Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/11/23
Area Forecast Discussion
National Weather Service Binghamton NY
1001 PM EST Sun Dec 10 2023
.SYNOPSIS...
Several waves of low pressure along a frontal boundary will
bring periods of rain changing to snow later this evening. A
low pressure across the Carolinas will deepen tonight and move
up the east coast with periods of snow and increasing wind.
High pressure builds into the region temporarily on Tuesday
before another cold front brings a reinforcing shot of cold air
and snow showers on Wednesday. Drying out with a warming trend
for the end of the work week.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
945 PM Update...
The flood watches were ended for all but Sullivan and Delaware
as the rain is transitioning to snow along and east of the I81
corridor. Some rainfall rates were still a quarter inch per hour
in Sullivan and Delaware so decided to keep the watches until
the transition occurs there.
615 PM Update...
Little change to the previous forecast. Temperatures have been
falling slowly as an initial cold front moved through a few
hours ago. Radar Correlation Coefficient is showing the
rain/snow line descending west of I81 and is at about 1500 feet
above the radar so about 3000 feet above sea level. Webcams are
still showing rain through much of the Finger Lakes even at
higher elevations. The NYSM Hartsville location may have just
finally switched over as wet bulb temperatures have fallen below
32 and the webcam is showing some snowflakes. SOC mesoanalysis
is showing that the surface low has become closed and is
starting to deepen. Water vapor satellite is also showing a good
baroclinic leaf with cooling cloud tops overspreading our area
also indicative of the deepening surface low. The 500 mb trough
is still fairly neutral but should start to become more
negatively tilted. With the low deepening, we should start to
see some dynamic cooling helping the cold air advection with
transitioning the rain to snow. The speed at which this occurs
will be monitored over the next few hours as that will help
determine where flood watches can be dropped or kept or if snow
totals need to be adjusted.
345 PM Update
Storm system is on track, with no significant changes to the
forecast with this update. The potential for higher elevation
snow has increased enough that Bradford, Tioga (NY), Tompkins
and Southern Cayuga counties were added to the winter weather
advisory for tonight into Monday morning. Winter Storm Warnings
remain in place for Otsego and Delaware counties where
confidence remains the highest to reach the 7"+ criteria. The
latest ensemble guidance, and WPC`s Winter Storm Outlook (WSO)
tool is hinting at the potential for higher snow totals to wrap
back into parts of CNY and NE PA; specifically the higher
elevations of Wayne, eastern Luzerne, eastern Lackawanna,
eastern Susquehanna, eastern Broome and far northern Sullivan
counties. Held off on upgrading any of these to a low end
warning at this time, as uncertainty in the exact thermal
profiles and QPF amounts overnight remains rather high. Will
need to keep a close watch on when these areas (higher elevations)
changeover and how efficiently the snow starts to accumulate
later this evening.
Held onto the flood watch at this time, but the overall rainfall
amounts are decreasing with this system and the latest river
forecasts no longer show any locations reaching flood stage.
Wanted to make sure no persistent heavy rain develops south and
east of the front this evening, before contemplating dropping
any of the flood watches. But again, the flood threat is
decreasing in our forecast area. Rainfall amounts are still
forecast to be 1.5 to 2 inches over the Catskills and eastern
portions of NE PA.
Latest water vapor and IR satellite loop shows a large plume of
moisture surging north along the East Coast, extending all the
way into the Gulf of Mexico...with thunderstorm activity noted
over the Carolinas, Georgia and Florida at this time. Regional
composite radar loop shows light to moderate rain over Central
NY and Northeast PA, extending all the way down the East
Coast...with another batch of steadier rain noted over VA/WV/NC
region at this time. SPC mesoanalysis shows an elongated area of
lower pressure centered over the Carolinas up into Central VA at
this time. As the upper level trough moves east and gradually
becomes negatively tilted tonight, a better defined surface low
should develop and move just south of Long Island by around
midnight and near Boston MA by daybreak Monday. Radar and
surface observations show that the initial wind shift and cold
front has already slid east along an Oneonta to Tunkhannock
line; and this front will continue moving east-southeast into
the evening hours. Temperatures will fall through the evening,
and as sub 0C air aloft moves in the rain will begin to
changeover to wet snow...first over the higher terrain of
Steuben county by around 7 PM this evening.
