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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Friday
• 
• High: 99 °
• Low: 72 °
• Partly Cloudy

• Saturday
• 
• High: 99 °
• Low: 70 °
• Clear

• Sunday
• 
• High: 97 °
• Low: 72 °
• Clear

• Monday
• 
• High: 95 °
• Low: 72 °
• Partly Cloudy

• Tuesday
• 
• High: 90 °
• Low: 64 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Phoenix Arizona 
250 am MST Friday may 24 2013 


Synopsis... 
low pressure center over the Pacific northwest is expected to keep 
the region under dry southwesterly flow aloft...with breezy 
conditions at times into next week. Anticipate little change in 
temperatures through Saturday. Thereafter...a trough along the 
West Coast is anticipated to deepen which will lead to some modest 
cooling Sunday and Monday with some more noticeable cooling Tuesday 
and Wednesday. 


&& 


Discussion... 
areawide weather has been on the quiet side this week and slightly 
warmer than expected the past couple days. The deep upper low over 
the Pacific northwest is not quite having as much of a cooling 
effect over the Desert Southwest as anticipated. 
However...temperatures have cooled noticeably across our western 
zones and slightly below normal temperatures are expected through 
the weekend there. Farther away from the cooler 
airmass...south-central Arizona remains above normal with metropolitan 
Phoenix readings around 100 the past couple days. Not expecting any 
noticeable change in temperatures across south-central Arizona today 
or even into Saturday. 


By Sunday...the persistent upper low over the Pacific northwest 
finally weakens and becomes more of an open trough. A shortwave does 
Peel off the main low and dives southward into the Great 
Basin...thus lowering heights across the Desert Southwest. This is 
expected to have a slight cooling effect across the region...but the 
more significant cooling won't occur until the middle of next week. 
Through Monday...dry southwesterly flow maintains it/S hold across 
the region...but changes in the flow starting Tuesday. 


A fairly strong shortwave trough is forecast to slide southeastward 
from the North Pacific Sunday into Monday coming onshore in 
California Monday night. The large scale troughing pattern across 
the western United States and a 120kt upper jet will aid in the 
quick progression of this shortwave into our region by Tuesday. 
Model differences are still problematic with the operational 
European likely on the overly strong side of the spectrum and the 
Gem on the opposite side of the spectrum with the main shortwave 
ending up across the Pacific northwest. The European and GFS 
ensemble means are fairly close to each other in speed and strength 
with more spread seen within the European ensemble members. Given 
this...have trended the current forecast toward the GFS...GFS 
ensemble mean...and European ensemble mean. This still results in a 
modest cooldown of 5-10 degrees for the middle of next week...and 
especially Tuesday and Wednesday with the potential for decent middle 
and high level moisture and resulting cloud cover. Precipitation 
chances still look fairly low given overall fairly dry airmass. Have 
elected to mostly ignore the operational European quantitative precipitation forecast forecast for 
the region given it/S overly strong solution...but have at least 
included slightly higher than climatology probability of precipitation for Tuesday into Wednesday. 
If other model solutions start trending toward the stronger 
European...higher probability of precipitation will be needed. 


&& 


Aviation... 
south-central Arizona...including kphx...kiwa...ksdl...southeast 
California/southwest Arizona...including kipl and kblh... 


Dry southwest flow aloft will keep skies clear to mostly clear 
through the taf period. Winds are expected to follow the usual 
diurnal trends in direction and speed...with westerly breezes 
developing during the afternoon and evening hours. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Sunday through Thursday... 
low pressure that is expected to remain along the West Coast on 
Sunday and Monday is forecast to move inland over the Desert 
Southwest on Tuesday and Wednesday...then off to the east into the 
Central Plains on Thursday. Dry southwest to west flow ahead of this 
low center will keep skies mostly clear and temperatures near normal 
on Sunday and Monday...with cooler temperatures...an increase in 
cloudiness...and gusty winds likely on Tuesday and Wednesday...as 
the low passes through the region. Warmer temperatures are then 
expected on Thursday as ridging begins to build in from the west. 
Single digit minimum humidities are expected on Sunday and 
Monday...with somewhat higher values on Tuesday and Wednesday...then 
falling back into the single numbers and low teens on Thursday. 


&& 


Psr watches/warnings/advisories... 


Arizona...none. 


California...none. 


&& 


$$ 


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Discussion...Kuhlman 
aviation...percha 
fire weather...percha