000
FXUS65 KTFX 241152
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
550 AM MDT Fri May 24 2013
UPDATED AVIATION SECTION
.DISCUSSION...
Friday through Sunday...Friday afternoon and Saturday continue to
show a decrease in widespread precipitation as the upper level trough
retrogrades back towards the Canadian Coast. More shortwave troughs
will move across the area...however they appear relatively
weak...and more likely to cause scattered showers than widespread
precipitation. Have increased the chance for showers and
thunderstorms Sunday morning and afternoon as models show another
decent shortwave trough moving through the area. Exact placement of
the disturbance is not in great agreement so have trended pops still
in the chance and slight chances across much of the area with the
highest percentages along the Rocky Mountain Front and other higher
terrain where the topographical enhancement could be enough to help
initiate convection. Temperatures remain near seasonal averages as
the drying trend helps temperatures rebound for the first half of
the weekend. Suk
Sunday night through Friday...The period begins with a persistent
upper trof over the Pacific Northwest. Short wave energy rotating
out from the base of the trof will continue to ride the southwest
flow aloft into the state. Scattered showers and thunderstorms will
continue to develop through Monday. By Tuesday, the models bring
another upper trof across the Rockies. Lift and diffluent flow aloft
will be strongest over southwest Montana Tuesday afternoon resulting
in another round of showers and thunderstorms. Isolated convective
activity will be possible across central and northern portions of
the county warning area. The remainder of the period, Wednesday
through Friday, will be characterized by continued unsettled
conditions as the area remains under the influence of a broad upper
trof. Temperatures will remain generally above seasonal averages to
start the period with readings dropping below seasonal averages by
the end of the week.
&&
.AVIATION...
UPDATED 1150Z
An upper disturbance continues to move across the area this morning
with widespread showers accompanying this feature. Rain will
gradually end by 18z as the disturbance moves north into Canada and
skies will begin to clear. Westerly surface winds will increase
after 18z and become gusty at times. MVFR conditions prevail this
morning due to low ceilings and rain. Conditions will become
predominately VFR after 18z. Mountains obscured through 18z.
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mountain snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 65 38 69 42 / 30 10 10 20
CTB 61 37 66 39 / 30 10 10 20
HLN 64 40 70 45 / 30 10 20 20
BZN 66 36 72 41 / 50 10 20 10
WEY 59 33 67 38 / 10 0 10 10
DLN 62 37 70 42 / 30 10 30 20
HVR 69 41 74 44 / 60 10 10 40
LWT 64 40 69 45 / 50 10 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Suk
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 240949
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
349 AM MDT Fri May 24 2013
.DISCUSSION...
Friday through Sunday...Friday afternoon and Saturday continue to
show a decrease in widespread precipitation the upper level trough
retrogrades back towards the Canadian Coast. More shortwave
troughs will move across the area...however they appear relatively
weak...and more like to cause scattered showers than widespread
precipitation. Have increased the chance for showers and
thunderstorms Sunday morning and afternoon as models show another
decent shortwave trough moving through the area. Exact placement
of the disturbance is not in great agreement so have trended pops
still in the chance and slight chances across much of the area
with the highest percentages along the Rocky Mountain Front and
other higher terrain where the topographical enhancement could be
enough to help initiate convection. Temperatures remain near
seasonal averages as the drying trend helps temperatures rebound
for the first half of the weekend. Suk
Sunday night through Friday...The period begins with a persistent
upper trof over the Pacific Northwest. Short wave energy rotating
out from the base of the trof will continue to ride the southwest
flow aloft into the state. Scattered showers and thunderstorms will
continue to develop through Monday. By Tuesday, the models bring
another upper trof across the Rockies. Lift and diffluent flow aloft
will be strongest over southwest Montana Tuesday afternoon resulting
in another round of showers and thunderstorms. Isolated convective
activity will be possible across central and northern portions of
the county warning area. The remainder of the period, Wednesday
through Friday, will be characterized by continued unsettled
conditions as the area remains under the influence of a broad upper
trof. Temperatures will remain generally above seasonal averages to
start the period with readings dropping below seasonal averages by
the end of the week.
&&
.AVIATION...
UPDATED 0500Z.
An upper disturbance will move northeast through the area late
tonight and Friday morning. Expect showers/rain ahead of the
disturbance. Most locations will see a period of MVFR or possibly
even IFR ceilings and visibilities in the precipitation. Along with
the lower conditions expect areas of mountain obscurement. Conditions
will improve to scattered clouds after the passage of the upper
disturbance and gusty downslope winds will develop over the plains.
Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 65 38 69 42 / 30 10 10 20
CTB 61 37 66 39 / 30 10 10 20
HLN 64 40 70 45 / 30 10 20 20
BZN 66 36 72 41 / 50 10 20 10
WEY 59 33 67 38 / 10 0 10 10
DLN 62 37 70 42 / 30 10 30 20
HVR 69 41 74 44 / 60 10 10 40
LWT 64 40 69 45 / 50 10 20 30
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Suk
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 240451
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1100 PM MDT Thu May 23 2013
UPDATED AVIATION SECTION
.UPDATE...
The upper trough is still forecast to swing northeast through the
forecast area later tonight and Friday morning. As of 830 pm one
band of precipitation extended from the western portions of
southwest Montana north to the Rocky Mountain Front. This was
associated with the upper trough. Another band of precipitation
over southcentral Montana was moving into central Montana and will
continue north the rest of this evening. The inherited high
chances of precipitation for the rest of tonight look good so did
not change them. Did add a mention of thunder over portions of
southwest Montana and central Montana for the rest of this evening
based on current observations/instability data. Also based on
current observations have lowered snow levels over western
portions of southwest Montana where snow levels are approaching
5000 feet MSL. Adjusted late evening winds to better reflect
current observations and made some minor adjustments for after
midnight as well. Forecast lows for tonight look on track so did
not make any changes to them. The forecast chances of
precipitation for the east slopes might be too high for Friday
morning as downslope should have kicked in along with drier air so
do not expect any precipitation. However will let midnight shift
make the final determination on this as they will have the benefit
of later model data and being able to see how the situation
evolves. Blank
&&
&&
.AVIATION...
UPDATED 0500Z.
An upper disturbance will move northeast through the area late
tonight and Friday morning. Expect showers/rain ahead of the
disturbance. Most locations will see a period of MVFR or possibly
even IFR ceilings and visibilities in the precipitation. Along with
the lower conditions expect areas of mountain obscurement. Conditions
will improve to scattered clouds after the passage of the upper
disturbance and gusty downslope winds will develop over the plains.
Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 600 PM MDT Thu May 23 2013/
Tonight through Saturday...A deep closed low pressure system will
remain over the Pacific tonight and another shortwave will rotate
around the low tonight. This will produce good lift across most of
the forecast area for widespread showers. At lower levels, a surface
low pressure trof will move into eastern Montana winds will become
westerly after midnight. This will help dry the airmass across the
plains Friday as the low pressure system weakens. Elsewhere, low
level moisture will be available and the airmass will become
slightly unstable during the afternoon, mainly across Southwest
Montana. However the airmass will be capped at higher levels and
thunderstorms should be shallow. Zelzer
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 64 40 68 / 100 30 10 10
CTB 38 60 35 65 / 100 30 10 10
HLN 38 63 38 69 / 90 30 10 20
BZN 34 65 35 72 / 80 50 10 20
WEY 30 57 33 66 / 40 10 0 10
DLN 32 61 34 69 / 80 30 10 30
HVR 47 68 42 73 / 90 60 10 10
LWT 42 65 39 68 / 100 50 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
SHORT TERM...BLANK
LONG TERM...BLANK
AVIATION...BLANK
weather.gov/greatfalls
000
FXUS65 KTFX 240305
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
905 PM MDT Thu May 23 2013
.UPDATE...
The upper trough is still forecast to swing northeast through the
forecast area later tonight and Friday morning. As of 830 pm one
band of precipitation extended from the western portions of
southwest Montana north to the Rocky Mountain Front. This was
associated with the upper trough. Another band of precipitation
over southcentral Montana was moving into central Montana and will
continue north the rest of this evening. The inherited high
chances of precipitation for the rest of tonight look good so did
not change them. Did add a mention of thunder over portions of
southwest Montana and central Montana for the rest of this evening
based on current observations/instability data. Also based on
current observations have lowered snow levels over western
portions of southwest Montana where snow levels are approaching
5000 feet MSL. Adjusted late evening winds to better reflect
current observations and made some minor adjustments for after
midnight as well. Forecast lows for tonight look on track so did
not make any changes to them. The forecast chances of
precipitation for the east slopes might be too high for Friday
morning as downslope should have kicked in along with drier air so
do not expect any precipitation. However will let midnight shift
make the final determination on this as they will have the benefit
of later model data and being able to see how the situation
evolves. Blank
&&
&&
.AVIATION...
UPDATED 0000Z.
An upper disturbance will move northeast through the area late
tonight and Friday morning. Expect showers/rain ahead of the
disturbance. Most locations will see a period of MVFR ceilings and
possibly MVFR visibilities in the precipitation though have low
confidence in how long the MVFR conditions will last. The most
favored area for seeing at least several hours of MVFR conditions
will be the plains and in particular the east slopes of the Rocky
Mountains. Along with the MVFR conditions expect areas of mountain
obscurement. Conditions will improve to scattered clouds after the
passage of the upper disturbance and gusty downslope winds will
develop over the plains. As for thunderstorms there will be a small
threat at KLWT and KBZN this evening but think the threat is low
enough that thunderstorms were not mentioned in the tafs. Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 600 PM MDT Thu May 23 2013/
Tonight through Saturday...A deep closed low pressure system will
remain over the Pacific tonight and another shortwave will rotate
around the low tonight. This will produce good lift across most of
the forecast area for widespread showers. At lower levels, a surface
low pressure trof will move into eastern Montana winds will become
westerly after midnight. This will help dry the airmass across the
plains Friday as the low pressure system weakens. Elsewhere, low
level moisture will be available and the airmass will become
slightly unstable during the afternoon, mainly across Southwest
Montana. However the airmass will be capped at higher levels and
thunderstorms should be shallow. Zelzer
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 64 40 68 / 100 30 10 10
CTB 38 60 35 65 / 100 30 10 10
HLN 38 63 38 69 / 90 30 10 20
BZN 34 65 35 72 / 80 50 10 20
WEY 30 57 33 66 / 40 10 0 10
DLN 32 61 34 69 / 80 30 10 30
HVR 47 68 42 73 / 90 60 10 10
LWT 42 65 39 68 / 100 50 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
SHORT TERM...BLANK
LONG TERM...BLANK
AVIATION...BLANK
weather.gov/greatfalls
000
FXUS65 KTFX 240002
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
600 PM MDT Thu May 23 2013
.DISCUSSION...
