Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/06/23
Area Forecast Discussion
National Weather Service Binghamton NY
926 PM EST Tue Dec 5 2023
.SYNOPSIS...
A weak clipper system moves through tonight bringing widespread
light snow though accumulations are expected to be less than an
inch. Temperatures slowly warm through the rest of the week
with a stronger storm impacting the region this weekend with the
potential for strong winds and rain.
&&
.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
915 PM update...
Some minor changes were made to PoPs with this update. Scattered
snow showers are being observed across the region. Some areas
are seeing high enough snowfall rates to reduce visibilities
down to a few miles. Re-evaluating snowfall totals, there were
some minor changes made to these as well. While snowfall totals
will generally be light, some localized totals may near an inch.
530 PM update...
Seeing that snow has moved in quicker than originally
forecasted, PoPs were updated. The RAP looked best compared to
radar, so that was blended in with the NBM and previous forecast.
Light snow showers to flurries are expected this evening with
not much accumulation. Snow will accumulate tonight with most
under a half of an inch, though localized amounts of around a
half inch will be possible. Snow totals were bumped up just
slightly given the earlier arrival of the snow showers. Other
than PoPs and snow totals, the forecast was doing well and
needed no change.
215 PM update...
A few snow showers are persisting along the NY thruway early
this afternoon but as a warm front lifts in ahead of an
approaching shortwave, the snow showers will come to an end.
Radar across Ohio into western PA has filled in with light
precipitation associated with the shortwave and water vapor
imagery shows the trough digging slightly. Chances of snow
showers were increased area wide for tonight as forcing looks
slightly better to get widespread snow. Forecast soundings are
showing the best lift outside of the dendritic growth zone so
snowfall rates likely will be light with accumulations expected
to be an inch or less for most of the region with isolated areas
in the Finger Lakes possibly seeing up to 2 inches.
Once the shortwave is east of the region tomorrow, cold air
advection drops 850 mb temperatures down to near -10C so lake
effect snow develops. Wind through the boundary layer will be
light and out of the NW at about 320 to 330 degrees. Some
organization to the lake effect bands are possible but with a
short lake fetch the intensity of the bands will be a little
lighter. Flow aloft becomes Northwesterly Wednesday night with
some lake effect showers likely continuing across the Finger
Lakes. Another shortwave begins to drop into the Great Lakes
region late Wednesday night with the potential for more light
snow headed into Thursday.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
310 PM Update...
Light snow is expected Thursday, followed by quiet conditions
the rest of the period.
A warm front will push northward across the area on Thursday and
weak isentropic lift should be enough to produce some widespread
light snow. Up to an inch of snow will be possible, but this
will be dependent on afternoon temperatures Thursday. The snow
could mix with rain in the afternoon, especially in the valleys
as surface temperatures rise into the upper 30s. However, wet
bulbing could keep precipitation falling as snow, but little to
no accumulation is expected in the valleys. Snow will end
Thursday evening from west to east as the warm front passes.
Ridging builds in overnight Thursday and Friday with warm southwest
low level flow bringing warmer air into the area. This period
will be warm and dry, with high temperatures Friday in the mid
to upper 40s.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
325 PM Update...
Heavy rain and strong winds will likely impact the region
Sunday into Monday.
Very warm and above average temperatures are expected this
weekend. A broad ridge will be in place over the Eastern U.S and
temperatures will likely climb well into the 50s Saturday and
again on Sunday.
However, deep SW return flow will start pumping moisture into
the area ahead of a deepening upper trough across the Central
U.S. That trough will turn negatively tilted and an intense
surface low will track northeast across the Great Lakes on
Sunday. Euro ensembles are indicating anomalous PWs of 3 to 4
standard deviations and an intense LLJ of 60+ knots. Winds will
increase to 15 to 20 mph with gusts up to 40 mph Sunday to
Monday. Slow moving cold front pushes in by midday Sunday and
heavy rainfall will be widespread across the region. Some hydro
issues will be possible, but being that this is still 5 to 6
days out, this is just something to monitor at this time.
