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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 46 °
• Low: 28 °
• Chance Rain

• Thursday
• 
• High: 46 °
• Low: 23 °
• Chance Rain

• Friday
• 
• High: 50 °
• Low: 28 °
• Chance of Rain

• Saturday
• 
• High: 48 °
• Low: 28 °
• Chance Rain

• Sunday
• 
• High: 48 °
• Low: 25 °
• Chance Rain

Area forecast discussion 
National Weather Service Great Falls Montana 
541 PM MDT Tuesday may 22 2012 


Discussion... 


Tonight through Thursday...downslope westerly flow across the 
plains has kept convective activity at Bay. That said...some 
showers and isolated thunderstorms have developed and will 
continue into the early evening hours. Surface winds have been 
gusty this afternoon though wind speeds are expected to remain 
below warning criteria. Winds should decrease later this evening. 
Broad upper trough will be over the area tonight with precipitation 
continuing over southwest Montana. Showers will become more 
widespread on Wednesday and temperatures will be cooler. A surface 
cold front will drop south out of Canada on Thursday. Snow levels 
will drop to around 5000 feet and some accumulating snow can be 
expected. Rain will fall below this level...although some areas 
may see a mix of rain and snow. Temperatures on Thursday will be 
some 15 to 18 degrees below seasonal averages. Emanuel 


Thursday night through Tuesday...the big forecast problem during the 
period will be the track of an upper low that is forecast to be near 
the Pacific northwest coast early Thursday evening. Models are in 
fair agreement in taking the upper low into the southwest U.S. On 
Friday. Thereafter models are very different in how they handle the 
upper low. The European model (ecmwf) model is fairly consistent with its earlier 
runs in taking the upper low north through Montana. The Gem model 
also GOES along with this idea but whereas the European model (ecmwf) takes the upper 
low through central Montana the Gem model takes the upper low 
through eastern Montana. The GFS solution tonight is very different 
than the European model (ecmwf)/Gem solutions in that it has a much weaker low move 
through southeast Montana. The GFS and European model (ecmwf) differences have 
important implications for the forecast area as the GFS only has 
some relatively light precipitation over southwest Montana and is 
dry elsewhere in our forecast area. The European model (ecmwf) on the other hand has 
widespread significant precipitation for the forecast area. There 
are also major differences with high temperatures as the GFS has 
readings 20 to 30 degrees warmer than the European model (ecmwf) by Sunday. At this 
point am leaning towards a blend of the European model (ecmwf) and Gem 
solutions...and am tending to discount the GFS solution. Looking to 
the early part of next week including the Memorial Holiday expect 
temperatures to trend to seasonal averages with scattered showers. 
Blank 


&& 


Hydrology... 
water is being released from Gibson Reservoir into the Sun River. 
River flow will increase and river levels will rise. 
Elsewhere...cooler temperatures are expected through the rest of the 
week and additions to river flows from melt water is expected to 
remain low. Showers are expected at times through the week with 
widespread precipitation possible late Friday and Saturday. 
However...rainfall amounts do not appear excessive at this time. 


&& 


Aviation... 
updated 2339z. 
A broad upper level low pressure trough will keep the airmass 
unsettled through Wednesday. Brisk west winds will continue across 
much of the region and become gusty again Wednesday afternoon. 
Scattered showers are again expected Wednesday afternoon. VFR conds 
are expected through the next 24 hours. 




&& 


Preliminary point temps/pops... 
gtf 43 60 38 48 / 10 40 40 60 
ctb 40 57 35 46 / 10 40 40 60 
hln 43 58 38 52 / 30 40 20 60 
bzn 38 56 33 52 / 50 40 30 60 
wey 32 46 27 44 / 70 60 40 50 
dln 38 55 31 52 / 40 40 20 50 
hvr 44 62 40 50 / 10 30 40 60 
lwt 39 56 35 46 / 20 30 30 60 


&& 


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


$$ 




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