850 
fxus65 kpsr 211735 
afdpsr 


Area forecast discussion 
National Weather Service Phoenix Arizona 
1030 am MST Sat Nov 21 2009 


Synopsis... 
dry weather is expected to continue at least through Thanksgiving. 
The weak southern portions of Pacific low pressure systems will bring 
temperatures down somewhat with a relatively small amount of high 
clouds this weekend...but for the most part...mostly clear nights and 
sunny days are expected to continue through Thanksgiving. High 
pressure aloft between Hawaii and Baja California California is expected to 
build northeast over our area with temperatures rising to well above 
average for late November by Thanksgiving day...in the upper 70s to 
near 80 degrees in the desert areas including Phoenix...Yuma and 
el centro. 


&& 


Discussion... 
under sunny skies...temperatures were generally close to the same in 
south-central and southwest Arizona including the greater Phoenix 
area and Yuma...1 to 3 degrees warmer in the southeast California 
desert areas and 5 to 10 degrees cooler in Joshua Tree National Park 
late this morning compared with the same time yesterday. Wind was 
generally calm or light mostly from the northeast and east in 
south-central and southwest Arizona...southeast and south in the 
southeast California desert areas...and northwest 5 to 15 miles per hour in 
Joshua Tree National Park. 


The forecast was updated to show sunny skies across the entire area 
today. High clouds have mostly dissipated or moved southeast out of 
our area...and it looks as if only a small amount of high clouds 
will affect our area the rest of the day. 


Dry weather is expected to continue at least through Thanksgiving. 
The flow aloft will generally be from the northwest through Tuesday. 
In this flow...the dry and weak southern portions of Pacific low 
pressure systems are expected to bring temperatures down somewhat 
this weekend...close to or just slightly above average for the 
latter part of November. A relatively small amount of high clouds is 
also expected this weekend...but overall mostly clear nights and 
sunny days are expected to continue through Thanksgiving. 


High pressure aloft between Hawaii and Baja California California is expected to 
build northeast over our area with temperatures rising to well above 
average for late November Wednesday and Thanksgiving day. Highs in 
the desert areas including Phoenix...Yuma and el centro are expected 
to be in the upper 70s to near 80 degrees Wednesday and 
Thanksgiving day. 


Surface high pressure is expected to build north and east of our area 
and bring some breeziness at times from the north and east by 
Wednesday and Thanksgiving. 


Previous discussion... 
Friday...forecasts start to diverge a bit...as the GFS takes the next 
shortwave east through the northern tier of states...while the European model (ecmwf) starts 
to dig the shortwave to the southeast...and towards Arizona. Tend to 
favor European model (ecmwf) a bit due to its track record over the GFS in past 
months...but at this time even its solution still appears dry with any quantitative precipitation forecast 
mostly staying north of Arizona Friday. Mex MOS numbers remain 
single digits at day 7. Thus will keep dry forecast in place for 
Friday. 


&& 


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


Light winds will continue to prevail through Sunday morning. Over 
the metropolitan Phoenix area...after the morning drainage winds 
diminish...afternoon winds will be light and variable...occasionally 
west. Northerly directions will be favored this afternoon over 
southeast California and the lower Colorado River valley. 
Otherwise...skies will be clear except for cirrus...decreasing from 
west to east during the day. 


Aviation discussion not updated for amended tafs. 


&& 


Fire weather... 
Monday through Friday... 
high pressure will build over the western states early next week... 
bringing warmer temperatures...low daytime humidity values and 
modest overnight recovery through Thanksgiving day. Winds will favor 
north and northeast...locally windy at times at the ridgetops. For 
the end of the week...there are indications that another trough will 
move through the Great Basin for a shift to southwesterly winds. 


&& 


Psr watches/warnings/advisories... 


Arizona...none. 


California...none. 


&& 


$$ 


National Weather Service Phoenix is on the internet at 


Weather.Gov/Phoenix 


Discussion...Ellis/cb 
aviation...aj 
fire weather...aj