Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 020259
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
859 PM MDT Fri Aug 1 2014

.UPDATE...
The strongest storms this afternoon/evening were along US Highway
2 between Cut Bank and Havre. One storm near Chester produced over
1 inch of rainfall and hail up to dime size. Brief heavy rain,
smaller hail, and wind gusts to 40 mph occurred with other storms.
At this time, a cluster of storms continues across north central
Chouteau County (in the Big Sandy area), but these storms should
diminish through midnight. Weaker storms were also common over the
mountains of western and southwest Montana. Currently, the storms
likely producing brief heavy rain extend from Boulder and Helena
northwest through Lincoln. Have therefore increased POPs to at
least scattered for that area through midnight. Overall, storm
activity will decrease overnight. However, a disturbance will
move through the area after midnight, keeping a chance of
scattered showers and thunderstorms northwest of a Great Falls to
Havre line, with a lesser chance elsewhere. Otherwise, the
forecast remains on track.
Coulston


&&

.AVIATION...
UPDATED 0300Z.
Scattered Showers and an isolated thunderstorm will continue to
move across the area this evening. Most of the shower activity is
expected to end before 06z. VFR conditions are expected to
dominate overnight, with a return to scattered convections
starting again in the afternoon hours Saturday confidence is low
on timing and likelihood of impacts to TAF sites at this
time...however subsequent TAF forecast will be able to better
define the convective threat on Saturday.

&&

.PREV DISCUSSION...
/ISSUED 250 PM MDT Fri Aug 1 2014/
Tonight through Sunday...Short wave energy moves across the area
tonight. With an unstable airmass already in place, isolated
thunderstorms have begun to develop and will continue through the
evening. As has been the case the past few days, bulk shear is
very low and severe convective activity is not too likely. Models
continue to place a vort center moving across northern Montana
overnight and this may keep showers going. A stronger mid level
impulse will move across the area Saturday with thunderstorms
developing again during the afternoon and becoming a bit more
widespread in areal coverage. Precipitable water values also
increase a bit on Saturday. The pattern will continue through the
weekend with additional short wave energy kicking off isolated
thunderstorms again Sunday afternoon. Temperatures will continue
slightly above seasonal averages.

Sunday Night through Friday...A repeat of the current pattern
continues through the long term. Warm temperatures and isolated to
scattered thunderstorms will develop each afternoon, generally
starting up over terrain. With the showery nature of monsoonal
moisture, uncertainty remains with precipitation amounts and
coverage. Areas near higher terrain have the best chance of seeing
precipitation, namely the Continental Divide and Southwest Montana.
Latest forecast model runs suggest that increased coverage of
showers will develop Sunday afternoon/evening as a more defined
shortwave trough moves through the region. Drier conditions return
later next week as a high pressure rebuilds over the region.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  88  60  89 /  20  30  20  20
CTB  54  83  57  84 /  30  30  30  20
HLN  59  90  59  89 /  40  30  30  20
BZN  53  91  56  88 /  20  30  30  20
WEY  44  79  48  80 /  30  20  20  30
DLN  52  87  54  86 /  30  30  30  20
HVR  58  88  61  90 /  20  30  20  20
LWT  56  85  58  86 /  10  30  20  20

&&

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

$$

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