Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/16/24
Area Forecast Discussion
National Weather Service Grand Rapids MI
1028 PM EST Fri Nov 15 2024
.KEY MESSAGES...
- Patchy Fog Tonight
- Low Chance of Rain Sunday Night
- Precipitation Likely Mid Next Week But Uncertainties Remain
&&
.UPDATE...
Issued at 1028 PM EST Fri Nov 15 2024
Cloud cover has remained and the current trend is that clearing
isn`t likely. Therefore the potential for fog developing is low.
The latest HRRR and RAP runs have backed off of fog development
compared to the previous runs mentioned in the discussion section.
&&
.DISCUSSION...
Issued at 214 PM EST Fri Nov 15 2024
- Patchy Fog Tonight
The current cloud cover was holding the afternoon humidity levels
up. Satellite trends do show some holes starting to open up in
the cloud cover, mainly north of Muskegon. There is also a general
diminishing trend to the cloud cover in eastern WI, which is
shifting east with time. Thus, if we do see any clearing later
this afternoon or evening, combining that with the elevated
humidity levels to start the night, we could see some fog
developing. The HRRR has bounced around with this fog risk so,
there is certainly some uncertainty. High pressure will be
building in from the southwest overnight, so the winds will be
relatively light as well. For now we will feature patchy fog for
the CWA, mainly after midnight.
- Low Chance of Rain Sunday Night
Our main weather concern for the latter half of the weekend comes in
the form of a weak cold front crossing the state on Sunday. Given
the cold front and attendant vorticity maxima crossing the state,
light showers are possible. The main limiting factor is that
moisture looks quite shallow, confined to the lowest 5kft in most
model soundings. Will have 20-30% chance of rain with little to no
QPF as the lack of moisture suggests any precipitation would be a
very light rain at most.
- Precipitation Likely Mid Next Week But Uncertainties Remain
Of far more note is the middle of next week as a significant pattern
change will be underway. Our first round of precipitation has high
confidence of being rainfall, and will be associated with the
ejection of a shortwave out of the Southern US. This shortwave
drives a surface low north into the upper Mississippi Valley, with
the warm air advection wing of the low bringing a round of rainfall
Monday Night into Tuesday.
Uncertainty increases into mid-next week as this ejecting shortwave
phases with a larger upstream trough. How exactly this phasing
occurs remains uncertain at this time range due to questions of how
a downstream blocking pattern breaks down. Model consensus is good
in driving this upper-low overhead and forming a secondary surface
low over the Upper Great Lakes bringing high precipitation chances
back to the region.
However, uncertainty in the extent of cold air intrusion is high
thanks to questions on how this happens. A deeper and more easterly
trough would allow more cold air to wrap around the back side and by
extension bring a chance of some lake effect snow mixing in. This is
favored by the deterministic GFS and the GEFS and to some extent the
CMC ensembles. However, a westerly and weaker trough limits the
extent of this cold air intrusion keeping snow out of the forecast
matching the current EPS thinking.
Given the elevated uncertainty will stick to the current NBM which
suggests plenty of clouds and mainly rain. We will monitor the
forecast over the coming days to see how things evolve. The other
thing to watch will be wind, as a surface low developing in the
region with that strong a trough may lead to breezy conditions,
especially given isallobaric response.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 612 PM EST Fri Nov 15 2024
Ceilings continue to hover around MVFR and VFR around 3000 feet.
This will continue overnight with light winds from the northwest
turning to the southeast overnight into Saturday. Cloud cover
remained overcast so it isn`t likely that we see the drop in
ceilings to IFR as mentioned previously, but some slight
reductions in visibility remain possible due to patchy fog around
the MKG to GRR area. Ceilings will gradually lift to VFR values
across the area Saturday afternoon.
&&
.MARINE...
Issued at 214 PM EST Fri Nov 15 2024
With high pressure moving in the winds will remain relatively
weak into the start of Saturday. The shifts east of the area
during the day on Saturday and the pressure gradient tightens up
Saturday night. We will likely need a small craft advisory as
southerly winds are likely to top 20 knots.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.
&&
$$
UPDATE...RAH
DISCUSSION...MJS/Thomas
AVIATION...RAH
MARINE...MJS
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
859 PM CST Fri Nov 15 2024
.KEY MESSAGES...
