Area Forecast Discussion Issued by NWS Marquette, MI
000
FXUS63 KMQT 140718
AFDMQT
Area Forecast Discussion
National Weather Service Marquette MI
318 AM EDT Thu Mar 14 2024
.KEY MESSAGES...
- Dry weather and above normal temps expected through Friday night
- A weekend storm system brings light rain/snow mix and blustery
conditions on Saturday.
- Below-normal temperatures and several days of accumulating
lake effect snow potential Saturday night thru Tuesday.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 318 AM EDT Thu Mar 14 2024
GOES-16 Night Fog shows a few high clouds among otherwise clear
skies over the UP. North of Lake Superior, a cloud deck with ceiling
heights of 600-1100 ft is proceeding south. Well to the south of the
UP, high clouds with a shortwave and associated surface low are
advancing north through southern Wisconsin. While no deterministic
models show precipitation making it as far north as the UP (most
showing precipitation staying south of Green Bay), a convergence of
high clouds from the south and low clouds from the north should
create mostly cloudy conditions today. Cloud cover blocking
radiational heating in conjunction with continued cold advection
from 850mb will keep highs today mainly in the 40s. This is still 5-
10 degrees above normal for Pi Day, but will be the coolest highs of
the week thus far. RHs will only fall to around 40 for the interior
west today, helping keep fire weather concerns lower than earlier in
the week. Northeasterly winds will gradually back northerly to
northwesterly tonight in response to the low pressure passing
through the southern Great Lakes today.
&&
.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 524 PM EDT Wed Mar 13 2024
A rex block building over British Columbia results in 500mb positive
height anomalies approaching 340m (+3 st devs) this weekend. This
blocking ridge forces a deepening trough downstream across eastern
North America Friday night through Wednesday. This deepening trough
provides most of the noteworthy weather during this forecast period.
The most prevalent hazards appear to be gusty west winds Saturday
into Sunday followed by a period of accumulating lake effect snow
Saturday night into Monday night. Meanwhile, daily temperatures
anomalies of +6 to +10 trend to -1 to -3 below normal behind a cold
front currently progged for Sunday morning through early next week.
A low pressure tracks to our south on Thursday and model guidance
continues to trend further south. As a result, Upper Michigan is
increasingly likely to stay dry, except for maybe the far southern
tip of Menominee County. Otherwise, steady northeast winds off Lake
Superior keep temperatures cooler (upper 30s) near the lakeshores on
Thursday with locations farther from the lake warming into the upper
40s. A high pressure ridge settles across the area Thursday night
into Friday allowing for light winds and a large diurnal temperature
swing exceeding 20F (lows in the 20s, highs in the 40s).
The primary weather maker approaches the region Friday night. The
event begins with a ~50 kt westerly low level jet resulting in WAA,
isentropic ascent, and perhaps some weak frontogenesis too.
Operational models have ~9 hour period of deep moisture aloft, but
the antecedent air mass is quite dry so I`m skeptical of the high
end PoPs advertised by NBM and decided to limit PoPs at 50% on
Saturday. Northern and eastern portions of our CWA are most likely
to get precipitation with this feature. NAM guidance advertises all
snow via evaporative cooling whereas the GFS guidance advertises
more of an elevation-dependent rain/snow mix. Either way, the going
forecast is likely too aggressive with the duration and magnitude of
Saturday`s precipitation chances. The other thing to watch on
Saturday is the potential for gusty west to northwest winds within
the cold air advection regime. Models are advertising fairly deep
mixing into a layer of moderate winds aloft and EFI guidance
highlights the potential for strong winds mainly across the west
half of Upper Michigan. As is usually the case, the Keweenaw looks
breeziest and EPS means already advertise peak gusts in the 40-45
mph range suggesting potential for a wind advisory.
Continued cold air advection increases lake effect snow potential
Saturday night and a secondary shortwaves digs into the base of the
trough. This disturbance should enhance any ongoing LES in
addition to sending a reinforcing cold front that should cool
temperatures below normal for the first time since Feb 29th.
With lake average temperatures around 2-3C, the critical 850 mb
temp threshold for pure lake effect is around -11C. Ensemble
means cool 850 mb temps below that threshold Saturday night and
don`t warm temps back above that threshold until Tuesday. Model
soundings advertises deeper moisture in addition to the lake-
induced inversion moving into the DGZ later on Sunday suggesting
fairly high coverage and higher SLRs. In addition to LES, we`re
also well into the time of year where cold upper level
troughing can support diurnal snow showers developing due to
daytime heating. Grand ensemble means advertise around 0.25
inches of QPF within the lake effect snow belts during the
period of LES and there should be locally higher amounts. In an
average year, this would not be particularly noteworthy but this
year is different.
&&
.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 750 PM EDT Wed Mar 13 2024
With dry air continuing to dominate thru the low and mid-levels, VFR
will be the rule tonight at IWD/CMX/SAW. However, will be monitoring
the southward progress of some low cloudiness currently well n of
Lake Superior. It appears that during early Thu morning, some of
these clouds will reach Upper MI. For now, only included a low MVFR
cig at SAW where sharpest upsloping will occur under NNE winds. At
CMX/IWD, kept mention of lower clouds to just few to sct at around
2000ft.
&&
.MARINE...
Issued at 653 PM EDT Wed Mar 13 2024
A sfc ridge building in from the northwest will keep winds below 20
kts as they become northeast this evening into tonight. Northeast
winds continue on Thursday to around 15-25 kts, backing north to
north-northeast Thursday night. Strongest winds are expected over
the east half on Thursday and west half Thursday night with internal
probabilistic guidance showing 60-90% probabilities of winds
exceeding 22 kts. Winds back southwest on Friday, but generally
remain below 20 kts.
Southwesterly winds continue increasing Friday night ahead of a low
pressure system with gusts of 20-30 kts possible. As this system
passes just north of the lake on Saturday, winds veer west then
northwest. Cold advection will result in unstable conditions over
the waters Saturday into early next week. Guidance suggests a 30-60%
chance for low-end west gales to 35 kts becoming northwesterly on
Saturday. Saturday night probabilities for northwest becoming north
gales to 35 kts are around 20-40%, mainly over the east half of the
lake.
Unstable conditions remain into the early part of next week, but
winds gradually diminish to around 20 kts for Tuesday and Wednesday.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...GS
LONG TERM...EK
AVIATION...Rolfson
MARINE...Jablonski