Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/05/23
Area Forecast Discussion
National Weather Service Boise ID
202 PM MST Mon Dec 4 2023
.SHORT TERM...Tonight through Wednesday night...Light rain
showers will continue through the afternoon, mainly across our
northern zones with the passage of the warm front. More stable
conditions setup for late tonight into Tuesday under upper level
ridge. There remains plenty of moisture in the boundary layer
overnight for fog and stratus development. HREF probabilities
along with the HRRR favor fog development in the Lower Treasure
Valley, Baker Valley, Camas Prairie and the Long Valley.
Stratus is also shown to move down valley from the Western Magic
Valley into parts of the Upper Treasure Valley. Expect some of
the stratus and fog to dissipate Tuesday afternoon with upper
level flow increases ahead of the next upper level trough.
Stratus and fog will likely remain in the Lower Treasure Valley
through Wednesday morning. The next upper level trough reaches
the Pacific Northwest Coast Wednesday increased the wind and
moisture aloft for terrain driven precipitation in the West
Central and Boise Mountains. Snow levels will remain quite high,
at or above 6000 feet, for rain in the mountains valleys.
Temperatures will remain above normal through the period.
.LONG TERM...Thursday through Monday...Models all remain in
good agreement along with the ensemble clusters through the
extended period. The upper ridge that was over the region
earlier in the week slides eastward Thursday in response to the
next upper trough. Snow levels lower to around 4000-5000 feet
Thursday. Mountains across Idaho and Eastern Oregon could see
anywhere between 6-10 inches of snow with McCall potentially
seeing another 4 inches. Active weather continues into the
weekend as yet another trough slides in to the region Thursday
night through Friday morning lowering the snow levels to the
lowest valley floors. Additional mountain snow amounts possible
with this feature. Models now in better agreement, compared to
the 00z/06z model runs in showing a third trough approaching the
coast. This brings strong overrunning conditions developing for
the region for Saturday and Sunday. More snow in the mountains
but snow levels across the Treasure/Magic Valleys could be
tricky, depending on how fast the cold air erodes out of the
lower elevations. Temperatures expected to be about 10 degrees
above normal through Thursday then lowering to near normal for
the weekend.
&&
.AVIATION...Generally VFR through the evening hours. MVFR/IFR
with local LIFR conditions developing after midnight across the
lower valleys in fog and stratus that would be affecting KMYL, KBKE,
KONO and KEUL. There should be sufficient southerly flow into KTWF
that inhibits and pushes fog/stratus northward towards KJER. Mtns
becoming obscured overnight.
Surface winds: SE-SW 5-15 kt. Winds aloft at 10k feet MSL: W-NW 10-
30kt, becoming SW 15-30 kt aft 05/06z.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...None.
OR...None.
&&
$$
www.weather.gov/Boise
www.facebook.com/NWSBoise
www.twitter.com/NWSBoise
SHORT TERM...JDS
LONG TERM....CR
AVIATION.....CR
Area Forecast Discussion
National Weather Service Indianapolis IN
936 PM EST Mon Dec 4 2023
.Key Messages...
- Dry this evening.
- Snow possible with minimal accumulations near Tippecanoe and
adjacent counties, arriving late tonight.
- Rain possible south of I-74, late tonight and early Tuesday.
- Return to near to above normal temperatures this week
- Extended period of rainfall possible this weekend
&&
.Forecast Update...
Issued at 936 PM EST Mon Dec 4 2023
Did not make any changes to the overnight as CAMs, radar and 290K
isentropic analysis all suggest showers will move into central
Indiana after 08-09z with light rain, possibly mixing in with snow
over the upper Wabash Valley to start. Hi-Res soundings are showing
deep moisture which will easily start off as snow aloft and a
freezing level below 1K feet. Currently, the showers extended from
Minnesota to northern Missouri, ahead of an upper wave, seen on H20
vapor from western Minnesota to southeastern South dakota and
northeastern Nebraska and within 290K isentropic lift and a
saturated layer.