Tonight through Saturday...A deep closed low pressure system will
remain over the Pacific tonight and another shortwave will rotate
around the low tonight. This will produce good lift across most of
the forecast area for widespread showers. At lower levels, a surface
low pressure trof will move into eastern Montana winds will become
westerly after midnight. This will help dry the airmass across the
plains Friday as the low pressure system weakens. Elsewhere, low
level moisture will be available and the airmass will become
slightly unstable during the afternoon, mainly across Southwest
Montana. However the airmass will be capped at higher levels and
thunderstorms should be shallow. Zelzer
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.AVIATION...
UPDATED 0000Z.
An upper disturbance will move northeast through the area late
tonight and Friday morning. Expect showers/rain ahead of the
disturbance. Most locations will see a period of MVFR ceilings and
possibly MVFR visibilities in the precipitation though have low
confidence in how long the MVFR conditions will last. The most
favored area for seeing at least several hours of MVFR conditions
will be the plains and in particular the east slopes of the Rocky
Mountains. Along with the MVFR conditions expect areas of mountain
obscurement. Conditions will improve to scattered clouds after the
passage of the upper disturbance and gusty downslope winds will
develop over the plains. As for thunderstorms there will be a small
threat at KLWT and KBZN this evening but think the threat is low
enough that thunderstorms were not mentioned in the tafs. Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 64 40 68 / 100 30 10 10
CTB 38 60 35 65 / 100 30 10 10
HLN 38 63 38 69 / 90 30 10 20
BZN 34 65 35 72 / 80 50 10 20
WEY 30 57 33 66 / 40 10 0 10
DLN 32 61 34 69 / 80 30 10 30
HVR 47 68 42 73 / 90 60 10 10
LWT 42 65 39 68 / 100 50 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 232053
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
253 PM MDT Thu May 23 2013
.DISCUSSION...
Tonight through Saturday...A deep closed low pressure system will
remain over the Pacific tonight and another shortwave will rotate
around the low tonight. This will produce good lift across most of
the forecast area for widespread showers. At lower levels, a surface
low pressure trof will move into eastern Montana winds will become
westerly after midnight. This will help dry the airmass across the
plains Friday as the low pressure system weakens. Elsewhere, low
level moisture will be available and the airmass will become
slightly unstable during the afternoon, mainly across Southwest
Montana. However the airmass will be capped at higher levels and
thunderstorms should be shallow. Zelzer
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.AVIATION...
UPDATED 1800Z.
An upper disturbance moving across the area today will continue to
generate showers today. Showers will decrease in coverage from about
18z til 22z. Showers and isolated thunderstorms will redevelop over
Southwest Montana after 22z. VFR conditions prevail before 22z with
MVFR conditions in the vicinity of showers. Conditions will degrade
with more widespread MVFR and areas of IFR after 00z as lower
ceilings and precipitation move from southern to northern Montana.
Mountains will become obscured after 00z. Winds will remain breezy
through the day before diminishing some after 06z.
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 64 40 68 / 100 30 10 10
CTB 38 60 35 65 / 100 30 10 10
HLN 38 63 38 69 / 90 30 10 20
BZN 34 65 35 72 / 80 50 10 20
WEY 30 57 33 66 / 40 10 0 10
DLN 32 61 34 69 / 80 30 10 30
HVR 47 68 42 73 / 90 60 10 10
LWT 42 65 39 68 / 100 50 10 20
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 231800
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1200 PM MDT Thu May 23 2013
.UPDATE...
Today...The deep upper level low pressure center remains over the
Pacific Northwest and periods of rain are expected over a large
portion of the central and northern zones. In addition, another
shortwave will be rotating around the low and will bring another
period of increased chances of rain across Southwest Montana.
Updated to freshen first period POPs and WX, also decreased max
temps a few degrees. Zelzer
&&
.AVIATION...
UPDATED 1800Z.
An upper disturbance moving across the area today will continue to
generate showers today. Showers will decrease in coverage from about
18z til 22z. Showers and isolated thunderstorms will redevelop over
Southwest Montana after 22z. VFR conditions prevail before 22z with
MVFR conditions in the vicinity of showers. Conditions will degrade
with more widespread MVFR and areas of IFR after 00z as lower
ceilings and precipitation move from southern to northern Montana.
Mountains will become obscured after 00z. Winds will remain breezy
through the day before diminishing some after 06z.
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Thu May 23 2013/
A shortwave and upper level jet maximum lifting north through
western MT around a vigorous upper low centered over the Pacific NW
continues to produce widespread precipitation over areas near the
Continental divide this morning. This feature will continue north
into Canada later this morning with precipitation diminishing from
south to north. Snow levels have lowered to around 5500 feet this
morning along the Continental divide and western portions of SW MT
with snow briefly being reported in Dillon overnight but occurring
for last several hrs in Butte as the cold airmass deepens
significantly west of the divide. Some wet snow is likely over
Homestake, Elk Park, MacDonald and Rogers Pass through early this
morning, but with temperatures at or above freezing, little
accumulation is expected on roadways. The next shortwave, an upper
level jet maximum, currently seen on satellite imagery moving into
SW Oregon, will rotate around the main upper low into the region
tonight with showers and thunderstorms redeveloping this afternoon
over SW MT ahead of this feature then spreading north this evening.
This wave tracks a bit further east than the previous one and should
bring a period of steady precipitation across much of forecast area
tonight through Friday morning before this wave lifts north into
Canada by midday Friday. Colder air associated with the upper low
will spread a bit further east late tonight with snow levels remain
around 6000 feet along the Continental divide and lowering to around
7000 feet by Friday morning as far east as the Little/Big Belt Mtns.
The main upper low center lifts north into BC late Friday through
Saturday and a somewhat drier SW flow aloft will result in drier
conditions overall, but weak disturbances within the flow and
afternoon instability will keep a small chance for showers/isolated
thunderstorms in the forecast Friday afternoon/evening with somewhat
better coverage of late day showers and thunderstorms expected
Saturday. Hoenisch
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 42 63 40 / 70 80 20 10
CTB 53 40 59 37 / 100 90 30 10
HLN 57 39 61 38 / 70 70 20 20
BZN 60 38 63 38 / 50 40 10 10
WEY 60 34 55 34 / 30 30 10 10
DLN 57 35 59 35 / 60 60 10 10
HVR 67 49 66 46 / 60 90 60 20
LWT 60 44 63 43 / 60 90 30 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 231613
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1013 AM MDT Thu May 23 2013
.UPDATE...
Today...The deep upper level low pressure center remains over the
Pacific Northwest and periods of rain are expected over a large
portion of the central and northern zones. In addition, another
shortwave will be rotating around the low and will bring another
period of increased chances of rain across Southwest Montana.
Updated to freshen first period POPs and WX, also decreased max
temps a few degrees. Zelzer
&&
.AVIATION...
UPDATED 1155Z.
An upper disturbance moving across the area this morning will
continue to generate showers. Showers will begin to decrease in
areal coverage from south to north after 17z. Surface winds will
remain gusty at times today. Showers and thunderstorms will become
more widespread again after 00z as another upper disturbance moves
across the area. VFR conditions prevail with MVFR conditions in the
vicinity of showers. Conditions will become predominately MVFR with
areas of IFR after 00z due to lowered ceilings and precipitation.
Mountains will become obscured after 00z.
&&
.HYDROLOGY...Widespread rain and high elevation snow will continue
at times through Friday morning. Snow levels should lower enough
to lessen the impact of moderate precipitation on the remaining
mtn snowpack in these areas, however local streams and rivers
could see delayed rises through the upcoming weekend. Persons
living near or planning activities near the mentioned areas during
the holiday weekend should be alert for rising river levels and
increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Thu May 23 2013/
A shortwave and upper level jet maximum lifting north through
western MT around a vigorous upper low centered over the Pacific NW
continues to produce widespread precipitation over areas near the
Continental divide this morning. This feature will continue north
into Canada later this morning with precipitation diminishing from
south to north. Snow levels have lowered to around 5500 feet this
morning along the Continental divide and western portions of SW MT
with snow briefly being reported in Dillon overnight but occurring
for last several hrs in Butte as the cold airmass deepens
significantly west of the divide. Some wet snow is likely over
Homestake, Elk Park, MacDonald and Rogers Pass through early this
morning, but with temperatures at or above freezing, little
accumulation is expected on roadways. The next shortwave, an upper
level jet maximum, currently seen on satellite imagery moving into
SW Oregon, will rotate around the main upper low into the region
tonight with showers and thunderstorms redeveloping this afternoon
over SW MT ahead of this feature then spreading north this evening.
This wave tracks a bit further east than the previous one and should
bring a period of steady precipitation across much of forecast area
tonight through Friday morning before this wave lifts north into
Canada by midday Friday. Colder air associated with the upper low
will spread a bit further east late tonight with snow levels remain
around 6000 feet along the Continental divide and lowering to around
7000 feet by Friday morning as far east as the Little/Big Belt Mtns.
The main upper low center lifts north into BC late Friday through
Saturday and a somewhat drier SW flow aloft will result in drier
conditions overall, but weak disturbances within the flow and
afternoon instability will keep a small chance for showers/isolated
thunderstorms in the forecast Friday afternoon/evening with somewhat
better coverage of late day showers and thunderstorms expected
Saturday. Hoenisch
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 56 42 63 40 / 70 80 20 10
CTB 53 40 59 37 / 100 90 30 10
HLN 57 39 61 38 / 70 70 20 20
BZN 60 38 63 38 / 50 40 10 10
WEY 60 34 55 34 / 30 30 10 10
DLN 57 35 59 35 / 60 60 10 10
HVR 67 49 66 46 / 60 90 60 20
LWT 60 44 63 43 / 60 90 30 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 231158
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 AM MDT Thu May 23 2013
UPDATED AVIATION SECTION
.DISCUSSION...
A shortwave and upper level jet maximum lifting north through
western MT around a vigorous upper low centered over the Pacific NW
continues to produce widespread precipitation over areas near the
Continental divide this morning. This feature will continue north
into Canada later this morning with precipitation diminishing from
south to north. Snow levels have lowered to around 5500 feet this
morning along the Continental divide and western portions of SW MT
with snow briefly being reported in Dillon overnight but occurring
for last several hrs in Butte as the cold airmass deepens
significantly west of the divide. Some wet snow is likely over
Homestake, Elk Park, MacDonald and Rogers Pass through early this
morning, but with temperatures at or above freezing, little
accumulation is expected on roadways. The next shortwave, an upper
level jet maximum, currently seen on satellite imagery moving into
SW Oregon, will rotate around the main upper low into the region
tonight with showers and thunderstorms redeveloping this afternoon
over SW MT ahead of this feature then spreading north this evening.
