Area forecast discussion 
National Weather Service Phoenix Arizona 
248 am MST Tuesday may 26 2015 


Synopsis... 
dry weather along with a warming trend is forecast for the remainder 
of this week and weekend. A dry weather system will bring a period of 
cloudiness on Wednesday...but thereafter skies will remain clear to 
mostly clear through the weekend. Afternoon temperatures for the 
lower deserts by Friday through Sunday will generally top out between 
100 and 105 degrees. 


&& 


Discussion... 
what you would expect temperatures to be across the Desert Southwest 
will finally come to fruition over the next several days as the past 
couple weeks of deep Pacific lows dominating the western U.S. Comes 
to an end. Gradually over the next couple days...a fairly robust 
upper level ridge will build over the eastern Pacific and eventually 
shift into the western Continental U.S. Late this week. Before that point...we 
will see somewhat quasi-zonal westerly dry flow with a very weak 
shortwave trough passing through northern Arizona today and a 
somewhat more significant trough passing across the southern portion 
of the the region on Wednesday. 


Heights aloft have built up over the past couple days and will 
remain fairly consistent through the middle of the week while 
temperatures warm slightly each day. Highs today and Wednesday will 
reach into the low to middle 90s across the deserts...or still a few 
degrees below normals. A shortwave trough currently seen on water 
vapor as a compact closed low circulation roughly 900 miles west of 
Southern California is forecast to weaken over the next day or 
so...reaching northern Baja California Wednesday morning. Models are in good 
agreement taking the associated pv anomaly mainly across northern 
Mexico Wednesday afternoon into Wednesday night...possibly skirting 
through far Southeast Arizona. Upper level relative humidity fields indicate enough 
moisture present with this system to bring in a good amount of high 
clouds on Wednesday and likely a brief period of mostly cloudy skies. 
This may influence high temperatures slightly Wednesday...but likely not 
much as most of the day will see quite a bit of filtered sunshine. 


The building Pacific Ridge will move into the region late this week 
with 500mb heights increasing to around 585dm by late Friday. This 
will allow temperatures to return to seasonal normals on Thursday and 
even a few degrees above normal starting Friday and into the weekend. 
Would not be surprised if a few warmer Lower Desert spots top out at 
around 105 on Saturday and Sunday with the ridge axis moving 
overhead. Long range models are currently in good agreement with a 
Pacific low affecting mainly the northern half of California and the 
northern portion of the Great Basin early next week. This should 
allow for a bit of cooling over our region...but nothing substantial. 


&& 


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


Just some high clouds moving in from the eastern Pacific through 
Tuesday evening. Light/diurnally driven winds expected at all sites. 
Weather impacts should be minimal through Tuesday evening. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Thursday through Monday... 
high pressure that will be gradually building over the region will 
keep dry conditions in place through the forecast period...with 
temperatures gradually warming into Saturday...before leveling off 
from Sunday into early next week. Lower Desert highs will likely 
reach 100 degrees at most locations by Friday...then rise into the 
101-105 degree range from Saturday Onward into next Monday. Minimum 
relative humidity values are expected to range from around 8 percent to the middle 
teens each day. Despite these low relative humidity values...the combination of 
light winds and fair-good overnight recoveries will continue to keep 
fire danger levels at relatively low levels through the forecast 
period. 


&& 


Psr watches/warnings/advisories... 
Arizona...none. 
California...none. 
&& 


$$ 


Visit US on facebook...twitter...and at weather.Gov/Phoenix 


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






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