- Areas of fog are likely (60-80% chance) late tonight from I-55
westward where visibility may fall below one-half mile.
- Rain returns Monday, with a slight (20%) chance for embedded
thunderstorms by Monday evening in areas south of Interstate 72.
Rain will be accompanied by gusty winds, particularly Monday
evening with average gusts between 30-40 mph.
- Temperatures will turn sharply colder by the middle of next
week, but how cold and for how long remains highly uncertain,
along with any prospects for accumulating snow.
&&
.UPDATE...
Issued at 859 PM CST Fri Nov 15 2024
Fog potential continues to be the main forecast question for
tonight. Although high pressure continues to slip eastward,
causing a light southeast flow to begin across the area, some
lowering of visibility has been developing outside of a low cloud
deck that remains entrenched over eastern IL. This cloud deck
should help prevent any significant fog, but how far westward it
spreads remains in question. In addition, a subtle increase in
winds overnight should help mitigate fog development. Will add
areas along the I-55 corridor and westward to patchy fog mention
overnight given the slower advance of low cloud cover westward
versus the afternoon forecast package. Otherwise, lows from the
upper 30s to lower 40s continue to look good for tonight.
37
&&
.DISCUSSION...
Issued at 1227 PM CST Fri Nov 15 2024
The main forecast challenge in the near term is pinning the fog
potential late tonight into Saturday morning.
Short-term guidance remains inconsistent with visibility
overnight, with the HRRR, NAMNest, RAP, and ARW all showing
pockets of sub- half-mile visibility, primarily west of a Peoria
to Springfield line. Worth mentioning, though, is the deterministic
HRRR which supports transient sub- half- mile visibility as far
east of I-57 overnight. Glancing at the most recent probabilistic
HREF guidance, there is a 60-80% chance for sub- half- mile
visibility across west central Illinois tonight. This, alongside
a favorable synoptic setup in which (a) skies will be clear, (b)
winds will be calm, and (c) shallow moisture will become trapped
beneath a subsidence inversion, has prompted us to add fog to our
gridded forecast in areas west of a Peoria-to-Springfield line for
late tonight. Trends will be monitored this evening on whether a
Dense Fog Advisory may be needed, but the answer is currently
unclear with a good chunk of Illinois likely becoming shrouded in
low stratus.
Attention then turns to Monday as a robust upper trough lifts
from Baja California and pivots across the Central Plains, with
its attendant surface low occluding over the Upper Midwest. The
moisture flux ahead of this wave looks rather robust as PWATs
approach the 95th percentile for mid- November climatology.
Rainfall associated with this wave looks to come in two waves: (1)
early Monday morning along the warm front, within a warm-
advection regime, and then (2) Monday evening ahead of the cold
front. Model QPF from both blended (NBM) and ensemble (LREF)
guidance suggests our rainfall goalposts (10th-90th) will range
between 0.25" - 1" in areas north of I-70. While severe weather
is not currently anticipated, blended guidance points to a slight
chance (20%) of thunder Monday evening as a strong LLJ noses into
the region and provides a few hundred J/kg of MUCAPE, which could
be enough to support an attendant wind risk. But even if it does
not storm, synoptic winds will be gusty, with the ensemble mean
from both the GEFS & EPS generally in the 30-40 mph range.
As we head into the middle of next week, there remains large
variance among global ensemble systems (GEFS, EPS and GEPS) with
respect to how the occluded surface low phases together with another
digging trough coming out of the Pacific Northwest. The majority
of the guidance supports a highly amplified pattern with gusty
winds and much colder temperatures spilling across the Midwest.
The position and amplitude of this upper low will determine how
windy and how cold we will get, as well as how long the cold will
stick around. While that is intentionally vague, we can look
toward the ensemble mean for a reasonable first guess for mid-week
gusts, which currently support 30-40 mph. Meanwhile, temperature
spreads for late next week are large, but we could return to sub-
freezing overnight lows as early as Wednesday night. And, with
showery precip likely within a strong cold advection regime, it
remains a good possibility that we squeeze out the season`s first
snowflakes across our northern half.
