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fxus65 ktfx 240420 
afdtfx 


Area forecast discussion 
National Weather Service Great Falls Montana 
1020 PM MDT Wednesday Jul 23 2008 


Update... 
will update zone and state forecasts by 10 PM MDT. Scattered 
showers and thunderstorms have developed on the leading edge of a 
shortwave trough approaching from the west this evening. Have 
received reports of wind gusts to 70 miles per hour...at least small 
hail...and heavy rain at times. Will increase the coverage of 
scattered evening thunderstorms to include most of north central 
and central Montana and keep mention of severe storms in...as am 
expecting them to increase over the area. Thunderstorms have also 
developed over southwest Montana this evening...but they should 
mainly only last through the evening...with only isolated 
thunderstorms lingering after midnight. However...farther 
north...across central Montana...wind shear will increase as the 
trough moves into Montana overnight. Therefore...will keep mention 
of possible severe thunderstorms across most of the area after 
midnight as well. Coulston 


&& 


Aviation... 
updated 0419z. 
An upper level low pressure shortwave will move across the area 
tonight. Scattered showers and thunderstorms will decrease by 
midnight...most will have moved into eastern Montana. Some 
thunderstorms may have heavy rain and hail in excess of 3/4inch in 
diameter. Also expected with are gusts in excess of 50 kts with some 
storms. Isolated thunderstorms will develop again Thursday 
afternoon. MVFR conditions are expected near thunderstorms. 
Elsewhere...VFR conditions will prevail during the next 24 hours. 




&& 


Previous discussion... 
/issued 528 PM MDT Wednesday Jul 23 2008/ 


Tonight through Friday...upper trough approaching western Montana at 
this time. Plenty of low level moisture out ahead of this feature 
and the airmass continues to destabilize. Thunderstorms are slowly 
beginning to develop and should continue to do so through the 
evening hours. Storm Prediction Center has placed a portion of the County Warning Area 
under a slight risk for tonight. The upper trough moves along the 
international border through the night with ridging taking place 
Post trough passage on Thursday. Isolated convective activity will 
continue over the eastern zones on Thursday before ending by 
evening. The upper ridge strengthens over the area Friday for 
generally warmer and drier conditions. A few isolated mountain 
thunderstorms are possible Friday afternoon. Temperatures will 
begin a warming trend. Readings on Thursday will be near seasonal 
averages with afternoon readings exceeding seasonal averages on 
Friday. Emanuel 


Friday night through Monday night...upper ridge flattens out Friday 
night. Should be dry except for perhaps an isolated tstrm over SW 
mountains in the evening. GFS and European model (ecmwf) both show a northwest to southeast 
oriented band of instability correlated with high vertical wind 
shear...suggesting potential for strong storms over mainly northern 
and eastern sections Sat afternoon and evening. This unstable 
region shifts somewhat east Sunday and Monday with more storms a 
good bet over eastern Montana...with perhaps a few storms far 
enough west to get into eastern sections of the Great Falls warning 
area have tweaked up high temperature forecasts for the weekend 
based on latest model guidance. Reilly 


Tuesday through Wednesday...models are in basic agreement during 
this period...with some differences in timing and amplitude of 
features. An upper level ridge builds over central Montana and 
remains quasistationary. Patchy monsoonal moisture and a somewhat 
unstable southwest to west flow aloft should combine for isolated... 
mainly afternoon and evening showers and thunderstorms. The storms 
will persist later into the night over eastern portions of our 
forecast area. Temperatures should be a little above seasonal 
averages. Ek 


&& 


Preliminary point temps/pops... 
gtf 52 80 48 86 / 50 10 0 0 
ctb 47 76 42 83 / 50 10 0 10 
hln 58 85 53 91 / 30 10 10 10 
bzn 51 89 48 94 / 40 20 10 20 
wey 44 79 43 83 / 20 10 10 10 
dln 50 85 46 90 / 20 10 10 10 
hvr 54 79 46 86 / 40 30 10 10 
lwt 51 78 45 82 / 40 30 10 10 


&& 


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


$$ 


Short term...coulston/Emanuel 
long term...Reilly/Ek 
aviation...zelzer 


Weather.Gov/greatfalls