The rain will continue changing over to snow over the higher
elevations first, then eventually into the valleys by late
evening or the predawn hours early Monday morning. The last
places to changeover will be the Wyoming Valley, eastern
Sullivan, Pike counties, and also along the lake plain near
Syracuse where lake modified air keeps the surface temperatures
elevated in the mid-30s. WPC HREF based snow band tool shows the
potential for 1 to 2 inch per hour snowfall rates over much of
the area along and east of I-81 in central NY and Northeast
PA...the limiting factor will be surface temperatures potentially
still above freezing for the valleys...which will reduce accumulation
efficiency and create very wet, sloppy snow accumulations below
1200 feet elevation. In this same area, above 1500 feet or so,
the snow will be able to achieve closer to 8-12:1 ratios which
will allow it to stack up and accumulate much more efficiently
with temperatures falling just below freezing mark. Model
guidance has between 0.25 to 0.90 inches of liquid equivalent
precipitation falling late tonight into Monday morning along and
east of I-81...so the exact snowfall totals will again be
determined by elevation, surface temperatures and ultimately the
snow to liquid ratios over the region. Overall the latest 18z
HRRR and 3km NAM nest are holding steady with the precip shield
placement and intensity overnight into Monday morning...so that
is good to see. The snow will gradually end from west to east in
the advisory/waring areas between about 7am to 11am...but will
then transition to occasional lake effect snow showers and
squalls across the north (Syracuse to Cazenovia, Utica and
Rome)during the afternoon and evening hours. Additional light
snow accumulations from lake effect will be possible, mainly 1
to 3 inches in locations that do see the snow bands overhead.
The rest of the area further south, including the Twin Tiers
and NE PA will be mainly dry Monday afternoon, evening and
night. Northwest winds increase during the day Monday,
areawide...expecting 15 to 25 mph with gusts between 30 to 40
mph. Temperatures may briefly get up into the mid to upper
30s...but then look to fall back below freezing in the afternoon
as cold air advection strengthens over the region. There could
be some localized blowing and drifting snow over the higher
elevations and colder areas north and east of Binghamton.
Otherwise, the lake effect snow showers lift north heading into
Monday night and out of our area before daybreak on Tuesday. It
will be colder, with lows in the 20s.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
350 PM FORECAST...
High pressure to the south and a trough moving north of the Great
Lakes will bring SW flow to the area Tuesday with weak WAA,
especially across the Finger Lakes into the Mohawk Valley. Temps
will climb into the mid 40s here, with upper 30s to low 40s
elsewhere. Conditions will be partly cloudy and dry thanks to the
influence from the high pressure system to the south.
A cold Front pushes through Tuesday night, bringing NW flow and cold
air back into the region. 850mb temps drop to -11C overnight and
remain there through the day. This will generate lake effect snow
showers north of a line from Ithaca to Cortland to Oneonta through
Tuesday night. Winds shift more northerly during the day Wednesday,
pushing the snow showers farther south into the Finger Lakes.
Temperatures will hover around freezing across NY with mid 30s in
NEPA thanks to the pocket of cold air aloft hanging around through
the day. Low level lapse rates are not as impressive as they were
yesterday so the chance for squally snow showers is much lower.
Model soundings show saturation reaching the DGZ so any snow showers
should have some nice flakes allowing for 1-3 inches of snow to fall
over portions of Onondaga, Madison and Oneida county. This will all
depend on where the lake effect showers set up, but the DGZ
saturation lends confidence to accumulating snow over this area.
Wednesday afternoon will see the best chance for heavier snow
showers, lightening up through the overnight hours as high pressure
builds in from the west. Temps Wednesday night will fall into the
mid to upper teens across much of the area, with low 20s in the
Finger Lakes to Mohawk Valley.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
350 PM FORECAST...
High pressure will be in control across the area through this
period. Consistent westerly flow ebbing between WNW and WSW will
advect in a much warmer airmass from the central US for the end of
the week through the weekend. Mostly clear to partly cloudy skies
are expected with highs in the 40s.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Initial cold front has pushed east of all TAF terminals, with NW
flow and falling temperatures moving in. Despite the frontal
passage, precipitation continues to expand across the area as
one of several waves moves up along the front. A few "holes"
have developed in the lower clouds, with VFR conditions at SYR
and ELM as of this writing. This is expected to be brief, with
Fuel Alt conditions expected to prevail, deteriorating to IFR
and LIFR as the evening progresses (except at ELM with downslope
flow and being closer to the back edge of precip). As rain
changes to snow, visibility will be the main driver of flight
categories/restrictions. Bumped the changeover an hour or two
later than the previous TAF set based on current observations.
Conditions will slowly improve at most locations by mid to late
morning Monday, with VFR prevailing by afternoon. However,
light lake effect snow showers will persist until afternoon
around SYR and RME.
Outlook...
Monday Night...Becoming VFR.
