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000
FXUS65 KGGW 280902
AFDGGW

Area Forecast Discussion
National Weather Service GLASGOW MT
302 AM MDT SAT MAY 28 2016

.SHORT TERM...for northeast Montana...today through Mon...

The day begins with a cold front lined up north-south across the
western zones. The front is associated with an upper trough
centered over Southern British Columbia. Flow aloft over Northeast
Montana will be southerly to southwesterly which will direct
moisture across the front. This will produce a narrow area of
moderate rain. Convective parameters become moderate by noon which
will initiate general thunderstorms along with the rain showers.
As the front and best lift progress east so does the convection
and rain. By early evening the trough lifts back north into
canada, allowing flow aloft to become westerly and ending the
showers and thunder.

Conditions remain unchanged for Saturday night and Sunday with
this western flow. Therefore expect pleasant weather conditions
with temperatures moving above average. Then conditions begin to
change again Sunday night as another trough drops into the Pacific
Northwest. Once again flow aloft backs to the southwest to bring
in more moisture and instability. Showers that begin after
midnight will become more widespread for Monday. The trough will
dig into Northeast Montana which will begin to increase winds as
the storm attempts to stack up over the area. With a more
energetic wind profile, some storms may become more vigorous with
the possibility of some dry slotting by afternoon. Expect
temperatures to return to near normal.

Templer

.LONG TERM...Mon night through Sat...

Upper low will be over Eastern Montana Monday Night. This low will
combine with an inverted surface trough and deep moisture to bring
showers with embedded thunderstorms to the forecast area. This low
will move into North Dakota on Tuesday and back side wrap around
moisture will remain over Eastern Montana the entire day with
showers and embedded thunderstorms continuing.

Tuesday Night and Wednesday, the low moves to Minnesota and upper
ridge moves into Western Montana. Drier air moves into the
forecast area allowing the showers to diminish.

The upper ridge moves into Eastern Montana on Thursday with warmer
temperatures and dry weather.

A weak shortwave trough Thursday Night and Friday will flatten the
ridge. With limited moisture, will maintain dry forecast. Ridge
rebounds on Saturday with warm and dry weather. Forrester



&&

.AVIATION...

SYNOPSIS: An upper level trough and frontal system will move
through Eastern Montana today. This will bring a good chance of
showers and thunderstorms with it. Expect MVFR briefly with the
showers as they move through the region. Otherwise VFR shall
continue to dominate the flight category for the terminals. High
pressure will bring mostly clear skies tonight.

Wind: East winds around 10 knots will turn to the west by
afternoon. Winds will be light and variable tonight.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

weather.gov/glasgow



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000
FXUS65 KTFX 280610 CCA
AFDTFX

Area Forecast Discussion...CORRECTED
National Weather Service Great Falls MT
1150 PM MDT FRI MAY 27 2016

Aviation Section Updated.

.UPDATE...Pacific cool front has pushed through much of the Great
Falls forecast area this evening. Scattered/numerous showers and a
few thunderstorms are still expected over eastern portions of
central Montana overnight and into Saturday morning. Some showers
and thunderstorms are also possible over far southern portions of
southwest Montana. However, much of the remainder of the forecast
area will likely see only isolated light rain showers or no
precipitation at all as a drier airmass moves into the region.
Have updated forecast PoPs/weather/QPF to take the latest model
runs and observations into account. Have also made minor tweaks to
max and min temperatures as well as the hourly diurnal temperature
curve based on latest short term model updates. mpj

&&

.AVIATION...
UPDATED 2355Z.

Drier air is advancing eastward following a Friday afternoon frontal
passage. Skies have cleared along the Rocky Mountain Front. For
eastern portions of central Montana, rain showers will be slow to
dissipate overnight. Hence MVFR conditions prevail at KHVR/KLWT
through early morning. VFR conditions prevail at all terminals
through the day Saturday. PN

&&

.PREV DISCUSSION...
/ISSUED 555 PM MDT FRI MAY 27 2016/

Tonight through Sunday...Water vapor pix show a low pressure trof
moving over the Rockies. The airmass has become slightly unstable
and radar shows isolated convective activity across most of the CWA.
A surface cold front is moving through the region...wind shift is
already into Eastern Montana...and cooler, drier air is moving in
from the west. However, convection will linger into the evening
across the southwest and eastern zones. The airmass will become
slightly unstable again Saturday and Sunday afternoons across
portions of Southwest Montana but the change to drier air will keep
most of the region dry through Sunday. West winds aloft will bring
stronger winds across the slopes of the Rockies and adjacent plains
Saturday and Sunday afternoon although, in general, winds will
remain light. Temperatures will remain below seasonal normals behind
the cold front but trend slowly upwards towards seasonal normals by
Sunday. Zelzer

