Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/09/25
Area Forecast Discussion
National Weather Service Gaylord MI
857 PM EST Sat Feb 8 2025
.KEY MESSAGES...
- Widespread snow will move out this evening. Lake effect snow
showers will build in tonight and linger into Sunday.
- Occasional, mainly light lake effect snow showers next week.
- Monitoring potential low pressure systems moving by to our south
mid-week and next weekend.
&&
.UPDATE...
Issued at 852 PM EST Sat Feb 8 2025
Widespread snow across the area this evening, with verified
reports of several inches of snow...especially south of M-72.
Widespread snow will come to a steady end from west to east
tonight as shortwave responsible for such exits stage right.
Likely to see some lake snows develop...especially off Lake
Superior where moisture will be more sufficient and convective
depths deeper. Expecting to see some light additional
accumulation through Sunday morning in our traditional eastern
upper snow belt locations. Narrow window for any meaningful lake
snows into northwest lower Michigan as better moisture quickly
departs. All headlines will remain, but will likely be able to
cancel most several hours early as snow departs.
&&
.SHORT TERM /THROUGH SUNDAY/...
Issued at 353 PM EST Sat Feb 8 2025
Forecast Pattern... Current radar and satellite depict widespread
light to moderate snow with areas of heavier snow over most of
northern MI. The heavier snow is mostly confined to locations south
of M-72. Visibilities of 0.5 to 1 SM have been seen under the
heavier bands of snow, however this is due to solely the heavier
snowfall and not from blowing snow as surface observations show
light winds (below 10 mph). Webcams are showing some snow covered
roads, however around 1 - 3 inches is estimated to have fallen over
areas south of M-72 so far.
The edge of the moisture and "warmer" air is over the triple point
of MN/IA/WI (which is reflected in the western extent of radar
returns this afternoon). A shortwave`s axis is also over this area
with an upper jet max stretching from the central plains to southern
MI. Snow will continue as all of this moves east, and for areas
south of M-72 snow will become heaviest from now through the evening
hours as the best forcing eventually makes it way over MI in the
next few hours. Another 2-4 inches is possible for the
aforementioned areas accumulating through late this evening/tonight.
Winds remain light through this evening. A Canadian airmass will
slip down the central plains to the southeast tonight, turning
surface winds northwest tonight into Sunday and moving cooler 850mb
temps overhead. LES will move over the typical snowbelts of NW lower
and eastern upper early Sunday morning into Sunday afternoon.
Forecast Details... Higher confidence exists for accumulations of
snow from LES over NW lower around a few inches or less due very
little background moisture with the airmass moving in tonight.
The 18Z HRRR does hint at a line of convergence over Lk MI near
forming near midnight and moving inland - dropping an additional 2
to 4 inches over the adjacent coastal areas including Traverse City.
The larger fetch over Lk Superior will result in better chances for
a well defined band to establish near Whitefish point and stream
over eastern upper during this time. Guidance at this point shows
snow accumulations under the heavier bands from a few inches up to
6+ inches near Whitefish Point with most of it falling Sunday
morning through Sunday evening. Stay tuned for more information.
&&
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 353 PM EST Sat Feb 8 2025
There are a few potential weather makers to keep tabs on over the
next several days. One thing that seems assured is that the cold air
will remain in place through the long term portion of the forecast.
Mainly light west northwest flow lake effect snow showers hang on
into Sunday night then diminish Monday. Could see a couple of inches
of accumulation near Whitefish Point and Paradise with less than an
inch at Sault Ste Marie and across northwest lower. An arctic cold
front dropping south Monday night is expected to bring a band of
snow across the region overnight with perhaps an inch or two of
accumulation. Mainly light lake effect snow showers are then
possible Tuesday into Wednesday. Attention then turns to our south
where extended guidance tracks an area of low pressure. Recent model
trends are farther north but this may not end up being the case as
northern Michigan is expected to remain fairly deeply entrenched
into the cold air. Something to monitor nonetheless. More chances
for lake effect late week. There is potential for yet another area
of low pressure to move by to our south next weekend but again there
is doubt over the track. Temperatures are expected to be at least a
few degrees below normal through the period.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 611 PM EST Sat Feb 8 2025
Widespread IFR producing snow will gradually end from west to
east this evening through the overnight. Winds will remain
light, again negating any blowing snow concerns. Expecting MVFR
to VFR conditions on Sunday. Northwest winds expected to become
a touch gusty on Sunday.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 AM EST Sunday for MIZ020>022-
025>029-031>036-041-042.
