Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/28/25
Area Forecast Discussion
National Weather Service Sioux Falls SD
516 PM CST Thu Feb 27 2025
.KEY MESSAGES...
- Near to above normal temperatures will persist through the
early parts of new week.
- Dry and mild conditions will promote locally elevated danger
through this evening.
- Strong 40 to 50 mph northwest winds on Friday will promote
near critical to critical fire weather conditions through the
evening hours. ALL planned burning activities should be
postponed.
- Measurable precipitation chances (50%-70%) will return from
Tuesday into Wednesday. While amounts remain uncertain, most
of this will fall as rain with most ensemble guidance showing
moderate to high probabilities (50%-70%) in a 0.10" inch or
greater of QPF across the area.
&&
.DISCUSSION...
Issued at 218 PM CST Thu Feb 27 2025
CURRENTS & TONIGHT: A mild and breezy day continues! Taking a look
across the area, mostly clear conditions continue with most areas
seeing temperatures in the low to upper 50s this afternoon. Expect
our highs to top out in the mid to upper 50s and low 60s by the late
afternoon before we lose diurnal heating. With breezy westerly winds
this afternoon, we`re starting to see some locally elevated fire
weather conditions as RH values as low as between 28 percent persist
east of I-29. Expect these conditions to persist through the evening
before our fire weather potential begins to taper down. More quiet
conditions will persist into the overnight hours as winds begin to
taper down. Lastly, overnight temperatures will only decrease into
the upper 30s to low 40s for the night.
THE WEEKEND: Heading into the weekend, the main focus continues to
be on the strong winds and fire weather concerns on Friday. Taking a
look aloft, 27.12z deterministic guidance continues to show a quick
clipper wave diving across the international border into the
northern plains with its associated cold front. While appreciable
precipitation isn`t expected, can`t completely rule out a few
isolated showers developing across southwestern MN by Friday
afternoon as elevated instability interacts with some weak PVA
associated with a secondary cold front. From here, our focus turns
towards our fire weather potential for the day. Taking a look at the
environment, the driest conditions will likely occur along the
Missouri River Valley and Hwy-20 corridors where 35-40 percent RH
values look the most likely according to the RAP and HRRR. Anywhere
north of that will fall within 45-60+ percent range mostly due to
falling temperatures and increased cloud coverage during the
afternoon hours.
Strong northwesterly winds are expected to accompany these drier
conditions a tightening SPG and a push of stronger cold air
advection (CAA) aloft lead to wind gusts between 40-50 mph with the
strongest gusts across southwestern MN. This combined with mild
temperatures in the upper 40s to upper 50s for the day will lead to
near critical to critical fire danger across parts of the area
through Friday evening. With all this in mind, decided to issue both
a Fire Weather Watch for the Missouri River Valley and portions of
northwestern IA and a Wind Advisory for our whole area. Both these
product will remain in effect through 6 PM CST with the wind
advisory staring at 9 am and the watch staring at 10 am respectfully.
Looking into the rest of the weekend, slightly cooler temperatures
temporarily return by Saturday as lingering CAA and northerly
surface winds keep temperatures capped to the 30s to mid 40s with
the mildest conditions across southcentral SD. These conditions will
be short-lived though as an amplified ridging bringing another dose
of WAA to the mid-levels leading to temperatures in the upper 40s to
upper 50s by Sunday. From here, a quick mid-level wave passes just
to the south and east of us by Sunday night potentially bringing a
few isolated showers across northwestern IA. However, with the
better dynamics south and east of us; not expecting much in terms of
accumulations. Ensemble guidance reflects this sentiment with most
model runs showing low confidence (30% or less) in any measurable
precipitation.
NEXT WEEK: Looking into the new week, the mild temperature train
will continue into early next week with multiple pushes of WAA
helping us keep temperatures in the 40s and 50s through Tuesday.
Lastly, measurable precipitation chances (50%-70%) will likely
return by Tuesday as a Colorado Low ejects into the central plains.
While overall amounts are still uncertain, 27.12z deterministic
guidance continues to come into better agreement with the placement
of the low. However, things have trended further to the south and
east this run of guidance with the center now expected to lift
through through eastern Kansas and central Missouri. With that being
said, temperatures are still on track to be in the 40s to 50s for
the day which should give us mostly rain with a gradual transition
to light snow as we look diurnal heating. While overall amounts are
still uncertain, most ensemble guidance shows moderate to high
confidence (50%-70%) in a 0.10" of an inch of QPF or greater.
Lastly, could see another dip in our overall temperatures by
Wednesday with highs only peaking in the upper 30s to low 40s.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 514 PM CST Thu Feb 27 2025
VFR conditions are expected into the overnight and through
Friday. Cirrus will continue to stream overhead, with northerly
winds staying breezy at times. Marginal LLWS may be possible
into Friday morning.
Northerly winds increase through Friday morning, and with the
passage of a cold front mid-day, wind gusts over 40 knots may be
possible at times.
&&
.FIRE WEATHER...
Issued at 222 PM CST Thu Feb 27 2025
Locally elevated fire weather conditions will persist through
the evening hours. Taking a look at the latest observations, RH
values are hovering between 28-35 percent across most areas with
breezy westerly winds between 20-30 mph. While this combined
with the milder temperatures could lead to a few hours of Red
Flag-like conditions this afternoon, the window for these
conditions will be limited. As a result, will not issue a fire
weather headline this for this period. With all this in mind,
make sure to limit any activity that could create a spark!