Tuesday and Wednesday...VFR-MVFR depending on lake effect
showers.
Thursday and Friday...Mainly VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...Winter Weather Advisory until 10 AM EST Monday for PAZ038.
Winter Weather Advisory until 1 PM EST Monday for PAZ039-040-
043-044-047-048-072.
NY...Winter Weather Advisory until 7 PM EST Monday for NYZ009-018-
036-037.
Winter Weather Advisory until 10 AM EST Monday for NYZ017-025-
055.
Winter Weather Advisory until 1 PM EST Monday for NYZ044-045-
056.
Winter Storm Warning until 1 PM EST Monday for NYZ046-057.
Flood Watch through Monday afternoon for NYZ057-062.
Winter Weather Advisory until 1 PM EST Monday for NYZ062.
&&
$$
SYNOPSIS...MJM
NEAR TERM...AJG/MJM
SHORT TERM...JTC
LONG TERM...JTC
AVIATION...JTC/MPH
AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
609 PM CST Sun Dec 10 2023
.UPDATE...
Issued at 608 PM CST Sun Dec 10 2023
Low stratus continues to move in from eastern North Dakota.
Visibility reductions have been observed under the low stratus
with visibilities as low as quarter of a mile in some places. As
00Z there are no visibility reductions in the county warning area
but that will change as low stratus pushes in. Rolla down to
Oakes will likely see areas of fog in the next few hours. The
forecast for fog remains more uncertain across central North
Dakota due to a surface trough moving into the region switching
the wind direction to southwesterly. This could hinder the low
stratus from pushing further west. Adjust the weather grids to
match current trends, no other updates are needed at this time.
&&
.SHORT TERM...(This Evening through Monday)
Issued at 315 PM CST Sun Dec 10 2023
The main forecast issue in the short term period will be fog
chances tonight and winds on Monday.
A low pressure system tracking across the northern Prairie
Provinces of Canada will pull a surface trough/warm front across
the area tonight, with a cold front dropping southeast through the
area Monday. The warm front is situated along the Montana border
this afternoon. Ahead of the warm front, mid and high level clouds
are tracking across the forecast area. There are some light
reflectivities showing up on radar, but we have yet to see any
precipitation reach the surface. We are still carrying a slight
chance of a flurry over the central this afternoon.
Fog will be the main concern tonight. Low stratus and fog have
been situated over eastern ND all day today. With a light
southwest flow it looks like it will not progress back west this
afternoon. Tonight though, ahead of the warm front a favorable
environment should be in place ahead of the warm front with a
light southerly flow and rather low T/Td spreads. The warm front
should lift through the northwest first, with less potential for
fog here as a drier southwest flow will persist to the west of the
front. It`s over central ND, mainly along and east of the Highway
83 corridor where the better potential lies, and especially the
James River Valley. The HRRR especially the RAP have consistently
depicted a signal for fog along/east of the Highway 83 corridor.
Minot and Bismarck are not necessarily within the fog but are
close enough for a potential. The NBM 4.1 an area from around
Linton to Jamestown as having a 30-40 percent probability of
visibilities under 3 miles from around midnight to mid morning
Monday and around a 20 percent chance of visibilities under a
mile. A similar but less continuous area was noted in the far
north central to the Turtle Mountain area. Also it should be noted
that early tonight areas in the west that have warmed up close to
or above freezing, may have enough low level moisture for some
patchy fog before the warm front pushes through. Lows tonight are
expected to range from near 10 above north central to the lower
20s southwest.
On Monday, a cold front will drop south through the forecast area.
The previous shift added some slight chance pops, basically
west and north central in the morning and south central into the
James River Valley in the afternoon. Made only minor tweaks to
these pops. Precipitation type is expected to be mostly snow, but
a rain/snow mix is possible in the west central/southwest Monday
afternoon. The main forecast issue Monday will be the winds.
Strong northwest winds are expected behind the cold front.
Strongest winds are expected in the north central, which will be
closer to the strongest cold advection and steeper lapse rates
Monday afternoon/evening. The winds may also linger through the
evening in the north central to the northern James River Valley as
steep lapse rates and strong pressure gradient remain well into
the evening. Any combination of falling snow and strong winds
looks short lived and negligible due to the lack low level
moisture and forcing. In fact the clouds associated with the cold
front look to be limited and skies should clear relatively quickly
behind the front. Wind speeds near the Turtle mountains look to be
near, but below advisory criteria. NBM 4.1 show about a 40 to 60
percent probability of sustained winds of 25 mph or greater along
and north of the Highway 2 corridor, with peak gusts in the 40-45
mph range. If this holds we should be able to get by without a
wind advisory. Will need to monitor. Highs Monday are expected to
range form the upper 20s north to the upper 30s southwest.