MARINE...None.
&&
$$
UPDATE...MSB
SHORT TERM...ELD
LONG TERM...AJS
AVIATION...MSB
Area Forecast Discussion
National Weather Service Marquette MI
830 PM EST Sat Feb 8 2025
.KEY MESSAGES...
- Scattered light lake effect snow showers are expected over the
northwest to west wind snow belts tonight through Tuesday.
Heavier lake effect snow is possible in the Keweenaw early
Monday morning.
- Near to slightly below normal temperatures will become below
normal next week. Single digit highs on Tuesday with lows near
-20F by Wednesday morning are expected in the west.
&&
.UPDATE...
The combination of RAP analysis and KMQT radar highlight well the
eastward drifting low pressure through the Ohio valley and trailing
synoptic snowfall moving through the forecast area. As of this
writing, synoptic precip is done in the west, with light lake effect
showers noted in the Keweenaw. In the east/central, widespread light
snowfall continues to slowly diminish. Webcams show some snow
covered roadways here and there. With the snow more or less over in
Menominee County, opted to cancel the inherited Winter Weather
Advisory.
GOES Water Vapor imagery highlights a shortwave pressing into Lake
Superior. There continues to be good agreement among the CAMS that
this feature will help tighten a surface trough over Lake Superior,
which will develop more widespread lake effect snow showers
overnight. As of now, no major changes have been made to the
forecast.
&&
.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 304 PM EST Sat Feb 8 2025
Water vapor imagery and RAP analysis shows a series of notable
shortwaves. One shortwave moving through IA is expected to merge
tonight over the Lower Great Lakes with a second shortwave now over
eastern SD. In turn, the associated sfc low with these features
deepens slightly as it moves from southern IN into the Ohio Valley
this evening. Weak coupled upper jet structure and associated
differential divergence with this system and some weak isentropic
ascent is supporting mainly widespread light snow across the U.P
today, with perhaps some moderate snow totals possible into south
central portions (based on webcams) where there is a winter weather
advisory in effect for Menominee County through this evening. As the
low slides east this evening system snow will be tapering off/ending
from the west.
Attention then turns to the shortwave over northern MN southern
Manitoba which is fcst to move into the Upper Great later tonight
and bring a shot of cold advection to the area as 850 mb temps lower
from the upper teens blo 0C to the lower 20s blo 0C. The shortwave
and CAA will also sharpen the lake induced sfc trough over the lake
leading to increased low-level convergence into the west-northwest
wind snowbelts later tonight and perhaps a slight rise in inversion
heights as noted on fcst soundings. Generally expect 1-2" of LES
over the west-northwest wind snow belts tonight with locally up to 3
inches for shoreline area from Grand Marias eastward. Expect min
temps tonight ranging from zero to 5 above interior west to lower to
mid teens east.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Issued at 304 PM EST Sat Feb 8 2025
Through the rest of the weekend and for the majority of the coming
work week, precipitation in Upper Michigan will be largely driven by
lake effect processes. Later this week, a system developing in the
Plains tracks northeast through the Ohio River Valley brings chance
for light "system" snow, however uncertainty continues on its exact
path and associated precipitation shield. With generally west to
northwesterly flow through much of the period, below normal temps
will dominate the forecast with highs in the teens to mid 20s and
lows in the single digits. The exception to this will follow the
deeper shortwave early next week bringing highs down into the single
digits to low teens (coldest west) and lows into the negative double
digits by Wednesday morning.
Come Sunday morning, lake effect snow will be ongoing in the NW wind
snowbelts. As high pressure meanders into the lower Mississippi
River Valley, boundary layer winds through the afternoon will begin
to back to the west, sending LES into the W to WNW snowbelts. This
develops a brief "Bayfield Bomber" type setup Sunday evening into
the overnight hours Monday, where a convergence band from the
Bayfield Peninsula will be focused into the Keweenaw, moreso in
northern Houghton and far northern Ontonagon counties. Latest 12z
HREF probabilities suggest snowfall rates between a quarter (60-
100%) and a half inch (20-40%) per hour along the M-26 corridor in N
Houghton county during the Monday morning commute hours, and a
highly localized 3-5" in 6 hours by 12z from roughly Houghton to
Twin Lakes. Coupled with terrain enhancement along the Keweenaw
spine and prolonged convergence band residence time, wouldn`t be
surprised to see localized higher amounts. West winds will be
lighter (~20-25 mph gusts) than the recent blizzard event this past
week, therefore, while hazardous travel is certainly on the table,
life threatening blizzard conditions are not expected. At this time,
going to leave any winter weather headline decisions to the midnight
team. Otherwise, expect mostly Sunny skies elsewhere on Monday with
light lake effect snow showers in northern Luce county, where lake
induced troughing helps focus a weak convergence band in the eastern
lake.