Sunday night through Friday...The period starts with a fairly potent
shortwave trough digging SE into the Pac NW. At this time, the
models still differ on the exact evolution of this feature. The
GFS/CMC/GEFS are stronger and more moist while the ECMWF/ECMWF
ensembles keep the wave open/weaker and more progressive with less
moisture. For now, planning to keep with previous forecasts and WPC
and lean towards the more progressive/slightly drier solution seen
in the ECMWF. Regardless of model choice, it appears that the axis
of heaviest precipitation with this system through Monday will be
across the eastern half of our CWA (ie. along and east of a Bozeman
to Havre line). In this area, the potential exists for up to an inch
of QPF for some locations, even if the drier solutions pan out.
Hydrology-wise, it will be something to keep an eye on given recent
rainfall in that area, especially for small streams/creeks, such as
Clear Creek. With Monday`s system, snow levels look to drop down
into the 7-8k ft range, but could drop a bit lower if the shortwave
slows down/closes off.

Once the Memorial Day system moves out, the models are in decent
agreement with building an upper level ridge across the western US,
something we haven`t seen in awhile. This should bring a period of
warmer/drier conditions. Of note, though, the GFS isn`t quite as
strong with the ridge and actually brings a few weak shortwaves
through the area. Will keep low chance pops in later next week, but
at this time it looks like the best chance of seeing a shower or
storm will be across the higher terrain. Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  63  41  69 /  20  10  10  10
CTB  37  61  39  65 /  10  10  10  10
HLN  42  64  42  70 /  20  10  10  20
BZN  40  63  39  71 /  50  20  10  10
WEY  34  54  32  60 /  60  30  20  10
DLN  38  62  38  68 /  40  20  10  10
HVR  46  66  42  70 /  80  30  10  10
LWT  42  63  41  68 /  90  30  10  20

&&

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

$$

weather.gov/greatfalls




000
FXUS65 KTFX 280323 CCA
AFDTFX

Area Forecast Discussion...CORRECTED
National Weather Service Great Falls MT
923 PM MDT FRI MAY 27 2016

.UPDATE...Pacific cool front has pushed through much of the Great
Falls forecast area this evening. Scattered/numerous showers and a
few thunderstorms are still expected over eastern portions of
central Montana overnight and into Saturday morning. Some showers
and thunderstorms are also possible over far southern portions of
southwest Montana. However, much of the remainder of the forecast
area will likely see only isolated light rain showers or no
precipitation at all as a drier airmass moves into the region.
Have updated forecast PoPs/weather/QPF to take the latest model
runs and observations into account. Have also made minor tweaks to
max and min temperatures as well as the hourly diurnal temperature
curve based on latest short term model updates. mpj

&&

.AVIATION...
UPDATED 2355Z.

A cold front continues to slowly progress ENE across the area at
this time. Scattered SHRA/TSRA associated with the front will
continue to lift slowly ENE through this evening as well. Occasional
MVFR VIS/CIGS and mtn obscurations will be possible as the showers
move through, mainly in the vicinity of KLWT/KHVR. The coverage of
SHRA may increase some from KLWT to KHVR tonight along and just
behind the front with a continued threat of MVFR CIGS/VIS and
mountain obscurations. The coverage of SHRA will gradually decrease
from west to east after 06z/SAT with improving VIS/CIGS. SHRA may
redevelop across SW MT on SAT, but for now, confidence isn`t high
enough to put SHRA at KBZN. In the wake of the front, gusty winds
are likely across north-central MT SAT afternoon. Martin

&&

.PREV DISCUSSION...
/ISSUED 555 PM MDT FRI MAY 27 2016/

Tonight through Sunday...Water vapor pix show a low pressure trof
moving over the Rockies. The airmass has become slightly unstable
and radar shows isolated convective activity across most of the CWA.
A surface cold front is moving through the region...wind shift is
already into Eastern Montana...and cooler, drier air is moving in
from the west. However, convection will linger into the evening
across the southwest and eastern zones. The airmass will become
slightly unstable again Saturday and Sunday afternoons across
portions of Southwest Montana but the change to drier air will keep
most of the region dry through Sunday. West winds aloft will bring
stronger winds across the slopes of the Rockies and adjacent plains
Saturday and Sunday afternoon although, in general, winds will
remain light. Temperatures will remain below seasonal normals behind
the cold front but trend slowly upwards towards seasonal normals by
Sunday. Zelzer

Sunday night through Friday...The period starts with a fairly potent
shortwave trough digging SE into the Pac NW. At this time, the
models still differ on the exact evolution of this feature. The
GFS/CMC/GEFS are stronger and more moist while the ECMWF/ECMWF
ensembles keep the wave open/weaker and more progressive with less
moisture. For now, planning to keep with previous forecasts and WPC
and lean towards the more progressive/slightly drier solution seen
in the ECMWF. Regardless of model choice, it appears that the axis
of heaviest precipitation with this system through Monday will be
across the eastern half of our CWA (ie. along and east of a Bozeman
to Havre line). In this area, the potential exists for up to an inch
of QPF for some locations, even if the drier solutions pan out.
Hydrology-wise, it will be something to keep an eye on given recent
rainfall in that area, especially for small streams/creeks, such as
Clear Creek. With Monday`s system, snow levels look to drop down
into the 7-8k ft range, but could drop a bit lower if the shortwave
slows down/closes off.