Localized rainfall amounts of 2+ inches will be possible with
this system.
Heavy rain will push east of the area by early Monday morning,
but we will remain under the upper level trough on Monday. Low
level flow out of the west and T850 dropping to around -10C,
means conditions will be favorable for some sort of lake effect
snow, however, way too early at this time to know how this will
unfold.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
18Z Update...
Light snow showers are increasing across the area, with a wide
range in visibilities between 2 and 10SM. Expect mainly
MVFR/fuel alt conditions as the snow showers move through, with
brief IFR mainly due to visibility restrictions.
Light snow will taper off in the morning, transitioning to
light lake effect snow/flurries which will mainly impact SYR and
possibly ITH. Elsewhere, MVFR ceilings will remain in place
across central NY, with fuel alt ceiling restrictions at BGM.
Conditions should improve to VFR at AVP in the afternoon.
Outlook...
Late Wednesday night...Becoming mainly VFR,
Thursday...A weak clipper system may bring occasional
restrictions in light rain or snow.
Friday through Saturday...Mainly VFR.
Sunday...Restrictions likely from rain and low ceilings as well
as strong winds.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...AJG
NEAR TERM...AJG/BTL
SHORT TERM...MPK/TAC
LONG TERM...MPK/TAC
AVIATION...AJG/BJG/MPH
FORECAST DISCUSSION...
Generally quiet and non-impactful conditions are expected
through the period with the main focus of weather across the
North Country and Vermont being the passage of an upper trough
currently over the Great Lakes. Several pieces of shortwave
energy rounding the base of the trough will have the potential
to produce some light precipitation, though the majority should
remain south of our region where the best upper level support
and deep moisture overlap. This afternoon though, we are seeing
a little lake effect response from the Tug Hill up into the
Adirondacks, and some of these light snow showers and/or
flurries will likely continue to affect the Adirondacks
overnight, possibly drifting into central/southern Vermont for a
short period. After sunrise though, surface high pressure
building south through Quebec will help to dry out the mid and
eventually low levels with any precipitation ending, and skies
clearing through the day from north to south. This will set up
favorable conditions for a very cold night across the region
Wednesday night with mostly clear skies and light winds
supporting temperatures falling into the single digits and teens
above zero. For tonight, lows will remain cool but closer to
normal in the teens north to mid 20s south, and highs Wednesday
will be similar to today in the low/mid 20s north to low 30s
south.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
As of 317 PM EST Tuesday...Warm, moist air will advect into the
forecast area Thursday, allowing some snow showers to develop off
Lake Ontario, falling upon portions of St. Lawrence County.
Otherwise, a cold (5-10 degrees below normal) and partly to mostly
cloudy day is expected. Highs will be in the 20s for the Greens
east, closest to surface high pressure, as well as 20s the
Adirondacks and northern Champlain Valley. Elsewhere anticipating
the lower 30s. Up to an inch of snow forecast for northern New York,
highest in southwestern St. Lawrence County.
Thursday night, mid to upper level ridging will move into the
region, gradually shutting off the lake effect snow machine. There
could be some lingering flurries, but a generally dry night is
forecast. Despite this ridging, clouds are expected to increase from
west to east. Lows will be in the single digits for the Northeast
Kingdom (most likely to have some clear spots) to upper 20s in the
St. Lawrence Valley (cloudiest area). Most areas between these two
extremes will be in the teens to lower 20s.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 317 PM EST Tuesday...Mid/upper ridging will keep conditions dry
for the late week. Under this ridging and with southerly surface
flow, temperatures will steadily rise into the lower 30s-lower 40s
Friday to as high as the upper 40s for some Saturday, near 10
degrees above normal. Lows will also be mild and above normal in the
lower 20s to mid-30s. Clouds will be on the increase ahead of our
next storm system.