MJA
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 551 PM CST Fri Nov 15 2024
As high pressure shifts eastward tonight, southeasterly flow will
start to push low cloud cover currently lingering in eastern IL
westward into the central IL terminals, especially those from
KDEC-KBMI eastward. To the west, fog could develop if cloud cover
doesn`t spread that far westward, creating some uncertainty about
the character of aviation concerns between low ceilings and/or
fog. For now, have included MVFR cigs from KBMI-KDEC eastward
starting 06Z-09Z, and for KPIA and KSPI deteriorated conditions to
IFR from around 10Z-15Z, with fog and low cigs mentioned in TAF.
Conditions should improve to VFR around 16Z as southerly flow
continues to increase. Winds SE under 5 kts initially, increasing
to 10-12 kts and becoming SSE by 16Z.
37
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
908 PM CST Fri Nov 15 2024
.KEY MESSAGES...
- Warm but breezy this weekend. Saturday highs in the 50s with
wind gusts around 35 mph. Sunday highs in the upper 40s to low
50s with wind gusts around 20 mph.
- Low pressure system bringing rain late Monday into Tuesday
with most locations seeing around an inch of rain.
- Widespread rain late Monday into Tuesday with most locations
seeing around an inch of rain.
- Cooling down to average high temperatures in the later part of
the week, high temperatures dropping down to the upper 30s.
&&
.UPDATE...
Issued at 905 PM CST Fri Nov 15 2024
Main trend to note with the 00z models is an increasing signal
for rain out toward Eau Claire about 24 hours from now with
enough saturation ocurring along the front to support the
development of rain. As a result, have started to boost PoPs out
by EAU for Saturday evening.
&&
.DISCUSSION...
Issued at 213 PM CST Fri Nov 15 2024
Low clouds and fog have been very slow to dissipate today across
central and western MN. Visibilities are still near 1/4 mile at
a few places, but overall improvement has accelerated early
this afternoon. The clouds will hamper much heating in these
areas and by sunset we may see an increase in low clouds and
some fog again. However, southeast winds will increase this
evening and overnight as well, which should limit the areal
extent of fog.
The trough across the western U.S. will bring three disturbances
northeast across the Plains to the Upper Midwest or Great Lakes,
one of which will bring us precipitation. The first disturbance
will track from the northern Rockies to the Dakotas and far
northwest MN Saturday. This potent system will have little
moisture to work with and is not expected to produce much, or
any, precipitation. There is a low chance for a rain shower or
two across WI Saturday evening as deeper moisture arrives with
steep mid level lapse rates of 7-8C/km. The bigger story will be
the gusty southeast winds ahead of the cold front. Forecast
soundings indicate 35-40 kt winds toward the top of the mixed
layer and thus 30-35 kt gusts appear likely across much of the
area from mid morning to mid afternoon. Temperatures will be
quite mild as 925 mb temps of +7 to +10C overspread the area in
the afternoon. Mixing to that layer would yield highs in the
upper 50s to lower 60s. Current forecast highs in the mid 50s
may be conservative. Temperatures cool a bit behind the front
Sunday, but still remain about 10 degrees above normal.
The next disturbance will originate quite far to the south in
northwestern Mexico Sunday. A subtropical ridge over Florida
will steer this disturbance northeast to the Upper Midwest by
Monday night. The origin and meridional flow from the tropics
means considerably more moisture will accompany this one. In
fact, pwats of 1.75 inches could reach as far north as northern
MO. Moderate to heavy rain will spread quickly from south to
north Monday afternoon and evening before ending early Tuesday.
Rainfall totals of 1-1.5 inches are likely. Confidence is high
for this portion of the system.