Widespread coverage is expected be near and north of I-74 through
12z and areas north of there will see the better chances of snow,
with the lower freezing levels there. This also aligns closely with
partial critical thicknesses. The snow mostly melt on the warm
ground, but would not rule out some slick spots or 0.1 inch amounts
in grassy surfaces.
&&
.Short Term...(This evening through Tuesday)
Issued at 246 PM EST Mon Dec 4 2023
Surface analysis this afternoon low pressure over southern Central
KY. High pressure was found over the southern plains, with a ridge
axis that stretched north across MO, IA/IL and into eastern WI.
Water Vapor showed a short wave aloft over eastern KY and this
feature was associated with the previously mentioned surface low.
Water Vapor also showed another quick moving short wave over the
Dakotas. Both of these waves were embedded with a quick NW flow that
was in place across much of the CONUS. GOES16 shows a classic comma
shield with the surface low providing cloud coverage to much OH and
KY. Residual moisture in the wake of the trough was producing
additional cloud cover across Illinois and Indiana. Radar shows some
light precipitation across southeastern Indiana, exiting the area
quickly with the departing short wave.
Tonight...
Quiet weather will be expected this evening as the quick northwest
flow aloft allows the surface ridge of high pressure to quickly
arrive and pass across Indiana over the next 12 hours. Forecast
soundings show a dry column this evening and early overnight, with
some saturation arriving aloft. This is mainly due to the subsidence
associated with the surface ridge and will mainly result in partly
cloudy skies and cool conditions.
Late tonight, after 09Z, the weather will begin to change. The
previously mentioned short wave over the Dakotas will arrive in
Illinois and Indiana. Forecast soundings trend toward saturation,
with best moisture found along and north of I-74. 290K GFS
Isentropic surface shows best lift arriving in west Central Indiana
near 09Z, and this appears to quickly move across the forecast area
through 15Z Tue. Forecast soundings show lower level temps in NW
Central Indiana just above freezing as this wave and the associated
precipitation arrives. This should result in p-type as snow in
Lafayette and surrounding counties. Farther south and east, the
lower levels have a thick enough warm layer that should allow
melting to rain or a rain/snow mix. Again, ground and road temps
remain rather warm, so any accumulations may be limited to grassy
and elevated areas. However an isolated slick spot cannot be ruled
out. Moisture appears limited with this feature as specific humidity
on the isentropic surface remain around 2 g/kg, and forecast
soundings show pwats at 0.5 inches or less. Thus any snow will
remain less than one-half of an inch as this quick system passes,
and most areas will still see just rain. It is important though to
remember that this system will be passing during the morning rush
hours, so impacts from slick spots and increased traffic remain
possible.
Summing up the tonight period, no pops through the evening.
Increasing clouds after midnight, with precipitation arriving after
09Z. Highest pops NW to lowest pops SE. Lows lower to middle 30s.
Tuesday...
The previously mentioned short wave will be passing across Central
Indiana as we start the day. Thus we expect ongoing precipitation
across mainly the northern parts of the forecast area, as this is
where the best forcing is expected and the HRRR continues to suggest
precipitation in that area. This forcing looks to exit Central
Indiana by late morning and precipitation will come to an end.
However, the models still suggest a troughy pattern in place across
central Indiana aloft, with lingering lower level moisture. A subtle
embedded wave within the trough is depicted over Central Indiana on
Tuesday afternoon. Forecast soundings as this feature is present
suggest a steep lapse rate, with saturated lower levels. Thus with
this pattern present, we will keep some precipitation chances for
Tuesday afternoon for possible light showers. Any precipitation
amounts will be very light from this secondary wave. Highs on
Tuesday will remain chilly, in the upper 30s and lower 40s.