Focus then shifts to said storm system, which could bring
precipitation (most likely rain with some mountain snow), gusty
winds due to a low level jet roaring overhead at 60-70 knots, and
melting snow with elevated temps and dew points. Temperatures Sunday
will peak impressively in the 50s, so during the day, even the
summits would have mainly rain. At this time, models are coming into
fairly good agreement with low pressure crossing the Great Lakes
Sunday then progressing across Ontario and Quebec to our north into
Monday. Meanwhile, a coastal low looks to develop on some models,
and the latest GFS run puts a particular emphasis on this low,
making it stronger and closer to the area than the 00Z run. The
latest GFS run is also pulling the breaks a bit, showing a more
reasonable and slower storm progression.
Ensemble river forecasts are showing increasing confidence in some
potential minor flooding across the region as median percentiles now
surpass minor flood stage for the Winooski, Mad, and Ausable rivers,
as well as Otter Creek. At other spots, median percentiles continue
to approach minor flood stage. We`ll continue to monitor the
potential for heavy rain, snow melt, and river flooding as the event
gets closer and we narrow down temperatures and forecast rainfall
amounts.
Another potential impact will be winds. We may need a Lake Wind
Advisory out for periods on Sunday and Monday, after a cold frontal
passage associated with the system. In addition to winds on Lake
Champlain being elevated, summits would be quite miserable with the
850mb jet, and downsloping winds are possible on the western slopes
of the Greens and Adirondacks. Additionally, southwesterly flow up
the St. Lawrence Valley is expected to be brisk on Monday,
especially if the ECMWF is correct in its deepening low placement
directly to the northwest of our area into Monday. Currently
forecasting widespread gusts to 25-35 mph and higher on summits.
After the surge of warmth, temperatures will gradually fall again
into next week following the frontal passage, with highs back in the
30s and 40s. There could also be some lingering showers behind the
system.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Through 00Z Thursday...MVFR ceilings will largely prevail
through the period with occasional breaks to VFR, currently
observed at SLK and RUT. Chances of IFR conditions at any
terminal are too low to mention during the period, but cannot be
ruled out, especially in the 10Z to 15Z period before low
clouds begin to scatter. At the same time, flurries or light
snow showers could accompany the lower clouds and help produce
brief IFR conditions, especially at EFK/SLK. Skies should more
rapidly clear after 18Z with VFR conditions currently favored
late in the period at all sites. Winds will remain light through
the period, mainly northerly at 8 kts or less during the
daytime hours.
Outlook...
Wednesday Night: VFR. NO SIG WX.
Thursday: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
Thursday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Friday: Mainly VFR, with areas MVFR possible. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. NO SIG WX.
Saturday Night: Mainly VFR, with local IFR possible. Slight
chance SHRA.
Sunday: Mainly MVFR, with areas VFR possible. Likely RA, Chance
SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Lahiff
NEAR TERM...Chai/Lahiff
SHORT TERM...Storm
LONG TERM...Storm
AVIATION...Kutikoff/Lahiff
Area Forecast Discussion
National Weather Service Quad Cities IA IL
745 PM CST Tue Dec 5 2023
.KEY MESSAGES...
* Quiet and seasonal tonight and Wednesday
* Dry, breezy, and much warmer late week, with exceeding 60
degrees possible (~25% chance) Thursday and Friday
* Strong storm system this weekend with rain changing to snow,
however still high uncertainty on precipitation duration and
amounts
* Much colder and windy by Saturday night and Sunday
&&
.UPDATE...
Issued at 745 PM CST Tue Dec 5 2023
We have made some small adjustments to the forecast for tonight,
revolving around the ongoing stratus cloud deck. Current GOES-
East satellite imagery reveals that the western edge of the
stratus is just about to move over Waterloo, IA this evening.
With the edge of clear skies closer than previously forecast, we
have made adjustments to the cloud cover forecast to gradually
clear out the clouds. Model guidance has struggled greatly to
capture the cloud coverage, but the 900 mb level RAP RH progs
seem to have the best handle on the position of the stratus, and
it has the stratus clearing out overnight. With the clearing
more likely, we have also lowered the overnight lows slightly,
down to the lower to middle 20s - coldest over northeastern Iowa
and warming towards the southeast.