This wave tracks a bit further east than the previous one and should
bring a period of steady precipitation across much of forecast area
tonight through Friday morning before this wave lifts north into
Canada by midday Friday. Colder air associated with the upper low
will spread a bit further east late tonight with snow levels remain
around 6000 feet along the Continental divide and lowering to around
7000 feet by Friday morning as far east as the Little/Big Belt Mtns.
The main upper low center lifts north into BC late Friday through
Saturday and a somewhat drier SW flow aloft will result in drier
conditions overall, but weak disturbances within the flow and
afternoon instability will keep a small chance for showers/isolated
thunderstorms in the forecast Friday afternoon/evening with somewhat
better coverage of late day showers and thunderstorms expected
Saturday. Hoenisch
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.AVIATION...
UPDATED 1155Z.
An upper disturbance moving across the area this morning will
continue to generate showers. Showers will begin to decrease in
areal coverage from south to north after 17z. Surface winds will
remain gusty at times today. Showers and thunderstorms will become
more widespread again after 00z as another upper disturbance moves
across the area. VFR conditions prevail with MVFR conditions in the
vicinity of showers. Conditions will become predominately MVFR with
areas of IFR after 00z due to lowered ceilings and precipitation.
Mountains will become obscured after 00z.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 59 42 63 40 / 40 80 20 10
CTB 53 40 59 37 / 100 90 30 10
HLN 58 39 61 38 / 50 70 20 20
BZN 60 38 63 38 / 50 40 10 10
WEY 56 34 55 34 / 30 30 10 10
DLN 57 35 59 35 / 70 60 10 10
HVR 69 49 66 46 / 40 90 60 20
LWT 64 44 63 43 / 60 90 30 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 231156
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 AM MDT Thu May 23 2013
UPDATED AVIATION SECTION
.DISCUSSION...
A shortwave and upper level jet maximum lifting north through
western MT around a vigorous upper low centered over the Pacific NW
continues to produce widespread precipitation over areas near the
Continental divide this morning. This feature will continue north
into Canada later this morning with precipitation diminishing from
south to north. Snow levels have lowered to around 5500 feet this
morning along the Continental divide and western portions of SW MT
with snow briefly being reported in Dillon overnight but occurring
for last several hrs in Butte as the cold airmass deepens
significantly west of the divide. Some wet snow is likely over
Homestake, Elk Park, MacDonald and Rogers Pass through early this
morning, but with temperatures at or above freezing, little
accumulation is expected on roadways. The next shortwave, an upper
level jet maximum, currently seen on satellite imagery moving into
SW Oregon, will rotate around the main upper low into the region
tonight with showers and thunderstorms redeveloping this afternoon
over SW MT ahead of this feature then spreading north this evening.
This wave tracks a bit further east than the previous one and should
bring a period of steady precipitation across much of forecast area
tonight through Friday morning before this wave lifts north into
Canada by midday Friday. Colder air associated with the upper low
will spread a bit further east late tonight with snow levels remain
around 6000 feet along the Continental divide and lowering to around
7000 feet by Friday morning as far east as the Little/Big Belt Mtns.
The main upper low center lifts north into BC late Friday through
Saturday and a somewhat drier SW flow aloft will result in drier
conditions overall, but weak disturbances within the flow and
afternoon instability will keep a small chance for showers/isolated
thunderstorms in the forecast Friday afternoon/evening with somewhat
better coverage of late day showers and thunderstorms expected
Saturday. Hoenisch
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationary as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.AVIATION...
UPDATED 1155Z.
An upper disturbance moving across the area this morning will
continue to generate showers. Showers will begin to decrease in
areal coverage from south to north after 17z. Showers and
thunderstorms will become more widespread again after 00z as another
upper disturbance moves across the area. VFR conditions prevail with
MVFR conditions in the vicinity of showers. Conditions will become
predominately MVFR with areas of IFR after 00z due to lowered
ceilings and precipitation. Mountains will become obscured after 00z.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 59 42 63 40 / 40 80 20 10
CTB 53 40 59 37 / 100 90 30 10
HLN 58 39 61 38 / 50 70 20 20
BZN 60 38 63 38 / 50 40 10 10
WEY 56 34 55 34 / 30 30 10 10
DLN 57 35 59 35 / 70 60 10 10
HVR 69 49 66 46 / 40 90 60 20
LWT 64 44 63 43 / 60 90 30 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 231045
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
445 AM MDT Thu May 23 2013
.DISCUSSION...
A shortwave and upper level jet maximum lifting north through
western MT around a vigorous upper low centered over the Pacific NW
continues to produce widespread precipitation over areas near the
Continental divide this morning. This feature will continue north
into Canada later this morning with precipitation diminishing from
south to north. Snow levels have lowered to around 5500 feet this
morning along the Continental divide and western portions of SW MT
with snow briefly being reported in Dillon overnight but occurring
for last several hrs in Butte as the cold airmass deepens
significantly west of the divide. Some wet snow is likely over Homestake,
Elk Park, MacDonald and Rogers Pass through early this morning,
but with temperatures at or above freezing, little accumulation is
expected on roadways. The next shortwave an upper level jet
maximum, currently seen on Satellite imagery moving into SW
Oregon, will rotate around the main upper low into the region
tonight with showers and thunderstorms redeveloping this afternoon
over SW MT ahead of this feature then spreading north this
evening. This wave tracks a bit further east than the previous
one and should bring a period of steady precipitation across much of
forecast area tonight through Friday morning before this wave
lifts north into Canada by midday Friday. Colder air associated
with the upper low will spread a bit further east late tonight with
snow levels remain around 6000 feet along the Continental divide
and lowering to around 7000 feet by Friday morning as far east as
the Little/Big Belt Mtns. The main upper low center lifts north
into BC late Friday through Saturday and a somewhat drier SW flow
aloft will result in drier conditions overall, but weak
disturbances within the flow and afternoon instability will keep a
small chance for showers/isolated thunderstorms int he forecast
Friday afternoon/evening with somewhat better coverage of late day
showers and thunderstorms expected Saturday. Hoenisch
Saturday night through Thursday...The period begins with a closed
upper low quasi-stationery as it fills over southwest Canada.
Circulation around this feature will continue to bring moisture and
instability to the area with scattered showers and/or thunderstorms
remaining a possibility through Sunday. The airmass will remain
unstable Monday as an upper trof remains over the west coast.
Diffluent flow aloft will aid in another round of scattered showers
and thunderstorms. The models begin to diverge with their solutions
on Tuesday. Though the airmass will remain unstable, drier air will
move into northern Montana while afternoon showers and thunderstorms
will continue to develop over southwest Montana. Unsettled and wet
conditions will continue Wednesday and Thursday as the west coast
upper trof rotates across the area. Showers and thunderstorms will
become widespread across the central and northern portions of the
county warning area. Temperatures will remain above seasonal
averages through the period.
&&
.AVIATION...
UPDATED 0430Z.
It now appears the only widespread rain the rest of tonight will be
near the Continental Divide with KBZN/KHLN/KCTB/KGTF seeing only
occasional showers. It also now appears that farther east (KHVR and
KLWT) should see mainly dry conditions the rest of tonight. There
could still be scattered areas of MVFR ceilings Thursday morning
but conditions should become VFR by early afternoon. There also
should not be much precipitation during the morning and early
afternoon with the exception of near the Rocky Mountain Front. Then
during the afternoon scattered showers and thunderstorms will
develop over southwest Montana. Thunderstorms will diminish by dark
as showers turn to widespread rain and spread north. With the
precipitation expect at least scattered MVFR ceilings and
visibilities with these conditions possibly becoming widespread over
the plains during the evening. Also with the precipitation expect
local IFR ceilings in heavier precipitation. Mountains will be
generally obscured over the Rocky Mountain Front with areas of
mountain obscurement elsewhere particularly late in the afternoon
and evening. Winds are another forecast problem as guidance differs
quite a bit on both wind speeds and directions. Hence confidence in
forecast winds in the tafs is lower than average. Blank
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 59 42 63 40 / 40 80 20 10
CTB 53 40 59 37 / 100 90 30 10
HLN 58 39 61 38 / 50 70 20 20
BZN 60 38 63 38 / 50 40 10 10
WEY 56 34 55 34 / 30 30 10 10
DLN 57 35 59 35 / 70 60 10 10
HVR 69 49 66 46 / 40 90 60 20
LWT 64 44 63 43 / 60 90 30 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until Noon MDT Friday FOR ELEVATIONS
ABOVE 5500 FEET FOR Northern Rocky Mountain Front...Southern
Rocky Mountain Front.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 230432
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1030 PM MDT Wed May 22 2013
UPDATED AVIATION SECTION
.UPDATE...
Numerous light rain showers continue to push northward over the
Treasure state...as this area of precipitation continues to rotate
around the main area of upper low pressure over the Pacific
Northwest. Expect this steadier shower activity to continue
through tonight over the western half of the CWA...while areas
around Lewistown...Harlem and Havre only seeing a passing shower
at best. Thus pops have been raised in the West and remain low in
the East for tonight. Also...the threat for thunderstorms has
greatly diminished...thus those have been dropped for tonight.
Forecast models indicate that most of the precipitation will come
to an end early on Thursday morning...and only a passing light
shower is expected in most areas during the day. The next main
area of precipitation should affect the region Thursday
night...especially over much of North Central MT.
The winter weather advisory continues for the Rocky Mountain
Front. A few inches will be possible on Marias Pass...but the most
significant snowfall should occur near ridge tops. Brusda
&&
.AVIATION...
UPDATED 0430Z.