&&
.Long Term...(Tuesday night through Monday)
Issued at 325 PM EST Mon Dec 4 2023
The long term period starts out closer to seasonal norms Tuesday
night and Wednesday; however a a pattern shift will lead to a big
warming trend through the week and an extended period of rain this
weekend.
.Tuesday night into Wednesday..
Lingering patchy light rain or wet snow Tuesday evening, should end
as a few flurries...as the final, rather weak slivers of mid-level
vorticity drag east across Indiana through the overnight. Latest
BUFKIT soundings today show leftover moisture trapped in the boundary
layer under a developing subsidence inversion as high pressure
pushes in. Lift associated with the passing of a mid level trough
axis/vort max may be enough to squeeze out drizzle across Central
Indiana late Tuesday night. Guidance shows the DGZ drying out during
this time period with the majority of the saturated lower layer at
or above freezing. Therefore, not too concerned with flurries or icy
conditions into Wednesday morning.
With surface high pressure just west of the region and a low level
ridge axis just to the west as well, expect cold, northerly flow
Wednesday to keep temperatures at or below normal for early
December. Low stratus Wednesday, associated with moisture trapped in
the boundary layer, may be hard to mix out with such a low sun angle
this time of year. Therefore, keeping temperatures on the cool side
with highs in the upper 30s in the north and low to mid 40s in the
south. Expect the lower cloud deck to rise and begin to break up
later in the day Wednesday as dry air continues to advect into the
region as high pressure slides by just south to the south.
.Thursday through Friday..
Surface high pressure and low level ridging become centered over the
Southeast CONUS on Thursday placing the entire Ohio Valley and lower
Great Lakes region in an area of strong southwesterly flow and warm
air advection. This weather pattern will set the stage for much
warmer air the rest of the week and into the weekend and lead to a
period of heavy rain by the weekend.
Thursday and Friday will then likely be the mildest days of the week
as a warmer, most air is pumped northward into the region from the
southwest. Highs in the 50s are likely across the region with
southwest wind gusts of 30+ mph at times.
Friday night through Sunday...
Guidance is continuing to note the potential for several periods of
precipitation this weekend amid the northern sectors of a developing
storm system as it twists up the Ohio Valley into the eastern Great
Lakes. Nearly all ensembles indicate some semblance of a slowly-
passing weekend weather system bringing an extended period of
rain...with so far considerable variability between low pressure
track, degree/timing/ location of intensification, as well as
location and liquid equivalent of possible snow towards the Sunday
timeframe. Embedded thunder during cyclogenesis is possible,
especially towards the Ohio Valley. Latest ensemble mean
probabilities note axis of potential heavier precipitation aligned
over central Indiana, with a 40-50% chance of 1.00+ inch of
precipitation in a 24-hr period over all of Indiana for the Friday
night into Saturday timeframe.
Potential for light accumulating snowfall on the system`s backside
would be led by subtle secondary H500 vorticity plunging down the
Missouri Valley and promoting a SW-NE cold-conveyor band...with
ensemble mean probabilities so far indicating a 30-40% chance of
measurable light snowfall over a portion of the region. At times
breezy to perhaps gusty northwest winds around the Sunday timeframe
are possible. Temperatures should trend from well above to near
normal through the weekend. The normal max/min at Indianapolis
through the long term is 43/28.
&&
.Aviation...(00Z TAF Issuance)
Issued at 546 PM EST Mon Dec 4 2023
Impacts:
- MVFR and worse flying conditions developing after 09z
- Rain/Snow mix possible at mainly KLAF and KIND 09z-13z
Discussion:
A low pressure system will pivot southeast across the Great Lakes
and Ohio Valley tonight and Tuesday. Limited moisture and synoptic
and isentropic lift will lead to light snow and rain overnight into
Tuesday morning with additional rain showers possible Tuesday
afternoon. MVFR and worse flying conditions will accompany the
precipitation and hang around Tuesday.
Winds will shift from WNW to S and SW toward morning and Tuesday as
the low pressure system moves through.