.LONG TERM...(Monday Night through Sunday)
Issued at 315 PM CST Sun Dec 10 2023
A rather uneventful long term period looks to be in store. It will
be a cold beginning with lows mainly in the single digits above
zero Tuesday morning. We utilized the NBM mean min temperatures.
If we were to lean towards the 25th percentile, some sub-zero
temperatures would be a possibility. Although conditions are not
ideal, they`re not bad, and some recent snows could help cooling.
Will pass this info along. Think a few sub-zero temperatures are a
definite possibility Tuesday morning. Winds may be the factor
keeping temperatures from bottoming out, but they will probably
create wind chills approaching 10 below zero. Well away from
advisory criteria, but colder than we`ve seen in a while.
Upper level ridging builds over the area mid-week for a
seasonably mild Wednesday and Thursday. A frontal passage in the
late Thursday-Friday timeframe could bring small chances (20
percent or less) for precipitation, but timing placement
differences are significant enough that the NBM is not producing
pops. Mean Raw Model guidance depicts a 20 percent probability of
a hundredth of an inch qpf across the northern half of the CWA
during this timeframe. Currently, this looks to be the best chance
for any measurable precipitation during the long term period.
Temperatures do cool a bit Friday-Sunday but remain at or above
mid December climatological normals.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 608 PM CST Sun Dec 10 2023
VFR conditions will persist for the western terminals tonight,
while fog is possible for the eastern terminals. Low stratus
continues to move in from eastern North Dakota and could impact
KJMS later tonight. KMOT and KBIS could see some patchy fog
development tonight as well, but it is less likely then KJMS.
Winds will remain light and variable tonight switching to
southwesterly by tomorrow morning. VFR conditions will return to
the eastern terminal tomorrow morning as low stratus pushes
eastward. A cold front is forecast to move through the region
tomorrow afternoon toward the end of the TAF cycle bringing forth
windy northwesterly winds.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Johnson
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...Johnson
Area Forecast Discussion
National Weather Service Quad Cities IA IL
551 PM CST Sun Dec 10 2023
.KEY MESSAGES...
- Low clouds will continue to hold on across the north and far
east through the night.
- Seasonable to above normal next week, and generally dry until
heading into next weekend.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 130 PM CST Sun Dec 10 2023
Cloud cover and temperatures will be the main challenge to the
forecast tonight, as the current clearing trend is a bit more
aggressive than models have happening, but with an early
sunset, the HRRR forecast of holding the stratus over northeast
Iowa through northern Illinois tonight might be accurate. This
persistence is due to the slow movement of the clearing line,
which really is poking along in north central Iowa through near
Macomb IL. Through the middle of the CWA, subsidence has thinned
the cloud cover, and is likely to produce clearing in much of
the CWA by mid afternoon. That process may not continue through
the night, and could revert to the more synoptic clearing line
mentioned above. This results in a forecast low near the NBM for
our southwest 2/3 or the CWA, and the 90-95 percentile in the
northeastern counties where cloud cover is most persistent.
Monday, another complicated sky cover forecast is in place, but
there`s certainly a better potential for much of the day to be
partly sunny or clearer than today. Highs in the upper 30s to lower
40s are in a mid range of guidance varying from lower to mid 30s on
the 5th percentile, to mid to upper 40s on the 90th percentile.
&&
.LONG TERM /MONDAY THROUGH SUNDAY/...
Issued at 130 PM CST Sun Dec 10 2023
Confidence remains high on a fairly benign week of weather, as the
pattern of northwest flow aloft transitions to broad ridging over
the second half of the week. Guidance suggests we`ll see a frontal
passage tomorrow night, but with a very dry air mass acting with the
front there will be no chance for rain or snow. The main impact
will be to have two more cold nights with the dry air in place. Lows
in the teens north to low 20s south are confidently forecast (
narrow guidance envelope) Tuesday night, with lows in the 20s both
Monday night and Wednesday night.
During the second half of the week, we`ll see a warming trend back
above normal with widespread highs in the 40s. NBM 75th-90th
percentile continues to hint that 50s could even be in the cards for
some if everything came together just right i.e. less cloud cover
and dry conditions, which is the trend especially during the late
week timeframe with the guidance now backing off on the idea of a
southwest trough emerging into the central CONUS and maintaining a
broad upper level ridge. This pattern may revert back to northwest
flow by next weekend bringing back more seasonable conditions while
staying mostly dry (precip chances 20 percent or less).
