Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/07/20
Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Thu Aug 6 2020
.SHORT TERM...(This evening through Friday)
Issued at 250 PM CDT Thu Aug 6 2020
Weak but increasing moisture transport and warm air advection
could spark some showers and isolated storms tonight, diminishing
Friday morning as the initial push of warm air advection weakens
and shifts north. Things could end up on the dry side for much of
the rest of the day, as the area remains under the influence of a
mid-level ridge and capping increases courtesy of a warm nose
around 800 mb. However, several of the 00Z and some of the 12Z
short-range models had been suggesting a cluster of showers/storms
develops in SD or northern Iowa and pushes eastward Friday, with
some models bringing it into parts of southeast MN/northeast Iowa
by Friday evening, and others keeping it south or not developing
it as much, allowing our area to stay largely dry. A more recent
trend has been for a few members to develop an area of convection
to our northwest, then progress it southeastward toward the area
even later. Will have to keep an eye on these features if they
develop, as higher instability sitting just to our west would
potentially allow a few stronger storms to sneak into our western
counties before succumbing to a rapid fall off in CAPE across our
area. Deep layer shear is rather marginal with 0-6 km bulk shear
under 30 kts and effective shear hovering near 30 kts, so not
anticipating widespread organized severe weather at this time, but
it is something to keep an eye on.
.LONG TERM...(Friday night through Thursday)
Issued at 250 PM CDT Thu Aug 6 2020
The mid-tropospheric ridge over the central portion of the U.S.
breaks down across the Northern Plains as a series of shortwaves
flattens affect the region. Friday night a stronger shortwave
tracks the Dakotas across northern Minnesota into the Upper
Peninsula of Michigan. The low level jet is initially focused
over the UP with a second area across Kansas into southern Iowa.
Overnight and Saturday, forecast soundings show a cap, however
above the cap, generally above 685mb, there are steep lapse rates
greater than 8 deg C/km with 1500to 2500J/km of CAPE. By 00Z, some
of the forecast soundings erode the cap. While shear is in
check...around 20kts, instability increases to over 4000J/km.
There is good agreement with several of the convective allowing
models that at the beginning of the long term, there will be a
convective complex near the Twin Cities area, some are farther
north and the HRRR has a second area over Iowa. Think the HRRR is
picking up on the second area, but does not appear to reach the
forecast area Friday night. Will continue to include scattered
showers and thunderstorms after midnight Friday night with the
shortwave trough. Greater chances are next to the MPX area,
however that will depend on how far south and how deep the
shortwave trough becomes. These showers/storms weaken during
Saturday morning as with low level winds decrease and mid level
winds become northwest with the passage of the wave. The organized
convection appears to be farther north out of the forecast area.
Later Saturday, destabilization develops, however with little to
get the storms going, rain chances appear isolated. Timing and
subtle waves can easily affect the forecast, so this will need to
be monitored. There are some hints with the low level moisture
Sunday night that there will be low clouds and fog and depending
on how quickly these can erode would affect the strength of any
storms Sunday. A weak boundary with the approach of a shortwave
trough Sunday could produce some isolated showers/thunderstorms
for parts of the area, however rain chances appear to be more
focused farther north into MN and northern WI. The new EC is
deeper with the trough and faster, so will need to assess this as
we get closer. Sunday night, the chance for rain improves with the
passage of the cold front. The rain chances may linger into
Monday.
Confidence is low for timing and coverage of rain chances
Tuesday through Thursday. Still have some periodic thunderstorm
chances with weak shortwaves traveling through the flow.
Seasonable highs in the 70s to lower 80s, however more humid
Saturday through Monday and highs 85 to 90 Sunday. Heat index
values around 90 Saturday and 95 Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 1000 PM CDT Thu Aug 6 2020
A band of warm air advection showers and maybe an isolated storm will
develop along a warm front overnight. Since it still uncertain
whether they will impact KRST just left the vicinity showers going
after 07.10z. Ceilings will range from 5 to 10K feet.