.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...MK
Short Term...Puma
Long Term...CM/AGM
Aviation...MK
Area Forecast Discussion
National Weather Service Jacksonville FL
607 PM EST Mon Dec 4 2023
...New UPDATE...
.UPDATE...
Issued at 605 PM EST Mon Dec 4 2023
For the latest NE FL and SE GA Daily Key Messages please visit:
https://www.weather.gov/media/jax/briefings/nws-jax-briefing.pdf
While the main front, with associated rain is well to the southeast,
a secondary front will pass through dry Tonight. High cloudiness
will continue to stream northeast across region along this frontal
zone Tonight. HRRR and NAM depict enough low level moisture for fog
development coming in from Gulf overnight. As a result, have added
fog potential to inland NE FL, and will monitor for development this
evening. The cloud cover should limit the fog, so leaning toward
patchy wording at this time.
Lows will range from the mid 40s inland, to the lower 50s coast.
&&
.SHORT TERM...
(Tuesday through Wednesday night)
Issued at 138 PM EST Mon Dec 4 2023
Synopsis...Dry conditions and cooler, with inland frost potential
Thu morning.
Tuesday, dry and cooler low level NNW flow funnels southward
across the area with surface high pressure west of the region
under near zonal upper level flow aloft continuing high clouds
across NE FL and mostly cloudy skies, with thinner high cirrus
across SE GA making for more peeks of sun. Early Wed, a dry
reinforcing cold front pushes southward across the area with the
passage of a long wave upper level trough, which will finally
shift cloudiness south of NE FL late Wed afternoon. Gusty NNW
winds of 25-35 mph will be possible trailing the frontal passage.
Trailing the front, deep layer NNW continues into Thu as an upper
ridge builds eastward across the eastern GOMEX & the surface ridge
centers builds north of the local area.
Temperatures will trend below normal with high in the 60, then
upper 50s north of the I-10 corridor Wednesday & Thursday trailing
the frontal passage. Lows will range in the 40s Tuesday night,
then cool into the 30s inland by daybreak Thursday & Friday
mornings. The `coolest` night of the period looks to be Wed
Night/Thu morning with clear skies and light northerly drainage
winds supporting low temperatures in the mid/upper 30s which will
bring frost potential. Thursday night, the surface ridge to the
north begins to build offshore of the SE Atlantic coast as high
cloudiness increases from the SW, with low temperatures moderating
into the 40s across much of NE FL to low 40s/upper 30s across SE
GA.
&&
.LONG TERM...
(Thursday through next Monday)
Issued at 138 PM EST Mon Dec 4 2023
Synopsis...Warmer into the weekend with rain & thunderstorm
chances returning late Sat into Sun.
Fri-Sat...The airmass begins to moderate further Friday into
Saturday as the surface high builds offshore of the SE Atlantic
coast with a return of warmer SSE low level winds and increasing
high cloudiness from the SW downstream of the next developing
storm system taking shape over the central CONUS. Locally, a
coastal trough (developing warm front), will be lifting northward
across the local area late Friday into Saturday, with a low chance
(< 15%) of light showers/sprinkles. Saturday, rain chances
increase from the west with the approach of a pre-frontal squall
line.
Sun-Mon...Rainfall overspread the area from west to east Sunday
with a chance of isolated thunderstorm with the entire are within
the warm-sector. Moderate kinematic forcing and plenty of moisture
will be in place for deeper convective growth, but once again the
limiting factor will be instability. Surface based instability
looks meaner, with maybe a nose of low level CAPEs nosing inland
from the GOMEX during the pre-dawn hours Sunday morning across the
Suwannee River Valley. Better instability looks to be elevated
generally in the 06-12z time frame where cooler mid levels
increase mid level lapse rates...but this looks un-phased with
the rain shield at this time. At this time, it does not appear
convective ingredients will coincide for an elevated severe storm
threat locally with this next event. Rain chances tapper off
Sunday evening from NW to SE, with a return to below normal
temperatures and dry conditions for the first part of next week as
surface high pressure builds west of the region.
