Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 310935
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
335 AM MDT Thu Jul 31 2014

.DISCUSSION...

Today and Friday...The hot temperatures will continue. Highs are
still forecast to be in the lower/middle 90s. In general,
afternoon and evening MLCAPE will peak in the 500-1000 J/kg range
across the area. However, on Friday afternoon a weak boundary and
associated wind shift will move southward out of Alberta into
northern NC Montana. The air mass behind the boundary
will be fairly moist with surface dewpoints in the 50s which will
potentially increase MLCAPE to near 1500 J/kg. 0-6 km shear will
remain below 30 kts, so only a few isolated strong storms are
possible mainly NW of Cascade County.

NAM and GFS both depict area of high 500 mb RH developing near the
Sierra Mountains Thursday evening and then tracking it northeastward
across the NW portion of my CWA Friday night. The NAM seems to be
over doing the QPF attendant to this feature and paints an area of
greater than 0.30 inches. The GFS and EC have benign sensible
effects associated with the disturbance so opted to ignore the NAM
for now.

Saturday...As the aforementioned airmass sags southward through
north-central Montana PW will also increase to near 1 inch as far
south as Great Falls. Isolated to scattered showers and storms are
expected with some storms likely producing brief heavy rain. Highest
instability will once again be found up along the Hi-line with
MLCAPE values approaching ~1000-1500 J/kg. More widespread
convective cloud development should hold temps in the mid/upper
80s. Uttech

Saturday Night through Thursday...Very warm temperatures and
isolated to scattered thunderstorms are expected across the Treasure
State this weekend through early next week. There still remains some
uncertainty regarding precipitation amounts/coverage due to
differences in the various forecast model solutions, however the
best precipitation chances will be along the Continental Divide and
southwest Montana. As for timing of precipitation, latest forecast
models suggest that the best chances will be Saturday and Sunday
afternoon/evening with stronger shortwave troughs and Monsoonal
moisture. Drier conditions will return by the latter half of next
week as a ridge of high pressure builds over the Northern Rockies.
MLV

&&

.AVIATION...
UPDATED 05Z.
VFR conditions will prevail through this TAF period. Isolated
showers and thunderstorms will develop and move across the area
Thursday afternoon until sunset when thermal convection will cut off
any overnight precipitation potential. Ceilings and visibilities may
drop briefly near any shower or thunderstorm...that may also produce
gusty erratic winds. Suk

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  93  59  91  61 /  20  20  10  20
CTB  91  53  88  55 /  20  20  20  30
HLN  95  60  93  61 /  20  20  10  20
BZN  90  53  90  54 /  20  20  10  20
WEY  79  42  79  43 /  40  40  30  30
DLN  86  53  86  54 /  30  30  20  30
HVR  98  57  96  59 /  20  20  20  20
LWT  92  56  91  56 /  20  20  10  20

&&

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

$$

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