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 230 PM CST Tue Dec 5 2023
The low pressure that brought a wintry mix and drizzle and fog to
the area this morning will be well east of the area tonight. High
pressure will build east into the area overnight. The low stratus
clouds are expected to linger over the area through much of the
night, with some partial clearing possible in the western parts of
the CWA. With the clouds holding for a longer time, opted to keep
the going forecast low temps which were slightly warmer than the new
model blend, which had clearing earlier. If skies do clear faster,
mins may be a bit colder. Current lows range from around 22 in the
NW to 28 in the east.
Wednesday, the high will be moving off to the east with return
southwest/south winds developing and increasing. Temps at 850h will
increase to 8-12C by late day. Bumped highs up a deg/two especially
west where gustier winds and some sunshine are anticipated. If
clouds hold longer through the day, highs may need lowering. Current
highs range from the upper 30s to low 40s NE to mid 40s SW.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 230 PM CST Tue Dec 5 2023
Details:
Thursday through Friday: A deep trough moves into the western
United States with a ridge building in the Southeast. This
pattern will bring much warmer temperatures into the forecast
area on breezy south winds with gusts 30+ mph. Even stronger
winds are expected south of the area as a 850 mb 40-50 kt speed
max moves through the flow. This is when the warmest days are
expected with potential for near record highs (see Climate AFD
below). As of now the 75th percentile that several models are
clustered in shows highs in the upper 50s to lower 60s. If we
can get some sunshine these readings could be several degrees
warmer given 850 mb temperatures of 10C (upper 5th percentile
for time of year).
This weekend: The GFS has been rather consistent the past couple of
runs showing a cyclone (1000 mb) tracking from the southern Plains
to the Great Lakes (when phasing causes rapid deepening to sub
985 mb). The ensemble means show spread but within that general
track. The 12Z ECMWF is slower at deepening the low but still
does by Sunday night has a 977 mb cyclone over the eastern Great
Lakes. With such a pattern, confidence is high in big changes
to occur in temperatures this weekend and with gusty winds.
As for precipitation, rain spreads into the area Friday night,
then changes to snow by Saturday night. The snow gradually ends
on Sunday. Much colder and very windy conditions expected on
Sunday with highs only in the 30s with northwest winds gusting
to at least 30 mph with some NBM members (20%) at 40+ mph.
Early next week: Northwest flow continues the cold weather with
highs in the 30s and lows in the teens to mid 20s. A clipper
system looks to track to our north but a farther south track
would bring the potential for some snow.
Haase
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 548 PM CST Tue Dec 5 2023
A widespread stratus cloud deck was observed across the area
early this evening, with largely MVFR ceilings. The latest
GOES-East satellite imagery shows the stratus dissipating from
the northwest, so a period of clearing skies is expected late
this evening into the overnight hours. Some MVFR fog is expected
at CID closer to a high pressure ridge axis that will keep winds
lighter, with more uncertainty for fog for DBQ and BRL. For now,
we have used 6SM to trend towards fog, but we will watch
conditions closely. Gusty southerly winds are expected for
Wednesday afternoon.
&&
.CLIMATE...
Issued at 230 PM CST Tue Dec 5 2023
Record highs for December 7th...
Burlington.......66 in 1916
Cedar Rapids.....62 in 1916
Dubuque..........61 in 1916
Moline...........66 in 1916
Record highs for December 8th...
Burlington.......69 in 1991
Cedar Rapids.....65 in 1958
Dubuque..........63 in 1946
Moline...........67 in 1991
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.
