108 
fxus65 ktwc 101008 
afdtwc 


Area forecast discussion 
National Weather Service Tucson Arizona 
308 am MST Wednesday Mar 10 2010 


Synopsis...a brief break in the wet weather can be anticipated 
today...before yet another storm system brings showers and mountain 
snow tonight and Thursday. Temperatures will remain cool through the 
week. Ridging will build in during the weekend and early next week 
for a dramatic warmup. 


&& 


Discussion...water vapor imagery shows the upper low that brought 
rain and mountain snow to the region yesterday afternoon is 
currently pushing into northwest New Mexico. Infrared satellite imagery 
shows extensive wrap around moisture with low to middle level 
cloudiness and precipitation occurring across southwest Colorado 
northwest New Mexico and the northeastern quarter of Arizona. The 
low clouds extend as far south as a line from around Florence to 
Dudleyville to Safford. 


The White Mountains of northern Graham and Greenlee counties should 
still see intermittent precipitation for another few hours or 
so...but I have allowed the Winter Weather Advisory to expire at 3 
am MST. The system will continue to move east during the day...but 
another storm system that currently extends from Oregon and northern 
California will affect mainly the northern fringes of my forecast 
area late tonight and into Thursday. Moisture with this next system 
will be limited...especially the farther south you go...so at this 
time not expecting the need for any headlines with this next system. 
Could pick up a few inches of snow in the higher terrain...but at 
this point I am expecting amounts to remain well below advisory 
criteria. Day shift can take another look at the system once the 12z 
model data comes in and make changes accordingly. 


The system will exit the region to the east on Thursday with ridging 
building in from the west on Friday. For the weekend and into next 
week both the GFS and European model (ecmwf) show a low dropping down from the 
north...but there are significant differences with regard to the 
position of the low. For example...by late Saturday afternoon the 
GFS shows the low over NE Utah...while the Euro shows it over 
extreme northwest Arizona. By late Sunday the GFS has the low over north 
central New Mexico...while the Euro has it over east central 
Arizona. At any rate...the moisture associated with this storm 
should remain mostly north and east of my forecast area...therefore 
I kept the slight chance probability of precipitation that I inherited in the grids/zones 
for Sunday and Sunday night. 


Another ridge should build in from the west with a significant 
warmup by the early part of next week. 


&& 


Aviation...middle level clouds across the northern sections of the 
forecast should either erode and/or move east as the upper low moves 
east. As another system makes its way across northern Arizona late 
tonight and early Thursday...expecting clouds to increase once 
again...but mostly to the north with scattered to numerous showers 
and isolated thunderstorms and rain for areas north and east of Tucson. Surface winds light 
and diurnal this morning then becoming west at 10 to 20 knots with 
gusts to 25 to 30 knots. Aviation discussion not updated for taf 
amendments. 


&& 


Fire weather...there are no fire weather concerns at this time. 


&& 


Twc watches/warnings/advisories...none. 


$$ 


Mollere 


Weather.Gov/Tucson