Once the Memorial Day system moves out, the models are in decent
agreement with building an upper level ridge across the western US,
something we haven`t seen in awhile. This should bring a period of
warmer/drier conditions. Of note, though, the GFS isn`t quite as
strong with the ridge and actually brings a few weak shortwaves
through the area. Will keep low chance pops in later next week, but
at this time it looks like the best chance of seeing a shower or
storm will be across the higher terrain. Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  63  41  69 /  20  10  10  10
CTB  37  61  39  65 /  10  10  10  10
HLN  42  64  42  70 /  20  10  10  20
BZN  40  63  39  71 /  50  20  10  10
WEY  34  54  32  60 /  60  30  20  10
DLN  38  62  38  68 /  40  20  10  10
HVR  46  66  42  70 /  80  30  10  10
LWT  42  63  41  68 /  90  30  10  20

&&

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

$$

weather.gov/greatfalls




000
FXUS65 KTFX 272355
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
555 PM MDT FRI MAY 27 2016

...Aviation Section Updated...

.DISCUSSION...

Tonight through Sunday...Water vapor pix show a low pressure trof
moving over the Rockies. The airmass has become slightly unstable
and radar shows isolated convective activity across most of the CWA.
A surface cold front is moving through the region...wind shift is
already into Eastern Montana...and cooler, drier air is moving in
from the west. However, convection will linger into the evening
across the southwest and eastern zones. The airmass will become
slightly unstable again Saturday and Sunday afternoons across
portions of Southwest Montana but the change to drier air will keep
most of the region dry through Sunday. West winds aloft will bring
stronger winds across the slopes of the Rockies and adjacent plains
Saturday and Sunday afternoon although, in general, winds will
remain light. Temperatures will remain below seasonal normals behind
the cold front but trend slowly upwards towards seasonal normals by
Sunday. Zelzer

Sunday night through Friday...The period starts with a fairly potent
shortwave trough digging SE into the Pac NW. At this time, the
models still differ on the exact evolution of this feature. The
GFS/CMC/GEFS are stronger and more moist while the ECMWF/ECMWF
ensembles keep the wave open/weaker and more progressive with less
moisture. For now, planning to keep with previous forecasts and WPC
and lean towards the more progressive/slightly drier solution seen
in the ECMWF. Regardless of model choice, it appears that the axis
of heaviest precipitation with this system through Monday will be
across the eastern half of our CWA (ie. along and east of a Bozeman
to Havre line). In this area, the potential exists for up to an inch
of QPF for some locations, even if the drier solutions pan out.
Hydrology-wise, it will be something to keep an eye on given recent
rainfall in that area, especially for small streams/creeks, such as
Clear Creek. With Monday`s system, snow levels look to drop down
into the 7-8k ft range, but could drop a bit lower if the shortwave
slows down/closes off.

Once the Memorial Day system moves out, the models are in decent
agreement with building an upper level ridge across the western US,
something we haven`t seen in awhile. This should bring a period of
warmer/drier conditions. Of note, though, the GFS isn`t quite as
strong with the ridge and actually brings a few weak shortwaves
through the area. Will keep low chance pops in later next week, but
at this time it looks like the best chance of seeing a shower or
storm will be across the higher terrain. Martin
&&

.AVIATION...
UPDATED 2355Z.

A cold front continues to slowly progress ENE across the area at
this time. Scattered SHRA/TSRA associated with the front will
continue to lift slowly ENE through this evening as well. Occasional
MVFR VIS/CIGS and mtn obscurations will be possible as the showers
move through, mainly in the vicinity of KLWT/KHVR. The coverage of
SHRA may increase some from KLWT to KHVR tonight along and just
behind the front with a continued threat of MVFR CIGS/VIS and
mountain obscurations. The coverage of SHRA will gradually decrease
from west to east after 06z/SAT with improving VIS/CIGS. SHRA may
redevelop across SW MT on SAT, but for now, confidence isn`t high
enough to put SHRA at KBZN. In the wake of the front, gusty winds
are likely across north-central MT SAT afternoon. Martin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  62  41  69 /  40  10  10  10
CTB  37  60  39  65 /  10  10  10  10
HLN  41  63  42  70 /  40  10  10  20
BZN  39  62  39  71 /  60  30  10  10
WEY  33  53  32  60 /  60  40  20  10
DLN  37  61  38  68 /  70  30  10  10
HVR  45  65  42  70 /  70  20  10  10
LWT  42  62  41  68 /  80  30  10  20

&&

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

$$

weather.gov/greatfalls



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000
FXUS65 KMSO 271513 CCA
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
347 AM MDT FRI MAY 27 2016

.DISCUSSION...The weather pattern TODAY THROUGH SUNDAY will be marked
by afternoon and evening scattered showers and perhaps a few thunderstorm
each day. Impacts will be relatively minimal but brief heavy downpours
and lightning are possible.