It now appears the only widespread rain the rest of tonight will be
near the Continental Divide with KBZN/KHLN/KCTB/KGTF seeing only
occasional showers. It also now appears that farther east (KHVR and
KLWT) should see mainly dry conditions the rest of tonight. There
could still be scattered areas of MVFR ceilings Thursday morning
but conditions should become VFR by early afternoon. There also
should not be much precipitation during the morning and early
afternoon with the exception of near the Rocky Mountain Front. Then
during the afternoon scattered showers and thunderstorms will
develop over southwest Montana. Thunderstorms will diminish by dark
as showers turn to widespread rain and spread north. With the
precipitation expect at least scattered MVFR ceilings and
visibilities with these conditions possibly becoming widespread over
the plains during the evening. Also with the precipitation expect
local IFR ceilings in heavier precipitation. Mountains will be
generally obscured over the Rocky Mountain Front with areas of
mountain obscurement elsewhere particularly late in the afternoon
and evening. Winds are another forecast problem as guidance differs
quite a bit on both wind speeds and directions. Hence confidence in
forecast winds in the tafs is lower than average. Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will
develop tonight along the Rocky Mtn Front and continue through
Thursday morning with additional precipitation expected Thursday
and Thursday night. Heaviest precipitation is expected late
tonight through Thursday morning with precipitation amounts locally
exceeding an inch and a half along the continental divide. Snow
levels should lower enough to lessen the impact of moderate
precipitation on the remaining mtn snowpack in these areas, however
local streams and rivers could see delayed rises through the
upcoming weekend. Persons living near or planning activities near
the mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 555 PM MDT Wed May 22 2013/
Tonight through Friday...The airmass is slightly unstable and some
good shear is available from Southwest Montana up towards Lewis and
Clark county. Scattered showers and thunderstorms are expected into
early evening. The main threat from these thunderstorms are strong
winds...hail should remain small. A closed upper level low will
rotate over the Pacific Northwest tonight and bring a period of
widespread precipitation centered over the Northern Rockies through
Friday morning. A jet will move through the flow aloft and develop
strong diffluence over central and north central Montana tonight
into Thursday morning. Snow levels show most of the snow to be above
6000 feet and the current watch will be changed to a winter weather
advisory. Elsewhere, all but the northwest zones will be slightly
unstable Thursday and the extreme southwest zones will be the most
unstable. The jet aloft will move across the zones again Thursday
afternoon, and the pattern should once again develop strong
diffluence over the zones. Winds will switch from the southeast to
southwest Thursday night and hasten the end of precip east of the
Rockies Friday...although higher elevations along the Divide will
remain very moist. Zelzer
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of QPF with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 55 40 64 / 100 70 70 40
CTB 40 54 38 62 / 100 100 70 50
HLN 40 58 39 63 / 100 70 70 40
BZN 42 63 37 66 / 100 60 60 30
WEY 38 61 34 59 / 60 30 40 10
DLN 38 59 35 62 / 100 50 60 30
HVR 49 68 45 69 / 30 60 80 70
LWT 45 63 41 65 / 50 60 90 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from Midnight tonight to Noon MDT Friday
FOR ELEVATIONS ABOVE 5500 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 230308
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
908 PM MDT Wed May 22 2013
.UPDATE...
Numerous light rain showers continue to push northward over the
Treasure state...as this area of precipitation continues to rotate
around the main area of upper low pressure over the Pacific
Northwest. Expect this steadier shower activity to continue
through tonight over the western half of the CWA...while areas
around Lewistown...Harlem and Havre only seeing a passing shower
at best. Thus pops have been raised in the West and remain low in
the East for tonight. Also...the threat for thunderstorms has
greatly diminished...thus those have been dropped for tonight.
Forecast models indicate that most of the precipitation will come
to an end early on Thursday morning...and only a passing light
shower is expected in most areas during the day. The next main
area of precipitation should affect the region Thursday
night...especially over much of North Central MT.
The winter weather advisory continues for the Rocky Mountain
Front. A few inches will be possible on Marias Pass...but the most
significant snowfall should occur near ridge tops. Brusda
&&
.AVIATION...
UPDATED 2355Z.
Showers will turn to widespread rain this evening except at KHVR and
KLWT. The rain will turn back to showers late tonight into Thursday
morning. The main forecast problem will be how low conditions will
go. Like yesterday some guidance forecasts VFR conditions while
other guidance forecasts MVFR/IFR conditions. Tended to take a
middle-of-the-road approach so over southwest Montana went with
primarily VFR conditions with occasional MVFR conditions. At KGTF
and KCTB on the other hand went with MVFR/IFR conditions later
tonight and continuing into Thursday morning. Do expect generally
VFR conditions Thursday afternoon over the entire forecast area with
MVFR/IFR conditions in local heavy precipitation. As for
thunderstorms the only threat for thunderstorms early this evening
will be over southwest Montana. For Thursday afternoon there will be
a few thunderstorms except at KCTB and the best threat for
thunderstorms at the taf sites will be at KLWT. Winds are another
forecast problem as guidance differs quite a bit on both wind speeds
and directions. Hence confidence in forecast winds in the tafs is
lower than average. Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will
develop tonight along the Rocky Mtn Front and continue through
Thursday morning with additional precipitation expected Thursday
and Thursday night. Heaviest precipitation is expected late
tonight through Thursday morning with precipitation amounts locally
exceeding an inch and a half along the continental divide. Snow
levels should lower enough to lessen the impact of moderate
precipitation on the remaining mtn snowpack in these areas, however
local streams and rivers could see delayed rises through the
upcoming weekend. Persons living near or planning activities near
the mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
&&
.PREV DISCUSSION...
/ISSUED 555 PM MDT Wed May 22 2013/
Tonight through Friday...The airmass is slightly unstable and some
good shear is available from Southwest Montana up towards Lewis and
Clark county. Scattered showers and thunderstorms are expected into
early evening. The main threat from these thunderstorms are strong
winds...hail should remain small. A closed upper level low will
rotate over the Pacific Northwest tonight and bring a period of
widespread precipitation centered over the Northern Rockies through
Friday morning. A jet will move through the flow aloft and develop
strong diffluence over central and north central Montana tonight
into Thursday morning. Snow levels show most of the snow to be above
6000 feet and the current watch will be changed to a winter weather
advisory. Elsewhere, all but the northwest zones will be slightly
unstable Thursday and the extreme southwest zones will be the most
unstable. The jet aloft will move across the zones again Thursday
afternoon, and the pattern should once again develop strong
diffluence over the zones. Winds will switch from the southeast to
southwest Thursday night and hasten the end of precip east of the
Rockies Friday...although higher elevations along the Divide will
remain very moist. Zelzer
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of QPF with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 55 40 64 / 100 70 70 40
CTB 40 54 38 62 / 100 100 70 50
HLN 40 58 39 63 / 100 70 70 40
BZN 42 63 37 66 / 100 60 60 30
WEY 38 61 34 59 / 60 30 40 10
DLN 38 59 35 62 / 100 50 60 30
HVR 49 68 45 69 / 30 60 80 70
LWT 45 63 41 65 / 50 60 90 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from Midnight tonight to Noon MDT Friday
FOR ELEVATIONS ABOVE 5500 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 230000
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 PM MDT Wed May 22 2013
UPDATED AVIATION SECTION
.DISCUSSION...
Tonight through Friday...The airmass is slightly unstable and some
good shear is available from Southwest Montana up towards Lewis and
Clark county. Scattered showers and thunderstorms are expected into
early evening. The main threat from these thunderstorms are strong
winds...hail should remain small. A closed upper level low will
rotate over the Pacific Northwest tonight and bring a period of
widespread precipitation centered over the Northern Rockies through
Friday morning. A jet will move through the flow aloft and develop
strong diffluence over central and north central Montana tonight
into Thursday morning. Snow levels show most of the snow to be above
6000 feet and the current watch will be changed to a winter weather
advisory. Elsewhere, all but the northwest zones will be slightly
unstable Thursday and the extreme southwest zones will be the most
unstable. The jet aloft will move across the zones again Thursday
afternoon, and the pattern should once again develop strong
diffluence over the zones. Winds will switch from the southeast to
southwest Thursday night and hasten the end of precip east of the
Rockies Friday...although higher elevations along the Divide will
remain very moist. Zelzer
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of QPF with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.AVIATION...
UPDATED 2355Z.
Showers will turn to widespread rain this evening except at KHVR and
KLWT. The rain will turn back to showers late tonight into Thursday
morning. The main forecast problem will be how low conditions will
go. Like yesterday some guidance forecasts VFR conditions while
other guidance forecasts MVFR/IFR conditions. Tended to take a
middle-of-the-road approach so over southwest Montana went with
primarily VFR conditions with occasional MVFR conditions. At KGTF
and KCTB on the other hand went with MVFR/IFR conditions later
tonight and continuing into Thursday morning. Do expect generally
VFR conditions Thursday afternoon over the entire forecast area with
MVFR/IFR conditions in local heavy precipitation. As for
thunderstorms the only threat for thunderstorms early this evening
will be over southwest Montana. For Thursday afternoon there will be
a few thunderstorms except at KCTB and the best threat for
thunderstorms at the taf sites will be at KLWT. Winds are another
forecast problem as guidance differs quite a bit on both wind speeds
and directions. Hence confidence in forecast winds in the tafs is
lower than average. Blank
&&
.HYDROLOGY...Widespread rain and high elevation snow will
develop tonight along the Rocky Mtn Front and continue through
Thursday morning with additional precipitation expected Thursday
and Thursday night. Heaviest precipitation is expected late
tonight through Thursday morning with precipitation amounts locally
exceeding an inch and a half along the continental divide. Snow
levels should lower enough to lessen the impact of moderate
precipitation on the remaining mtn snowpack in these areas, however
local streams and rivers could see delayed rises through the
upcoming weekend. Persons living near or planning activities near
the mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 55 40 64 / 90 70 70 40
CTB 40 54 38 62 / 100 100 70 50
HLN 40 58 39 63 / 80 70 70 40
BZN 42 63 37 66 / 70 60 60 30
WEY 38 61 34 59 / 50 30 40 10
DLN 38 59 35 62 / 70 50 60 30
HVR 49 68 45 69 / 20 60 80 70
LWT 45 63 41 65 / 50 60 90 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from Midnight tonight to Noon MDT Friday
FOR ELEVATIONS ABOVE 5500 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 222113
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
313 PM MDT Wed May 22 2013
.DISCUSSION...
Tonight through Friday...The airmass is slightly unstable and some
good shear is available from Southwest Montana up towards Lewis and
Clark county. Scattered showers and thunderstorms are expected into
early evening. The main threat from these thunderstorms are strong
winds...hail should remain small. A closed upper level low will
rotate over the Pacific Northwest tonight and bring a period of
widespread precipitation centered over the Northern Rockies through
Friday morning. A jet will move through the flow aloft and develop
strong diffluence over central and north central Montana tonight
into Thursday morning. Snow levels show most of the snow to be above
6000 feet and the current watch will be changed to a winter weather
advisory. Elsewhere, all but the northwest zones will be slightly
unstable Thursday and the extreme southwest zones will be the most
unstable. The jet aloft will move across the zones again Thursday
afternoon, and the pattern should once again develop strong
diffluence over the zones. Winds will switch from the southeast to
southwest Thursday night and hasten the end of precip east of the
Rockies Friday...although higher elevations along the Divide will
remain very moist. Zelzer
&&
.AVIATION...
UPDATED 1800Z.