&&
.AVIATION...
(00Z TAFS)
Issued at 555 PM EST Mon Dec 4 2023
While, prevailing VFR conditions are expected for much of this
cycle, a period of restrictions due to fog will be possible
overnight. The best chance for fog will be inland.
&&
.MARINE...
Issued at 138 PM EST Mon Dec 4 2023
High pressure will build west of the region tonight through
Tuesday. A dry cold front will cross the local waters early
Wednesday morning, trailed by strengthening northwest winds and
Small Craft Advisory conditions over the outer waters. Winds and
seas begin to weaken Wednesday night as high pressure builds north
of the local waters through Thursday. The high builds offshore of
the southeast Atlantic coast Friday.
Rip Currents: Low rip current risk through Wednesday. Elevated rip
current risk returns Thursday.
&&
.FIRE WEATHER...
Issued at 138 PM EST Mon Dec 4 2023
Dry and cooler through Thursday under prevailing WNW winds. A
reinforcing dry cold front will move across the region Wednesday,
with breezy winds near 15 mph and gusts 20-30 mph at times with
elevated dispersion possible in the afternoon due to strong
transport winds.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 43 65 43 59 / 0 0 0 0
SSI 50 66 47 61 / 0 0 0 0
JAX 48 68 45 61 / 0 0 0 0
SGJ 52 69 48 62 / 0 0 0 0
GNV 48 69 45 61 / 0 0 0 0
OCF 50 71 46 62 / 0 0 0 0
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AM...None.
&&
$$
Area Forecast Discussion
National Weather Service Memphis TN
803 PM CST Mon Dec 4 2023
...New UPDATE...
.UPDATE...
Issued at 743 PM CST Mon Dec 4 2023
Cool and mostly clear conditions are in place across the Mid-South
this evening with temperatures in the 40s areawide. Overnight,
expect temperatures to fall near freezing. By mid-morning, a dry
cold front will impact the region, resulting in slightly cooler
temperatures for Wednesday.
ANS
&&
.SYNOPSIS...
Issued at 219 PM CST Mon Dec 4 2023
Dry weather is expected to continue across the Mid-South through
Friday. A dry cold front will move through the region on Tuesday.
Temperatures will turn colder behind this front for Tuesday night
and remain below normal on Wednesday. Milder air will move back
into the region for Thursday and Friday. A large storm system will
move into the Mid- South this weekend with showers and
thunderstorms expected.
&&
.DISCUSSION...
(This evening through next Sunday)
Issued at 219 PM CST Mon Dec 4 2023
A few clouds can be found over much of the northern half of the
Mid-South with mostly sunny skies found across the remainder of
the region. Temperatures this afternoon are currently in the 50s.
A low pressure system is currently over northern South Dakota with
a cold front extending across northeast Nebraska and into
northeast Colorado.
This low pressure system will move southeast tonight reaching
northern Illinois by Tuesday morning with the associated cold
front just west of the Mid-South. Little moisture will be found
ahead of the front with dry weather expected across the region
tonight. Temperatures will be close to normal levels for early
December with lows Tuesday morning in the mid 30s. The cold front
will move across the region from northwest to southeast on Tuesday
with no rain expected to accompany it. Ahead of the front,
temperatures will be a little warmer on Tuesday with highs from
the mid 50s to lower 60s. Behind the cold front, high pressure
will build into the region Tuesday night with dry weather
continuing. Temperatures will be colder for Tuesday night and
Wednesday with highs in the upper 40s to lower 50s.
Dry weather will continue across the Mid-South for Thursday and
Friday. As the surface high moves east of the region by Thursday
morning, milder air will return to the Mid-South for Thursday and
Friday.