Southwest winds will be on the increase this afternoon in west central
Montana. Expect gusty conditions ranging from 20-30 mph from mid afternoon
through the early evening hours. These gusty winds will cause some choppy
conditions on Flathead and other area lakes.

Saturday and Sunday mornings are looking like they will start off
pretty chilly with overnight lows in the valleys dipping into the
mid 30s and possibly flirting with the freezing mark, if only for
a brief time. The potential for frost is increasing both mornings
which may have a mild impact to agricultural interests.

The best potential for widespread precipitation will be on
Memorial day. Models have actually diverged a bit with their
solution for the strength or intensity of the approaching weather
system. So while widespread precipitation still looks favorable
the amounts expected are still in question.

A much warmer and drier pattern is likely the latter part of next
week through the following weekend as a ridge of high pressure
replaces the persistent trough of late. In fact, some forecast
models indicate daytime temperatures reaching 15-20 degrees above
normal by next Friday and Saturday.

&&

.AVIATION...Scattered showers and an isolated thunderstorm are
possible at all terminals across the Northern Rockies today but
especially this afternoon and evening through 28/02z. Brief
moderate to heavy rains can be expected with the heavier showers.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$




000
FXUS65 KGGW 271446
AFDGGW

Area Forecast Discussion
National Weather Service GLASGOW MT
846 AM MDT FRI MAY 27 2016

.SHORT TERM...for northeast Montana...today through Sun...

Morning Update... Morning fog across Nemont is expected to
rapidly burn off leaving scattered mid level clouds. A frontal
boundary just outside the CWA to the northeast is expected to move
forward and generate an area of showers and thunderstorms across
the northeastern third of the CWA. While conditions are stable at
the moment they are expected to become more unstable with the
surface layer baking through the late morning and early afternoon.
A second wave of showers and thunderstorms are expected tonight
along a narrow could frontal boundary entering from the west.
These seem to be accounted for rather well at the moment. GAH


Previous Short Term Discussion...
While the upper low has moved into North Dakota overnight, the
cyclonic circulation associated with the low will continue over
the eastern half of the forecast area this morning. This will
combine with somewhat unstable air mass to allow a few showers to
develop over the area today.

To the west, an upper trough currently over the Pacific NW will
move into Western Montana this afternoon and bring a frontal
boundary into Central Montana. This front will move through
Eastern Montana late tonight and Saturday and become the focus for
showers and thunderstorms. At this point, it looks like the precip
will limited to about a 100 mile wide area along the front as the
lift will be primarily frontal with subsidence to the east and
west of this area. As a result, the eastern zones will be mainly
dry tonight and the chances of precip will quickly diminish
Saturday afternoon in the west and Saturday Night in the east
once the front moves to the east. The upper trough moves northeast
through the forecast area Saturday afternoon and evening and into
Saskatchewan late Saturday Night.

Look for zonal flow aloft on Sunday with surface high pressure
over the area and dry weather under mostly clear skies. Forrester


.LONG TERM...Sun night through Fri...

The extended period begins Sunday evening with a weak ridge in
place over the Northern High Plains and western flow aloft
producing mild conditions. Off to the west an upper trough will be
digging into British Columbia and the Pacific Northwest producing
cooler conditions and widespread precipitation there.

As the trough plows through the Northern Rockies upper flow over
Northeast Montana will begin to back to the southwest, introducing
moisture and instability. Expect rain showers sometime after
midnight, spreading east and increasing on Monday.

With the associated cold front moving across the area, convective
parameters become moderate to strong, enough to produce afternoon
and evening thunderstorms with the showers. Expect the upper and
lower low centers of this storm to stack up by tuesday morning
into a compact cyclone with strong gusty winds and areas of heavy
rain. The storm will be a slow mover, not exiting the region until
Wednesday afternoon.

Wednesday evening a strong upper level ridge will have developed
over the West Coast producing northwest flow aloft over Montana.
This ridge will slowly progress eastward for the remainder of the
period, bringing warmer and drier conditions.

High confidence for the general upper flow pattern, and becoming
stormy by Monday, then diminishing the unsettled conditions
around late Wednesday, followed by increasing temperatures and dry
conditions late in the period. Generally continued the trend to
raise pops.

Templer


&&

.AVIATION...

FLIGHT CATEGORY: VFR.