Still plenty of uncertainty on whether any of the area will be
impacted by showers and storms on Friday evening. As a result,
kept the forecast dry.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
SHORT TERM...Lee
LONG TERM...Zapotocny
AVIATION...Boyne
Area Forecast Discussion
National Weather Service Bismarck ND
919 PM CDT Thu Aug 6 2020
.UPDATE...
Issued at 919 PM CDT Thu Aug 6 2020
The main adjustment for this update was to spread pops a bit
farther north into parts of south central North Dakota tonight.
The latest radar mosaic across the region shows thunderstorms
moving eastward across parts of eastern Montana and western South
Dakota. The latest HRRR suggests a few thunderstorms could work
their way towards I-94 overnight as the low level jet increases
and the upper waves moves into the area. Will also continue with
the slight chance pops in the northwest part of the state
overnight, though the latest iteration of the HRRR suggests the
convection will wane before reaching that part of the state.
Took a quick glance into Friday, and the current idea of the
overnight convection lingering into the morning still looks good.
UPDATE Issued at 622 PM CDT Thu Aug 6 2020
The main change to the forecast was to add small pops to southwest
North Dakota this evening.
Late afternoon MRMS radar mosaic shows showers and thunderstorms
increasing in coverage across southeast Montana in response to a
upper wave moving across the region. The majority of short term
model solutions continue to suggest most of the rain chances
should diminish before reaching southwest North Dakota, but with
increasing mid level clouds and the ongoing convection to our
west, opted to add a small chance pop to southwest North Dakota
for the evening.
The better chances may still come later tonight as the low level
jet increases and the wave moves into western parts of the state.
Considered adding a slight chance pop to more of the forecast area
overnight, but held off for now. Will watch trends and see if more
solutions suggest overnight convection with the next update.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 218 PM CDT Thu Aug 6 2020
The main forecast challenge in the short term will be the severe
weather potential Friday afternoon and evening.
Broad ridging will will east tonight, with the axis centered over
Minnesota by 06z Friday. As a west coast trough nudges closer, a
leading impulse will spark showers and thunderstorms off this
evening across portions of eastern Montana and western South
Dakota. Some guidance suggests that this activity will transition
into an MCV and continue thunderstorm development into far western
North Dakota and far southern North Dakota overnight. While a few
of these storms could become strong, the better chance for severe
weather tonight will be to our west and south. QPF in the coarser
models appear to be a bit on the high side with regards to this
MCV feature, possibly because of convective feedback which only
adds to the uncertainty in storm coverage overnight. Temperatures
will be mild tonight with lows in the upper 50s to mid 60s as
southerly flow continues to pump in moisture.
Quite a bit of uncertainty still remains with regards to severe
weather potential during the day on Friday. There are 2 low
predictability and conditional scenarios that may unfold.
1. If an MCV does form overnight, we may start to see
thunderstorms redeveloping by early to mid Friday afternoon
across the James River valley. By 18z Friday, models are already
advertising anywhere from 2500 to 4000 J/kg of MLCAPE across the
James River valley and deep layer shear ranging from 30 to 40
knots. If storms can redevelop in this environment before the MCV
exits into the Grand Forks forecast area, there may be a brief
window in the afternoon for some supercells across the James River
valley. Further, 0-1 km shear values in the 15 to 25 knot range
would suggest at least some tornado threat if storms can become
surface based.