Confidence drops off from Tuesday afternoon onward, but run-to-
run model consistency has been improving. As the potent
disturbance from Monday night is absorbed by another incoming
trough over the northern Plains by Tuesday night, a sharp
negatively-tilted shortwave over the mid Mississippi Valley
could spawn another deep surface low over the southern/eastern
Great Lakes on Wednesday and Wednesday night. This would refocus
the trough over the eastern Great Lakes and New England for
late week. In other words, there may not be much precipitation
other than sporadic light rain and/or snow showers or flurries
for the Upper Midwest mid week. Any accumulation whatsoever
would be hard to come by. This is still 5 or 6 days out so
there is plenty of room for things to change, but I wouldn`t be
planning snow-related activities until further notice.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 504 PM CST Fri Nov 15 2024
The last of last nights fog/stratus will be clearing AXN
shortly, with strengthening southeast winds, we will not see
another round of stratus and fog tonight. Southeast winds will
become gusty on Saturday. In addition, followed the lead of the
HRRR/RAP that we`ll see a band of 1200-2k foot stratus develop
over the center of MN (from an east-west perspective) Saturday
afternoon that will be moving into the MN/WI border region by
00z Sunday (6pm Sat).
KMSP...21z RAP shows MVFR stratus potential beginning at 21z
Sat. Initially the stratus would come in around 2k feet, but
the RAP shows this cloud deck descending to near 1k feet
Saturday evening.
/OUTLOOK FOR KMSP/
SUN...VFR. Wind W 10-15G25kts.
MON...VFR. Wind SE 5-10kts.
TUE...MVFR/RA. IFR likely. Wind E 10-15kts bcmg NW 20G30 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
UPDATE...MPG
DISCUSSION...Borghoff
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
703 PM EST Fri Nov 15 2024
.KEY MESSAGES...
- Rain chances return Saturday and continue into Sunday. Windy
conditions also return late Saturday.
- Southerly low-end gales are expected over central Lake Superior
Saturday night, followed by westerly gales of 35 to possibly
40 knots behind the cold front Sunday afternoon and evening
across the western half of the lake.
- Still plenty of model uncertainty regarding the storm system
developing over the Midwest/Great Lakes region for mid-late
next week. That said, expect rainfall Monday night through
Tuesday.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 249 PM EST Fri Nov 15 2024
The latest RAP analysis this afternoon shows an omega block pattern
across the CONUS with the mid level ridge centered over the
Mississippi Valley and a shortwave lifting northeast away from the
Great Lakes as it flattens out. At the sfc, high pressure has begun
extending into the UP allowing for drier air to filter in and clear
skies out over the far western UP. Where skies have remained mostly
overcast, temps have hung around in the low to mid 40s. As this
continues to build over the Upper Great Lakes, any additional
warming this afternoon will yield highs in the mid 40s to low 50s.
Dry weather across the UP and clearing skies from west to east will
continue into tonight.
The high pressure shifts east toward the Lower Great Lakes tonight
and mid level ridging becomes centered overhead resulting in calm
winds this evening through much of tonight. Some mid to high clouds
begin filtering in from the west ahead of a low pressure system
lifting northeast through the Plains tonight. Lows settle into the
upper 20s to upper 30s, coldest interior central Upper MI where
clearing holds on the longest. Some patchy fog is also possible
tonight, but confidence in significant visibility reductions is low.
(Only ~30% chance for less than 1 mile visibility)
&&
.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 323 PM EST Fri Nov 15 2024
Rainfall returns this weekend as a shortwave low ejects from the
Rockies towards far northern Ontario. While we remained socked-in
with moisture in the lowest levels of the atmosphere Saturday
morning over the western U.P., we could see some patches of fog
develop in the cold pool drainage areas and where winds are lighter.
However, expect the fog chances to go away by the early afternoon
hours as the surface begins to warm up, even despite the cloud
cover. As moisture advects in from the Gulf ahead of the low`s cold
front, we could see some drizzle showers develop, mainly across the
central U.P. with some help from upsloping. In addition, with the
pressure gradient tightening over us ahead of the cold front, expect
winds from the south to begin picking up throughout the day, with
gusts up to 30 to 40 mph possible by the evening and overnight hours
(HREF shows a 10 to 50% chance of winds over 40 mph over most of the
west). In addition, the HREF shows some of the higher elevations in
the western U.P. possibly gusting over 45 mph (around 30% for the
most part). As we head into the overnight hours, rain chances
increase, with showers expected to begin developing over the central
U.P. around midnight. The line of showers intensifies as it heads
eastwards late Saturday night through Sunday morning. Overall, some
spots in the far west could see nothing, while areas in the east
could see up to around 0.30 inches of liquid by the time the front
moves through Sunday morning. While we may see some light lake-
effect rain showers behind the front Sunday, expect the lake-effect
rain to be relegated to the far east near Whitefish Bay and maybe
the Keweenaw by Sunday afternoon, with lake-effect rain chances
ending by early Monday morning.
