Area Forecast Discussion
Issued by NWS Great Falls, MT
FXUS65 KTFX 252329
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
530 PM MDT Sat May 25 2013
...UPDATE TO AVIATION...
Tonight through Monday...A persistent broad upper level trough
will continue to reside over the Pacific Coast and keep southwest
flow over the region. Expect multiple shortwave troughs to move in
over Montana helping to amplify showers and thunderstorms by
giving support to surface based convection. Good precipitable
water values will keep seasonal chances for showers through the
short term. The potential for widespread showers and scattered
thunderstorms will increase Sunday and Monday as embedded troughs
move through the flow. Expect temperatures to remain mild with
highs mostly in the mid 60s to low 70s.
Monday night through Saturday...No significant changes in the medium
range. Unsettled conditions will persist through the period as the
area will be under the influence of a broad upper trof with multiple
shortwaves rotating through the flow. Southwest flow aloft will
continue to bring moisture, instability, and lift into southwest
Montana resulting in the development of afternoon thunderstorms that
will spread north and east across the plains through the period.
Models agree on this overall picture but differ on specifics
regarding precipitation amounts and locations of heavier rain.
Temperatures will remain near or slightly below seasonal averages.
Variably moist and somewhat unstable southwest flow aloft will
remain over western and central Montana through late Sunday
afternoon. Scattered showers and a few thunderstorms will move
through the forecast area through 04Z with local MVFR possible in
heavy downpours. Skies clear overnight after evening convection dies
off with widespread VFR conditions expected through 18Z Sunday.
After 18z, another wave moves over the region with scattered to
numerous showers and thunderstorms developing across southwest and
central Montana once again. mpj
.PRELIMINARY POINT TEMPS/POPS...
GTF 42 70 46 66 / 20 40 50 50
CTB 40 73 45 62 / 20 30 60 70
HLN 44 71 47 69 / 30 50 50 60
BZN 40 73 42 68 / 30 40 50 40
WEY 35 64 36 62 / 20 30 50 40
DLN 39 67 40 69 / 30 50 50 30
HVR 44 77 47 69 / 20 40 50 60
LWT 43 69 46 66 / 30 50 50 50