2. Height rises behind the possible MCV and strong capping will
likely keep convection from firing further west during the
afternoon. Neutral to slightly falling heights are noted across
the north after 00z Saturday but most of the forcing stays well
north of the International Border. Still, we may see storms fire
along a frontal boundary somewhere in central North Dakota (north
central is favored at this time due to better forcing and weaker
capping) by Friday evening or Friday night. The 12z NAM advertises
CAPE values from 1500 to 2500 J/kg and marginal deep layer shear
in the 25 to 35 knot range along the boundary by 03z Saturday
along the highway 83 corridor. The deep layer shear vectors will
be orthogonal to the boundary so if storms do form, they may start
out discrete. However, the shear profile is fairly unidirectional
which may promote storm splits and unfavorable storm interactions
given the marginal shear environment, eventually congealing into
a cluster or line. That being said, with strong capping and most
of the energy residing north of the border, storms very well could
not fire at all. Hopefully the next couple rounds of guidance
will give us better confidence one way or the other. With so much
uncertainty still in place, elected to keep mention of severe out
of the gridded forecast for now.
Friday will also be quite warm with highs in the mid 80s to mid
90s.
.LONG TERM...(Saturday through Thursday)
Issued at 218 PM CDT Thu Aug 6 2020
The cold front moves east by early Saturday morning, with
slightly cooler highs during the afternoon (generally in the
80s). There is a slight chance for a few showers and thunderstorms
on Saturday across the far south, before better and more
widespread chances move in overnight and into Sunday with another
frontal system. Shear and instability profiles suggest the chance
for a strong storm or two across the far south on Saturday, but
the best chance for severe storms this weekend appears to be on
Sunday across the southern James River valley. We still have a
ways to go before specific details can be ironed out so stay
tuned!
Looking into the work week, we dry out on Monday and Tuesday with
chances of precipitation coming back into the forecast mid to late
week. Temperatures will be near to above average, with highs
generally in the 80s to lower 90s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 622 PM CDT Thu Aug 6 2020
Will start with VFR for the 00Z TAFs, but there are a few things
to keep an eye on. Isolated thunderstorms are possible later
tonight, and though odds of them reaching a terminal location
don`t look too great, that possibility can`t be totally ruled out.
Will monitor and update as needed. Another concern will be
stratus, especially in eastern aerodromes. Increasing low level
moisture occurs tonight, and with that the potential for at least
MVFR ceilings at KJMS for a few hours early Friday morning.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CK
SHORT TERM...ZH
LONG TERM...ZH
AVIATION...CK
Area Forecast Discussion
National Weather Service Cleveland OH
1007 PM EDT Thu Aug 6 2020
.SYNOPSIS...
High pressure over the Great Lakes region will remain over the
area through Saturday. A warm front will approach the region
from the south on Monday. A cold front will approach the area
from the west on Tuesday.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
Opted to include a chance of waterspouts later this morning,
primarily from 5 am through 11 am off Erie/Lorain/Cuyahoga
Counties. HRRR is the most aggressive in forming a convergent
wind field with low level RH fields nearing 90% and northeast
winds primarily less than 10 knots. This would keep a nearly
stationary boundary, at least for a few hours, as a weak land
breeze forms tonight. Other models, however, suggest a quicker
arrival of the stronger northeast winds, 10 to 15 knots, which
would hinder any waterspout/funnel chances.
Previous Discussion... Surface high pressure will
continue to influence the weather across the region through the
near term. This will result in low precipitation chances, mostly
sunny skies, and near normal temperatures (highs near 80 and
lows near 60). The exception to the low precipitation chance is
for northwest Pennsylvania where an isolated shower/thunderstorm
may be possible tomorrow afternoon.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Predominantly zonal (i.e. westerly) flow aloft is expected over our
CWA as a subtle high pressure ridge aloft drifts from the Great
Lakes region toward the northeast United States and vicinity.
