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Area forecast discussion 
National Weather Service Great Falls Montana
1130 PM MDT Monday may 4 2015

Aviation section updated

Update... current radar imagery shows two groups of isolated
showers with a few short-lived embedded thunderstorms, one in
central Blaine County and the second one over the southeast corner
of Fergus County. Locations under this activity may see brief light-
t0-moderate rainfall before the cells move eastward out of the area
by 9:00-9:30 PM. Have adjusted precipitation chances upward
slightly over the mentioned areas, while reducing them over the
remainder of central and southwest Montana through this evening as
moisture has thinned out across the region.



Tonight through Wednesday...southwest flow aloft continues to
bring moisture and instability to southwest Montana. The airmass
has destabilized and isolated thunderstorms have begun to develop.
Cape values are low and shear is virtually nonexistent so severe
storm development does not seem likely. The closed low
approaching the West Coast and moves inland Tuesday. Showers and
thunderstorms will become more widespread during the afternoon
and evening. Again, storms are not expected to reach severe
criteria but a few strong storms are possible. A cold front will
move across the area Tuesday night and the models are in general
agreement depicting the heaviest precipitation occurring overnight
Tuesday into early Wednesday morning. Quantitative precipitation forecast totals from midday
Tuesday to midday Wednesday are generally in the .10 to .20 range.
Precipitation across the plains comes to an end Wednesday
afternoon but scattered showers linger over the southwest.
Temperatures will remain will above seasonal averages Tuesday but
cool to near seasonal averages on Thursday.

Wednesday night through upper level trough of low pressure
will generally reside over the central Rocky Mountain states
through much of this period. This will allow for scattered showers
to continue over much of southwest Montana through the entire
extended. Further north...the chances for showers look to be a bit
more limited...but an isolated passing shower can not be ruled
out. Another concern though for the extended will be overnight low
temperatures. With cool Canadian air residing over the
region...night time lows will be near 30 degrees at times at lower
elevations and in the 20s in the mountains. These temperatures
could cause minor problems for those who have Spring Time
vegetation outside already. Additionally...snow will mix in at
times...but any snow accumulations should be confined to the
mountains. Total precipitation amounts will generally be 0.10 to
0.20 inches during this period...but some isolated heavier pockets
of precipitation will be possible...especially in the mountains. Brusda


updated 0530z.
VFR conditions will prevail through 21z Tuesday. Expect a few light
showers through 14z Tuesday over north central Montana. Then after 21z Tuesday
showers/ts will develop over SW Montana and move northeast through the
region. Some ts will produce brief heavy rain/gusty winds.
Thunderstorms will gradually diminish after 06z Tuesday. Brusda


Preliminary point temps/pops...
gtf 46 76 42 60 / 10 30 60 10
ctb 39 70 33 57 / 10 30 40 10
hln 45 75 40 62 / 10 30 60 10
bzn 42 73 40 60 / 20 40 60 40
wey 33 67 32 58 / 20 40 40 40
dln 43 71 40 59 / 20 40 40 40
hvr 41 80 42 63 / 10 20 60 10
lwt 46 76 43 60 / 20 30 60 20


Tfx watches/warnings/advisories...




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