A deeper shortwave dives across the UP late Monday into Tuesday,
sending a cold front across the region. 850mb temps drop to near -23
to -27C over the lake, reinvigorating light to moderate lake effect
snow over the NW to W wind snowbelts Tuesday into Wednesday, however
not expecting anything more than a trace to a fluffy couple inches
at this time. With cold air locked in Tuesday, high temps will only
climb into the single digits across the interior west and low teens
elsewhere. Low temperatures into Wednesday will bottom out below
zero for the entire UP under mostly clear skies, plummeting further
into the negative teens to near -20 for the typical cold spots of
the interior west and central.
The next forecast puzzle to solve comes late next week where a
deepening trough over the southwest US lifts northeast, sending a
sfc low into the Ohio River Valley Thursday that tracks through the
lower lakes into Friday. 12z ensemble guidance is split on how far
north and west the precipitation shield extends into Upper Michigan.
The American GEFS is the current outlier to its European and
Canadian ensemble friends, depicting a widespread 20-50% probability
of 1" of snow through Thursday evening, whereas the others show 0-
20% across the entire UP save for the far south and east portions
closer to the low. This will be something to watch over the coming
days. Behind this low, CAA will filter over the lake and resurrect
lake effect snow chances in the W to NW snowbelts Friday.
&&
.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 621 PM EST Sat Feb 8 2025
Synoptic snow will push east of KSAW this evening followed by
improving conditions to VFR overnight. Colder air building in from
the west will support lake effect snow showers into KIWD/KCMX this
evening and overnight at KCMX. Expecting primarily MVFR conditions
in these showers, but PROB30 included at KCMX for potential IFR
visibilities at times into the morning hours. Gusty northwest winds
near 20-25 knots expected at KCMX.
&&
.MARINE...
Issued at 304 PM EST Sat Feb 8 2025
Northwest winds ramp up this evening to around 15-25 kts behind the
next passing system. These winds continue through Sunday, gradually
backing westerly Sunday morning. West winds diminish below 20 kts
Sunday night, but quickly ramp back up to 15-25 kts for Monday
afternoon. A passing cold front brings northwest 20-30 kt winds
Monday night into Tuesday. Current guidance has a relatively low
probability of gales to 35 kts (~25%) with the passing cold front.
Northwest winds fall to 20 kts or less by Tuesday afternoon, backing
west by Tuesday evening. Southwest winds 20 kts or less are expected
on Wednesday. Another cold front late in the day Thursday brings
back west to northwest winds of 15-25 kts for Thursday night into
Friday.
Otherwise, freezing spray is expected over the east half of on
Sunday. Freezing spray returns across much of the lake Monday night
into Tuesday; some heavy freezing spray is possible (~50% chance).
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
UPDATE...JTP
SHORT TERM...Voss
LONG TERM...BW
AVIATION...JTP
MARINE...BW
Area Forecast Discussion
National Weather Service Phoenix AZ
432 PM MST Sat Feb 8 2025
.UPDATE...Updated Aviation Discussion.
&&
.SYNOPSIS...
High pressure will continue to be the dominant feature over the
Desert Southwest through this weekend, promoting above-normal
temperatures into the start of next week. An unsettled pattern is
then expected to take hold over much of the western United States
during much of next week, resulting in cooling temperatures and
increasing rain chances during the latter portion of the week.
&&
.DISCUSSION...
Current 500mb RAP analysis reveals broad upper-level ridging
continuing to encompass much of the southern CONUS, with a weakening
troughing feature over the Pacific Northwest and northern
Rockies. Closer to home, the influence of the above-mentioned area
of high pressure will continue to promote above-normal
temperatures across the Desert Southwest, with just some periods
of passing high clouds being the only noticeable change in
conditions. Much like the past few days, afternoon high
temperatures will range from the middle to upper 70s, with a few
spots reaching into the lower 80s. These unseasonably warm
temperatures will persist through the at least the start of the
upcoming week as the ridge will not budge much during the next few
days.