Looking into Friday, a well-mixed environment along will the
passage of multiple cold fronts will result in much stronger
northwesterly winds with gusts between 40-50 mph at times. With
lower dew points behind the cold fronts, expect RH values to
vary somewhere between 30-40 percent south of I-90 and 50-60
percent north of I-90. While relative humidity values will be a
bit more borderline south of I-90, there could be a narrow
corridor along the Missouri River Valley and Hwy-20 corridors
that true Red Flag Warning conditions will be possible. However,
with some lingering uncertainty regarding RH values and falling
temperatures behind the cold fronts; decided to put the outlined
areas in a Fire Weather Watch instead of a warning at this
time. Either way, with very high to extreme fire danger expected
by Friday afternoon make sure to follow your local burning
restrictions!
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory from 9 AM to 6 PM CST Friday for SDZ038>040-050-
052>071.
Fire Weather Watch from Friday morning through Friday
afternoon for SDZ050-063-068>071.
MN...Wind Advisory from 9 AM to 6 PM CST Friday for MNZ071-072-080-
081-089-090-097-098.
IA...Wind Advisory from 9 AM to 6 PM CST Friday for IAZ001>003-
012>014-020>022-031-032.
Fire Weather Watch from Friday morning through Friday
afternoon for IAZ020>022-031-032.
NE...Wind Advisory from 9 AM to 6 PM CST Friday for NEZ013-014.
Fire Weather Watch from Friday morning through Friday
afternoon for NEZ013-014.
&&
$$
DISCUSSION...05
AVIATION...Dux
FIRE WEATHER...05
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
755 PM CST Thu Feb 27 2025
.KEY MESSAGES...
- Strong winds are expected Friday with gusts as high as 45 mph in
east central Illinois from late morning into early afternoon.
Gusty winds will continue into the evening as winds shift from
southwesterly to northwesterly. Fire danger will be enhanced
Friday from late morning into afternoon as minimum relative
humidity values lower to 25 to 35 percent along with the strong
winds.
- Above normal temperatures will continue through Friday, with
highs in the low to mid 60s. Temperatures will dip down to near
or just below seasonal normals this weekend followed by another
warm up Monday into Tuesday ahead of the next storm system.
- Precipitation chances will be minimal through the weekend then a
potent weather system will likely bring windy conditions along
with rain Tuesday into Wednesday. Thunderstorms are possible
mainly Tuesday night.
&&
.DISCUSSION...
Issued at 308 PM CST Thu Feb 27 2025
A surface high pressure ridge will pass through the area tonight,
decreasing winds from this afternoon`s gusty 30-40 mph readings.
Temperatures look to fall into the mid 30s for most of the area
tonight. Meanwhile, a low moving into the northern Great Lakes will
promote a low level jet early in the morning, that should be located
over eastern IL in the late morning, promoting strong wind gusts to
around 45 mph in the late morning into early afternoon as deep
mixing develops. A wind advisory is in effect for east-central IL. A
cold front will surge into central IL from the northwest, driven by
this low, promoting cold advection late in the day, that should
efficiently mix down another region of strong winds aloft, that
could also approach 45 mph, mainly north of Peoria. At this time, it
appears we`ll stay just short of advisory criteria. Dry conditions
will also be prevalent, and dewpoints into the 20s with temperatures
in the 60s should produce relative humidity dipping as low as 25
to 30 percent, enhancing fire danger threat.
Following Friday`s cold front, cooler air will move in for the
weekend, bringing temperatures closer to normal with highs in the
upper 30s to lower 40s over the weekend, and lows in the 20s, but
high pressure will bring dry conditions and lighter winds.
The next potential feature looks to be a weakening shortwave Monday,
that could produce light rain and snow as temperatures increase
during the day. A more significant feature will be Tuesday as a low
rapidly deepens east of the Rockies and ejects northeastward into
the Great Lakes. Ensemble system averages around a 990 mb low by the
time the system moves into the Great Lakes Wednesday morning, but
10th to 90th percentile range is from around 980 to 1000 mb,
indicating considerable uncertainty in the strength of this system.
Likewise, precipitation ranges from 1-2 inches in the more powerful
systems, to a quarter to half inch in the ensemble members with
weaker systems. Thunderstorms could also accompany this system,
mainly Tuesday night, as some instability accompanies either an
occluded zone or warm sector with strong deep layer shear. CSU
machine learning indicates up to a 15 percent probability for severe
weather, while SPC at this point keeps 15 percent probability south
of the Ohio River.
Highs look to reach the 50s for the first half of next work week,
dropping off again for Thursday and Friday behind the Tuesday night
system.
37
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 510 PM CST Thu Feb 27 2025
Main aviation concerns for this TAF set are with the winds. As a
strong cold front approaches toward daybreak, a 4-5 hour period of
LLWS is expected at all sites, before the gusts mix down to the
surface. Wind gusts 30-40 knots are likely from about 15Z through
the end of the period. Southwest winds turn northwest with frontal
passage, currently timed around 18-19Z at KSPI/KPIA/KBMI, and
20-21Z at KDEC/KCMI.