SYNOPSIS: The closed low pressure system that brought rain
showers to the area Thursday will stall over southern Manitoba and
Western North Dakota this morning, which will continue bringing
isolated rain showers to Northeast Montana through today and into
this evening. Convective parameters will be on the weak side, but
isolated general thunderstorms will remain possible in the
afternoon and early evening. A narrow, weak ridge over the local
area will make the showers much more intermittent by evening. Near
the end of the TAF cycle a cold front from teh west will bring a
second round of showers and thunderstorms with impacts starting
at KGGW right towards the end of the cycle and spreading to the
remaining terminals just beyond.

WIND: From the east at less than 10kts.

Templer/GAH


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.


&&

$$

weather.gov/glasgow




000
FXUS65 KTFX 271205
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
605 AM MDT FRI MAY 27 2016

UPDATED AVIATION SECTION

.DISCUSSION...
Today through Sunday...The airmass remains unstable today as an
upper trof begins to push into the area from the west. The
southwest flow aloft will become increasingly diffluent this
afternoon. Additionally, the trof will push a cold front across
the area this afternoon. Showers and thunderstorms will develop
behind the front. Models indicate the best chances for convective
activity will be east of a Cut Bank to Great Falls to Helena line.
Severe storms are not anticipated as CAPE values are generally
less than 200 J/kg and bulk wind shear values will be in the 30
to 35 kt range. QPF amounts will likely fall between a quarter
inch to a half inch. Convective activity will push into the
eastern portion of the county warning area this evening before
ending by daybreak Saturday. West winds Saturday will bring drier
air to the area though a few lingering showers will persist over
the western and southwest mountains. Another upper trof will move
east of the continental divide Sunday bringing another round of
scattered showers and/or thunderstorms to the western and
southwest mountains Sunday afternoon. Temperatures will remain
near to slightly below seasonal averages through the period.

Sunday Night through Friday...A shortwave trough is forecast to
cross the PacNW Sunday night. This will produce showers and
thunderstorms across North-central and Southwest MT on Memorial Day.
Model solutions begin to vary on Monday with the intensity and speed
of motion for this wave. Have followed WPC`s lead and opted for a
model blend and keeping rainfall generally below 0.5 inch.  Snow
will be possible again Sunday night and Monday night at elevations
above 7000 feet. Tuesday`s forecast presents a challenge due to the
differences in which models carry the trough away to the east. A
strong and resilient upper level ridge is anticipated to develop
sometime on Wednesday and persist through next weekend. Temperatures
will finally move above average, with  a slight chance for mainly
mountain showers and isolated thunderstorms. PN

&&

.AVIATION...
UPDATED 1205Z.
The airmass will destabilize after 18z as an upper level disturbance
and a surface cold front move across the area. Showers and/or
thunderstorms will develop again after 20z and continue through 04z.
VFR conditions prevail with MVFR conditions possible in the vicinity
of showers and/or thunderstorms. Gusty erratic winds are also
possible near thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  41  62  40 /  50  50  10  10
CTB  61  37  60  38 /  20  30  10  10
HLN  61  41  63  42 /  60  50  20  10
BZN  62  39  62  38 /  60  70  20  10
WEY  54  34  53  32 /  40  50  20  10
DLN  58  38  60  38 /  60  60  20  10
HVR  67  45  65  42 /  40  60  20  10
LWT  62  42  61  41 /  60  70  20  10

&&

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

$$

weather.gov/greatfalls



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000
FXUS65 KBYZ 270914
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
314 AM MDT FRI MAY 27 2016

.SHORT TERM...valid for Tdy and Sat...

Minor changes to the short term forecast this morning, with
models remaining in good agreement on disturbance dropping into
the region today and Saturday.

Although the strongest energy remaining to our west and northwest
across north central Montana today, a Pacific front will move into
the area this afternoon. This should bring increasing chances for
showers and thunderstorms across western areas. Raised pops across
western zones slightly, and extended slight pops a bit further
east for lingering showers this evening. The best area for
stronger thunderstorms appears to be around Billings by mid
afternoon, with small hail and erratic gusty winds, as cold pool
moving east combines with good pwats at peak heating, and likely
multiple outflow boundaries from earlier activity. Any stronger
activity should taper off quickly after sunset.

Zonal flow aloft develops over the region Saturday. Weak upper
level energy and vorticity will continue to stream across the
area, bringing continued potential for showers and isolated
thunderstorms, but with less coverage overall than recent days.
Eastern zones should see best chances with improved CAPES.

Afternoon highs Friday and Saturday will be around normal with
readings in the upper 60s to lower 70s. Gilstad

.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...


Models struggling with consistency for Monday-Tuesday storm
system. Latest Canadian and GFS models drop a stronger wrapped
up system from the Pacific NW through the area during this period, while
the ECMWF is faster bringing the energy across as an open wave and
keeps main area of dynamics well north of the area along the
Canadian border. Given the differences in the models have kept
chance pops going and will await better consistency before making
adjustments for this period. Models come to better agreement with
strengthening ridge of high pressure developing mid to late week
and continuing into next weekend. This will trend drier and
warmer heading through the end of the week. Chambers
&&

.AVIATION...


