Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 181735
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1133 AM MDT Mon Aug 18 2014

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...
No update necessary this morning as current forecast looks on track.
Weak high pressure will keep the area generally dry today. The
exception being southwest Montana where some monsoonal moisture will
contribute to possible isolated thunderstorms as well as along the
northern Rocky Mountain Front. Temperatures look good.

&&

.AVIATION...
UPDATED 1733Z.
VFR conditions will prevail through this forecast period. Weak
daytime instability will result in a few -SHRA or TS but only
mentioned VCTS at KLWT for the late aftn/evening. Felt probability
was too low at other terminals to mention precip. Also, gusty
erratic outflow winds will likely accompany any showers that form
across the region. Uttech

&&

.PREV DISCUSSION...Issued 349 AM MDT Mon Aug 18 2014

Today through Wednesday...A weak upper level ridge of high
pressure will be over the region today and tomorrow. This will
allow for very warm temperatures to move back into the
region...with afternoon highs generally ranging from the mid 80s
to lower 90s. There will be a chance for an isolated thunderstorm
today through tomorrow, but most of the storms will be confined to
Southwest Montana and the Glacier Park region. The main Canadian
cold front that will bring the return of cooler temperatures is
expected to move through the region on Wednesday afternoon. As a
result, Wednesday temperatures will still be on the warm side ahead
of the cold front. There will be enough dynamics/instability with
this cold front that a few strong storms could develop between Cut
Bank and Havre...and then in Southwest Montana...mainly south of a
Dillon to Bozeman line. I have added gusty thunderstorm winds to the
forecast for Wednesday over the north where the change in 3-hour
surface pressure is the greatest. We will continue to monitor the
severity of thunderstorm potential over the next few days. Brusda

Wednesday Night through Monday...Models continue to trend toward a
significant change in the weather later this week. An upper level
jet will carve out a broad trough over the Northern Rockies for an
increasing chance of showers and thunderstorms Wednesday night and
Thursday. Models also continue to suggest that there will be a good
chance for widespread precipitation across North Central Montana by
Friday so have continued to trend PoPs higher for late this week.
Temperatures are expected to fall below seasonal averages with the
coolest temperatures anticipated for Friday and Saturday. Higher
elevations of Glacier Park may see snow mixed in with the rain early
Saturday morning but widespread accumulations are not anticipated.
Models diverge Sunday and Monday with the ECMWF continuing to
accelerate the upper trough eastward while the GFS holds it back
over the Northern Rockies. Will continue cool temperatures with PoPs
remaining above seasonal averages for now. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  86  56  89  58 /   0   0  10  10
CTB  83  58  84  56 /  20  10  10  10
HLN  88  56  90  59 /   0   0  10  10
BZN  86  49  89  54 /  20  10  20  30
WEY  77  40  78  47 /  20  20  20  30
DLN  84  49  85  49 /  20  10  20  20
HVR  86  56  91  61 /   0   0   0  10
LWT  82  55  88  58 /   0   0  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

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