Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 281459
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
859 AM MDT Sun May 28 2017

.UPDATE...

Isolated rain showers continue to drift toward the SSE across
N-central MT this morning. Additional rain showers and and
thunderstorms are expected through this afternoon across Central
MT. The current forecast is in good shape, not needing updates at
this time.


&&

.SYNOPSIS...

An upper level ridge of high pressure currently over the Pacific
Northwest will slowly move eastward over the next few days. As a
result, scattered showers and thunderstorms today, will become more
isolated for Monday and Tuesday. Afternoon temperatures will be near
normal today, then gradually warm to near 10 degrees above normal by
Tuesday afternoon.

&&

.DISCUSSION...


&&

.AVIATION...
Updated 1133Z.

One cold front is drifting south across central MT at this time and
will be accompanied by brief SHRA over the next few hours (mainly
impacting KGTF/KLWT). A second, stronger, cold front will drop south
out of Canada later today bringing another round of SHRA/TSRA. MVFR
VIS will be possible with any heavier SHRA/TSRA this afternoon, as
well as gusty winds in excess of 30kt and perhaps some small hail.
SHRA/TSRA will gradually decrease from north to south as the front
shifts south. From KHVR to KLWT, a tight pressure gradient behind
the front will lead to a period of stronger wind gusts this
afternoon. By tonight, high pressure moves in with decreasing winds
and perhaps some BR/FG. Martin

&&

.PREV DISCUSSION...
/ISSUED 533 AM MDT Sun May 28 2017/

Today through Tuesday...The main focus in the short term is the next
24 hrs or so. Beyond that, an upper level ridge will gradually build
in with shower and thunderstorm activity expected to be limited to
the higher terrain.

Latest SFC analysis shows one cold front stretching from Cut Bank to
Great Falls and then east through the remainder of Montana. To the
north, a secondary cold front was dropping south through central
AB/SK. Showers associated with the first front have remained
isolated, with a general decreasing trend in coverage noted. A few
lightning strikes have been noted over southern AB early this
morning, but much of our area remains fairly stable and for now,
opted to keep out any mention of thunder for the rest of the AM, but
this will be closely monitored.

The second front will push into central Montana by early this
afternoon, then reach SW MT by this evening. Ahead of this front,
isolated to scattered showers and thunderstorms will likely develop
with the heating of the day, mainly along and south of a Cut Bank to
Lewistown line. While instability still looks better today compared
to the past couple of days, it remains on the weaker side, as does
shear. Still, any stronger storm today could produce gusty winds of
30-40 mph and small hail. In the wake of the front, a tightening
pressure gradient and steep lapse rates will lead to breezy
conditions from Havre to Lewistown with 30+ mph gusts likely. High
pressure then builds in tonight with much cooler temperatures,
lighter winds, and perhaps some patchy fog. Martin

Tuesday night through Sunday...An upper level ridge of high pressure
will be over the region to begin the period, but then gradually
breaks down by next weekend. How much the ridge breaks down
differs quite a bit when you compare the GFS/EC models. However,
the GFS continues to prog a fairly good chance for precipitation
Thursday afternoon/evening...thus pops have been raised closer to
the National Blend solution for this period. Isolated showers
continue for Fri/Sat...while another round of a better chance for
showers/thunderstorms arrives next Sunday afternoon/evening.
Temperatures will likely be above normal through the extended
period, with Wednesday likely being the warmest day with afternoon
temperatures about 8 to 12 degrees above normal. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  69  43  73  45 /  40  10   0   0
CTB  69  42  72  43 /  20  10   0   0
HLN  73  47  77  48 /  20  10   0   0
BZN  70  41  74  42 /  30  20   0   0
WEY  61  34  66  34 /  30  10  10  10
DLN  71  43  74  44 /  20  10  10  10
HVR  74  39  73  41 /  10   0   0   0
LWT  65  39  67  41 /  30  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/greatfalls


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