&&
.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 545 PM CST Sun Dec 10 2023
MVFR ceilings are anticipated at DBQ overnight with VFR at the
other terminals. Winds will remain light through the period with
prevailing VFR on Monday.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
SHORT TERM...Ervin
LONG TERM...Ervin/McClure
AVIATION...Uttech
Area Forecast Discussion
National Weather Service Grand Rapids MI
1010 PM EST Sun Dec 10 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 1010 PM EST Sun Dec 10 2023
Ongoing light lake effect precipitation may transition to
predominately drizzle/freezing drizzle/snow grains overnight into
Monday morning. The DGZ has been only marginally saturated today
and the latest HRRR soundings at BIV show further drying (almost
completely) of the DGZ overnight as the inversion height lowers a
tad more. Also decent omega is shown to linger in the cloud layer
through mid morning Monday.
Road temps are still in the mid 30s so there probably won`t be
too much impact over the next several hours should the precip
become predominately freezing drizzle, but it is certainly
something to watch for the Monday morning commute since sfc temps
are expected drop off a few degrees by that time. Will update the
Hazardous Weather Outlook to include a FZDZ possibility near and
west of Hwy 131.
&&
.SHORT TERM...(This evening through Monday night)
Issued at 240 PM EST Sun Dec 10 2023
- Showers continue through tonight
Rain and snow showers continue with the positive vorticity
advection moving through paired with the northwest flow over Lake
Michigan. Colder air will continue to advect over the area with
temperatures dropping overnight into the mid 20s to low 30s. Any
rain is expected to transition to snow this evening with showers
focusing more along the lakeshore overnight with amounts under an
inch. There is also a chance (20 to 30 percent) for a lake effect
snow band to reach Clare County and bring some light
accumulations under an inch this evening.
Drier air moves in for Monday and continues into Monday night with
a brief shortwave ridge setting up. Lake effect clouds linger
within the northwest to west flow, but the saturation doesn`t
look deep enough for any precipitation. This will keep high
temperatures in the 30s for another gloomy day.
.LONG TERM...(Tuesday through Sunday)
Issued at 240 PM EST Sun Dec 10 2023
Very little in the way of active weather is expected through the
long term period of Tuesday through Sunday. Upper troughing will be
in place to start the forecast period on Tuesday, replaced by zonal
flow and much higher heights for the remainder of the period.
Temperatures through the long term will be above normal warming from
the 30s on Tuesday to the 40s and near 50 by the end of the week and
into next weekend.
As for any sensible weather there is a cold front that the models
show passing through the area on Tuesday. Limited moisture means the
front will pass through dry. This will be a time of windy conditions
with southwest winds of 15 to 25 mph becoming northwest. Potential
for some gusts to around 30 mph.
The only other time where there may be some precipitation will be
out in the Friday time frame with another cold front. There is
differences however in the operational models with the GFS pushing a
cold front through while the ECWMF has ridging transitioning into a
southwest flow. Bottom line, low confidence in this precipitation
and left the small pops (20 pct) in our model blends in the
forecast. So, we have a 20 pct chance of rain showers Friday into
Friday night. Overall a very quiet forecast given the this time of
year where we can be quite active.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 655 PM EST Sun Dec 10 2023
In general tonight will feature MVFR cigs and scattered light snow
or mixed rain and snow showers west of GRR and BTL (including MKG
and AZO). VFR/dry weather is expected to prevail elsewhere/inland.
On Monday as northwest winds of 5 to 10 kts back to the west-
southwest those lower MVFR cigs closer to the lakeshore may press
a bit farther inland into GRR and BTL for a time in the morning.
Otherwise all areas should see cigs lift into VFR category after
18Z Monday as any remaining light lake effect precipitation ends.
&&
.MARINE...
Issued at 240 PM EST Sun Dec 10 2023
Winds and waves gradually subside this evening with a lull in
Small Craft conditions expected until Monday night when southwest
winds and waves build again. Winds turn back to the northwest
Tuesday with the front with Small Craft conditions lingering into
Wednesday.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 7 AM EST Monday for LMZ844>849.
&&
$$
UPDATE...Meade
SHORT TERM...RAH
LONG TERM...Duke
AVIATION...Meade
MARINE...RAH
Area Forecast Discussion...Updated
National Weather Service Lincoln IL
752 PM CST Sun Dec 10 2023
.UPDATE...