&&
$$
UPDATE...Schultz
SHORT TERM...Philip
LONG TERM...Haase
AVIATION...Schultz
CLIMATE...Haase
Area Forecast Discussion
National Weather Service Grand Rapids MI
958 PM EST Tue Dec 5 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 958 PM EST Tue Dec 5 2023
Winds over Lake Michigan will shift from north to northwest
overnight which will bring about a period of clouds and light lake
effect snow showers. From roughly 100am tonight to 100pm on
Wednesday there will be potential for both lake clouds and lake
snow. Delta T`s during this time frame will near near 16C between
the water surface and 850mb`s, so enough instability will be
present. Relative humidity in the 1000-850mb layer is sufficient
through both the overnight hours and the morning hours of
Wednesday for some snow. Snow showers should be light overall,
with any accumulation over the western CWA limited to a dusting or
less. Moisture depth is not all that great, so there may be some
light rain showers or drizzle mixed in near in the lakeshore.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 204 PM EST Tue Dec 5 2023
- Diminishing light showers through mid afternoon
Radar shows some light returns mainly down in the Interstate 94
corridor. Trends show them weakening. A few observations sites
such as LWA and AZO has some rain in the past hour. With surface
temperatures in the upper 30`s in that region, no impacts are
predicted as this area of light precipitation shifts south and
east of the CWA.
- Light Lake Effect Precipitation possible later tonight
The 850 mb thermal trough shifts through the forecast area later
tonight. Temps are shown to be around -8 deg C where it will be
moist. Low level convergence looks most favorable for lift along
the lakeshore zones. In this region of low level lift and
moisture, there could be a few light showers. The moisture depth
decreases by late morning Wednesday, which should decrease any
precipitation chances. Surface temperatures will once again be
near freezing so, if we do end up with any precipitation, this
could result in a few slick spots.
- Risk for rain/snow showers Wednesday night
A mid level wave drops southeastward through the east side of the
state Wednesday night. Meanwhile, an associated low level jet
will be feeding into the west side of this system. There may be
enough saturation to generate light precipitation as this feature
drops through. The 18z HRRR and the 12z NAM were generating light
precipitation Wednesday night. The Canadian ensemble forecasts
were showing precipitation as well. We will therefore have a low
chance for precipitation in the forecast mainly northeast zones
Wednesday night.
.LONG TERM...(Thursday through Tuesday)
Issued at 204 PM EST Tue Dec 5 2023
-Warm and Dry Thursday and Friday
Upper-level ridging and warm air advection in robust southwest flow
will warm temperatures across West Michigan late this week. This
robust warm air advection promotes 850 mb temperatures warming into
the 7-10C range (for reference, the 90th percentile of 850 mb temps
Friday is 6 degrees C which puts us solidly above normal). This
translates into highs well in the 40s Thursday and in the 50s
Friday. Upper-level ridging also keeps the area dry through this
period. However lingering low level moisture Thursday morning, and
moisture streaming in ahead of our next system Friday, will keep at
least some clouds during this window. Thursday afternoon looks to be
the best chance for substantial clearing as West Michigan will lie
in the gap between the two moisture sources.
-Monitoring The Potential For A Weekend Storm System
Upper-level jet divergence arrives over the area Friday night into
Saturday as we sit in the right entrance region of a jet streak.
This forcing, in tandem with an approaching trough and northward
streaming moisture, causes rain chances to increase for Friday night
into Saturday.
We are continuing to monitor increasing potential for a deepening
low pressure system to move through the Great Lakes late this this
weekend. The expected evolution of the synoptic pattern has a
digging longwave trough over the central United States ejecting
northeastward as a negatively tilted wave. This wave forms a surface
low along a tight baroclinic zone stretching across the plains,
driving the low northeastward as well. This allows for ample
moisture to stream into the Great Lakes region with PWAT values
around 1 inch moving north.
Notable uncertainty in the potential surface low track still exists,
which is common this far out, providing uncertainty in precipitation
types and amounts. This is because the upper-level wave expected to
drive this event is just now reaching Alaska, and by extension
beginning to be sampled by our upper-level weather balloon
network. The range of solutions includes locally heavy rainfall, and
even potentially thunder if we end up on the warm side of the
system, as the warm conveyor belt streams moisture into the region.
