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Area forecast discussion 
National Weather Service Great Falls Montana
320 am MDT Tuesday Jun 2 2015

Discussion...

Today through Thursday...an upper level low pressure system will be
over the Pacific northwest Tuesday and move very little through
Thursday. This will leave the zones underneath disturbed and rather
moist southwest flow aloft. Water vapor indicates considerable
moisture in the southwest flow ahead of the system. This is
associated with a disturbance rotating through the flow aloft and
will bring precipitation across mainly the northern zones this
morning. Instability will not be as great this afternoon as
yesterday although the convective temperature will be quite low, and
afternoon and evening convection is again expected. Greatest
instability will generally be along and south of a Great Falls to
Lewistown line. Wednesday will be a day between shortwaves and
will not be as active. However, afternoon instability will develop
again with showers and afternoon thunderstorms in the area.
Another good disturbance will move through the area late Wednesday
night and Thursday and bring scattered to numerous showers across
the zones. The airmass will trend cooler through Wednesday before
warming again Thursday. Temperatures will remain below normals
through Thursday. Zelzer

Thursday night through Monday...medium range models are in very good
agreement with the overall pattern. An upper level trough of low
pressure will remain over the western United States through the
period with its low pressure center initially staying over the
California coast. The chance for showers/thunderstorms will decrease
Thursday night as a shortwave trough exits the area. Another
shortwave will eject from the trough and bring a good chance of
showers and thunderstorms to the area again for Friday afternoon and
evening. The low pressure center will then move north into the
western Great Basin for Saturday through Sunday. This will keep a
good chance of showers and thunderstorms over southwest Montana, but
weak high pressure to the north of this low will hinder shower and
thunderstorm development across north central Montana. The low will
then weaken as it moves north into the northern rockies on Monday,
but with it moving overhead, there will be a good chance for showers
and thunderstorms for the entire forecast area. Temperatures will
remain fairly constant through the period. Highs will be near normal
(upper 60s to lower 70s), but lows will be quite mild (mid 40s to
lower 50s), remaining 5 to 10 degrees warmer than normal.
Coulston

&&

Aviation...
updated 0550z.

VFR conditions are generally expected to continue, unless otherwise
mentioned. The moist and unsettled southwest flow aloft will
continue over the forecast area through at least Tuesday evening. A
surface boundary will remain draped northwest to southeast across
north central and central Montana. Lift to the north of the boundary
will keep showers with low VFR/high MVFR conditions and mountain
obscuration along the hi-line through the period. Central and
southwest Montana will see a brief respite from showers through
around 15z, allowing patchy fog to form with low MVFR/high IFR
conditions possible at times. However, showers/storms will linger
along the Continental Divide, obscuring mountains there. Another
disturbance will move through the area after 12z and spread numerous
showers with low VFR/high MVFR conditions and mountain obscuration
over southwest and central Montana. The airmass will also become
weakly unstable between 18z and 03z, allowing scattered embedded
thunderstorms to form, but they will likely remain weak. Coulston

&&

Preliminary point temps/pops...
gtf 62 46 66 49 / 70 40 40 60
ctb 53 41 64 43 / 90 50 20 40
hln 67 47 69 50 / 70 40 40 60
bzn 67 44 68 47 / 60 50 30 40
wey 62 35 62 38 / 30 20 30 50
dln 66 43 66 44 / 50 40 50 50
hvr 59 45 69 47 / 70 60 30 50
lwt 62 45 65 48 / 70 50 40 50

&&

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

$$

Weather.Gov/greatfalls

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