185 
fxus65 kpsr 202038 
afdpsr 


Area forecast discussion...updated 
National Weather Service Phoenix Arizona 
140 PM MST Sat Mar 20 2010 


Synopsis... 
high pressure will build over the region and bring warm temperatures 
and dry conditions through the weekend into early next week. 
Temperatures will warm once again to above normal starting Sunday 
and Monday before cooling as another low pressure system moves 
across mainly south-central Arizona Tuesday into Wednesday. High 
pressure will return Thursday for dry conditions and another warming 
trend. 


&& 


Discussion... 
high pressure ridge is building back in over southeast California 
and Arizona with mostly clear skies except for some cirrus spreading 
into southeast California from a system moving into the northwest 
coast. Temperatures were a little lower than yesterday at this time 
across most locations with dew points falling into the teens. 
Surface winds were generally northeast at 10 to 15 miles per hour across 
Arizona. 


Models in agreement that next few days will be mild for the region 
with high pressure ridge stretching across the Great Basin. By late 
Monday an cutoff low pressure system will begin to approach Baja California 
California. At the same time another low pressure system will drop 
down over the Great Basin. The first system is forecast to mainly 
impact northwest Mexico. The larger system west of The Rockies will 
drop down and begin impacting the region by late Tuesday as the low 
migrates from Utah down into northeastern Arizona. This should bring 
some shower activity to the northeast half of Arizona. Precipitation 
amounts do not appear to be very great...mostly less than a tenth of 
an inch. By Wednesday afternoon the two low pressure systems will 
merge and move into the central U.S. For the time being will keep 
slight chance of showers for Tuesday-Wednesday over northeast 
portions of the County Warning Area...especially zone 24. Winds should pick up on 
Wednesday as the low pressure system begins to exit the region. 


Temperatures should remain at or a bit above normals until Wednesday 
when they will fall back a little below normal reflecting the low 
pressure over northeast Arizona. By Thursday temperatures will climb back 
above normals. 


&& 


Aviation... 
kipl...kblh...and surrounding airfields... 
expect northeasterly winds...generally less than 10 kts...through 
02z. Winds should take on their usual diurnal directions after 02z 
with light west winds at ipl and northerly winds at blh. 


Kphx...kiwa...and surrounding airfields... 
northeasterly winds will continue through early afternoon. Winds 
will try and turn around a bit around 22z but there is some 
uncertainty if they will make it all the way around to 270 degrees. 
All model guidance is indicating a more 300-320 direction this 
afternoon and that is what I put in the phx/iwa tafs. Winds will 
become light and easterly late this evening. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Monday through Friday... 
above normal maximum temperatures and dry conditions are expected 
Monday...before another low pressure system tracks across the region 
Tuesday into Wednesday providing the forecast area with cooler 
maximum temperatures...breezy conditions...and a slight chance of 
precipitation for south-central Arizona. High pressure returns 
Thursday...along with warmer and drier conditions through Friday. 


&& 


Psr watches/warnings/advisories... 


Arizona...none. 


California...none. 


&& 


$$ 


National Weather Service Phoenix is on the internet at 


Weather.Gov/Phoenix 


Discussion...waters 
aviation...leins 
fire weather...paddock