A more easterly/southerly component to the low track would keep us
on the cold side of the low bringing the potential of impactful
accumulating snowfall.
Examining the latest 12z ECMWF and GFS deterministic and ensemble
runs shows a northerly shift in low track and maintains the westward
shift shown in the 00z set of guidance. This outcome would favor
more rain for west Michigan and keep heavy snow north of the area.
However, the 12z Canadian suite and some members of the GEFS/EPS
ensembles are still showing a more easterly/southerly low track
which would provide a swath of 6+ inches of snowfall across the
area. Additional shifts in guidance are likely in the coming days as
additional observations are obtained, and we will continue to
monitor model trends as solutions converge.
The other concern to monitor is the potential for gusty winds as
shown in the ECMWF Extreme Forecast Index and ensemble guidance.
Depending on the track and strength of the low, gusty conditions are
possible later Sunday into Monday.
Regardless, temperatures fall significantly Sunday night into Monday
allowing for precipitation to turn to snow. As 850 mb temps fall
into the -10C range, lake enhancement to any precipitation becomes
possible. Longwave troughing overhead keeps the potential for light
precipitation during the day Monday and into the day on Tuesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 715 PM EST Tue Dec 5 2023
No major weather systems will affect the 24 hour TAF period of
00z this evening to 00z on Wednesday evening. There are two main
players in aviation weather over the next 24 hours. The first...
lower ceilings that are persisting in the wake of a clipper
system that is moving away to our southeast this evening. And
second...some lake effect clouds that will push through the TAF
sites mainly between 06z and 18z. Bottom line, we are looking at
conditions varying between VFR and MVFR over the next 24 hours.
MVFR will be from ceilings and not visibilities. Improvement is
expected after about 20z on Wednesday when ceilings lift above
3,000 feet. Winds will be light tonight and increase out of the
west and southwest Wednesday afternoon to 10-15 knots.
&&
.MARINE...
Issued at 204 PM EST Tue Dec 5 2023
Low level winds will start increasing Wednesday afternoon and more
so Wednesday evening. Marine headlines will likely be needed
starting Wednesday night. The winds at 925 mb increase to over 35
knots Wednesday night which will support impactful conditions.
Most ensemble wind forecasts support conditions remaining under
gale force.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
UPDATE...Duke
SHORT TERM...MJS
LONG TERM...Thomas
AVIATION...Duke
MARINE...MJS
Area Forecast Discussion
National Weather Service Marquette MI
705 PM EST Tue Dec 5 2023
.SHORT TERM...(Through Tonight)
Issued at 257 PM EST TUE DEC 5 2023
Key Messages:
-Light snow showers continue, waning tonight
-Isolated areas of high terrain could reach 2 inches of snow by
Wednesday morning, most should see a half inch or less.
Radar reflectivity returns show light to moderate snow associated
with a weak 1019 mb low in the vicinity of the Keweenaw Peninsula
this afternoon per RAP analysis. HRRR runs today showed a meso-low
type feature forming out of this setup, though that has been
difficult to verify given multiple layers of obscuring higher
clouds, evident by the GOES-16 Day Cloud Phase RGB product. Still,
CMX airport has reported visibilities as low as a mile and a half at
times while some moderate snow showers have been seen on various
webcams over the Keweenaw. With METARs showing surface temperatures
already into the mid 30s at the surface and BUFKIT soundings showing
omega maximized below the DGZ, snow ratios should be too low for
significant snow accumulations with QPF limited by weak forcing. NAM
850mb analysis shows the lake-850mb temperatures gradient right on
the cusp of lake effect, so some lake enhancement will likely be
occurring with these snow showers. All things considered, while a
couple of isolated locations with terrain enhancement could see a
couple inches of snow, but the vast majority of the UP should see a
half inch or less of snow. Overnight, with cloud cover persisting,
temperatures will only fall into the low to mid 20s, with only about
a 50% chance of the typical cold spots reaching into the mid to
upper teens per the NBM.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 420 PM EST TUE DEC 5 2023
Key messages:
- Breezy Wednesday with a few light snow showers; no impacts
expected.