Issued at 752 PM CST Sun Dec 10 2023
Back edge of the stratocu deck has made nice eastward progress
this evening, stretched from near Lacon to Lawrenceville just
before 8 pm. Where skies have cleared temperatures have plummeted,
as low as 22F at Galesburg, while cloudy areas near the IN border
are still in the lower 30s. 00z surface map indicated a ridge
axis stretched from the TX Gulf coast up the Mississippi River
Valley, and will provide light to calm winds overnight. Some
upstream cirrus is evident on IR satellite imagery over IA, but
this looks fairly thin and will likely not inhibit radiational
cooling much. So based on trends have undercut guidance by a few
degrees, and lowered mins to the low/mid 20s.
25
&&
.DISCUSSION...
Issued at 125 PM CST Sun Dec 10 2023
Key Message:
* Dry weather to prevail this week with temperatures moderating
to above normal levels.
Early afternoon visible satellite imagery shows that the clearing
line has managed to make it to about a Burlington-Carlinville
line, though a few thinner spots in the overcast were occurring
just north of the forecast area as well. 850 mb humidity plots off
the RAP suggest it may take until early to mid evening to make it
all the way over to the Indiana border. The arrival of some
mid/high clouds around that time would result in mainly partly
cloudy skies overnight across the forecast area.
Not a lot has changed in the forecast thinking for temperatures
this week. The overall upper level pattern will preclude any
significant cold air intrusions, with highs mainly in the 40s,
with lower 50s likely toward the weekend.
Precipitation also appears to be minimal during this period. The
passage of a cold front Tuesday will only result in some increase
in clouds behind it. Models have been backing off from this time
24 hours ago in the strength of the northern Plains wave Friday
night and Saturday, with only the GFS trying to close anything
off from it. With a large upper low still progged to over the
southwest U.S. and taking a southern track near the Gulf coast
this weekend, this should preclude any significant moisture
advection into any northern system. Thus, the forecast will be dry
through the upcoming weekend.
Geelhart
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 514 PM CST Sun Dec 10 2023
Back edge of the MVFR stratocu deck has cleared KPIA-KSPI and is
just west of KDEC at 23z. KDEC should clear out soon, then lower
confidence on when KBMI-KCMI will clear as the back edge
typically slows after sunset. Guidance holds onto the MVFR
ceilings and KCMI until 12z, but based on current trends have sped
this up a few hours. After that, periods of VFR level clouds will
affect the area into Monday evening. A ridge axis shifts overhead
tonight, bringing light/variable winds. After the ridge shifts
east by late morning, south/southwest winds at 8-10 kt will
prevail.
25
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
756 PM CST Sun Dec 10 2023
.UPDATE...
Issued at 756 PM CST Sun Dec 10 2023
No significant changes were made to forecast this evening with the
exception being to the sky cover. Earlier guidance had cloud cover
diminishing overnight into Monday morning. While there is a
little pocket of improvement over northwest Indiana, most of the
sky remains shrouded in clouds. Therefore the forecast was
adjusted to keep cloudy conditions overnight before gradually
becoming partly cloudy Monday afternoon. Overnight lows were
adjusted up a degree due to the increased cloud cover, but it did
not alter the overall low temperature forecast of expecting mid
20s overnight. Otherwise, no other changes were made to the
extended forecast listed below.
DK
&&
.SHORT TERM...
Issued at 101 PM CST Sun Dec 10 2023
Through Monday night...
Key Messages:
* A pocket of fine drizzle/mist will continue moving east-
southeastward this afternoon and evening followed by
drying/clearing overnight
* A period of quiet weather is shaping up tomorrow onward.
Discussion:
A subtle 850-700mb vort max and associated area of fine drizzle/mist
continues to pinwheel through northeastern Illinois. With surface
temperatures right at or just above freezing, the mist/drizzle has
not contributed to any additional icing like what occurred in
northwestern Illinois this morning. The shallow wave is expected to
continue into northwestern Indiana this afternoon and depart the
area this evening (the RAP 850mb RH appears to be a good proxy for
the back edge).
Light northwesterly winds continue to transport an extensive stratus
deck across the area though there are signs of thinning across
eastern Iowa and far southwestern Wisconsin. With continued
subsidence behind the low-level wave responsible for the ongoing
drizzle as well as modest thermal mixing induced by the low-angle
sunshine, the hole in stratus may continue growing while moving into
northwestern Illinois this afternoon and evening. The HREF, which
appears to be handling the ongoing stratus well, shows a similar
thinning trend this evening into the overnight hours. As a result,
our forecast will feature a gradual decreasing trend in clouds
overnight.