Simultaneously, multiple and weak shortwave troughs are forecast to
ripple eastward through the aforementioned ridge. At the surface,
ridging should affect our area as the embedded high pressure center
moves from the eastern Great Lakes to the southern Appalachians. At
this point, odds favor fair weather through the period. Saturday
afternoon highs in the upper 70`s to mid 80`s should be followed by
Saturday night lows in the upper 50`s to mid 60`s. Sunday afternoon
highs in the 80`s to near 90 degrees and Sunday night lows in the
60`s to lower 70`s are forecast. Humidity will increase through the
period as a low-level return flow of moisture from the Gulf of
Mexico develops over our region.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Multiple shortwave troughs embedded in the zonal flow aloft should
affect our CWA Monday through Tuesday. At the surface, a cool front
should drift eastward through our CWA Monday night through Tuesday
as the aforementioned high pressure center meanders over the
southeast United States. Isolated to scattered showers and
thunderstorms are possible along and ahead of the cool front and
shortwave troughs. Monday afternoon`s highs should reach the mid
80`s to lower 90`s and be followed by lows in the mid 60`s to lower
70`s Monday night. Tuesday afternoon`s highs should reach the 80`s,
while Tuesday night`s lows are forecast to mainly reach the 60`s.
Flow aloft should become more cyclonic Tuesday night through
Thursday as a longwave trough and embedded shortwave disturbances
become established over the Great Lakes and vicinity. At the
surface, very weak high pressure ridging should build behind the
cool front departing generally toward the east. Isolated to
scattered showers and thunderstorms remain possible. Overnight low
temperatures should remain slightly above-normal (i.e. in the 60`s
to lower 70`s), while Wednesday and Thursday afternoon highs should
be near-normal (i.e. in the low to mid 80`s).
&&
.AVIATION /00Z Friday THROUGH Tuesday/...
VFR this evening across the TAF sites and VFR conditions
expected to persist throughout the TAF period. Mostly northerly
winds will diminish over the next several hours to 5 knots or
less. A land breeze could develop at CLE/ERI overnight which
would shift winds towards the south.
Outlook...Non-VFR possible with showers and thunderstorms on
Monday and Tuesday
&&
.MARINE...
Winds are expected to trend northeasterly to northerly at about 5 to
15 knots the rest of today through Friday night as a high pressure
center meanders over southern Ontario. These winds will veer
gradually to southerly and then to southwesterly this weekend as the
high pressure center drifts toward the southern Appalachians and
continues extending a ridge over Lake Erie. Southwesterly winds of
about 5 to 15 knots should veer gradually to westerly Monday night
and Tuesday as a weak cold front drifts eastward over Lake Erie.
Waves are forecast to be no larger than 1 to 3 feet through the
period.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Saunders
NEAR TERM...Kahn/Saunders
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Kahn
MARINE...Jaszka
Area Forecast Discussion
National Weather Service Pueblo CO
309 PM MDT Thu Aug 6 2020
.SHORT TERM...(This evening through Friday)
Issued at 309 PM MDT Thu Aug 6 2020
Currently...
As of 2pm showers and thunderstorms have formed in northern El Paso
County and Southern Las Animas County. Low level moisture and
instability are still plentiful with temperatures hanging around the
low 80s and dewpoints in the low 60s across the eastern plains. The
western plains and I-25 corridor have begun to dry out a bit as more
westerly flow sets in with current dew points dipping from the low
40s into the high 30s. The mountains are currently noticeably dry
with dewpoints in the mid-high 20s.
Later today through tonight...
Strong to severe storms are possible
as current thunderstorms move eastward into Kiowa county over the
next few hours. Current SPC analyses show 1500-2500 J/Kg of CAPE
over the plains and shear between 20-30 kts. CAPE is currently
forecasted to increase to near 3000 over some parts of the plains
over the next few hours, and the latest HRRR runs have been showing
a strong storm moving through Kiowa County around 1Z, so confidence
in the severe potential for this area is relatively high at this
time. If storms do manage to become severe, gusty winds over 50 mph
and half-dollar sized hail will be possible. The latest SPC guidance
as well as HRRR runs also show thunderstorms moving throw El Paso
and Baca county later this afternoon through early evening, but
there is low confidence that these storms will become severe,
although a few small hail reports can`t be ruled out.