Geelhart
&&
.FIRE WEATHER...
Issued at 755 PM CST Thu Feb 27 2025
Significant concern exists for enhanced fire danger on Friday,
with strong winds and lowering relative humidity. Latest HRRR
guidance continues to suggest dew points in the 20s during the
midday and afternoon hours, which would drop humidity levels into
the 25-30% range over a large part of central and southeast
Illinois. However, 10-hour dead fuel levels are forecast to be
11-15%, which is a bit high for red flag conditions. Nevertheless,
with dormant/dead vegetation around, any fire would get out of
control quickly. Wind gusts of 35-40 mph will be common from mid
morning through much of the afternoon, highest over east central
Illinois. Winds will turn from southwest to northwest as the cold
front goes through, mainly in the afternoon, shifting the track
of any wildfire that does occur.
Geelhart
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 9 AM to 2 PM CST Friday for ILZ031-038-
043>046-053>057-063.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
839 PM CST Thu Feb 27 2025
.KEY MESSAGES...
- Mild, dry, and very windy conditions Friday. Gusts over 45
mph possible at times. An increased threat for grass and brush
fire spread will exist.
- Conditions will be much cooler this weekend with highs in the
30s expected on both Saturday and Sunday.
- An active weather pattern will develop across the region next
Tuesday and Wednesday, with details in potential impacts (snow
and/or thunderstorms) to the area expected to become more
clear over the coming days.
&&
.UPDATE...
Issued at 839 PM CST Thu Feb 27 2025
Forecast is in good shape for tonight and no changes made. Did
make some slight upward adjustment to temps and downward
adjustment to dewpoints Friday for the southern CWA, especially
south of the Kankakee River. Guidance has been generally
running too cool lately, including for Thursday`s high temps
which ended up 5F+ warmer than most guidance.
Tomorrow has the look of one of the windy, deep mixing days that
the HRRR and RAP tend to perform better than most other guidance
in terms of temps and dewpoints. HRRR/RAP is running about 3-6F
warmer than our forecast highs for the southern CWA on Friday.
Have nudged temps and dewpoints about 50% toward the RAP/HRRR
for Friday, or about a 2-3F upward trend in temps and 2-3F down
in dewpoints. This does have implications for fire weather
concerns that the overnight shift and day shift Friday will
need to assess. Didn`t adjust temps fully toward RAP/HRRR as
there should be a good deal of high cloudiness around, but that
doesn`t mean the HRRR/RAP temps won`t verify, just that
confidence isn`t there to go all in on the warmer temps or an
evening shift update.
No other changes made to the going forecast. Wind advisory
looks good and if the warmer solutions pan out, the advisory may
need to be extended out a couple of more hours, if anything, in
the southern CWA.
Updated grids and derived temps products are out.
- Izzi
&&
.DISCUSSION...
Issued at 310 PM CST Thu Feb 27 2025
Through Friday Night:
Friday is shaping up to be a windy and warm day across the area
as a strong clipper type system quickly tracks east-southeastward
across the upper Great Lakes. Strong southwest winds will start
the day as a robust clipper type system rapidly shifts east-
southeast across the Upper Great Lakes. Warm air advection will
push high temperatures well into the 50s into early Friday (some
60+ degree readings also possible south of I-80), before a cold
frontal passage sends temperatures falling back into the 20s late
Friday night on gusty west-northwest winds. The primary weather
concern during the period revolves around the strong winds
expected for Friday. Specifically, there looks to be two distinct
notable periods and areas favorable for advisory level gusts (45+
mph).
The first concern for strong wind gusts comes from mid morning
through early afternoon (roughly 9am through 1 or 2 pm),
primarily in areas near and southeast of I-55. Strong southwest
wind gusts (up to 50 mph) are expected to rapidly onset during the
morning in this region as diurnal mixing begins to tap into a
strong low-level jet (up to 60 kt at 850 mb). This period of
strong wind gusts will only persist for a few hours, with speeds
likely easing quite a bit in the afternoon as the low-level jet
quickly shift out of the area. With confidence high in this 2 to 4
hour period of strong wind gusts, we opted to hoist a wind
advisory from 9am through 2 pm for areas generally along and
southeast of I-55.
A wind advisory has also been hosted for the remainder of northern
IL for Friday afternoon (from noon to 6 pm), as a second period
of strong wind gusts is anticipated from the west-northwest
following an afternoon cold frontal passage. This period of strong
wind gusts looks to be the most notable across far northern IL,
where some gusts up around 45 mph may be realized for a period in
the afternoon. Wind gusts will then ease into Friday night.
While primarily dry weather is anticipated, a period of scattered
rain and snow showers is possible Friday evening as a secondary
cold front shifts across the area. We added a small (20%) chance
for this to the latest forecast. We could see some areas of light
coatings of snow (under a half inch) in the areas these showers
impact, but significant impacts are not anticipated at this
time.
The very windy and dry conditions will also result in a
heightening threat of fire spread on Friday, especially south
of I-80. For more on this reference the fire discussion below.