A large storm system will move into the Plains Friday and across
the Mississippi Valley on Saturday. As it approaches the Mid-
South, showers will move into the region Friday night. By
Saturday, showers and even some thunderstorms will become
widespread across the region. There is a possibility of some
strong to severe thunderstorms over southwest sections of the
Mid-South for Saturday afternoon and evening.
The cold front associated with this storm system will move through
the region Saturday night with precipitation slowly ending on
Sunday. Colder air will return to the Mid-South behind this front
for Sunday.
&&
.AVIATION...
(00Z TAFS)
Issued at 547 PM CST Mon Dec 4 2023
Post-frontal stratocu over mainly West TN should gradually push
east this evening. Winds will diminish to less than 5 kts
overnight which may lead to some patchy fog as the clouds clear
out. The latest HRRR and the HREF ensemble probs point to this
possibility at MKL and TUP. Have added some light fog at those
sites. Another fast moving system will race through the Ohio
Valley and push another cold front through on Tuesday with gusty
winds but little in the way of clouds or sensible weather.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...ARS
AVIATION...SJM
Area Forecast Discussion
National Weather Service Marquette MI
622 PM EST Mon Dec 4 2023
.SHORT TERM...(Through tonight)
Issued at 402 PM EST MON DEC 4 2023
Key Messages:
-Increasing clouds and a slight chance (15%) for light snow
across the far western UP after midnight tonight.
Quiet weather with light and variable winds under a patchwork of
clear/cloudy skies. The west and east-central portions of the UP
were mostly cloudy with patches of sunny skies interspersed.
Temperatures were slow to warm UP this morning, but low to mid 30s
are present across the area. Farther upstream across MN, a broad
shield of mid/upper level clouds is pivoting toward the UP
associated with a clipper system that tracks to our south tonight.
The clipper system passes to our south with most of our just seeing
increasing cloud cover as a result. However, model soundings show
deep saturation for portions of the far western UP (mainly Gogebic
County) where the three major ensemble suites advertise 60-80%
chances of getting 0.01" QPF by Tuesday morning. HREF guidance
indicates if precip occurs then it will begin shortly after
midnight. Otherwise, low temperatures may become problematic across
the eastern UP where temps in the teens are forecast. The same air
mass allowed some single digit (7-9F) temperatures for our western
areas last night so it`s possible that will occur across the east
tonight.
.LONG TERM...(Tuesday through Monday)
Issued at 402 PM EST MON DEC 4 2023
Key Messages:
-Scattered lake effect snow showers Tuesday and Tuesday night for
the north wind snow belts may yield an inch or less of snow with
locally higher amounts up to 2 inches possible.
-A warm front may bring rain/snow late Wednesday, but chances for
more than 1 inch of snow are very low <10%.
-A warm period may yield temperatures at least 10F warmer than
normal between Wednesday night and Friday night.
Overall, not much has changed in the forecast for the coming week.
There`s still a couple opportunities for light precip, a warm up,
and a couple systems moving through the Upper Great Lakes. The
eastward trend of the late weekend system suggests a continuation of
generally dry weather though a cool down is increasingly likely
early next week.
A shortwave tracking southeast across Iowa and into Illinois by
Tuesday morning extends an inverted surface trough northward into
our forecast area. With 850mb temps cooling to around -10C by
Tuesday evening, the environment should support some scattered lake
effect snow showers across the western and central in the north to
northwest wind snow belts. HREF guidance continues to suggest light
QPF in these showers, which would result in snow accumulations on
the order of an inch or less. HRRR and most other CAMs continue
to spin up a meso-low feature over central Lake Superior during
the day that may move onshore Tuesday evening. This feature may
force locally higher snowfall rates aided by light winds/long
residence time over the lake. The maximum 24-hr QPF on HREF
guidance indicates patches of 0.25" suggesting potential for
localized snow amounts of 2-3" by Tuesday morning for north wind
snow belts between Michigamme Highlands and Munising (possibly the
Keweenaw too). Digging deeper into 18z HRRR guidance with point
and click soundings in the most robust snow showers shows
inversions extending up to around 10kft with strong omega
throughout the DGZ. NAM 3km soundings suggest similar potential
for a briefly heavy snow shower.
