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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 79 °
• Low: 46 °
• T-Storms

• Thursday
• 
• High: 70 °
• Low: 39 °
• Chance of a Thunderstorm

• Friday
• 
• High: 64 °
• Low: 45 °
• Chance of T-Storms

• Saturday
• 
• High: 66 °
• Low: 46 °
• Chance of T-Storms

• Sunday
• 
• High: 68 °
• Low: 46 °
• Partly Cloudy

Area forecast discussion 
National Weather Service Great Falls Montana 
905 PM MDT Tue Jun 18 2013 


Update... 
a few strong thunderstorms continue to push northward through the 
region. The thunderstorm watch will continue a bit longer where it 
is currently in effect in case a severe storm develops. The flash 
flood warnings will continue a bit longer as well. Expect a few 
thunderstorms to continue after midnight. Otherwise current 
forecast is on track. Brusda 


&& 


Aviation... 
updated 2355z. 
Widespread thunderstorm activity, mainly west of I-15 and north of 
kbtm, will continue into the evening hours. Some storms are 
producing large hail and very heavy rain. Less than VFR conditions 
can be expected in heavy precipitation. Convective activity 
diminishes after 06z but another round of thunderstorms will develop 
Wednesday. Mpj 


&& 


Hydrology... 
more widespread showers and thunderstorms are possible along the 
Rocky Mountain front and adjacent plains this afternoon and 
evening and over most of the plains of north central/central 
Montana on Wednesday. Some of these storms may produce brief heavy 
rainfall. These periods will need to be monitored for possible 
areal flood/flash flood highlights. The greater area of concern is 
across eastern portions of north central and central Montana for 
Wednesday that still have moist soil that would not be able to 
absorb much rapid rainfall. If rainfall from storms today are 
significant along the Rocky Mountain front additional rainfall on 
Wednesday will increase the flooding threat there as well. 


&& 


Previous discussion... 
/issued 555 PM MDT Tue Jun 18 2013/ 
today through Thursday...a low pressure system moving over the 
Pacific northwest coast today will bring increased moisture and 
instability to Montana. These factors will help generate showers and 
thunderstorms over terrain this afternoon. A frontal boundary 
associated with this system will also move into western Montana 
today providing a good forcing mechanism for storm development. As a 
result the Storm Prediction Center continues to keep western and 
central Montana under a slight risk for severe thunderstorms. Storms 
decrease overnight, but another round of potentially severe weather 
is expected for Wednesday as the main system continues to move east 
across the northern rockies. The most unstable conditions will also 
shift northeast into central and eastern Montana, where the Storm 
Prediction Center has a slight risk for Wednesday as well. The 
potential for the strongest storms will be along and east of a 
Havre-to-Stanford line as wind shear and instability are strongest 
there. Precipitation from storms may be heavy adding the potential 
for flash flooding. The system will lift northeast across the area 
later Wednesday night into Thursday keeping high pops in the 
mountains. Westerly down-slope winds will hinder shower/thunderstorm 
development Thursday though. Winds strengthen along the Rocky 
Mountain front Thursday making high wind highlights possible. 
Temperatures cool Wednesday as the main front moves through the area. 


Thursday night through Tuesday...no significant changes made to 
the medium range forecast. An unsettled pattern will persist 
through Saturday as a closed upper low will remain quasi- 
stationary over northwest Montana. Short wave energy will 
continue to rotate out from the base of the low and help initiate 
shower and thunderstorm development each day. The strength of 
these storms will depend on availability of low level moisture 
and the strength of the divergent flow aloft. The models also 
continue to differ on the upper low's position which, in turn, 
will affect where and how strong thunderstorms will be. Because 
of these differences, have continued to broad-brush the pops 
through Saturday. By late Saturday, the models move the low to 
northeast Montana and lift it out as an upper ridge begins 
building over the Pacific northwest. The ridge breaks down on 
Sunday as short wave energy ripples across the area within the 
westerly flow aloft. Isolated thunderstorms will remain a 
possibility Sunday and Monday. By Tuesday, weak upper ridging 
returns though isolated showers will persist over the Southwest 
Mountains. Temperatures will remain below seasonal averages to 
start the period due to cloud cover and periodic cold advection 
from transient shortwaves. Temperatures should rise above 
seasonal averages to start the week. 


&& 


Preliminary point temps/pops... 
gtf 54 76 46 67 / 40 80 80 20 
ctb 52 73 45 64 / 100 100 90 30 
hln 53 75 46 67 / 50 70 60 30 
bzn 48 79 42 69 / 20 50 40 20 
wey 38 70 32 61 / 10 30 20 20 
dln 48 71 39 65 / 20 60 50 20 
hvr 59 84 51 73 / 20 80 90 20 
lwt 53 80 44 69 / 20 60 80 20 


&& 


Tfx watches/warnings/advisories... 


Severe Thunderstorm Watch until 10 PM MDT this evening eastern 
Glacier...eastern Pondera...eastern Teton...Liberty...northern 
Rocky Mountain front...southern Rocky Mountain front...Toole. 


&& 


$$ 


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