwards of 20 mph before calming
slightly through the week.


Spotter activation is not expected.




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