If we clear up quickly, overnight lows may fall into the lower 20s
if not upper teens. However, if clouds manage to hold on (as would
be suggested by the RAP/HRRR), overnight lows will hold steady near
or just below the freezing mark. Interestingly, the RAP/HRRR also
show splotches of QPF overnight which would manifest as freezing
drizzle. However, forecast BUFKIT soundings do not look supportive
of precipitation given a lack of, well, any forcing mechanism.
Besides, any remaining cloud cover may simply be too thin to support
precipitation. For these reasons, as well as the expectation for at
least some clearing overnight, we`ll keep our official forecast dry.
Tomorrow looks pleasant with at least filtered it not complete
sunshine and light southwesterly winds. Highs will be near
seasonable values and in the mid to upper 30s. As a surface high
pressure system slides overhead tomorrow night, clear skies and calm
winds will facilitate efficient radiational cooling. Overnight lows
appear poised to tank into the teens, if not colder.
Borchardt
&&
.LONG TERM...
Issued at 101 PM CST Sun Dec 10 2023
Tuesday through Sunday...
Key Message:
* No impactful weather is expected in the long term period.
Discussion:
The long-term period looks remarkably quiet. A surface high pressure
system will lead to light winds and periods of sunshine Tuesday
through Friday. Highs temperatures Tuesday and Wednesday will be
similar to tomorrow and in the mid to upper 30s. A building upper-
level ridge will allow for temperatures to warm Thursday into the
weekend with highs returning to the upper 40s and potentially 50.
The next chance of precipitation looks centered on the Sunday/Monday
timeframe, though ensemble spread is vast in location and amount.
Until a more meaningful signal materializes, our official forecast
will be completely dry through Sunday.
Borchardt
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Concerns:
* MVFR ceilings persist into Monday afternoon.
Region remains within weakly cyclonic low level flow beneath an
upper trough early this evening. An extensive area of MVFR
ceilings remain in place across the upper Midwest, and though the
clearing line extends from eastern IA into central IL, the
northwesterly trajectory of our low level flow suggests this clearing
will not make it into the terminals tonight. MVFR ceilings have
rising to around/just above 2000 ft and this is expected to
prevail this evening, though guidance does indicate bases
settling back below 2000 ft again after midnight and into Monday.
Models continue to show some spread in timing of improvement to
VFR, though generally indicate VFR conditions developing at KRFD
around midday/early afternoon and across the Chicago terminals
during the afternoon.
Winds are expected to be 10 kts or less through the period,
initially northwest tonight, then gradually backing westerly
Monday morning and flipping southwest by midday.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
719 PM EST Sun Dec 10 2023
.SHORT TERM...(Through Tonight)
Issued at 330 PM EST SUN DEC 10 2023
Key Messages:
- NW flow lake effect snow showers diminishing/ending from the west
through tonight with light additional snow accumulations east.
Latest water vapor imagery and RAP analysis show the trailing
shortwave in the mid-level trough axis moving into the western fcst
area late this afternoon. Weak q-vector convergence/forcing ahead of
this shortwave along with 850 mb temps around -10C has sustained
some light NW wind LES into mainly north central and eastern
sections of the fcst area today. Under mostly cloudy skies and weak
CAA temps haven`t risen much today with highs generally ranging from
the mid 20s to the lower 30s, warmest east.
Models indicate that the shortwave/mid-level trough axis will
continue to move east across the area tonight exiting east of the
Upper Great Lakes late tonight. Given the loss of any weak
enhancement by early evening, sfc-850 mb flow becoming more
anticyclonic with time, and inversion heights of 4kft or less,
expect any additional NW flow LES accumulation to be light...an inch
or less through tonight over the eastern counties. Min temps tonight
will range from the lower teens interior west where there may be
clearing late due to building high pressure to the lower 20s east
and along the Great Lakes shores under more lake clouds.
.LONG TERM...(Monday through Sunday)
Issued at 343 PM EST SUN DEC 10 2023
Key messages:
- Next shortwave/cold front brings gusty west winds especially to
Lake Superior/Keweenaw late Monday night/Tuesday.
- An unseasonably warm and gusty day is expected for Thursday.
- Other than near normal temperatures Monday through Wednesday,
above normal temperatures are expected for late this week into next
week.
-No widespread, significant system snowfalls across Upper MI over
the next 10 days.
The light lake-effect snowfall ends across the area Monday as weak
ridging builds into the area. While a trace of snowfall may fall
across the Keweenaw and east Monday morning, no more than that will
be seen. This ridging brings sunny skies to the area by Monday
afternoon. While it may feel warmer with the sun out, with 850mb
temperatures staying in the single negative digits, the high
temperatures will generally be in the low to mid 30s.