VFR conditions prevail with the exception of MVFR conditions from
KLWT to KHVR that will slowly lift this afternoon. The airmass will
become unstable after 21z with scattered showers and thunderstorms
developing first over Southwest Montana before spreading north and
east during the afternoon and early evening. Best chance for
thunderstorms will be from West Yellowstone to Helena and south.
East to southeast surface winds will remain gusty through this
evening. Expect more widespread steady rain to move into the region
through the night with most impact along the terrain of the
Continental Divide. Widespread terrain obscuration due to low
ceilings and precipitation is expected after 00z and will continue
through the 24 hour TAF period. Widespread MVFR conditions will be
possible after 06z with the increase in shower activity.
&&
.HYDROLOGY...Widespread rain and high elevation snow will
develop tonight along the Rocky Mtn Front and continue through
Thursday morning with additional precipitation expected Thursday
and Thursday night. Heaviest precipitation is expected late
tonight through Thursday morning with precipitation amounts
locally exceeding an inch along the continental divide. Snow
levels should lower enough to lessen the impact of moderate
precipitation on the remaining mtn snowpack in these areas,
however local streams and rivers could see delayed rises through
the upcoming weekend. Persons living near or planning activities
near the mentioned areas during the holiday weekend should be
alert for rising river levels and increased stream flows.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 55 40 64 / 90 70 70 40
CTB 40 54 38 62 / 100 100 70 50
HLN 40 58 39 63 / 80 70 70 40
BZN 42 63 37 66 / 70 60 60 30
WEY 38 61 34 59 / 50 30 40 10
DLN 38 59 35 62 / 70 50 60 30
HVR 49 68 45 69 / 20 60 80 70
LWT 45 63 41 65 / 50 60 90 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from Midnight tonight to Noon MDT Friday
FOR ELEVATIONS ABOVE 5500 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 221804
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1200 PM MDT Wed May 22 2013
.UPDATE...
Scattered showers have developed along the Rocky Mountain Front this
morning as moisture streams in from the southwest. POPS were raised
in this area to better reflect activity shown on radar...and
furthermore blended with 12Z model guidance. Gusty southeast winds
continue over the north central plains...which were backed about 20
degrees closer to east in line with observations. Finally, added 1-3
degrees to high temperatures over the plains after blending with
fresh guidance and noting gaps in clouds over the area. Rest of
forecast package remains on track. Nutter
&&
.AVIATION...
UPDATED 1800Z.
VFR conditions prevail with the exception of MVFR conditions from
KLWT to KHVR that will slowly lift this afternoon. The airmass will
become unstable after 21z with scattered showers and thunderstorms
developing first over Southwest Montana before spreading north and
east during the afternoon and early evening. Best chance for
thunderstorms will be from West Yellowstone to Helena and south.
East to southeast surface winds will remain gusty through this
evening. Expect more widespread steady rain to move into the region
through the night with most impact along the terrain of the
Continental Divide. Widespread terrain obscuration due to low
ceilings and precipitation is expected after 00z and will continue
through the 24 hour TAF period. Widespread MVFR conditions will be
possible after 06z with the increase in shower activity.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Wed May 22 2013/
Today through Friday...A vigorous upper low, currently centered
over the Pacific NW, will remain nearly stationary through the
remainder of this week with several lobes of shortwave energy and
associated upper level jet maximums rotating around the low
through the Northern Rockies and MT. First piece of energy will
lift north through western MT tonight with convection initiating
over SW MT this afternoon, which then looks to lift north across
north central MT tonight. Instability and shear parameters are
marginal for a few stronger storms across SE portions of the
forecast area through early this evening, mainly across Gallatin and
Meagher counties. Expect convection to weaken as is spreads north
into a more stable airmass over north central MT this evening with
an area of widespread precipitation developing over western portions
of north-central MT overnight. At the same time, a frontal boundary
and cold pool aloft associated with the upper low will spread east to
areas along the Continental divide overnight, lowering snow levels
to around 6000 ft by Thursday morning. Heaviest precipitation will
be focused along the Rocky Mtn Front region where favorable jet
dynamics and upslope SE flow will exist. Precipitation amounts
through Thursday morning could exceed 1 inch along the divide in
this area with significant snow accumulations generally confined to
areas above 6500 feet. Some of the cold air aloft spills east into
central MT Thursday, however S to SE flow aloft around the low will
limit its extent with the bulk of the colder air remaining west of
the divide. Additional lobes of shortwave energy lift across the
region Thursday and Friday with periods of more widespread showers
associated with each disturbance along with a chance of
thunderstorms during the afternoon/evening periods. Models are still
having some difficulty with timing and location of these
disturbances, but all focus on western portions of north central MT
for greatest precipitation amounts. Snow levels will fluctuate
around 6500 along the rocky Mtn front with additional snow
accumulation possible across the highest elevations.
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of QPF with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 43 58 43 / 20 70 60 60
CTB 63 41 55 41 / 40 80 80 70
HLN 68 44 60 43 / 60 70 60 60
BZN 67 42 66 44 / 60 70 50 50
WEY 64 35 61 36 / 60 50 30 30
DLN 68 39 62 41 / 40 60 40 50
HVR 71 49 68 47 / 10 30 60 70
LWT 63 44 63 44 / 20 50 60 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from 6 PM MDT this evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 221637
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1037 AM MDT Wed May 22 2013
.UPDATE...
Scattered showers have developed along the Rocky Mountain Front this
morning as moisture streams in from the southwest. POPS were raised
in this area to better reflect activity shown on radar...and furthermore
blended with 12Z model guidance. Gusty southeast winds continue
over the north central plains...which were backed about 20 degrees
closer to east in line with observations. Finally, added 1-3
degrees to high temperatures over the plains after blending with
fresh guidance and noting gaps in clouds over the area. Rest of
forecast package remains on track. Nutter
&&
.AVIATION...
UPDATED 1155Z.
Area of low clouds this morning and MVFR conditions from KLWT to
KHVR. These clouds should dissipate after 15z. The airmass will
become unstable after 18z with scattered showers and thunderstorms
developing over southwest Montana. Showers and thunderstorms will
then spread north and east during the afternoon and early evening.
East to southeast surface winds will be gusty today through this
evening. VFR conditions prevail with the exception of MVFR
conditions at KLWT and KHVR through 15z. Areas of mountain
obscurement due to low ceilings and precipitation are possible after
00z.
&&
.PREV DISCUSSION...
/ISSUED 555 AM MDT Wed May 22 2013/
Today through Friday...A vigorous upper low, currently centered
over the Pacific NW, will remain nearly stationary through the
remainder of this week with several lobes of shortwave energy and
associated upper level jet maximums rotating around the low
through the Northern Rockies and MT. First piece of energy will
lift north through western MT tonight with convection initiating
over SW MT this afternoon, which then looks to lift north across
north central MT tonight. Instability and shear parameters are marginal
for a few stronger storms across SE portions of the forecast area
through early this evening, mainly across Gallatin and Meagher
counties. Expect convection to weaken as is spreads north into a
more stable airmass over north central MT this evening with an area of
widespread precipitation developing over western portions of north-
central MT overnight. At the same time, a frontal boundary and
cold pool aloft associated with the upper low will spread east to
areas along the Continental divide overnight, lowering snow levels
to around 6000 ft by Thursday morning. Heaviest precipitation will
be focused along the Rocky Mtn Front region where favorable jet
dynamics and upslope SE flow will exist. Precipitation amounts
through Thursday morning could exceed 1 inch along the divide in
this area with significant snow accumulations generally confined
to areas above 6500 feet. Some of the cold air aloft spills east
into central MT Thursday, however S to SE flow aloft around the
low will limit its extent with the bulk of the colder air
remaining west of the divide. Additional lobes of shortwave energy
lift across the region Thursday and Friday with periods of more
widespread showers associated with each disturbance along with a
chance of thunderstorms during the afternoon/evening periods.
Models are still having some difficulty with timing and location
of these disturbances, but all focus on western portions of north
central MT for greatest precipitation amounts. Snow levels will
fluctuate around 6500 along the rocky Mtn front with additional
snow accumulation possible across the highest elevations.
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of qpf with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 43 58 43 / 20 70 60 60
CTB 63 41 55 41 / 40 80 80 70
HLN 68 44 60 43 / 60 70 60 60
BZN 67 42 66 44 / 60 70 50 50
WEY 64 35 61 36 / 60 50 30 30
DLN 68 39 62 41 / 40 60 40 50
HVR 71 49 68 47 / 10 30 60 70
LWT 63 44 63 44 / 20 50 60 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from 6 PM MDT this evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 221156
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 AM MDT Wed May 22 2013
UPDATED AVIATION SECTION
.DISCUSSION...
Today through Friday...A vigorous upper low, currently centered
over the Pacific NW, will remain nearly stationary through the
remainder of this week with several lobes of shortwave energy and
associated upper level jet maximums rotating around the low
through the Northern Rockies and MT. First piece of energy will
lift north through western MT tonight with convection initiating
over SW MT this afternoon, which then looks to lift north across
north central MT tonight. Instability and shear parameters are marginal
for a few stronger storms across SE portions of the forecast area
through early this evening, mainly across Gallatin and Meagher
counties. Expect convection to weaken as is spreads north into a
more stable airmass over north central MT this evening with an area of
widespread precipitation developing over western portions of north-
central MT overnight. At the same time, a frontal boundary and
cold pool aloft associated with the upper low will spread east to
areas along the Continental divide overnight, lowering snow levels
to around 6000 ft by Thursday morning. Heaviest precipitation will
be focused along the Rocky Mtn Front region where favorable jet
dynamics and upslope SE flow will exist. Precipitation amounts
through Thursday morning could exceed 1 inch along the divide in
this area with significant snow accumulations generally confined
to areas above 6500 feet. Some of the cold air aloft spills east
into central MT Thursday, however S to SE flow aloft around the
low will limit its extent with the bulk of the colder air
remaining west of the divide. Additional lobes of shortwave energy
lift across the region Thursday and Friday with periods of more
widespread showers associated with each disturbance along with a
chance of thunderstorms during the afternoon/evening periods.
Models are still having some difficulty with timing and location
of these disturbances, but all focus on western portions of north
central MT for greatest precipitation amounts. Snow levels will
fluctuate around 6500 along the rocky Mtn front with additional
snow accumulation possible across the highest elevations.
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of qpf with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.AVIATION...
UPDATED 1155Z.
Area of low clouds this morning and MVFR conditions from KLWT to
KHVR. These clouds should dissipate after 15z. The airmass will
become unstable after 18z with scattered showers and thunderstorms
developing over southwest Montana. Showers and thunderstorms will
then spread north and east during the afternoon and early evening.
East to southeast surface winds will be gusty today through this
evening. VFR conditions prevail with the exception of MVFR
conditions at KLWT and KHVR through 15z. Areas of mountain
obscurement due to low ceilings and precipitation are possible after
00z.