KJB
Saturday through Thursday:
This weekend will be much cooler than recent days following a
cold frontal passage on Friday. Highs on Saturday are forecast
in the lower and middle 30s; some areas may even fail to exceed
freezing. Saturday will begin on a breezy note picking up from
a windy Friday and Friday night. We should start the day with
gusts in the 20 to 25 mph range, possibly higher, but winds
should gradually subside during the afternoon as mixed layer
flow eases. A large region of high pressure will overspread the
Midwest keeping rain and snow chances at bay during the weekend.
Saturday should see more blue sky than clouds, especially after
the morning, and mostly sunny skies are expected on Sunday. The
high will drift to our southeast during the day on Sunday and
the return flow will pull temperatures up a few degrees from
Saturday, but most of the area should still be stuck in the 30s.
The warm advection will carry into the week ahead of a couple of
approaching waves. Highs look to be back in the middle and upper
40s for Monday. The remnants of a dying Pacific upper low will
approach the area from the west late Sunday bringing a potential
for precip to Monday. Most guidance is handling this with just
a few hour push of light snow Monday morning transitioning to
rain or a rain/snow mix as conditions warm.
The highlight of the long term forecast is a large synoptic
system that will roll through the region next Tuesday and
Wednesday, but there is still much to be resolved with this
storm. Models mostly agree that the corridor of highest precip
totals will be found immediately north of the low track. Where
that low track will end up and what those highest totals will
look like remain inconsistent. The operational Euro recently
underwent a big shift to the northwest now placing those higher
totals across northwest IL and up into southern and central WI.
The GFS has been bouncing the higher totals all around the
region between runs. Ensemble systems continue to generally
favor areas to our southeast for the most precip and may be on a
bit of a northwestward trend as well, but they too vary quite a
lot among individual members. The 25th-75th percentile spreads
from the GEFS, ENS, and GEPS each exceed 0.5" area-wide. Heavy,
soaking rain is the main concern with this system for the time
being, but thunderstorms and even a little bit of snow are also
possible in the area between Tuesday and Wednesday, both very
dependent on the storm track. Details on exact impacts locally
will become more clear over the next several days.
Doom
&&
.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 526 PM CST Thu Feb 27 2025
Key Aviation Messages for the current TAF period:
- Low level wind shear expected early Friday morning
- Strong wind gusts expected on Friday, beginning as southwest
in the morning then becoming northwesterly in the afternoon
The main impact through the forecast period will be from winds
as all other conditions are expected to be dry and VFR. Winds
are presently out of the northwest and breezy. However, gusts
around 20 to 25 knots will slowly diminish and become more
intermittent through the evening. Winds will then back to the
south Friday morning as a strong low level jet moves over the
area just before day break. While some 20 knots gusts are
possible, with the jet projected between 55 and 60 knots just
1500 feet off the deck, there remains a risk for low level wind
shear tomorrow morning. The jet is expected to weaken slightly,
but surface gusts will remain strong through Friday. Winds are
expected to start out in the morning out of the southwest, but
by Friday afternoon, they should turn to the west-northwest.
Wind gusts tomorrow are expected between 30 to 35 knots, but
cannot rule out a few gusts to 40 knots. As the winds rotate
from south to west late morning/early afternoon, there could be
a period of sub-30 knot gusts, but given the short duration it
was decided to keep the wind gust forecast strong. Winds gusts
are expected to diminish to around or less than 25 knots Friday
evening.
DK
&&
.MARINE...
Issued at 314 PM CST Thu Feb 27 2025
- Gale Warning in effect for the nearshore waters Friday
morning through Friday evening.
A strong area of low pressure under 29.30 in Hg will track from
northern Minnesota and across Lake Ontario on Friday. This will
bring a period of strong winds to the southern part of Lake
Michigan.
Southwesterly wind gusts are expected to increase rapidly on
Friday morning to near 40 knots before turning to out of the
west-northwest during the afternoon. It`s possible that gales
diminish for a period across parts of the Indiana nearshore
waters roughly east of Gary around midday Friday, but are
expected to increase again during the late afternoon and into
the evening. With confidence increasingly, we have opted to
convert the Gale watch to a Gale Warning.
Carlaw/KJB
&&
.FIRE WEATHER...
Issued at 314 PM CST Thu Feb 27 2025
- Elevated Fire Danger expected across most of the area on
Friday.
An initial "pop" of southwesterly winds gusting near 45 mph may
occur between about 9 AM and noon, mainly for locales east of
about I-55 on Friday morning. This will be followed by winds
turning out of the west-northwest and routinely gusting 40-45+
mph during the afternoon. Afternoon relative humidity values are
currently forecast to fall into the 30-40 percent range, with
the driest conditions (RHs near 30 percent) expected south of
about I-80. In these areas, it`s possible that RH values may
even trend a bit lower, towards 25 percent on a brief basis.
This combination is expected to result in an increased threat
for grass and brush fire spread across the entire region, but
particularly along and south of I-80 Friday afternoon.
Carlaw/KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Wind Advisory from noon to 6 PM CST Friday for ILZ003-ILZ004-
ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012.
Wind Advisory from 9 AM to 6 PM CST Friday for ILZ013-ILZ103-
ILZ104.
Wind Advisory from 9 AM to 2 PM CST Friday for ILZ019-ILZ020-
ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ105-ILZ106-ILZ107-
ILZ108.