A few areas of stratus/fog are possible across the area this
morning with local ifr conditions through 16z. Isolated shower
activity late this morning over western zones will evolve into
scattered thunderstorms by mid day, spreading into central zones
around Billings by 23z. Wind gusts to 35kts and small hail will be
possible with storms this afternoon/evening along with brief heavy
rainfall. Additional stratus and fog development are possible
Friday night into Saturday morning. Chambers
&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Sat     Sun     Mon     Tue     Wed     Thu
-------------------------------------------------------
BIL 069 048/067 046/075 049/070 046/063 044/068 046/075
    6/T 63/T    21/B    25/T    34/T    42/W    11/B
LVM 063 041/063 039/071 043/065 041/060 039/068 042/075
    6/T 63/T    21/B    34/T    43/T    32/W    11/U
HDN 072 047/070 045/077 049/074 045/064 042/068 045/077
    3/T 53/T    20/B    24/T    34/T    43/W    11/B
MLS 071 051/072 049/078 053/074 050/065 046/067 047/077
    2/T 24/T    21/U    34/T    44/T    43/T    21/B
4BQ 071 046/071 045/077 049/075 046/066 043/067 043/077
    2/T 24/T    21/B    23/T    33/T    33/T    21/B
BHK 069 046/071 044/076 049/072 045/065 042/064 041/073
    2/T 16/T    31/B    25/T    44/T    43/T    21/B
SHR 069 043/068 042/075 045/072 043/063 040/067 042/075
    4/T 33/T    22/T    25/T    34/T    43/W    11/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings




000
FXUS65 KTFX 270023
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
323 PM MDT THU MAY 26 2016

...UPDATE TO AVIATION...

.DISCUSSION...
This Afternoon through Saturday Evening...Latest analysis shows
the upper- level low pressure system that wandered around north
central and eastern MT last two days has moved downstream into N.
Dakota. Almost all of the moisture/rain showers directly
associated with the low are now east of our area, with just a few
showers skirting eastern Blaine/far eastern Fergus counties. Weak
high pressure ridging currently over Idaho and western MT will
work its way east of the Divide this evening bringing us mostly
dry conditions overnight. However, before that happens, residual
moisture from the exiting low and a second area of moisture
crossing through the ridge will combine with marginal instability
and a bit of aftn heating/mixing to generate another round of
scattered showers and thunderstorms along and west/south of a line
from Cut Bank to Lewistown/Judith Gap. With CAPE (potential
energy) values of only 300-600 J/kg and very weak wind shear in
the lower atmosphere, thunderstorms that form today will be of the
short-lived, pulse variety, producing some locally moderate
rainfall and pea- to dime- sized hail. All the convective activity
should steadily dissipate this evening.

Friday begins dry but our next weather system is already moving into
the PacNW with its leading edge of moisture along the ID/WA border.
The system`s low pressure center is forecast to track along the
US/Can border tomorrow and Sat and will push a cold front through
our region tomorrow aftn, sparking more widespread showers and
thunderstorms.  Forecast models are indicating better low-level wind
shear (30-40 kts) at that time but CAPE values remain marginal for
strong to severe storms.  As the front heads into eastern MT Fri
eve, drier conditions move in for Sat under westerly flow aloft.
Some spotty areas of moisture may produce a few showers along the
Rocky Mtn Front and over the southwest mtn ranges Sat aftn.  With
increasing clouds from late morning onward, high temps on Fri will
only reach the upper 50s to low 60s.  More sunshine on Sat will
result in slightly warmer temps, mainly in the low-mid 60s.
Waranauskas

Saturday night through Thursday...From Saturday night through early
Monday morning, an upper level trof will swing through the northern
portions of the region and then gradually move east of the region.
Thus there will be a chance for showers early in the period, but
some dry conditions are possible late Saturday night and into Sunday
morning, before isolated showers/thunderstorms redevelop on Sunday
afternoon. For Monday through Wednesday, significant differences
have developed in the models from the GFS/EC. The GFS progs
moderate/heavy precipitation to move through Central MT Monday
afternoon thru Tue, while the EC is significantly less. For now, I
have blended the solutions, with more confidence given to the EC
solution. The precipitation gradually exits the region on Wednesday,
with weak upper level ridging trying to build over the region by
next Thursday. Thus precipitation chances on Thur are confined
mainly to the western mountains. Temperatures will generally be
below normal through the period, with Tuesday being the coolest day,
but temperatures will start to warm to near normal by next Thursday
as the upper level ridge starts to rebuild.
Brusda

