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afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
237 PM MDT Tuesday Mar 16 2010 


Discussion... 
Tuesday afternoon through Thursday night...upper level ridge 
bringing the fine Spring-like temperatures this afternoon will continue 
to move into eastern Montana this evening. A couple of sites from Great 
Falls northward will get close to tying or setting maximum temperature 
record for the day as highs climb into middle-upper 60s. Warm spell 
will be short-lived as Pacific northwest trough currently near 
Washington/or/ID should cross east of The Divide after midnight and then 
push steadily across the County Warning Area during tomorrow morning/early afternoon. 
Associated surface cold front will usher in cooler airmass... 
dropping highs about 5-8 degree below today's values. Models are very 
consistent in showing little/if any precipitation with this system...so 
only have slight chance probability of precipitation across Southwest Mountains and northern 
Rocky Mountain front. Skies will clear across most of the region on Wednesday 
afternoon as weak ridging follows the trough. Conditions remain quiet 
through about midday Thursday when stronger trough begins to drop south 
from Canada. Models are depicting mostly widespread light rain/snow 
mix with the Canadian system beginning Thursday afternoon which will spread 
over most of County Warning Area on Thursday evening. Cooler conditions will be reinforced 
with this system as well...with highs on Thursday only reaching upper 30s to 
middle 40s. Waranauskas 


Friday through Sunday night...a trough may bring widespread showers 
along with cooler temperatures to the area so have continued to 
increase probability of precipitation over the forecast area. Thursday night a weak upper 
trough moves southeast through the area along the Continental 
Divide. The flow aloft will be northwesterly across most of the 
region and both models show a good chance of widespread light 
precipitation. As pockets of moisture and energy move through the 
flow...scattered mountain snow will develop along with isolated rain 
and/or snow showers over the plains. The trough and associated 
precipitation both look to exit the area Saturday and another round 
of drier conditions begin. Models are in good agreement through 
Sunday but begin to diverge after that. The European brings a 
weak upper ridge to the area while the GFS continues with a more 
moist westerly flow. Temperatures starting Saturday will be fairly 
steady with highs in the 40s and 50s and lows in the 20s at most 
locations. Gustafson 


Monday and Tuesday...long term models are in general agreement over 
a weak shortwave trough moving out of the north over the area. 
Leaned towards European model output for temperatures which are 
significantly colder than GFS ensembles and bias corrected grids. 
Precipitation was kept slightly above climatology due a vorticity maximum 
over central Montana both major models that increases the chance of 
enhanced instability allowing for showers during these two days. Suk 


&& 


Aviation... 
updated 1735z. 
High pressure aloft will continue to provide dry and stable 
conditions. Some high clouds will move across the area from time to 
time. VFR conditions prevail. 


&& 


Preliminary point temps/pops... 
gtf 38 56 28 42 / 0 10 10 40 
ctb 33 51 24 40 / 0 10 10 40 
hln 33 55 29 42 / 0 10 20 30 
bzn 31 55 25 43 / 0 20 20 30 
wey 18 48 21 40 / 0 20 40 40 
dln 31 56 28 42 / 0 10 20 30 
hvr 24 43 20 34 / 0 10 10 20 
lwt 31 56 27 40 / 0 10 20 40 


&& 


Tfx watches/warnings/advisories... 
none. 
&& 


$$ 


Short term...waranauskas 
long term...gustafson 
aviation...Emanuel 


Weather.Gov/greatfalls