IN...Wind Advisory from 9 AM CST /10 AM EST/ to 2 PM CST /3 PM EST/
Friday for INZ001-INZ002-INZ010-INZ011-INZ019.
LM...Gale Warning from 6 AM to 10 PM CST Friday for the IL and IN
nearshore waters.
&&
$$
Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Marquette MI
659 PM EST Thu Feb 27 2025
.KEY MESSAGES...
- Widespread snow moves into the Keweenaw, north-central, and
eastern Upper Michigan. This will impact the Friday morning
commute. Highest snow amounts expected in the Keweenaw and
east where amounts up to 10 inches will be possible.
- Strong winds expected Friday afternoon, particularly in the
Keweenaw. Widespread 30 mph winds will be possible. Gusts to
45 mph are expected in the Keweenaw Friday afternoon and
evening.
- Near to slightly below normal temperatures return this
weekend with lows Friday and Saturday night near zero and
windchills as low as - 15F for potions of the interior west
and central.
&&
.SHORT TERM /THROUGH FRIDAY/...
Issued at 314 PM EST Thu Feb 27 2025
Shortwave and associated cold front pressing through the region can
be picked out from surface observations, GOES Water Vapor imagery,
and RAP analysis. As of 1230pm EST, widespread snow is currently
falling across central Upper Michigan, with lake effect west into
the Keweenaw. Brief white outs have been observed here and there,
but the features are pretty transient. Temperatures have been
observed in the 30s so far today.
As we progress through the remainder of the afternoon, snow will
continue to move through the region while precip shifts to lake
effect downwind of Lake Superior. Accumulations should be low given
near 5k inversion heights which fall through the afternoon and
increasing dry air aloft. But as noted above, some brief white outs
can`t be ruled out. Perhaps an inch or two will be observed in
favored locations by the time precip ends this evening.
Upstream, a robust shortwave and surface low is organizing. Caught
within northwest flow aloft, this system will track through Lake
Superior/Upper Michigan Friday. There continues to be good agreement
on the structure of the storm during this transit, which will result
in strong winds across the western half of Upper Michigan Friday and
a swath of snow moving southeast through Upper Michigan. There is
continued uncertainty in the exact track of the system, which will
impact where the higher snow amounts end up overall. However, 12z
guidance and recent CAMS have narrowed the field of possible
solutions, which suggests the system will track near or just south
of Houghton southeastward through Marquette County to near
Manistique through the day Friday. Deviations to this among GEFS,
GEPS, and EPS ensemble members are generally ~50 miles north and
south this line. The track will end up being important because
because isentropic ascent alongside strong 925-850mb fgen is
anticipated along the low`s northern flank, which, in addition to
favorable jet dynamics, will support a swath of moderate to heavy
snowfall. Within this band, HREF suggests snowfall rates of 0.5 inch
per hour will be possible (33-50% chance). There is good agreement
that initially, snow will spread southeast through the Keweenaw and
into central and eastern Upper Michigan after midnight, which will
impact the morning commute. Snowfall amounts prior to sunset could
amount to 2 to 4 inches for most of central Upper Michigan and 5 to
8 inches north of Houghton. In the east which is likely to remain
under the main swath of snow into Friday afternoon, could end up
with storm total amounts of 8 to 10 inches. Areas along the
stateline are likely to see only light snow overnight before dry
slotting moves in Friday morning. As the snow spreads through the
area Friday, increasing warm air advection will enable some rain to
mix in by late morning along the southern edge of precipitation
shield. However, cold air wrapping around the system will quickly
end this and support all snow by mid-afternoon as lake enhanced snow
begins to press into western and central Upper Michigan. Friday snow
amounts in these locations could yield 2 to 4 inches, with another 2-
5 being possible in the higher terrain areas of the Michigamme
Highlands, Gogebic Range and Porkies, and Spine north of Houghton.
For headlines, upgraded the inherited watch to Winter Storm Warnings
for Keweenaw, Alger, northern Schoolcraft, and Alger, then added
Advisories for Delta, Marquette, Houghton, and Baraga. Impacts
should end in Delta after the morning commute. A break in the snow
will be possible for Marquette county westward in the morning, at
least until the lake enhanced snow builds in by afternoon.
The system is also expected to be tightly wrapped and strong
pressure gradient forces alongside the cold air advection behind the
system will yield strong southerly winds becoming north to
northwesterly behind the low. Model soundings show potential of
mixing down 40 mph winds for much of the western half and EPS
probabilities reinforce this potential, especially across the
Keweenaw through the entire day. However, I suspect some of this is
over done save for the Keweenaw Peninsula. There, confidence is high
(>75%) for 45 mph wind gusts in the Keweenaw by afternoon. Opted to
issue a Wind Advisory for the northern Houghton and Keweenaw County
18z-3z.