Dry weather returns Monday as ridging moves across the area, with
highs still remaining above normal as warm air from the South cycles
into our area. The troughing pattern over the western U.S. slowly
makes its way into the central CONUS mid next week, eventually
ejecting a low that lifts from the Southern Rockies to the Upper
Midwest/Canadian Prairies. With the placement of the low improving
over the past 24 hours, and it being now further westward than
previously predicted, the chances for the precipitation type being
solely rain, at least early in the event, have significantly
increased (100% chance of rain if precipitation occurs). As for when
the precipitation begins, medium range model guidance has also
significantly reduced the spread when compared to yesterday, with
most suites now showing the rain moving in from Wisconsin Monday
night and continuing through Tuesday. This could be another soaking
rainfall event across the area as some fairly notable Q-Divergence
is seen aloft as the warm front of the low passes overhead and PWATs
near 1.00 inch. While precipitation is expected to continue through
the mid week into the latter portion of next week as the low then
digs into the Great Lakes region, there is high model spread in
regards to temperatures as it is fairly unknown how much of the cold
air from Canada is able to sneak down into the U.S. for the latter
half of next week. Should the cooler solutions be true, we may see
some lake-effect snowfall late next week across Upper Michigan. If,
however, the warmer solutions are true, we may see more lake-effect
rain instead, and lake-effect snowfall (should it occur) will have a
harder time accumulating at the surface.
&&
.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 702 PM EST Fri Nov 15 2024
Skies continue to clear from west to east across the UP this evening
as high pressure moves over the area. IWD and CMX have both cleared
out already, and VFR conditions will prevail as both terminals
through the TAF period. The clearing has yet to make it to SAW,
where MVFR ceilings are still present. The clearing line is just to
the west of the terminal, so we expect VFR conditions to develop at
SAW by 1Z. Conditions at SAW will drop again to MVFR after 5z this
evening as fog develops. There is also a 30 percent chance that IFR
fog develops at SAW overnight. South winds increase into Saturday
with gusts in the 20 to 30 kt range at all sites in the afternoon.
&&
.MARINE...
Issued at 323 PM EST Fri Nov 15 2024
Light winds of 20 knots or less continue this evening into Saturday
morning as high pressure continues to leave the area to the east. As
a low lifts from the Northern Plains to far northern Ontario this
weekend, winds begin to pick up from the south Saturday, eventually
becoming 20 to 30 knots across the lake Saturday night with gales up
to 35 knots expected over the central lake (east of the Keweenaw); a
Gale Warning has been issued for these gales from 7 PM EST Saturday
to 4 AM EST Sunday. While the winds weaken a little early Sunday
morning, expect them to pick back up again from the west behind the
aforementioned low`s cold front by early Sunday afternoon, with
westerly gales of 35 knots to a few gusts up to 40 knots near the
Keweenaw possible. Thus, a Gale Watch has been issued for the
western half of the lake 1 PM EST to 10 PM EST Sunday. As ridging
builds in behind the cold front late Sunday night, winds rapidly
weaken as they veer northwest, becoming 20 knots or less again by
Monday morning. However, do not expect the light winds to remain all
that long, as a low lifting from the Southern Rockies heads towards
the Canadian Prairies/Upper Midwest through the middle of next week.
This will increase winds from the east to southeast across Lake
Superior, with gales up to at least 35 knots being possible by
Tuesday (40 to 50% chance according to the NBM). As the low digs
back towards the Great Lakes region Wednesday to Thursday, the model
spread in the winds greatly increases; however, some stronger winds
look to return by late next week as the low looks to reamplify over
the Great Lakes region.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Sunday afternoon through Sunday evening for
LSZ162.
Gale Watch from Sunday afternoon through Sunday evening for
LSZ242>244-263-264.
Gale Warning from 7 PM Saturday to 4 AM EST Sunday for LSZ244-
245-265-266.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...TAP
AVIATION...RM
MARINE...TAP