&&

.AVIATION...
UPDATED 0023Z.
Several upper level disturbances in an unstable west-northwest flow
aloft will move over Montana this evening through late Friday
afternoon. Scattered showers and thunderstorms will cause short-
lived MVFR conditions due to heavy rain and small hail reducing
visibility. Convection over the region is expected to diminish by
04Z but another round develop after 20Z Friday. VFR conditions will
prevail outside of any storms moving across the forecast area. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  44  61  41  62 /  40  60  50  10
CTB  41  61  38  59 /  40  20  40  10
HLN  45  61  41  63 /  30  50  60  20
BZN  41  62  39  62 /  30  60  60  20
WEY  34  54  33  53 /  30  40  30  20
DLN  40  58  37  60 /  30  60  60  30
HVR  45  67  45  64 /  10  50  60  20
LWT  42  62  42  61 /  20  60  70  30

&&

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

$$

weather.gov/greatfalls




000
FXUS65 KTFX 261618
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1018 AM MDT THU MAY 26 2016

.UPDATE...
Extensive cloud cover over most of the forecast area this morning
(except for sunnier skies over the central Hiline and
Madison/Beaverhead counties) with a narrow band of rain showers
stretching from Cut Bank to Townsend and spotty, lighter showers
over southern Blaine/parts of Fergus County. The precip is all
moving north to south as our region is still on the backside of
the upper-level low pressure system over far eastern MT. The low
will continue to move into the Dakotas today, but enough moisture
and instability remains for scattered showers and thunderstorms
to develop later this aftn. Similar to yesterday, storms will
likely be the short-lived, pulse type, producing some locally
moderate rainfall (>0.10 inch) and maybe some pea-sized hail.
Current forecast looks good. Made a few adjustments to increase precip
chances with the Cut Bank to Townsend showers.
Waranauskas

&&

.AVIATION...
UPDATED 1105Z.
A moist and somewhat unstable NW flow aloft continues across the
region today with upper level low centered over eastern MT, drifting
east tonight. Isolated showers this morning will increase in
coverage this afternoon with a few weak thunderstorms also possible.
VFR conditions will generally prevail with some localized MVFR and
mountain obscuration in the vicinity of showers/thunderstorms. The
airmass stabilizes this evening for decreasing precipitation with
drier air moving in from the west as well. Surface winds remain
generally light and below 10kts with a few gusts in excess of 15 kts
near showers and thunderstorms. Hoenisch

&&

.PREV DISCUSSION...
/ISSUED /

Today through Saturday....Mid-upper level circulation center
evident in satellite imagery this morning over NE MT will slowly
edge east into ND by tonight, maintaining a moist and somewhat
unstable cyclonic NW flow aloft across the region today with
shortwave ridging building in from the west tonight. Airmass
destabilization this afternoon will again lead to an increase in
showers and thunderstorms with models indicating greatest coverage
along a corridor from roughly Cut Bank SE to White Sulphur
Springs. Flow aloft and corresponding wind shear is relatively
weak today for primarily pulse type thunderstorms with little or
no thunderstorm organization expected. Next upper level low,
currently upstream with center near Queen Charlotte Island, will
move SE with trough axis extending S into the Pacific NW Friday.
Initial shortwave energy ahead of the trough will move into the
Northern Rockies Friday with the bulk of the shortwave energy
lifting NE across N-central MT Friday night through early
Saturday. Showers and thunderstorms will increase again Friday
afternoon in SW flow aloft with an inverted surface trough
sharpening across central MT. Opposite of today, CAPE values
appear marginal Friday afternoon with somewhat better shear as
winds aloft increase ahead of the trough for just a small chance
of any organized convection Friday afternoon and evening.
Shortwave and upper jet energy lifting NE across the region Friday
night will likely lead to an area of widespread rain across
central/eastern portions of the forecast area with drier air
working in from the west Saturday afternoon. Hoenisch

Saturday night through Thursday...From Saturday night through early
Monday morning, an upper level trof will swing through the northern
portions of the region and then gradually move east of the region.
Thus there will be a chance for showers early in the period, but
some dry conditions are possible late Saturday night and into Sunday
morning, before isolated showers/thunderstorms redevelop on Sunday
afternoon. For Monday through Wednesday, significant differences
have developed in the models from the GFS/EC. The GFS progs
moderate/heavy precipitation to move through Central MT Monday
afternoon thru Tue, while the EC is significantly less. For now, I
have blended the solutions, with more confidence given to the EC
solution. The precipitation gradually exits the region on Wednesday,
with weak upper level ridging trying to build over the region by
next Thursday. Thus precipitation chances on Thur are confined
mainly to the western mountains. Temperatures will generally be
below normal through the period, with Tuesday being the coolest day,
but temperatures will start to warm to near normal by next Thursday
as the upper level ridge starts to rebuild. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  65  44  62  41 /  50  30  60  60
CTB  64  41  61  38 /  60  40  30  40
HLN  66  45  62  41 /  50  30  50  60
BZN  65  41  62  40 /  40  30  60  60
WEY  56  35  55  33 /  50  30  30  30
DLN  63  41  58  37 /  40  30  60  60
HVR  67  45  68  44 /  20  10  50  60
LWT  63  43  63  42 /  30  20  60  70

&&

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

$$

weather.gov/greatfalls




000
FXUS65 KBYZ 261517
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
917 AM MDT THU MAY 26 2016

.UPDATE...

