Weather Service Report


985 
FXUS65 KTFX 291655
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1055 AM MDT Mon May 29 2017

UPDATED AVIATION

.UPDATE...

Little needed for update this morning. SPC has continued its
general risk of thunderstorms from about Cut Bank to Lewistown to
Billings and westward. Most of the instability in this area will
be confined to the mountains...making for a few isolated mountain
thunderstorms today...with some gusty winds and small hail. Those
recreating at the higher elevations should be alert for changing
weather. There is a small chance a thunderstorm or two may 
venture away from the mountains in Glacier County later this 
afternoon into the evening hours. Elsewhere will see a warm and 
mainly dry day...with light winds coming out of the north and 
northeast. Anglin

&&

.SYNOPSIS...

With an upper level ridge of high pressure residing over the
region for the next few days, expect above normal temperatures
across the region. Wednesday looks to be the warmest day this
week, with afternoon highs in the mid 80s. Precipitation chances
will be confined mostly to the mountain areas today through 
Wednesday.

&&

.AVIATION... 
Updated 1655Z.

Mainly VFR and quiescent conditions expected next 24-hours as high 
pressure continues building-in from the west. Thus, northwesterly 
flow aloft will persist. A few showers and thunderstorms may develop 
over higher terrain by mid to late afternoon and persist through 
about 03Z/Tue. Cannot completely rule out a shower or thunderstorm 
drifting over the plains immediately east of the Rocky Mountain 
Front, including KCTB.
Jaszka

&&

.PREV DISCUSSION...
/ISSUED 342 AM MDT Mon May 29 2017/
Today through Wednesday...With an upper level ridge over the
region, a nice warming trend is expected across the entire region.
Afternoon highs will be above normal today through Wednesday, with
Wednesday likely being the warmest day this week. I did raise
temperatures a few degrees over the national blend during the
afternoon hours each day. A weak mid level disturbance moving 
southward along the front range of the Rockies this morning is 
producing some light rain showers. Most of these showers will 
diminish by mid morning. However, additional showers/isolated 
thunderstorms could develop this afternoon, mostly over the 
mountains. A repeat of mainly mountain showers/thunderstorms is 
possible Tue/Wed...mainly during the afternoon and evening hours. 
At this time the main threat from any thunderstorms that do 
develop looks to be brief heavy rain and gusty winds. Brusda

Wednesday Night through Monday...The upper level ridge in place at 
the start of the period is unlikely to stick around long as a broad 
upper level trough begins to be carved out from the Pacific Ocean 
into the Western US. Given the pattern, it is likely that a more 
active and unsettled period will ensue across the area beginning mid-
week and potentially continuing beyond Day 7.

Within this pattern, it is likely that several Pacific cold fronts 
will traverse the region, each bringing a chance of showers and 
thunderstorms. Right now, it appears the greatest coverage of 
showers/storms will be Thursday and again later Sunday into Monday, 
although the timing is likely to change somewhat, especially with 
the front over the weekend. With both fronts, shear looks to be more 
than adequate for organized convection. However, instability remains 
the bigger question mark which leads to lower confidence regarding 
the potential of strong/severe storms. That said, the pattern 
certainly looks favorable for a few strong to severe storms if 
enough instability can be realized. Of note, CIPS Analog guidance 
shows a decent signal for a few strong/severe storms, especially on 
Thursday. Otherwise, the only other impact of note is the potential 
for stronger wind gusts Friday and again on Monday. Friday looks 
like the best setup for stronger, but below high wind criteria, 
winds. Late in the period, the models are hinting at a brief shot of 
below/well below normal temps, but too early to get specific on 
that. Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  75  50  81  50 /   0   0  10   0 
CTB  74  48  79  47 /  10  20   0   0 
HLN  77  52  83  52 /   0   0  10  10 
BZN  73  45  80  45 /   0   0  10  10 
WEY  65  39  72  36 /  10  10  20  10 
DLN  74  48  79  47 /   0   0  20  10 
HVR  75  46  81  47 /   0   0   0   0 
LWT  69  45  74  47 /   0   0   0   0 

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

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