Tomorrow...
As the upper-level ridge axis moves east of Colorado tomorrow, flow
aloft becomes more westerly and will lower POPs a bit. Overall
tomorrow will be a few degrees hotter than today and stay
consistently dry, with the chance for a few isolated storms over the
mountains tomorrow afternoon. High temps will be in the mid 80s in
the valleys and near 100 over the plains.
.LONG TERM...(Friday night through Thursday)
Issued at 309 PM MDT Thu Aug 6 2020
Friday night through Saturday...An upper ridge of high pressure is
expected to hang on across the area through Sat, with the ridge axis
positioned roughly along the CO and KS border. Southwest flow aloft
is feeding some moisture up across the Four Corners and into the
Great Basin, fueling isolated to scattered convection across the CWA
through Sat though the best chances will remain over the higher
terrain and I-25 corridor. Look for highs in the 80s for the high
valleys, and 90s to near 100F for the plains.
Sunday through Wednesday...Models still indicate that the southern
US ridge flattens out as it slides to the west across NM and AZ.
This will allow a more westerly flow aloft to settle in across the
region for Sun through midweek, decreasing available moisture while
keeping the maximum temps up. There will be isolated convection
possible each aftn, mainly tied to the mts, with the main storm
threat each day being gusty winds as well as cloud to ground
lightning. Expect highs each day in the upper 70s to mid 80s for the
high valleys, and upper 80s to upper 90s for the plains.
The one outlier will be Mon, when a weak cold front pushes south
across eastern CO through the morning. This will help cool temps
slightly for Mon, as well as introduce isolated convection across
the eastern plains during the late aftn. High temps Mon are forecast
to be about 5 to 7 degrees cooler, as compared to Sun, Tue or Wed.
Thursday...A longwave upper trough redevelops and pushes onto the
West Coast, swinging the flow aloft to a more southwest direction
once again for the Four Corners region as the upper ridge moves east
across TX and OK. Convection chances start to increase along the
Continental Divide as the moisture plume opens up, while the
remainder of the higher terrain will see isolated storm activity.
High temps will climb into the 80s for the high valleys, and mid 80s
to mid 90s for the plains. Moore
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 309 PM MDT Thu Aug 6 2020
KALS...
VFR conditions expected at the TAF site over the next 24
hours. Gusty southwest winds are expected to persist over the area
through about 02Z, before weakening overnight and into tomorrow.
COS...
Thunderstorms are currently passing northeast of the
terminal, but not close enough to directly impact it. Outflow and
gusty winds could impact the terminal over the next hour, will
monitor for possible updates. Storms are expected to move out of the
area within the next 2 hours. Otherwise VFR conditions are expected
through tonight and tomorrow morning with winds weakening after
sunset.
KPUB...
VFR conditions expected at KPUB during the entire forecast
period. There is a chance of an isolated thunderstorm passing
through Pueblo county before 00Z, but it is unlikely that any
convection will impact the terminal directly. Tonight winds will
calm and cloud cover should remain consistent into tomorrow morning.
-MG
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH/GARBEROGLIO
LONG TERM...MOORE
AVIATION...HODANISH/GARBEROGLIO
Area Forecast Discussion
National Weather Service Springfield MO
645 PM CDT Thu Aug 6 2020
...AVIATION UPDATE...
.SHORT TERM...(This evening through Friday)
Issued at 233 PM CDT Thu Aug 6 2020
In the near term will be watching the evolution of a small
cluster of convection over far south central KS into northeast OK
near and northeast of a sfc warm front. Some guidance briefly
brings a small area of storms into our far southwest counties.
Have added a specific mention of this in the HWO (4pm-8pm...mainly
using the HRRR as guidance). A low end wind/hail risk exists if
the storms can grow upscale at all.