- Becoming much warmer than normal Thursday/Friday.
- A low pressure system will approach from the southwest over the
weekend. A widespread plowable snowfall is possible if the low track
is favorable; however, at this time probabilities are less than 30%.
High-amplitude midlevel ridge will shift from the northern
Rockies/northern Plains into the Upper Great Lakes Wednesday into
Thursday. This ridge is characterized by standardized 500 mb height
anomalies of +1 to +2 sigma. Complex evolution of western US
troughing will have big implications for the rest of the forecast
period. Lead wave should pass mostly west of the area on Friday as
it ejects from MN to southern ON. Meanwhile, a strong Pacific jet
will dig a deep trough into the southern Plains on Saturday. How
quickly this trough goes negatively tilted, and whether it can phase
with trailing energy associated with the northern stream, will
determine where the attendant surface low develops as it tracks
northeast over the weekend.
Some light precipitation is possible Wednesday due to isentropic
lift along the leading edge of the warm advection associated with
the building ridge, but forecast soundings show only sporadic
saturation and significant dry layers within the column, so do not
expect anything to be significant or impactful. It will be breezy
with wind gusts around 25 mph. By Thursday, 850 mb temps warm into
the mid/upper single digits (C), which correspond to standardized
height anomalies of +1 to +3 sigma. While mixing will not be that
deep, it will likely be more than GFS/NAM soundings forecast given
lack of significant snowpack. Friday, the low associated with the
aforementioned lead wave tracks to our northwest into Ontario, which
will leave us in a quasi-warm sector. This too looks favorable for
deeper mixing relative to forecast soundings. The NBM forecast which
incorporates bias-corrected warmer guidance looks good. This shows
highs in the low/mid 40s Thursday and mid/upper 40s Friday, both of
which would challenge records at WFO MQT (see climate section
below).
Significant differences exist in the ensemble guidance for the
potential storm over the weekend, both in terms of timing and track.
A somewhat narrow swath of significant snowfall is possible along
the northwest side of this low (as shown by ECMWF Shift of Tails > 0
over the eastern UP 00Z Sun through 00Z Mon, implying some snowy
outliers in the ensemble guidance), but Extreme Forecast Index less
than 0.5 reflects the high spread. Latest probabilities of >6" snow
are less than 30% from the GEFS/EPS; however, at this time range,
that doesn`t mean we should discount the potential of an impactful
storm. Behind this low early next week, transition to a
colder/troughy pattern is likely, which could be accompanied by
bouts of lake effect snow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 705 PM EST TUE DEC 5 2023
MVFR/VFR conditions will prevail through tonight as a weak surface
low continues to produce light snow showers. VFR will become the
predominant flight category though by mid-morning tomorrow. Other
than some northwest winds up to 13 kts at CMX this evening, winds
are light and variable. They will become southwesterly after Wed
12Z.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 420 PM EST TUE DEC 5 2023
Winds will remain light over the lake through tonight, but they will
increase out of the south to southwest with gusts of 25-30 kt
Wednesday afternoon and evening. There could be a few higher gusts
briefly Wednesday evening to 35 kt at higher platforms and along the
tip of the Keweenaw, but overall the potential for gales is less
than 20%. Winds diminish to less than 20 kt late Wednesday night
into Thursday, but increase again Friday as low pressure passes to
our northwest. Southwesterly winds could gust 25 to 35 kt, highest
over the western half where gale probabilities are 10-30% at this
time. Winds over the weekend will depend on the timing and track of
a possibly strong low pressure system approaching from the
southwest. If the track is far enough west, gales will be possible
especially later in the weekend.
&&
.CLIMATE...
