Area Forecast Discussion
Issued by NWS Phoenix, AZ
FXUS65 KPSR 271259
Area Forecast Discussion
National Weather Service Phoenix AZ
559 AM MST FRI MAY 27 2016
Updated Aviation and Fire Weather sections.
A broad area of low pressure will persist over the western United
States through the beginning of next week yielding somewhat cooler
than normal temperatures and dry conditions. Strengthening high
pressure much of next week will bring a warming trend with high
temperatures in the lower deserts pushing near 100 degrees by the
middle of the week.
Upper low and associated negative height anomaly across CO that
produced the severe weather in the Plains Thursday continues to
migrate slowly eastward this morning. In its wake, a subsident
northwesterly flow has developed across the Desert Southwest.
Latest operational models remain in good agreement over the next
several days, indicating steady thickness rises through Saturday.
Thereafter, mid-level heights will essentially level off through
Tuesday as another weak short-wave trough off the CA coast slowly
moves eastward and traverses the area.
Temperatures today will jump generally between 5 and 7 degrees from
those observed Thursday. However, below normal temperatures will
persist as a long-wave trough remains prevalent across the western
CONUS. Latest raw and post-processed guidance continues to indicate
that temperatures in the lower deserts will return to the triple
digits by Tuesday as a ridge in the eastern Pacific builds eastward.
NAEFS anomalies/percentiles are not extreme, suggesting that
temperatures will fall well short of records. Nevertheless, a warming
trend will continue through the end of next week with a return to
above normal temperatures as the ridge eventually slides eastward.
Precipitation chances remain near zero through next week, except
across southern Gila county. Some timing differences are evident between
the ECMWF and GFS and their respective ensembles, though there is
some potential (albeit very small) for showers or thunderstorms
across the higher terrain associated with the compact upper low
moving through AZ Tuesday/Wednesday.
South-Central Arizona Including KPHX, KIWA, and KSDL, and
Southeast California/Southwest Arizona Including KIPL and KBLH
A departing upper trough will lead to weakening flow aloft today.
Surface winds will be lighter as well (though some occasional gusts
up to 15 kts still possible this aftn./eve.). Skies clear over the
deserts. Isolated afternoon storms possible over Mogollon Rim and
Aviation Discussion not updated for amended TAFs.
Sunday through Thursday...
A weak upper low will slowly pass over Southern California and
Arizona during the first half of next week but with little impact
except for a minor increase in humidity. As the system departs, high
pressure builds in for a warming trend with temperatures climbing
well above normal. Minimum humidities will be in the 10-15% range on
the lower deserts with fair to good overnight recovery. No strong
winds are forecast but there will be some locally breezy conditions
at times - most noticeably on Tuesday and Wednesday.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not expected.
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