Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Phoenix Arizona
323 am MST Friday may 22 2015
a fairly strong upper level low will affect the region today into
early Saturday bringing cooler temperatures...and breezy to locally
windy conditions for today. Chances for showers and thunderstorms
today will be confined to mainly higher terrain areas from southeast
California northeastward into central and northern Arizona. Dry
conditions and a warming trend will then take over through next week
with temperatures climbing to around seasonal normals by the middle
of next week.
today and Saturday will see the main upper level low swing through
Arizona into the central rockies with the majority of our County Warning Area
staying dry...but with continued breezy to windy conditions. Current
satellite imagery shows the low center right over Los Angeles with
middle and upper level moisture wrapping around mainly on the northern
periphery of the low. A 110 knots upper jet maximum rounding the base of the
trough will lift northeastward today with a pronounced dry slot
moving through southwest Arizona by 18z and into northeast Arizona by
00z Saturday. Strong southwesterly low level flow this morning will
allow for a narrow band of modest boundary layer moisture to move
into Arizona ahead of a diffuse frontal boundary. Best
chances...albeit still only a slight chance...for any showers and
maybe a few thunderstorms will from late morning into the afternoon
from jtnp eastward through northern Maricopa County as a strong pv
anomaly lifts northeastward through the area.
The low center will reach into the central rockies Saturday with
increasingly subsident northwest flow aloft taking over across our
region. The large scale trough will however still remain spread over
the Desert Southwest keeping relatively cool air in place. Highs
Saturday will improve over Friday/S middle 70s to lower 80s...but
only by a couple degrees. A compact shortwave trough is then shown to
quickly move through southern Arizona from the northwest later Sunday
into Sunday night...but with little to no moisture to work
with...only single digits probability of precipitation are in the forecast. Temperatures
will start to get a boost Sunday into Monday...but we will still be
several degrees shy of normal.
Next week looks to be more on the quiet side with no significant
weather systems on the horizon. Quasi-zonal westerly flow with
gradually increasing upper heights will allow high temperatures to
reach near normals by the middle of next week...and possibly nearing
100 degrees in a few Lower Desert spots for next Friday.
Aviation... south-central Arizona including kphx...kiwa...and
Gusty west winds have tapered off following sunset...and should
start to back ahead of the approaching trough...turning to the
southeast by around 09z. They will veer again towards the
south/southwest by late morning Friday and become west again in the
afternoon with a few gusts over 18kt possible. Otherwise...the
mostly clear skies will give way to scattered low/middle cloud decks by
12z with bases mostly at or above 7k feet but there may be a few ceilings
developing during the day down to 5-6k feet as the main upper low
tracks by to our north. No precipitation is expected at any taf site next
24 hours...although there may be a stray shower or even a
thunderstorm along the far northern fringes of the greater Phoenix
area during the afternoon/early evening tomorrow.
Southeast California and southwest Arizona including kipl and kblh...
strong surface winds will be the main aviation concern through Friday
morning. Westerly gusts will persist until around midnight before
gradually weakening. Kblh will experience S/SW gusts not nearly as
strong...but also prevailing into the overnight hours. Occasional
middle/high level ceilings will be present...however should pose no impact.
Continued breezy conditions at kipl through the day on Friday.
No precipitation expected at any taf site through Friday evening.
Aviation discussion not updated for amended tafs.
Sunday through Thursday...
several weak weather disturbances will move through the district
next week...however dry weather will still prevail. A gradual
warming trend will also Grace the region bringing temperatures
closer to the seasonal normal. However...winds will generally remain
light following typical daily patterns leading to minimal fire
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