908 
fxus65 kpsr 101057 
afdpsr 


Area forecast discussion 
National Weather Service Phoenix Arizona 
356 am MST Wednesday Mar 10 2010 


Synopsis... 
as one low pressure system leaves Arizona...another one approaches 
from the west. Temperatures will stay cool in spite of some sun 
across the deserts today. The last in the series of Pacific systems 
will move across northern Arizona tonight...resulting in another 
chance of light showers...and light snow in the mountains. High 
pressure will build into the region on Friday and Saturday for dry 
and warmer weather. A weak system from the Pacific will move toward 
the 4 corners by Sunday...but dry conditions will persist into early 
next week. 


&& 


Discussion... 
variable cloudiness continues across most areas early this morning 
as the most recent closed low exits eastern Arizona near the White 
Mountains. Satellite imagery indicated the main precipitation band was 
well east and north of Gila County...although wrap-around clouds and 
flurries were seen over the higher terrain of northern Arizona. Nothing 
significant in the way of snow reported from Tuesday. Temperatures were 
cool...into the 40s in most of the desert zones...while 38 degree was 
the latest reading from Globe at 2 am. The moisture content was 
still high...and stratus...rather than fog was the main concern. 
Some lower visibility may occur early this morning in the high 
country but I am not looking for any widespread fog problems. 


Tonight and Thursday... 
models still keep the moisture in place over eastern Arizona while a 
100 knots jet core cuts through southeastern calif. Thus...an 
increasing chance of snow showers for zone 24 for tonight. Snow 
level should stay near 4500 feet. On the deserts...Phoenix probability of precipitation will 
edge upward after dark...but again amounts will be very light. 
Height falls not nearly as strong as the last system...but dynamics 
and cold air aloft will spread a little farther west than older 
models had advertised. By early Thursday...zone 24 will still have 
some light precipitation around...but amounts not expected to be heavy 
enough for a Winter Weather Advisory. Sunny skies will be the rule 
on the lower deserts on Thursday afternoon...and the start of a 
welcome warming trend. 


Friday and Saturday... 
strong upper ridge to build into the region...with dry and warmer 
weather. GFS/European model (ecmwf) both move the ridge axis east of Phoenix by 
Friday night...and some high thin clouds likely to spread from west 
to east by middle day Saturday. 


Sunday and Monday... yet another weak system due to move across the 
western states with the center remaining well to our north. Except 
for some high clouds...not calling for much change in temperatures. Based 
on latest GFS guidance...highs in Phoenix will stay in the 70s into 
early next week. 


&& 


Aviation... 
southeast California and southwest Arizona...including kipl and kblh... 
through 03z Thursday...scattered clouds at or above 15 thousand mean sea level...but between 20z Wednesday 
and 03z Thursday west winds 15 kts gusting to 25 knots. 


South central Arizona including kphx and kiwa... 
through 03z Thursday...scattered clouds at or above 10 thousand mean sea level...but between 20z Wednesday and 
03z Thursday west winds 10 kts gusting to 20 knots. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Friday through Sunday... 
a high pressure system will build into the region Friday and 
Saturday...resulting in warmer temperatures. Lower humidity levels 
will also remain across the area due to dry northerly winds from 
Utah and Nevada. However...late Saturday and Sunday another Pacific 
low pressure system will move into the region...bringing windy 
conditions...cooler temperatures...but little or no rainfall. 


&& 






Psr watches/warnings/advisories... 


Arizona...none. 


California...none. 


&& 


$$ 


National Weather Service Phoenix is on the internet at 


Weather.Gov/Phoenix 


Discussion...Sipple 
aviation...vasquez 
fire weather...vasquez