&&
.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 308 PM EST Thu Feb 27 2025
The long term forecast period begins Friday evening where the
previously discussed clipper low will have traversed southeast
across Upper Michigan and become positioned atop Lake Huron / the
Georgian Bay. This places the UP on the backside of the departing
sfc low, allowing northerly flow across Lake Superior to provide
ample lake enhancement of ongoing synoptic snow as 850mb
temperatures descend around -15 to -17C. At the same time, snowfall
will receive a boost from northerly flow into the terrain of central
Marquette county and for western UP in the Porkies and Gogebic
range. As 850mb temps continue to decrease below -20C, snow ratios
increase overnight as well from "wetter" 10-15:1 system snowfall
towards more typical LES ratios near 20:1+. From Friday evening
through Saturday morning, an additional 3-5" for the aforementioned
terrain enhancement locations is possible on top of what previously
fell through Friday afternoon. Elsewhere, 1-3 inches can be expected
across the north wind snowbelts. Through the rest of your Saturday,
snowfall across the UP will have transitioned to pure LES and will
begin backing to the NW wind snowbelts, favoring snowband
development mostly in the east half. Canadian high pressure begins
descending into the western Great Lakes through the afternoon.
Lake induced inversion heights gradually decline below 5kft in the
west and effectively shut off LES through the evening. However, the
east will benefit from the longer fetch across the lake and
lingering cold air aloft. There, lake inversion heights between 5-
7kft persist into early Sunday morning before the subsidence
inversion erodes LES showers and winds turn offshore. That said, 1-
3" of fluffy snow is expected Saturday through Sunday morning for
areas of the east UP, namely northern Schoolcraft, eastern Alger,
and Luce counties.
Otherwise, mostly quiet conditions are expected elsewhere as high
pressure continues into the Ohio river Valley rounding out the
weekend. As ridging aloft moves over the area, high temperatures
climb above freezing to begin next week, but as a shortwave
traverses the Rockies during this time, it will be worth monitoring
whatever potential surface low pressure emerges from that shortwave.
Even a low track that doesn`t directly impact the UP could induce
decent NE to N or NW wind lake effect snowfall, so this feature
bears some monitoring. This morning`s 12z ensemble low centers have
begun trending further south and east, however, its worth noting
that at least the Euro Ens still supports a 30-50% chance for at
least 3" of snow across the entire UP through Wednesday evening, so
impactful snow is not altogether off the table.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 659 PM EST Thu Feb 27 2025
Sfc high pres ridge will quickly move across the area this evening,
followed by a strong low pres tracking se across Upper MI on Fri. At
IWD, cloud bases have lifted above 3000ft, and VFR will continue
thru this evening. Pcpn and MVFR may brush IWD overnight into early
Fri ahead of the approaching low. In response to the low, low-level
winds will also ramp up, leading to a period of LLWS overnight. MVFR
will then set in Fri morning with -ra/-sn transitioning to -sn in
the aftn. Gusty nw to n winds to 30-35kt expected in the aftn at
IWD. At CMX, expect VFR to prevail thru the evening. Snow and IFR,
possibly a period of LIFR, will then develop overnight along with
low-level wind shear by daybreak. IFR will largely prevail on Fri at
CMX with a wind shift to gusty nw winds to 30kt late morning then n
winds gusting to 35-40kt in the aftn. At SAW, expect MVFR to prevail
into the overnight. Developing snow will lead to IFR late, and LLWS
will develop before daybreak. MVFR will prevail Fri morning into
early aftn as winds swing sw then nw. Another wind shift to n winds
late aftn/early evening will bring gusts to 40kt and LIFR in
-shsn/blsn.
&&
.MARINE...
Issued at 308 PM EST Thu Feb 27 2025
Winds briefly slacken tonight below 15 knots lake wide before a more
prominent clipper arrives from the NW, increasing winds to near 30
kt out of the SE Friday morning becoming gales to 45 kt out of the
NE by Friday afternoon with chances of a few storm force gusts to 50
kt at around 30-50%. Gales of 35 to 40 kt are expected to linger out
of the north overnight Friday before falling to 25 kt out of the NW
Saturday and falling below 20 kt Sunday. The next significant wind
event will be the midweek period of next week, but uncertainty in
the track of a low pressure emerging out of the Rockies is high.
With the gales Friday, heavy freezing spray is expected with waves
of up to 17 feet between Isle Royale and the Keweenaw Peninsula.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Storm Warning from 1 AM Friday to 1 AM EST Saturday for
MIZ001.
Wind Advisory from 1 PM to 10 PM EST Friday for MIZ001-003.
Winter Weather Advisory from 11 AM EST /10 AM CST/ Friday to 1
AM EST /midnight CST/ Saturday for MIZ002-009.
Winter Weather Advisory from 1 AM Friday to 1 AM EST Saturday
for MIZ003>005-084.
Winter Storm Warning from 4 AM Friday to 1 AM EST Saturday for
MIZ006-007-085.
Winter Weather Advisory from 4 AM to 10 AM EST Friday for
MIZ013.
Winter Weather Advisory from 4 AM to 10 PM EST Friday for
MIZ014.
Lake Superior...
Gale Warning from 11 AM EST /10 AM CST/ to 7 PM EST /6 PM CST/
Friday for LSZ162.
Gale Warning from 10 AM EST /9 AM CST/ Friday to 1 AM EST
/midnight CST/ Saturday for LSZ240>242-263.
Heavy Freezing Spray Warning from 10 AM EST /9 AM CST/ Friday
to 1 AM EST /midnight CST/ Saturday for LSZ240>242-263.
Gale Warning from 7 AM Friday to 4 AM EST Saturday for LSZ243-
244-249>251-264-266-267.