Otherwise, still looking at an area of convection developing after
after 09z/400 am over eastern KS into western MO in a elevated
frontal/baroclinic zone on the eastern periphery of stronger low
level/850mb winds. Elevated/mucape 1000-1500 j/kg would support a
large hail risk late tonight into Friday morning. Convection will
weaken later in the morning and shift off to the southeast. Can`t
rule out some additional Friday afternoon activity (similar to
today) as the effective warm front lifts northeast into our cwfa.
Additional nocturnal/early morning convection will be possible
late Friday night into Saturday, again within the elevated
frontal zone ahead of the sfc warm front.
.LONG TERM...(Saturday through Thursday)
Issued at 233 PM CDT Thu Aug 6 2020
Saturday-Sunday: An upper level ridge axis over the eastern
Rockies/western High Plains will shift east Friday and through the
weekend. We will see hot/humid weather return with some spotty
storm activity. With the ridge axis overhead, we may see very
little to no convection on Sunday afternoon. Afternoon heat index
values in the upper 90s to around 100 degrees will be common.
Monday-Thursday: The upper ridge will weaken/flatten out and
eventually retrograde or re-form back to the west. Despite this,
we will be south of the main upper level westerlies, but a weak
sfc front will move as far south as central MO on Monday/Tuesday.
Weak ill defined upper level disturbances/shear axes will be able
to focus convection at times especially in the heat of the day
during the afternoon/evening. It will be hard to pinpoint areas
and times this far out. In general temperatures will be near
normal for the time of year with some degree of chances for pulse
storms or clusters each day.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Pilots flying in and out of the southwest Missouri airports will
need to monitor radar information this evening.
A shortwave disturbance had forced a cluster of showers and
thunderstorms to form and impact the region. We think by 1z Joplin
will be in the clear until late tonight.
This cluster will shift over Springfield and Branson by around 1z
and last for roughly an hour and a half.
A second round of showers and thunderstorms are expected to
develop after midnight tonight and linger into Friday morning.
This activity could also lower flight conditions if storms
directly impact an airfield.
These storms should exit the Ozarks region by mid to late morning.
Safe Travels.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...DSA
LONG TERM...DSA
AVIATION...Cramer
Area Forecast Discussion
National Weather Service Great Falls MT
912 PM MDT Thu Aug 6 2020
.UPDATE...
Updated POPs over the next few hours to reflect current conditions
and trends. Thunderstorm activity is generally dying down over
the CWA, but showers will persist through at least midnight.
Between midnight and 12z, another round of showers and a few
thunderstorms appear increasingly possible from Great Falls north
and west, so POPs were increased in those areas by blending in
some of the latest hi-res model guidance. HRRR shows some discrete
cells on the eastern edge of an area of stratiform rain, so
thunder chances were fudged to at least isolated/slight chance
levels. -Kredensor
&&
.SYNOPSIS...
Scattered showers and thunderstorms in an unstable southwest flow
aloft will spread northeast across the region through this evening.
Gusty winds and brief rainfall will accompany most storms, but a
few stronger storms could produce damaging winds and small hail.
A Pacific cold front will then move through the area overnight,
bringing cooler, but still dry air to the area on Friday, along
with gusty westerly winds. Dry and breezy conditions with slightly cooler
than normal temperatures will persist through the weekend with
temperatures warming again next week.
&&
.AVIATION...
Updated 1134 AM MDT Wed Aug 6 2020 (06/18Z TAF Period)
Showers and areas of broken mid level clouds will continue to lift
north across the region through early this afternoon with
thunderstorm development beginning across SW MT. Thunderstorm
coverage will increase this afternoon and continue through this
evening with greatest concentration shifting from central MT this
afternoon to eastern portions of North-central MT this evening.
Thunderstorms this afternoon and evening could produce strong
outflow winds with gusts in excess of 40kts while potential for
heavy rain and possible hail will be more isolated and limited to
areas directly beneath the thunderstorm cells. Showers and a few
isolated thunderstorms along with broken mid level cloud-cover could
linger beyond this evening with a cold front shifting winds to west
late tonight followed by clearing. Hoenisch
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing
runway closure.
