Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 201610
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1010 AM MDT Sun Jul 20 2014

.UPDATE...
Minor forecast updates this morning. Removed the mention of smoke
across Central Montana as satellite shows most has moved into
southern Canada and eastern Montana. Breezy west winds will
continue today but should slowly taper off through the evening. A
High Wind Warning remains in effect for the northern Rockies but
winds should diminish there as well. Overall should be a mostly
sunny warm day with highs in the mid to upper 80s.

&&

.AVIATION...
UPDATED 1155Z.
Increasing southwest flow aloft bringing moisture and instability,
coupled with a disturbance aloft approaching from the west, will
result in isolated thunderstorms over the mountains of southwest
Montana after 21z. Surface winds will again become gusty after 16z
with the strongest winds over the Northern Rocky Mountain Front.
Winds should diminish after 00z. VFR conditions prevail with MVFR
conditions possible in the vicinity of thunderstorms.

&&

.PREV DISCUSSION...
/ISSUED 555 AM MDT Sun Jul 20 2014/
Sunday through Tuesday...Zonal winds will remain strong through
the day Sunday before becoming more Southwesterly as the
upper level trough over Canada moves eastward towards the Hudson
Bay, and a second closed low moves south off the Canadian Pacific
Coast towards Portland Oregon. This southwesterly flow will bring
a few shortwave troughs that should create a better chance of
showers and thunderstorms to develop Monday and Tuesday across the
area...especially during the peak heating of the afternoon hours.
Temperatures are expected to remain near seasonal averages, and
gusty winds are expected to develop Sunday afternoon especially
over the mountains of the Northern Rocky Mountain Front where a
high wind warning is in effect. Smoke from fires in Oregon Idaho
and Washington will continue to move into the area and could
reduce visibility along with reducing air quality. Suk

Tuesday night through Sunday...Not many significant changes to the
medium range period. The period begins with the upper ridge axis
over eastern Montana and southwest flow aloft continuing to bring
moisture and instability to the area, resulting in scattered
thunderstorms Tuesday night. Wednesday will find a closed upper low
approaching the Pacific Northwest with increasing diffluent flow
aloft over the area. Short wave energy spinning out from the low and
associated trof will aid in thunderstorm development across the area
Wednesday afternoon through evening. The models are fairly
consistent placing the upper low over southern Alberta by Thursday.
The ECMWF has the low further north than either the GFS or the GEM.
Regardless, none of the models have much in the way of qpf
associated with this feature, mainly isolated convective activity
across the northeast. With the low moving east into Saskatchewan
Friday, the flow aloft becomes westerly once again and the airmass
begins to dry. Upper ridging over the area during the weekend brings
dry condition, though some moisture works its way north from the
southwest U.S. Sunday and brings a chance of isolated thunderstorms
over the southwest mountains. Temperatures will be above seasonal
averages to start the period but will drop below seasonal averages
from midweek through the weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  87  58  81  58 /  10  10  50  30
CTB  80  53  80  50 /  10  20  20  10
HLN  90  60  82  59 /   0  10  50  40
BZN  90  56  79  53 /   0  10  60  50
WEY  80  45  71  40 /  10  20  70  50
DLN  88  55  76  51 /   0  10  60  40
HVR  88  57  85  56 /  10  20  30  20
LWT  89  57  81  56 /  10  10  50  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WARNING until Midnight MDT tonight Northern Rocky
Mountain Front.

&&

$$

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