Heading into next week, the aforementioned trough will eventually
strengthen before diving south across the Great Basin. Due to
orientation and trajectory of this feature, limited moisture will be
available, and much like many of the systems that have moved
through so far this winter, rain chances will be little to none.
However, there will be some noticeable impacts associated with
this disturbance, mainly a drop in temperatures closer to seasonal
normals and periods of breezy to locally windy conditions. In
terms of day-to-day changes in temperatures, highs on Tuesday are
projected to generally be in the middle to upper 60s for lower
desert areas, a good 8-10 degree drop compared to Mondays
forecasted highs. Shifting perspectives, the tightening of the
regional pressure gradient as this system moves closer and over
the region will help generate periods of strong winds, especially
for areas out in SE California, around the Lower Colorado River
Valley, and high terrain areas north and east of the Phoenix
metro. NBM probabilities give these areas anywhere from a 30-60%
chance of achieving gusts greater than 40 mph Tuesday afternoon
and evening. If confidence increases that gusts of this magnitude
will be achieved, Wind Advisories are likely to be issued at some
point in the coming days.
By late Tuesday into early Wednesday, global ensembles indicate a
secondary shortwave moving through the region, providing a
reinforcement of cooler air and potentially bringing the Arizona
high terrain some very light rainfall. As of now, ensemble PWAT
forecasts are not in agreement regarding an increase in necessary
moisture associated with this wave to help spark showers over the
previously mentioned areas. The GFS indicates that moisture will
begin to increase, and reach above normal levels, starting
Wednesday morning, while the ECMWF keeps below normal PWATs over
most of our forecast area into Thursday morning. The dynamics with
this disturbance do not look overly impressive, but they should
be enough to get at least some rainfall activity as long as
sufficient moisture is available. So, this model discrepancy and
how it evolves will play the biggest role in the precipitation
forecast for Wednesday. If the ECMWF leans towards the GFS
forecast, then increased rainfall chances can be expected, and
vice versa. One parameter that the models do agree on is the the
continuation of more seasonal temperatures during the middle
portion of the week, with daily highs through Thursday in the
middle to upper 60s, with a few spots touching 70 degrees.
This unsettled pattern will continue through the end of the week
and potentially into the weekend as yet another piece of shortwave
energy is shown traversing the Desert Southwest. The passage of
this system will be in conjunction with a potential Atmospheric
River that is expected transport a robust amount of moisture
(200-250% of normal) over SE California and much of southern
Arizona. This setup will likely result in the best chances for
precipitation we have seen so far this winter and could result in
some decent rainfall for even areas in the lower deserts. However,
there is still some slight disagreement amongst the the models
regarding how deep this system gets and how far it digs south.
This will ultimately determine how much rain is received across
the region, with a deeper system favoring more widespread activity
and likely higher QPF totals. The best timing looks to be
Thursday into Friday, but a more detailed outlook will be possible
as we move closer to this event.
&&
.AVIATION...Updated at 2332Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Typical diurnal wind patterns are expected through Sunday, with
wind speeds mostly aob 8 kts. SCT to BKN high clouds will continue
to stream over the area through Sunday.
Southeast California/Southwest Arizona including KIPL and KBLH:
A N-NW wind will persist at KBLH, with speeds up to 10 kts, while
winds at KIPL favor a light (< 7 kts) W to NW component through
much of the period. Periods of light and variable winds are
expected throughout the next 24 hours, particularly at KIPL. SCT
to BKN high clouds will continue to stream over the area through
Sunday.
&&
.FIRE WEATHER...
Weak high pressure over the region will continue to bring above
normal temperatures and dry conditions through Monday before a
much more unsettled weather pattern settles into the region for
the rest of next week. MinRHs today will mostly range between
20-30% before lowering into the teens areawide for Sunday and
Monday. Winds will remain fairly light through the period, but
expect some afternoon and evening breeziness with gusts of 20-25
mph mainly across the Lower CO River Valley. Multiple weather
disturbances are likely to affect our region during the latter
half week resulting in cooler temperatures, increased winds, and
higher humidities. Precipitation chances also looking more likely
late next week.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...RW
AVIATION...Smith/Benedict
FIRE WEATHER...Kuhlman