Heavy Freezing Spray Warning from 7 AM Friday to 4 AM EST
Saturday for LSZ243-244-249>251-264-266-267.
Gale Warning from noon Friday to 1 AM EST Saturday for
LSZ245>248-265.
Heavy Freezing Spray Warning from noon Friday to 1 AM EST
Saturday for LSZ245>248-265.
Lake Michigan...
Gale Warning from 4 PM to 10 PM EST Friday for LMZ248-250.
&&
$$
SHORT TERM...JTP
LONG TERM...BW
AVIATION...Rolfson
MARINE...BW
Area Forecast Discussion
National Weather Service Blacksburg VA
724 PM EST Thu Feb 27 2025
.SYNOPSIS...
Wind gust up to 35 mph are expected this evening and rain
showers will cross the mountains west of the Blue Ridge. An
additional cold front will push through the region Saturday
bringing cold temperatures back into the region to end the
weekend.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 650 PM EST Thursday...
Key Messages:
1) Gusty winds continue through the overnight hours before
diminishing throughout the day on Friday.
2)Rain and snow showers in southeast West Virginia and western
Virginia this evening with Western Greenbrier likely seeing
light snow.
Showers had exited the piedmont and were entering southeast West
Virginia and western Virginia as of 00Z. Cold air aloft
associated with the short wave crossing the Ohio Valley was
resulting in melting levels around 8500 ft agl, Convective
Available Potential Energy around 50-75 J/kg and Lifted Index
values around zero. Enough instability for showers to grow
above the melting layer and produce lightning. FV3/3km NAM and
HRRR have the showers moving southeas this evening but
dissipating before reaching the foothills by 06Z/1AM. Have
isolated thunder based on radar trends and latest NBM
probabilities.
Temperatures have dropped into the upper 30s to upper 40s in
the mountains and into the 50s in the foothills and piedmont. No
changes to low temperatures at this time.
Previous Discussion...
As of 200 PM EST Thursday...
An secondary upper level shortwave currently across Illinois and
Indiana is expected to dig southeastward through the southern
Appalachians later this evening. As this happens, additional
showers are expected to push through areas primarily west of the
Blue Ridge. Some areas may see a few flakes mixed in as surface
temperatures look to be in the mid 30s as the showers push
through the area. Winds will continue to remain elevated behind
the cold front passing through the area today, with gusts up to
30-35 mph possible at times through the overnight hours. These
winds are expected to diminish during the morning hours on
Friday, and slowly transition to southwesterly winds during the
afternoon hours, which will allow temperatures to climb to
slightly above normal values. Overall, skies will remain clear
east of the Blue Ridge, and partly to mostly cloudy west of the
Blue Ridge; however, they should clear west of the Blue Ridge
by the afternoon hours on Friday.
Temperatures are expected to fall into the low to mid 30s
across the area by Friday morning, but rebound back into the
upper 50s to low 60s east of the Blue Ridge, and upper 40s to
mid 50s west of the Blue Ridge. This partially due to 500mb
heights quickly rebounding across the area as a surface high
pressure quickly pushes east into the southeast throughout the
day on Friday.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 200 PM EST Thursday...
Key Messages:
1) Confidence is moderate for a chance of rain or snow showers in
southeast West Virginia on Saturday.
2) Colder and drier conditions will follow for Sunday.
A broad upper level trough will cross the eastern United States
during Friday night into Saturday. A weak cold front should move
eastward to bring a chance of rain or snow showers for southeast
West Virginia. Snowfall accumulations appear to be limited to just
western Greenbrier County during Saturday with up to a half an inch
expected. Otherwise, most locations will see a gusty west wind and
increasing clouds. Gusts up to 40 mph may be possible along the
highest elevations. The downslope flow east of the Blue Ridge should
boost high temperatures into the 50s and 60s.
Colder and drier air will follow by Saturday night with low
temperatures falling into the teens and 20s. Wind chill values may
drop into the single digits for the higher terrain by early Sunday
morning. High pressure should gradually build towards the Mid
Atlantic on Sunday, but the gusty wind may not completely diminish
until Sunday night as the upper level trough departs offshore.
Temperatures will turn notably lower despite the sunshine on Sunday
as highs only climb towards the 30s and 40s, and Sunday night should
become cold due to good radiational cooling and light winds.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 200 PM EST Thursday...
Key Messages:
1) Confidence is high for dry weather to start the new work week.
2) A cold front may bring the next chance of widespread rain on
Wednesday, and mountain snow showers could follow by Thursday.
With high pressure in control on Monday, dry weather will persist
across the Appalachian Mountains. Temperatures should recover from
the chill of Monday morning as the the flow aloft turns more zonal.
High pressure should drift offshore by Monday night, and a southerly
flow will provide warm air advection on Tuesday. Meanwhile, an upper
level trough should cross the Rocky Mountains and spark a low
pressure system to develop in the Plains. Tuesday night could
feature increasing winds and rising chances of rain showers. The
bulk of the rain arrives on Wednesday as a cold front approaches.
Some models hint at a little instability and a risk of convection by
Wednesday afternoon, but confidence is too low to offer further
details at this time. By Wednesday into Thursday, colder air should
return with mountain snow showers amidst a gusty northwest flow.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 715 PM EST Thursday...