Increasing dry air and anticyclonic flow should result in less
shower activity as we move through Tuesday night though an isolated
shower or two may linger between Marquette and Munising. Wednesday
appears to be mostly dry, although a swath of isentropic and
frontogenic forcing increases along a warm front pushing east
across the area late Wednesday. Rain and snow chances associated
with the passing warm front move quickly leading to just a brief
window for precip. NAM-3km and FV3 soundings show steep lapse
rates above roughly 600mb implying some potential for CSI
resulting in a brief convective shower, but overall precip amounts
appear light and may end up only being realized in the east half.
Increasing warm air building into the region after the front will
kick off an abnormally warm spell Thursday and Friday. This may
support widespread low to mid 40s for highs both days thanks to
850mb temps warming upwards of +6 to 8C. On Friday, a ~990mb low is
expected to track northeastward across Ontario while dragging a cold
front across Upper Michigan. There might be some precip along and
behind the front, but chances are low 20-30%. As this system pulls
away, attention shifts to potential for a rapidly deepening low
pressure developing on the South-Central Plains. There continues to
be good agreement among the guidance packages that this system will
lift northeast into the Great Lakes region, but ensemble spread
remains large due to a complex phasing interaction. There`s still
some hope for us snow lovers though, albeit is low (<20% chance),
given some EC and GEFS ensemble members aren`t convinced on the
eastern/southern track. Whether or not the deepening sub-990mb
surface low tracks close enough for synoptic precip, a period of
lake effect is increasingly likely early next week as temperatures
trend below normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 621 PM EST MON DEC 4 2023
With a disturbance moving across the Upper Mississippi Valley, the
northern edge of some -sn/flurries may brush IWD later this evening
into the overnight. Otherwise, expect initial VFR at IWD to fall to
MVFR in the next few hrs with further deterioration to IFR late
tonight thru Tue morning, mainly due to low cigs. As a light/calm
wind becomes nw later Tue morning, expect sct -shsn. Improvement to
MVFR will occur at IWD in the aftn. At CMX, expect VFR to give way
to MVFR cigs by late evening. MVFR should then prevail thereafter.
As a light/calm wind becomes nw early Tue aftn, sct -shsn will be
possible at CMX. At SAW, VFR should prevail thru the night. Expect
MVFR cigs to develop in the morning. MVFR will persist thru the aftn
with the potential of -shsn late in the aftn.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 402 PM EST MON DEC 4 2023
Model guidance continues to suggest winds will remain below 20 knots
through early Wednesday. An increasing pressure gradient and a
modest ~40 knot low level jet moving overhead results in increasing
southerly winds. There continues to be good agreement that enough
instability will exist on Lake Superior to support mixing stronger
winds near 30 knots to the surface. However, stronger wind gusts are
possible at higher elevation observation platforms or in localized
areas of terrain effects such as the tip of the Keweenaw. At the
moment, ensemble systems suggest a low to medium chance (25-50%) for
southerly 35 kt gales with the highest chances across eastern Lake
Superior. These stronger winds continue into late Wednesday night.
The latest model guidance suite is in good agreement that a tightly
wrapped up low lifts northeast from the Northern Plains into Ontario
on Friday. There are some notable spatial differences, but
clustering of the ensemble members generally agree the low tracks
across Ontario just to the north of Lake Superior. The low`s cold
front should progress across the lake during the day Friday, with
southeast winds increasing to around 25 kt ahead of the front.
Behind the cold front, cold air advection combined with a
substantial pressure gradient could yield westerly gales. At this
point, confidence in gales of 35 to 40 knots is medium (~50%) and
anything higher is low (<25%).
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...EK
LONG TERM...EK
AVIATION...Rolfson
MARINE...EK