&&
.HYDROLOGY...
Widespread rain and high elevation snow will develop tonight along
the Rocky Mtn Front and continue through Thursday morning with
additional precipitation expected Thursday and Thursday night.
Heaviest precipitation is expected late tonight through Thursday
morning with precipitation amounts locally exceeding an inch along
the continental divide. Snow levels should lower enough to lessen
the impact of moderate precipitation on the remaining mtn snowpack
in these areas, however local streams and rivers could see delayed
rises through the upcoming weekend. The situation will continue
to be closely monitored over the the next several days in case any
hydrologic headlines are needed. Persons living near or planning
activities near the mentioned areas during the holiday weekend
should be alert for rising river levels and increased stream
flows. Hoenisch
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 43 58 43 / 20 70 60 60
CTB 62 41 55 41 / 20 80 80 70
HLN 67 44 60 43 / 50 70 60 60
BZN 68 42 66 44 / 50 70 50 50
WEY 63 35 61 36 / 40 50 30 30
DLN 66 39 62 41 / 20 60 40 50
HVR 69 49 68 47 / 10 30 60 70
LWT 61 44 63 44 / 10 50 60 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from this evening through Thursday morning
FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 221132
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
532 AM MDT Wed May 22 2013
.DISCUSSION...
Today through Friday...A vigorous upper low, currently centered
over the Pacific NW, will remain nearly stationary through the
remainder of this week with several lobes of shortwave energy and
associated upper level jet maximums rotating around the low
through the Northern Rockies and MT. First piece of energy will
lift north through western MT tonight with convection initiating
over SW MT this afternoon, which then looks to lift north across
north central MT tonight. Instability and shear parameters are marginal
for a few stronger storms across SE portions of the forecast area
through early this evening, mainly across Gallatin and Meagher
counties. Expect convection to weaken as is spreads north into a
more stable airmass over north central MT this evening with an area of
widespread precipitation developing over western portions of north-
central MT overnight. At the same time, a frontal boundary and
cold pool aloft associated with the upper low will spread east to
areas along the Continental divide overnight, lowering snow levels
to around 6000 ft by Thursday morning. Heaviest precipitation will
be focused along the Rocky Mtn Front region where favorable jet
dynamics and upslope SE flow will exist. Precipitation amounts
through Thursday morning could exceed 1 inch along the divide in
this area with significant snow accumulations generally confined
to areas above 6500 feet. Some of the cold air aloft spills east
into central MT Thursday, however S to SE flow aloft around the
low will limit its extent with the bulk of the colder air
remaining west of the divide. Additional lobes of shortwave energy
lift across the region Thursday and Friday with periods of more
widespread showers associated with each disturbance along with a
chance of thunderstorms during the afternoon/evening periods.
Models are still having some difficulty with timing and location
of these disturbances, but all focus on western portions of north
central MT for greatest precipitation amounts. Snow levels will
fluctuate around 6500 along the rocky Mtn front with additional
snow accumulation possible across the highest elevations.
Friday night through Wednesday...The period begins with a slowly
filling upper low over British Columbia. Southwest flow aloft
associated with this feature will continue to bring moisture and
instability in the form of scattered thunderstorms to the area
Friday night. Generally drier conditions will return Saturday though
afternoon isolated thunderstorms will remain as the flow aloft
becomes more southerly. By Sunday, southwest flow aloft strengthens
as an upper trof approaches the west coast. The airmass remains
moist and instability increases during the afternoon with scattered
thunderstorms the result. The medium range models differ in their
handling of qpf with the European being the wetter model. Model
confidence is low for Memorial Day. The GFS brings the upper trof to
the Pacific Northwest and develops widespread precipitation. The
European model, on the other hand, develops weak ridging over the
area and dry conditions. Given the progressive nature of the GFS
solution, have leaned toward the wetter outcome for Memorial Day.
Continued southwest flow aloft Tuesday and Wednesday ahead of a west
coast upper trof will keep scattered showers and thunderstorms in
the picture. Temperatures will remain above seasonal averages
through the period.
&&
.AVIATION...
UPDATED 0430Z.
The main forecast problem will be the possibility of MVFR or lower
ceilings near and northeast of a line from KLWT to KCTB late tonight
through Wednesday morning. Latest guidance still has significant
differences with regard to ceilings Wednesday morning. Some guidance
keeps conditions VFR while other guidance has ceilings as low as
LIFR. Do not expect LIFR ceilings. Did go with MVFR ceilings at KCTB
and KLWT with confidence in these lower ceilings at a moderate but
not high level. Even if the MVFR or lower ceilings develop Wednesday
morning expect ceilings will become VFR Wednesday afternoon. Expect
gusty southeast to east winds over the plains. Scattered showers and
possibly isolated thunderstorms will develop over southwest Montana
Wednesday afternoon then will increase in areal coverage Wednesday
evening as they spread northeast. There could be brief MVFR ceilings
and visibilities in the showers. Widespread showers will develop
over the Rocky Mountain Front later Wednesday afternoon and continue
through the evening. Expect areas of mountain obscurement with the
showers. Blank
&&
.HYDROLOGY...
Widespread rain and high elevation snow will develop tonight along
the Rocky Mtn Front and continue through Thursday morning with
additional precipitation expected Thursday and Thursday night.
Heaviest precipitation is expected late tonight through Thursday
morning with precipitation amounts locally exceeding an inch along
the continental divide. Snow levels should lower enough to lessen
the impact of moderate precipitation on the remaining mtn snowpack
in these areas, however local streams and rivers could see delayed
rises through the upcoming weekend. The situation will continue
to be closely monitored over the the next several days in case any
hydrologic headlines are needed. Persons living near or planning
activities near the mentioned areas during the holiday weekend
should be alert for rising river levels and increased stream
flows. Hoenisch
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 66 43 58 43 / 20 70 60 60
CTB 62 41 55 41 / 20 80 80 70
HLN 67 44 60 43 / 50 70 60 60
BZN 68 42 66 44 / 50 70 50 50
WEY 63 35 61 36 / 40 50 30 30
DLN 66 39 62 41 / 20 60 40 50
HVR 69 49 68 47 / 10 30 60 70
LWT 61 44 63 44 / 10 50 60 70
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from this evening through Thursday morning
FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky Mountain
Front...Southern Rocky Mountain Front.
&&
$$
SHORT TERM...HOENISCH
LONG TERM...EMANUEL
AVIATION...EMANUEL
weather.gov/greatfalls
000
FXUS65 KTFX 220427
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1030 PM MDT Tue May 21 2013
UPDATED AVIATION SECTION
.UPDATE...
No significant changes to the forecast this evening as some
scattered showers continue over Southwest Montana. Will slightly
increase pops for these showers through Midnight...shower activity
is not currently expected to continue into the morning hours. And
has already decreased significantly after sunset. Moisture aloft
continue to flow into the area and the wetter conditions for the
rest of the week currently appear on track. Suk
&&
.AVIATION...
UPDATED 0430Z.
The main forecast problem will be the possibility of MVFR or lower
ceilings near and northeast of a line from KLWT to KCTB late tonight
through Wednesday morning. Latest guidance still has significant
differences with regard to ceilings Wednesday morning. Some guidance
keeps conditions VFR while other guidance has ceilings as low as
LIFR. Do not expect LIFR ceilings. Did go with MVFR ceilings at KCTB
and KLWT with confidence in these lower ceilings at a moderate but
not high level. Even if the MVFR or lower ceilings develop Wednesday
morning expect ceilings will become VFR Wednesday afternoon. Expect
gusty southeast to east winds over the plains. Scattered showers and
possibly isolated thunderstorms will develop over southwest Montana
Wednesday afternoon then will increase in areal coverage Wednesday
evening as they spread northeast. There could be brief MVFR ceilings
and visibilities in the showers. Widespread showers will develop
over the Rocky Mountain Front later Wednesday afternoon and continue
through the evening. Expect areas of mountain obscurement with the
showers. Blank
&&
.HYDROLOGY...
The low pressure weather system expected to remain over the PacNW
this week will bring periods of light to occasionally moderate rain
from Wed evening through Fri afternoon. Forecast models continue to
show some rainfall amounts in excess of one inch are possible along
the Rocky Mtn Front, including Glacier NP. Local streams and rivers
could see some quick rises, especially over the foothills and
adjacent plains west of Interstate 15. Right now, widespread
flooding is not expected, but the situation will be closely
monitored over the coming days in case any hydrologic headlines are
needed. Persons living near or planning activities near the
mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
Waranauskas
&&
.PREV DISCUSSION...
/ISSUED 540 PM MDT Tue May 21 2013/
Tonight through Thursday...Expect gradually more active weather to
move into the region over the next 24 to 48 hours...as the main
upper level low that is currently just off the West coast starts
to move inland over the Pacific Northwest. A few isolated
thunderstorms are starting to develop over southern Idaho this
afternoon...and these storms should move into Southwest Montana by
this evening and then continue to expand northward along the
divide over the Rocky Mountain Front. For Wednesday...expect
another upper level disturbance to rotate northward through the
region around the upper level low over the Pacific Northwest. Some
thunderstorms will once again be possible over Southwest
Montana...while numerous showers are expected along the front
range. The precipitation becomes a bit heavier Wednesday night and
into Thursday morning along the divide...as snow levels also begin
to lower. The snow level will lower to around 6000 feet by
Thursday morning...with a significant snowfall possible for
elevations above 6000 feet. Thus a winter storm watch has been
issued for the higher elevations of the Rocky Mountain Front. A
steadier rain is expected over much of Central and North Central
Montana on Thursday morning per the NAM model. The NAM model is
also much colder than the GFS model...bringing snow levels down
to around 4000 feet. I have not gone this low with the snow
levels...but will continue to monitor this closely. Afternoon
temperatures will generally be near/slightly below normal for both
Wednesday and Thursday for most locations. Brusda
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 74 41 67 40 / 0 10 10 70
CTB 74 40 63 39 / 0 10 30 80
HLN 76 42 67 42 / 10 10 40 80
BZN 73 38 68 40 / 10 10 40 60
WEY 61 34 64 34 / 10 10 40 50
DLN 74 39 66 38 / 10 30 30 50
HVR 75 43 70 46 / 0 0 10 30
LWT 69 38 63 42 / 0 10 20 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from Wednesday evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
SHORT TERM...Suk
LONG TERM...WARANAUSKAS
AVIATION...BLANK
weather.gov/greatfalls
000
FXUS65 KTFX 220316
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
916 PM MDT Tue May 21 2013
.UPDATE...