Showers had exited the piedmont and were entering southeast West
Virginia and western Virginia as of 00Z. Cold air aloft
associated with the short wave crossing the Ohio Valley was
resulting in melting levels around 8500 ft agl, Convective
Available Potential Energy around 50-75 J/kg and Lifted Index
values around zero. Enough instability for showers to grow
above the melting layer and produce lightning. Fv3/3km NAM and
HRRR have the showers moving southeas this evening but
dissipating before reaching the foothills by 06Z/1AM. Have
isolated thunder based on radar trends and latest NBM
probabilities, but no thunder in the local TAFs at this time.
Ceilings were VFR for the beginning of the TAF forecast period,
Wind direction was backing to the west and southwest ahead of
the Ohio Valley short wave and will turn back to the northwest
overnight once the wave passes. Wind gusts of 15 to 30 knots
will continue. Ceilings will also lower to MVFR to KLWB and KBLF
behind the wave until around 12Z/7AM.
Some LLWS could return to the region between 03-06Z/10PM-1AM.
This would most likely be at KLWB and KBCB.
Skies look to clear throughout the morning on Friday, with winds
and wind gusts expected to diminish by the early afternoon
hours.
.EXTENDED AVIATION OUTLOOK...
Increasing clouds are expected by Saturday morning as another,
stronger cold front arrives. This may bring some
-SHRA/-SHSN to BLF and LWB and MVFR ceilings through the weekend.
West winds become gusty to 25 to 35 kts with the frontal
passage on Saturday, diminishing to 20 kts from the NW Sunday.
Monday and Tuesday will be VFR.
However, another large low pressure system in the central
United States will bring widespread precipitation and sub-VFR
conditions by this middle of the week. Timing of this system is
questionable and it may impact the local area as early as
Tuesday or Tuesday night.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...EB
NEAR TERM...AMS/EB
SHORT TERM...PW
LONG TERM...PW
AVIATION...AMS/EB
Area Forecast Discussion
National Weather Service Topeka KS
537 PM CST Thu Feb 27 2025
.KEY MESSAGES...
- Very high fire danger conditions are forecast for much of the
area Friday afternoon.
- Cooler weekend with an active pattern ramping up with several
rain chances returning Sunday evening through Tuesday. A few
rumbles of thunder may occur during this period. More active
weather for early next week.
&&
.DISCUSSION...
Issued at 220 PM CST Thu Feb 27 2025
Dry northwest flow aloft stretches through the central plains this
afternoon while an embedded wave rounds the ridge into the northern
plains and a southern stream closed low traverses the Desert
Southwest. The northern stream system ushers in another cold front
tomorrow, increasing the threat for elevated fire danger in the
afternoon as the colder airmass far lags behind the sfc boundary
(see Fire Weather Discussion for more details). H85 thermal ridge
around 13C shifts eastward through eastern Kansas while BL profiles
mix down from 800 mb. Model spread amongst the HREF is less than 4
degrees, lending to the high confidence of reaching the low 70s for
highs. The colder airmass and lighter winds arrive for the weekend
with highs generally in the 50s and lows near the freezing mark.
The aforementioned southern stream closed low kicks east into the
central plains by Sunday afternoon as warmer air and cloud cover is
advected northward in advance of the wave arriving overnight into
Monday. GFS solutions are hinting at marginal instability south of
Interstate 70 to warrant a few thunderstorms, however higher
probabilities currently reside towards south central and southeast
Kansas at this time. It is also important to note that the EC
ensembles are trending south with the upper low, a bit of an outlier
compared to the Canadian model so have opted to stay in the chance
range for precip.
The active pattern persists with a more expansive upper low axis
tracking east into the central plains in the Tues-Wed. time frame. A
few thunderstorms may be possible Tuesday afternoon and evening, in
the vicinity of a warm front. At this time, more optimal forcing and
moisture resides further south so overall confidence is low on precip
chances for northeast Kansas.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 537 PM CST Thu Feb 27 2025
VFR conditions will continue with the lower troposphere
remaining dry. Winds will back over the next several hours as
the boundary layer decouples and a moderate low-level jet
develops. Appears the jet will be close enough to the ground and
veered from surface flow to form low-level wind shear after 06Z.
Cold front passes around 15Z and could see minor wind shear or
turbulence persisting before mixing deepens toward 18Z when
some gusts are likely.
&&
.FIRE WEATHER...
Issued at 220 PM CST Thu Feb 27 2025
Very high fire danger conditions are anticipated for Friday
afternoon as a cold front shifts light west winds to the northwest
from 15 to 25 mph with gusts in upwards of 30 mph. Sfc pressure
gradient is consistently tightest along the NE border so confidence
in higher wind speeds is best along and north of highway 36.
Meanwhile, RH values are fairly consistent between short term
guidance, with the HRRR and RAP solutions being even drier than the
forecast while the HREF seems to be exhibiting a high bias. Current
forecast of 20-25% for minimum RH seemed reasonable given the higher
wind speeds and high confidence for highs near 70 degrees. Overall
weather conditions combined with marginal fuels at this time led to
withholding from a Red Flag Warning at this issuance.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION...Prieto
AVIATION...Poage
FIRE WEATHER...Prieto