Forecast looks to be in good shape with only a few minor tweaks
with this mornings update. An upper low continues to be located
over Northeast Montana this morning and will slowly shift
east/southeast today. Satellite showing quite a bit of clear skies
from Treasure County to Carter County so I did adjust sky cover to
reflect more sun this morning for these areas. However, with cold
air aloft associated with this upper low, I expect these clearing
areas to fill in with clouds by early afternoon. However, there
will still be breaks of sun across the forecast area today.

Radar is showing some shower activity across Big Horn and
Sheridan Counties, as well as across the northeast portions of the
state associated with the upper low. Overall, look for scattered
showers and isolated thundestorms today. Freezing levels remain
low so about any thunderstorm will most likely produce some pea
size hail or possibly slightly larger, but widespread
strong/severe weather is not expected today. Updated forecast has
been sent. Hooley

&&

.SHORT TERM...valid for Tdy and Fri...

Last evenings thunderstorms were stronger than expected...even
though most of the hail reported was only about a half inch. Post
analysis showed several outflow boundaries floating about the area
from late afternoon convection. These eventually collided just
north of Billings and lead to some rapid development due to steep
lapse rates thanks to the cold mid level temps aloft (related to
the upper low over us). Billings Heights and nearby locations thus
ended up with some strong convection and plenty of hail...with one
report of quarter size a couple of miles northeast of the city.

That upper low will again be the primary driver for the short term
forecast. Models show it gradually wobbling to a position a little
further east than yesterday...generally placing it over the
Montana/Dakota border. So it would appear associated vorticity
forcing will be best further east than last night. We will look
for the stronger storms to be over our east today...with the
largest population affected around Miles City. We will still carry
scattered thunderstorms elsewhere simply due to the cyclonic flow
and instability, and the possibility of colliding boundaries once
again.

Friday will see another actively convective day. The upper low
will have finally merged with the broader trough axis to the south
and moved into the Dakotas, but leaves our east in a deformation
zone. This should result in scattered convection along our
furthest east zones such as Fallon, Custer and Carter counties. In
the meantime, another progressive upper low will slide into the
northern Rockies from British Columbia aiding convective
development over the Montana high country. So some activity over
the Beartooths and nearby areas is also expected...though the
stronger convection here may be northwest of our CWA.

Look for highs today to remain seasonal, and then a bit warmer
for Friday. BT

.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...

Several relatively minor changes to the extended forecast period
this morning. The broad upper level trof keeps the region in a
generally unsettled and mild pattern through the period, with
models in reasonably good agreement.

The upper low will slowly east east through Wednesday, with
shortwaves rotating through the area. Raised pops for two more
significant waves progged through the region Saturday and Monday
into Tuesday. The best potential for stronger storms will also
accompany these waves...especially for the Monday wave in the
East. Also increased Wednesday pops...as main trof axis is progged
across the region.

Models prog a ridge to build over the west starting late
Wednesday into Thursday, potentially bringing drier weather to the
region. Temps will continue to run near to slightly below normal.
Gilstad

&&

.AVIATION...

Isolated to scattered showers and a few thunderstorms will be
accompanied by MVFR conditions this morning. Expect localized
mountain obscurations. Chances for thunderstorms will increase
this afternoon and continue this evening. Some storms will be
accompanied by small hail and wind gusts to 45 kt. MVFR/IFR
conditions will accompany the thunderstorms...along with areas of
mountain obscuration. A few showers will linger over the
mountains and E of KBIL overnight through Fri. morning with
localized mountain obscurations. Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 067 046/070 047/067 046/072 048/069 046/065 044/068
    4/T 33/T    54/T    32/T    34/T    44/T    43/T
LVM 066 041/065 040/062 040/067 041/066 041/062 040/067
    4/T 35/T    64/T    32/T    34/T    44/T    32/T
HDN 069 043/073 047/070 045/074 048/073 047/066 043/069
    3/T 23/T    34/T    32/T    34/T    55/T    43/T
MLS 066 048/073 051/072 049/076 051/075 051/068 047/068
    4/T 32/T    24/T    32/T    44/T    55/T    55/T
4BQ 069 044/073 046/071 045/075 048/075 047/068 044/069
    4/T 22/T    25/T    32/T    44/T    55/T    44/T
BHK 066 043/071 045/071 045/074 046/073 047/068 044/067
    5/T 33/T    15/T    32/T    44/T    55/T    44/T
SHR 066 040/070 043/067 041/073 043/071 043/065 041/067
    3/T 22/T    24/T    43/T    34/T    44/T    43/T

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings




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