A Clipper low makes its way into Upper Michigan Monday night,
bringing breezy conditions across our area and lake-effect snow to
the west-northwest wind snow belts. While delta-Ts are looking to be
in the upper teens, with ensemble guidance showing PWATs dropping
down to 0.15 inches with the Clipper, the dry air looks to dampen
snowfall amounts. The strong cold air advection will bring west-
northwesterly gusts as high as 40 mph over the Keweenaw Monday night
into Tuesday, with gusts up to 30 mph being seen everywhere else. As
this strong cold air advection continues into Tuesday, expect the
lake-effect snow and breezy conditions to continue. While there is
some signal in the high-res Canadian for a convergent band to form
over the west in Ontonagon County and east over northern Luce
County, thinking snowfall amounts will be a fluffy couple of inches
across the west-northwest snow belts Monday night into Wednesday.
Now, if these convergent bands do occur, it is possible (~40%
chance) that snowfall rates up to 1 inch/hour could be seen at
times. If that occurs, snowfall could accumulate rapidly. Otherwise,
the other hazard to look out for is blowing snow along the
lakeshores; this will cause reduced visibilities in spots, making
travel hazardous at times. While the colder air is overhead, it will
feel a bit more like actual winter, with highs Tuesday and Wednesday
being in the mid 20s to the low 30s and lows Tuesday night getting
down into the teens.
Expect the more normal weather for this time of year to begin ending
Wednesday as high pressure ridging builds into the area, ending the
lake-effect snowfall. Moving into Thursday, vigorous and
unseasonable warm air advection moves over the Northern Plains and
stretches over the Upper Midwest, with the NAEFS and ENS showing
temperatures getting up to around the 98th percentile of modeled
climatology. While the NBM calls for highs in the 40s, given that
the ridging brings sunny skies over us, I`m thinking there is a good
chance (50 to 60%) that some spots reach 50 Thursday; therefore, I`m
thinking some high temperature records could be broken Thursday. In
addition, with a tight pressure gradient overhead, gusty westerly
winds are very likely (90+% chance) to be seen across the region.
Moving to the end of this week and into this weekend, the above
normal temperatures look to continue. While model guidance suggests
additional shortwaves moving through the area, confidence is low as
to when exactly they move through Upper Michigan late this week
through this weekend. As we move into next week, the Climate
Prediction Center shows very favorable chances (70 to 80%) of above
normal temperatures, with chances also leaning (40 to 50% chance)
towards below normal precipitation too. Therefore, it looks like we
will be lacking snowfall chances as we head towards the latter half
of December, thus increasing chances that we will have a brown
Christmas.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 719 PM EST SUN DEC 10 2023
Persistent MVFR cigs will continue at all TAF sites into the night
and possibly into tomorrow morning at IWD and CMX, will continue to
monitor. Once this cloud deck clears out though, VFR will become
the prevailing flight category through the end of the TAF period.
Look for southwest winds to become strong with gusts up to 25 kts at
IWD and CMX tomorrow afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 343 PM EST SUN DEC 10 2023
Winds die down to 20 knots or less this evening as ridging builds
into the region tonight. However, as a Clipper moves over the lake
Monday night, expect the winds to increase from the southwest ahead
of it Monday afternoon before becoming gales of 30 to 40 knots along
its cold front Monday evening. As the front pushes through Monday
evening, some gusts up to 45 knots could (60 to 70% chance) be seen
near the Keweenaw Peninsula. Behind the front, west-northwest gales
of 35 to 40 knots continue across the lake Monday night through
Tuesday, with the stronger winds being realized over the eastern
half. As the cold air advection ceases Tuesday evening, the winds
slowly die down, with the gales ending over the far eastern lake by
Wednesday morning. While ridging moves over the lake Wednesday into
Thursday, a tight pressure gradient develops over the lake Wednesday
night into Thursday. This brings southwesterly gales of 35 to 40
knots back across Lake Superior. The winds calm down as we head into
next weekend.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
Gale Watch from Monday evening through Tuesday evening for
LSZ162.
Gale Watch from Monday evening through late Tuesday night for
LSZ241-242-263.
Gale Watch from Monday evening through late Tuesday night for
LSZ243-244-264.
Gale Watch from Monday evening through Wednesday morning for
LSZ250-251.
Gale Watch from Monday evening through late Tuesday night for
LSZ265.
Gale Watch from Monday evening through late Tuesday night for
LSZ266.
Gale Watch from Monday evening through Wednesday morning for
LSZ267.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...TAP
AVIATION...TDUD
MARINE...TAP