&&
.FIRE WEATHER...
Thunderstorm this afternoon and evening resulted in some cloud-
to-ground lightning strikes on drying fuels, but thankfully many
of the cells did not appear to have a high proportion of CG
strikes. Wetting precip occurred with some of the storms, but the
chance for new fire starts will increase. The cold front
responsible for the storms today will move east of the area
overnight, bringing cooler temperatures for Friday, but afternoon
relative humidity will fall into the 15 to 25 percent range for
much of the area with westerly winds gusting to 30 mph at times,
especially across north-central MT. Breezy winds with relatively
dry conditions will continue into the day on Saturday, though
winds speeds will not be as strong and mainly limited to the
afternoon period.
&&
.PREV DISCUSSION...
/ISSUED 306 PM MDT Thu Aug 6 2020/
Tonight through Saturday...
Thunderstorm development currently underway across SW and central
MT will lift northeast across central and eastern portions of
north-central MT through this evening. Warm/dry conditions in the
lower levels will set up a favorable environment for strong
outflow winds with these storms along with some potential for hail
in the strongest cells. Additional thunderstorm development
likely later this afternoon and evening over western MT ahead of
the main upper level trough moving inland across WA, and this
activity could bring another round showers and thunderstorms later
this evening. Surface cold front ahead of the trough will move
east across the continental divide this evening and sweep east
most of the forecast area overnight. Westerly winds and drier air
behind the front will bring clearing and an end to precipitation
from west to east late tonight with windy conditions developing
initially along the Rocky Mtn front tonight then spreading east
across most of the forecast area by Friday morning. Strongest
winds aloft move across the region Friday morning but westerly
flow aloft remains quite strong (for early August) through Friday
evening. Areas along the northern Rocky Mtn front and the east
side of Glacier National Park could see a period of wind gusts
over 50 mph early Fri morning as the strongest winds aloft pass in
conjunction with a strong pressure gradient across the Rockies.
Gusts in to 25 to 35 mph range are likely further east across much
of north-central MT beginning Friday morning and continuing
through Friday evening before diminishing. Winds will not be as
strong across SW MT, but afternoon gusts of 20-30 mph are likely.
Temperatures will be 10-20 degrees cooler for most areas on Friday
with afternoon temperatures ranging from the lower 70s near the
Canadian border to the mid 80s across the SW MT valleys. Winds
decrease Friday night but breezy conditions will likely redevelop
on Saturday. Hoenisch
Sunday through next Thursday...
Weak upper level ridging will return to Montana early next week,
which should keep the area dry as temperatures slowly warm back up
to normal by Tuesday. Another low pressure trough will then bring
a good chance for showers and thunderstorms to the area once
again Wednesday and Thursday (and possibly longer), along with
cooler than normal temperatures. Coulston
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 55 78 48 81 / 40 0 0 0
CTB 52 74 48 76 / 30 0 0 0
HLN 53 80 48 84 / 40 0 0 0
BZN 51 84 46 86 / 30 0 0 0
WYS 44 80 40 79 / 20 10 0 0
DLN 49 80 44 81 / 30 0 0 0
HVR 58 79 51 84 / 40 20 0 0
LWT 54 79 48 82 / 50 0 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 9 PM MDT Friday Central and
Eastern Lewis and Clark National Forest Areas...Chouteau and
Fergus Counties...Eastern Glacier/Toole/Central/Eastern
Pondera/Liberty...Helena and Townsend Ranger Districts of the
Helena National Forest...Hill and Blaine Counties...Lewis and
Clark National Forest Rocky Mountain District-Rocky Mountain
Front...Lincoln Ranger District of the Helena National Forest.
&&
$$
http://www.weather.gov/greatfalls