No significant changes to the forecast this evening as some
scattered showers continue over Southwest Montana. Will slightly
increase pops for these showers through Midnight...shower activity
is not currently expected to continue into the morning hours. And
has already decreased significantly after sunset. Moisture aloft
continue to flow into the area and the wetter conditions for the
rest of the week currently appear on track. Suk
&&
.AVIATION...
UPDATED 2340Z.
There should be a few showers from southwest Montana to the Rocky
Mountain Front early this evening but they should diminish by dark.
A stray lightning strike is not out of the question. There will be a
better threat for showers and thunderstorms from southwest Montana
to the Rocky Mountain Front Wednesday afternoon. Mountains could
become obscured in the precipitation over the Rocky Mountain Front
Wednesday afternoon. The main forecast problem will be the
possibility of MVFR or lower ceilings near and northeast of a
line from KLWT to KCTB late tonight through Wednesday morning. Some
guidance keeps conditions VFR while other guidance has ceilings as
low as LIFR. Do not expect LIFR ceilings. Did go with MVFR ceilings
at KCTB and KLWT with confidence in these lower ceilings at a
moderate but not high level. Have moderate confidence in forecast
wind speeds and directions in the tafs over the plains. Blank
&&
.HYDROLOGY...
The low pressure weather system expected to remain over the PacNW
this week will bring periods of light to occasionally moderate rain
from Wed evening through Fri afternoon. Forecast models continue to
show some rainfall amounts in excess of one inch are possible along
the Rocky Mtn Front, including Glacier NP. Local streams and rivers
could see some quick rises, especially over the foothills and
adjacent plains west of Interstate 15. Right now, widespread
flooding is not expected, but the situation will be closely
monitored over the coming days in case any hydrologic headlines are
needed. Persons living near or planning activities near the
mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
Waranauskas
&&
.PREV DISCUSSION...
/ISSUED 540 PM MDT Tue May 21 2013/
Tonight through Thursday...Expect gradually more active weather to
move into the region over the next 24 to 48 hours...as the main
upper level low that is currently just off the West coast starts
to move inland over the Pacific Northwest. A few isolated
thunderstorms are starting to develop over southern Idaho this
afternoon...and these storms should move into Southwest Montana by
this evening and then continue to expand northward along the
divide over the Rocky Mountain Front. For Wednesday...expect
another upper level disturbance to rotate northward through the
region around the upper level low over the Pacific Northwest. Some
thunderstorms will once again be possible over Southwest
Montana...while numerous showers are expected along the front
range. The precipitation becomes a bit heavier Wednesday night and
into Thursday morning along the divide...as snow levels also begin
to lower. The snow level will lower to around 6000 feet by
Thursday morning...with a significant snowfall possible for
elevations above 6000 feet. Thus a winter storm watch has been
issued for the higher elevations of the Rocky Mountain Front. A
steadier rain is expected over much of Central and North Central
Montana on Thursday morning per the NAM model. The NAM model is
also much colder than the GFS model...bringing snow levels down
to around 4000 feet. I have not gone this low with the snow
levels...but will continue to monitor this closely. Afternoon
temperatures will generally be near/slightly below normal for both
Wednesday and Thursday for most locations. Brusda
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 74 41 67 40 / 0 10 10 70
CTB 74 40 63 39 / 0 10 30 80
HLN 76 42 67 42 / 10 10 40 80
BZN 73 38 68 40 / 10 10 40 60
WEY 61 34 64 34 / 10 10 40 50
DLN 74 39 66 38 / 10 30 30 50
HVR 75 43 70 46 / 0 0 10 30
LWT 69 38 63 42 / 0 10 20 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from Wednesday evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
SHORT TERM...Suk
LONG TERM...WARANAUSKAS
AVIATION...BLANK
weather.gov/greatfalls
000
FXUS65 KTFX 212342
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
540 PM MDT Tue May 21 2013
.DISCUSSION...
Tonight through Thursday...Expect gradually more active weather to
move into the region over the next 24 to 48 hours...as the main
upper level low that is currently just off the West coast starts
to move inland over the Pacific Northwest. A few isolated
thunderstorms are starting to develop over southern Idaho this
afternoon...and these storms should move into Southwest Montana by
this evening and then continue to expand northward along the
divide over the Rocky Mountain Front. For Wednesday...expect
another upper level disturbance to rotate northward through the
region around the upper level low over the Pacific Northwest. Some
thunderstorms will once again be possible over Southwest
Montana...while numerous showers are expected along the front
range. The precipitation becomes a bit heavier Wednesday night and
into Thursday morning along the divide...as snow levels also begin
to lower. The snow level will lower to around 6000 feet by
Thursday morning...with a significant snowfall possible for
elevations above 6000 feet. Thus a winter storm watch has been
issued for the higher elevations of the Rocky Mountain Front. A
steadier rain is expected over much of Central and North Central
Montana on Thursday morning per the NAM model. The NAM model is
also much colder than the GFS model...bringing snow levels down
to around 4000 feet. I have not gone this low with the snow
levels...but will continue to monitor this closely. Afternoon
temperatures will generally be near/slightly below normal for both
Wednesday and Thursday for most locations. Brusda
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.AVIATION...
UPDATED 2340Z.
There should be a few showers from southwest Montana to the Rocky
Mountain Front early this evening but they should diminish by dark.
A stray lightning strike is not out of the question. There will be a
better threat for showers and thunderstorms from southwest Montana
to the Rocky Mountain Front Wednesday afternoon. Mountains could
become obscured in the precipitation over the Rocky Mountain Front
Wednesday afternoon. The main forecast problem will be the
possibility of MVFR or lower ceilings near and northeast of a
line from KLWT to KCTB late tonight through Wednesday morning. Some
guidance keeps conditions VFR while other guidance has ceilings as
low as LIFR. Do not expect LIFR ceilings. Did go with MVFR ceilings
at KCTB and KLWT with confidence in these lower ceilings at a
moderate but not high level. Have moderate confidence in forecast
wind speeds and directions in the tafs over the plains. Blank
&&
.HYDROLOGY...
The low pressure weather system expected to remain over the PacNW
this week will bring periods of light to occasionally moderate rain
from Wed evening through Fri afternoon. Forecast models continue to
show some rainfall amounts in excess of one inch are possible along
the Rocky Mtn Front, including Glacier NP. Local streams and rivers
could see some quick rises, especially over the foothills and
adjacent plains west of Interstate 15. Right now, widespread
flooding is not expected, but the situation will be closely
monitored over the coming days in case any hydrologic headlines are
needed. Persons living near or planning activities near the
mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 67 40 60 / 10 10 70 70
CTB 40 63 39 57 / 10 30 80 80
HLN 42 67 42 59 / 10 40 80 60
BZN 38 68 40 66 / 10 40 60 50
WEY 34 64 34 62 / 10 40 50 30
DLN 39 66 38 64 / 30 30 50 40
HVR 43 70 46 69 / 0 10 30 40
LWT 38 63 42 64 / 10 20 60 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from Wednesday evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 212049
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
249 PM MDT Tue May 21 2013
.DISCUSSION...
Tonight through Thursday...Expect gradually more active weather to
move into the region over the next 24 to 48 hours...as the main
upper level low that is currently just off the West coast starts
to move inland over the Pacific Northwest. A few isolated
thunderstorms are starting to develop over southern Idaho this
afternoon...and these storms should move into Southwest Montana by
this evening and then continue to expand northward along the
divide over the Rocky Mountain Front. For Wednesday...expect
another upper level disturbance to rotate northward through the
region around the upper level low over the Pacific Northwest. Some
thunderstorms will once again be possible over Southwest
Montana...while numerous showers are expected along the front
range. The precipitation becomes a bit heavier Wednesday night and
into Thursday morning along the divide...as snow levels also begin
to lower. The snow level will lower to around 6000 feet by
Thursday morning...with a significant snowfall possible for
elevations above 6000 feet. Thus a winter storm watch has been
issued for the higher elevations of the Rocky Mountain Front. A
steadier rain is expected over much of Central and North Central
Montana on Thursday morning per the NAM model. The NAM model is
also much colder than the GFS model...bringing snow levels down
to around 4000 feet. I have not gone this low with the snow
levels...but will continue to monitor this closely. Afternoon
temperatures will generally be near/slightly below normal for both
Wednesday and Thursday for most locations. Brusda
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.AVIATION...
UPDATED 1742Z.
Central and Southwest Montana are sitting underneath weak high
pressure which is generally keeping the airmass dry. Weak
instability will develop over Southwest Montana this afternoon and
isolated thunderstorms are possible. A low pressure system to the
west is approaching the region. Southwest winds will increase and
become gusty, and the airmass will moisten as this system continues
to approach. Low level moisture could cause some MVFR cigs beginning
tonight. Areas affected include KCTB, KHVR, and KLWT.
&&
.HYDROLOGY...
The low pressure weather system expected to remain over the PacNW
this week will bring periods of light to occasionally moderate rain
from Wed evening through Fri afternoon. Forecast models continue to
show some rainfall amounts in excess of one inch are possible along
the Rocky Mtn Front, including Glacier NP. Local streams and rivers
could see some quick rises, especially over the foothills and
adjacent plains west of Interstate 15. Right now, widespread
flooding is not expected, but the situation will be closely
monitored over the coming days in case any hydrologic headlines are
needed. Persons living near or planning activities near the
mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 41 67 40 60 / 10 10 70 70
CTB 40 63 39 57 / 10 30 80 80
HLN 42 67 42 59 / 10 40 80 60
BZN 38 68 40 66 / 10 40 60 50
WEY 34 64 34 62 / 10 40 50 30
DLN 39 66 38 64 / 30 30 50 40
HVR 43 70 46 69 / 0 10 30 40
LWT 38 63 42 64 / 10 20 60 50
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from Wednesday evening through Thursday
morning FOR ELEVATIONS ABOVE 6000 FEET FOR Northern Rocky
Mountain Front...Southern Rocky Mountain Front.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 211802
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1159 AM MDT Tue May 21 2013
.UPDATE...
Forecast is on track with clear skies across central MT this morning.
Early morning patchy valley fog dissipated quickly as expected. Made
only cosmetic changes to the POP and hourly temperature grids
following an earlier adjustment to min temperatures. Forecast
still indicates increasing clouds with isolated thundershowers
over the higher terrain of SW MT. Expect increasing east-southeast
winds up to 30 mph this afternoon over the north central plains as
low pressure deepens to our west. Nutter
&&
.AVIATION...
UPDATED 1742Z.
Central and Southwest Montana are sitting underneath weak high
pressure which is generally keeping the airmass dry. Weak
instability will develop over Southwest Montana this afternoon and
isolated thunderstorms are possible. A low pressure system to the
west is approaching the region. Southwest winds will increase and
become gusty, and the airmass will moisten as this system continues
to approach. Low level moisture could cause some MVFR cigs beginning
tonight. Areas affected include KCTB, KHVR, and KLWT.
