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000
FXUS65 KTFX 211746
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1140 AM MDT Fri Sep 21 2018

Aviation Section Updated.

.UPDATE...

Few updates needed this morning. Flat ridging pattern will bring
warmer, and at times breezy southwest flow today. Bumped up temps a
little bit to account for these warming winds. Areas across the
north will see patchy fog linger through much of the morning hours,
then quickly burn off around noon. A stalled frontal boundary could
bring a few brief isolated rain showers to the north today, while
moist sw flow brings some chances for scattered showers along the
Rocky Mountain Front. Precip activity diminishes tonight. Saturday
looks to see mainly dry conditions, seasonal temperatures, and some
increased afternoon breezes at times. Anglin

&&

.SYNOPSIS...

Weak high pressure and westerly flow aloft will bring warmer and
drier conditions to the region today through Saturday with breezy
afternoon winds. A weak cold front slides southeast across north-
central and southwest Montana Sunday for a chance of showers and
cooler temperatures.

&&


.AVIATION...
Updated 1740Z.

VFR conditions prevail at area terminals. SCT low clouds persist
this afternoon over the Northern Rockies and extend east across the
HiLine. Stronger westerly winds aloft are producing a Chinook Arch,
or high clouds along and east of the Continental Divide. Satellite
imagery reveals wave activity that could suggest turbulence across
the region. Breezy winds are expected this afternoon along the east
slopes of the Rockies as well as portions of SW MT before
diminishing again tonight. Fog may be possible near the KCTB/KHVR
terminals early Saturday, but do not have sufficient confidence to
include so late in the TAF period.

&&

.PREV DISCUSSION...
/ISSUED 511 AM MDT Fri Sep 21 2018/

Weak upper level ridging shifts east across the Northern Rockies
and MT today for generally dry conditions though substantial
cloud-cover will stream across northern portions of the forecast
area. Areas of fog have developed in the Milk river vicinity
early this morning where skies partially cleared overnight and may
persist through mid morning before dissipating. Temperatures warm
above seasonal averages this afternoon and again on Saturday as
flow aloft shifts slightly southwesterly ahead of an upper level
trough moving onto the west coast. Weak surface low pressure
developing from the Great Basin NE into central MT later today
through Saturday will allow for winds to become breezy during the
afternoon period today and again Saturday.

Upper trough moving onto the west coast Saturday shifts east
across the Northern Rockies and MT Sunday with an associated
Pacific front at the surface sliding southeast across the area.
Scattered showers accompany the front on Sunday with greatest
coverage over portions of central and SW MT. Temperatures also
cool back to slightly below seasonal averages Sunday.

A NW flow aloft follows Monday through much of next week as an
upper level ridge amplifies off the west coast while an upper
level ridge deepens across central portions of North America.
Through mid-week, models are in fair agreement but differ with
timing and amount of moisture associated with embedded
disturbances in NW flow aloft. Good agreement does exist however
on the arrival of a cooler airmass from the north around the
Wed/Thurs period. Hoenisch

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  72  44  71  44 /   0   0   0  30
CTB  66  37  64  38 /  10  10  10  10
HLN  74  44  73  46 /   0   0   0  20
BZN  73  41  76  43 /   0   0   0   0
WEY  64  29  71  32 /   0   0   0   0
DLN  72  40  73  43 /   0   0   0   0
HVR  67  42  69  43 /  20  10  10  20
LWT  70  42  70  42 /   0   0   0  10

&&

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

$$

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