Area Forecast Discussion
Issued by NWS Great Falls, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KTFX 121000
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
400 AM MDT Sat Jul 12 2014

.DISCUSSION...
Today through Monday...High pressure will generally remain in
place through the weekend meaning warm and mainly dry conditions
will continue. Moisture and weak disturbances originating from the
Southwest US will move into the region bringing a continued
chance for afternoon and evening thunderstorm activity along the
ID and WY border. High pressure gradually shifts to the east
Sunday before a shortwave trough from the Pacific heads towards MT
Monday. Expect an increased chance for more widespread showers and
thunderstorms Monday afternoon and evening as a result.
Temperatures will remain close to 90 in many locations through
Sunday, before cooling about 5 to 10 degrees Monday.

Monday Night through Saturday...Forecast models in reasonably good
agreement on expected conditions through midweek, but vary widely,
even from their own previous solutions, for the latter half of the
week. Extended period begins with a shortwave trof reaching the
Continental Divide Mon evening.  This system will bring along some
Pacific moisture, and possibly a small area of monsoonal moisture,
which the models turn into a broad swath of showers and
thunderstorms covering most of the area along/west of the Interstate
15 corridor on Mon night.  Have increased chances of precip for the
mentioned area but have some lingering concerns about how much
moisture will remain after storms develop west of the Divide on Mon
aftn. The trof weakens on Tues, but retains enough energy to
generate another round of scattered thunderstorms over southwest and
portions of central MT before slipping into south central MT and
Wyoming on Tues evening.  Dry conditions and warming temperatures
return for Wed through early Thurs aftn as high pressure ridging
moves across the state.  Forecast confidence from Thurs evening
onward is marginal at best, as model solutions struggle to find even
a hint of consensus at this point.  Since the ECMWF model shows at
least some slight continuity with its previous runs, current
forecast leans toward its solution of northwest flow aloft with
embedded shortwaves bringing scattered precipitation to central and
north-central MT on Fri and Sat, while southwest MT remains mostly
dry both days.  High temps will cool back to the upper 70s to low
80s in response to the northwest flow.
Waranauskas

&&

.AVIATION...
UPDATED 0445Z.
VFR conditions are expected to continue through at least Saturday
evening. Monsoonal moisture moving over the weakly unstable airmass
over southwest Montana will continue to cause isolated thunderstorms
with wind gusts to around 35 kt, brief heavy rain, and small hail
over the area south of KHLN (including the KBZN terminal) through at
least 10Z. Isolated storms will likely regenerate over this same
area after 21Z on Saturday as the moisture feed remains in place.
Otherwise, the weak northwesterly flow aloft will persist across
north central and central Montana, likely only bringing scattered
mid/high level cloudiness to that area.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  88  56  90  56 /   0   0   0   0
CTB  86  52  88  52 /   0   0   0   0
HLN  91  58  94  59 /  20  20   0   0
BZN  87  52  89  52 /  20  20  10  10
WEY  80  42  83  42 /  40  40  10   0
DLN  86  54  89  56 /  30  30  10  10
HVR  90  55  90  52 /   0   0   0   0
LWT  86  54  88  52 /  10   0   0   0

&&

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

$$

weather.gov/greatfalls
www.twitter.com/NWSGreatFalls
www.facebook.com/US.NationalWeatherService.GreatFalls.gov





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.