&&
.HYDROLOGY...
The low pressure weather system expected to remain over the PacNW
this week will bring periods of light to occasionally moderate rain
from Wed evening through Fri afternoon. Forecast models continue to
show some rainfall amounts in excess of one inch are possible along
the Rocky Mtn Front, including Glacier NP. Local streams and rivers
could see some quick rises, especially over the foothills and
adjacent plains west of Interstate 15. Right now, widespread
flooding is not expected, but the situation will be closely
monitored over the coming days in case any hydrologic headlines are
needed. Persons living near or planning activities near the
mentioned areas during the holiday weekend should be alert for
rising river levels and increased stream flows.
Waranauskas
&&
.PREV DISCUSSION...
/ISSUED 535 AM MDT Tue May 21 2013/
Today through Thursday...Weak upper level ridging between the
large upper low centered over the northern plains states and an
incoming upper low off the Pacific NW coast will drift east across
the Northern Rockies and MT today for generally dry and seasonably
warm conditions. Relatively weak flow aloft under the ridge axis
will begin to shift more southerly late this afternoon and evening
as the ridge axis shifts east and this combined with surface
heating may allow for the buildup of convective clouds over the
higher terrain of SW MT with an isolated shower or thunderstorm
possible. Southerly flow strengthens on Wednesday as the Pacific
NW upper low moves inland and the first in a series of shortwaves
and associated upper level jet energy rotates up through the
Northern Rockies late Wednesday through Wednesday night with
another wave expected to rotate around the nearly stationary upper
low across the region late Thursday. Showers and thunderstorms
will develop Wednesday afternoon over SW MT and lift north across
the remainder of the forecast area Wednesday evening with steadier
precipitation developing along the Rocky Mtn Front/Glacier Park area
Wednesday night with a short break early Thursday morning before
another surge of precipitation lifts through the area Thursday
afternoon. Models continue to focus greatest precipitation amounts
across the Rocky Mtn Front/Glacier Park region where total amounts
late Wednesday through Thursday may exceed an inch. Snow levels
will also lower to around 6500 ft in this area by Thursday with
several inches of wet snow likely over the highest elevations near
Glacier National Park and the Bob Marshall Wilderness areas.
Thunderstorms on Wednesday and Thursday will be most likely over
portions of SW MT where instability will be greatest with lesser
chances further north where easterly low level flow and its
associated stable layer will make it difficult for surface based
convection, although some elevated thunderstorms will be possible.
Hoenisch
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 72 43 68 45 / 0 10 20 60
CTB 71 43 63 42 / 0 10 30 70
HLN 74 45 67 44 / 10 10 50 70
BZN 71 41 70 43 / 10 10 50 60
WEY 62 37 63 37 / 10 10 40 40
DLN 70 42 67 40 / 10 20 30 30
HVR 72 45 71 51 / 0 0 10 40
LWT 65 41 65 46 / 0 10 20 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 211743
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1142 AM MDT Tue May 21 2013
.UPDATE...
Forecast is on track with clear skies across central MT this morning.
Early morning patchy valley fog dissipated quickly as expected. Made
only cosmetic changes to the POP and hourly temperature grids
following an earlier adjustment to min temperatures. Forecast
still indicates increasing clouds with isolated thundershowers
over the higher terrain of SW MT. Expect increasing east-southeast
winds up to 30 mph this afternoon over the north central plains as
low pressure deepens to our west. Nutter
&&
.AVIATION...
UPDATED 1742Z.
Central and Southwest Montana are sitting underneath weak high
pressure which is generally keeping the airmass dry. Weak
instability will develop over Southwest Montana this afternoon and
isolated thunderstorms are possible. A low pressure system to the
west is approaching the region. Southwest winds will increase and
become gusty, and the airmass will moisten as this system continues
to approach. Low level moisture could cause some MVFR cigs beginning
tonight. Areas affected include KCTB, KHVR, and KLWT.
&&
.PREV DISCUSSION...
/ISSUED 535 AM MDT Tue May 21 2013/
Today through Thursday...Weak upper level ridging between the
large upper low centered over the northern plains states and an
incoming upper low off the Pacific NW coast will drift east across
the Northern Rockies and MT today for generally dry and seasonably
warm conditions. Relatively weak flow aloft under the ridge axis
will begin to shift more southerly late this afternoon and evening
as the ridge axis shifts east and this combined with surface
heating may allow for the buildup of convective clouds over the
higher terrain of SW MT with an isolated shower or thunderstorm
possible. Southerly flow strengthens on Wednesday as the Pacific
NW upper low moves inland and the first in a series of shortwaves
and associated upper level jet energy rotates up through the
Northern Rockies late Wednesday through Wednesday night with
another wave expected to rotate around the nearly stationary upper
low across the region late Thursday. Showers and thunderstorms
will develop Wednesday afternoon over SW MT and lift north across
the remainder of the forecast area Wednesday evening with steadier
precipitation developing along the Rocky Mtn Front/Glacier Park area
Wednesday night with a short break early Thursday morning before
another surge of precipitation lifts through the area Thursday
afternoon. Models continue to focus greatest precipitation amounts
across the Rocky Mtn Front/Glacier Park region where total amounts
late Wednesday through Thursday may exceed an inch. Snow levels
will also lower to around 6500 ft in this area by Thursday with
several inches of wet snow likely over the highest elevations near
Glacier National Park and the Bob Marshall Wilderness areas.
Thunderstorms on Wednesday and Thursday will be most likely over
portions of SW MT where instability will be greatest with lesser
chances further north where easterly low level flow and its
associated stable layer will make it difficult for surface based
convection, although some elevated thunderstorms will be possible.
Hoenisch
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 72 43 68 45 / 0 10 20 60
CTB 71 43 63 42 / 0 10 30 70
HLN 74 45 67 44 / 10 10 50 70
BZN 71 41 70 43 / 10 10 50 60
WEY 62 37 63 37 / 10 10 40 40
DLN 70 42 67 40 / 10 20 30 30
HVR 72 45 71 51 / 0 0 10 40
LWT 65 41 65 46 / 0 10 20 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
000
FXUS65 KTFX 211547
AFDTFX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
947 AM MDT Tue May 21 2013
.UPDATE...
Forecast is on track with clear skies across central MT this morning.
Early morning patchy valley fog dissipated quickly as expected. Made
only cosmetic changes to the POP and hourly temperature grids
following an earlier adjustment to min temperatures. Forecast
still indicates increasing clouds with isolated thundershowers
over the higher terrain of SW MT. Expect increasing east-southeast
winds up to 30 mph this afternoon over the north central plains as
low pressure deepens to our west. Nutter
&&
.AVIATION...
UPDATED 1135Z.
Current clear skies across the region will persist through midday
and possibly well into the afternoon. Only area of possible weather
today will be increased mid-level clouds and some isolated showers
and a thunderstorm or two over southwest MT. Have included a mention
of VCSH at KBZN this evening, but expect most convective activity
will remain south of that location. Light and variable winds this
morning will turn breezy this aftn, primarily over the central and
north-central plains where gusts should reach 20-25 kts vcnty
KHVR/KLWT.
Waranauskas
&&
.PREV DISCUSSION...
/ISSUED 535 AM MDT Tue May 21 2013/
Today through Thursday...Weak upper level ridging between the
large upper low centered over the northern plains states and an
incoming upper low off the Pacific NW coast will drift east across
the Northern Rockies and MT today for generally dry and seasonably
warm conditions. Relatively weak flow aloft under the ridge axis
will begin to shift more southerly late this afternoon and evening
as the ridge axis shifts east and this combined with surface
heating may allow for the buildup of convective clouds over the
higher terrain of SW MT with an isolated shower or thunderstorm
possible. Southerly flow strengthens on Wednesday as the Pacific
NW upper low moves inland and the first in a series of shortwaves
and associated upper level jet energy rotates up through the
Northern Rockies late Wednesday through Wednesday night with
another wave expected to rotate around the nearly stationary upper
low across the region late Thursday. Showers and thunderstorms
will develop Wednesday afternoon over SW MT and lift north across
the remainder of the forecast area Wednesday evening with steadier
precipitation developing along the Rocky Mtn Front/Glacier Park area
Wednesday night with a short break early Thursday morning before
another surge of precipitation lifts through the area Thursday
afternoon. Models continue to focus greatest precipitation amounts
across the Rocky Mtn Front/Glacier Park region where total amounts
late Wednesday through Thursday may exceed an inch. Snow levels
will also lower to around 6500 ft in this area by Thursday with
several inches of wet snow likely over the highest elevations near
Glacier National Park and the Bob Marshall Wilderness areas.
Thunderstorms on Wednesday and Thursday will be most likely over
portions of SW MT where instability will be greatest with lesser
chances further north where easterly low level flow and its
associated stable layer will make it difficult for surface based
convection, although some elevated thunderstorms will be possible.
Hoenisch
Thursday Night through Tuesday...Large closed low pressure system
discussed above expected to remain over PacNW through Fri eve then
begin to fill/weaken and lift into southwest Canada during the
weekend. Forecast models still indicating broad area of light to
moderate rain over much of central and southwest MT Thurs night into
Fri morning, with precipitation amounts over the Rocky Mtn Front and
adjacent slopes possibly exceeding 0.5 inch during that period.
There will also be rain/snow mix near mountain pass levels and a few
inches of accumulating snow above pass level along the Rocky Mtn
Front. The rain/snow activity will gradually taper off Fri eve as
much of the energy and moisture of the PacNW system swings northward
into BC/Alb, bringing drier conditions across our region for the
first half of Memorial Day weekend. A secondary shortwave trof
rotating through the remnants of the weakened closed low circulation
is forecast to arrive Sun eve and should generate scattered light
rain showers that continue through most of Mon. Kept at least a
chance of showers across our region on Tues, mostly as a compromise
between the wetter GFS and drier ECMWF solutions. Daily high
temperatures still expected to remain in the low to mid 60s, which
slightly warmer temps possible on Sunday thanks to decreased cloud
cover and good southerly flow aloft.
Waranauskas
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 72 43 68 45 / 0 10 20 60
CTB 71 43 63 42 / 0 10 30 70
HLN 74 45 67 44 / 10 10 50 70
BZN 71 41 70 43 / 10 10 50 60
WEY 62 37 63 37 / 10 10 40 40
DLN 70 42 67 40 / 10 20 30 30
HVR 72 45 71 51 / 0 0 10 40
LWT 65 41 65 46 / 0 10 20 60
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
weather.gov/greatfalls
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