Issued at 420 PM EST TUE DEC 5 2023
Record highs for WFO Marquette in Negaunee Township:
Dec. 7: 38F (1963)
Dec. 8: 44F (1984)
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...GS
LONG TERM...Thompson
AVIATION...TDUD
MARINE...Thompson
CLIMATE...Thompson
Area Forecast Discussion
National Weather Service Pocatello ID
200 PM MST Tue Dec 5 2023
.SHORT TERM...Tonight through Wednesday night.
Main impact tonight will again be some patchy fog development with
most widespread in the Bear Lake region. Think extensive high
clouds increasing will limit the development a bit. On Wednesday
an upper level Pacific trof moves on shore with moisture beginning
to make it`s way into Idaho. Precipitation will begin late in the
afternoon in the Sawtooths and central mountains and spread into
the upper snake highlands and eastern mountains overnight. Snow
levels will be very high at the onset at about 7 thousand feet and
drop to about 6 thousand feet overnight. Snow accumulations above
6500 feet Wednesday night will be about 3 to 5 inches with locally
higher amounts over passes in the Sawtooths and 2 to 4 inches in
the Island Park area. Snow will continue Thursday and winter
weather advisories may be issued in the future mainly targeting
the Central Mountains and Upper Snake Highlands as that is where
the heaviest snow will fall and amounts will increase through the
day on Thursday. Overnight lows tonight will be in the 20s and
30s and highs Wednesday once again mainly in the 40s.
.LONG TERM...THURSDAY THROUGH NEXT TUESDAY...
Continued unsettled/active weather is expected throughout the long-
term period of the forecast as a series of multiple shortwave
troughs affect southeast Idaho. The most organized period of impacts
still appears to be Thu/Fri, during which time anywhere from 2 to 10
inches of fresh snow will accumulate in our mntn ranges (higher
totals in the upper elevations of the Sawtooths) while rain at lower
elevations Wed eve will slowly trend to all snow by Thu eve as
colder air starts to move in, with the brunt of the cold air taking
hold by Fri behind a more definitive cold front. We`re still
monitoring the potential need for Winter Weather Advisories.
Accumulation of snow below 6,000 feet might be a hard sell until Thu
eve when temps become more favorable, so watch Thu night into Fri as
far as snow trying to stick on many of our major highways and
interstates. It also continues to look quite breezy Thu afternoon,
especially in the Snake Plain (borderline Wind Advisory criteria
with WSW wind gusts to 45 MPH), but luckily the strongest winds may
be offset (earlier) from the arrival of temps more favorable for low-
elevation snow (later), thus helping to keep overall travel impacts
in-check until again later Thu evening. Fri afternoon may be equally
breezy in the ern Magic Valley. Best chance for a brief, organized
break in the pattern remains Sat. 01
&&
.AVIATION...
High pressure will generally support quiet, VFR conditions and light
winds, with SCT to BKN high-level clouds rotating over the ridge.
The low elevations will be quite moist again tonight with some fog
and low stratus possible, although we MIGHT be inching just a touch
drier overall compared to last night. Best potential lies at KIDA
where both the HRRR and NBM try to nudge in fog and/or stratus from
the west, although confidence on occurrence and timing is currently
low. Broad window appears to be 06z-17z/11pm-10am tonight/Wed AM.
This will be the continued focus for the upcoming 00z TAF
package...IF activity can develop, then IFR conditions for either
cigs/vsbys would be possible. Precip associated with the next
approaching series of shortwave troughs may begin to impact KSUN as
early as late Wed afternoon, expanding regionwide thereafter. 01.LONG TERM...
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Raleigh NC
910 PM EST Tue Dec 5 2023
.SYNOPSIS...
An upper level disturbance and a weak surface low will move east
through the Mid Atlantic region tonight through Wednesday morning.
Surface high pressure will then build into the Southeast from
Wednesday afternoon through early Friday, before moving offshore
Friday night. A storm system will move into the region late in the
weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 910 PM Tuesday...
Forecast largely on track, with minor tweaks. The anticipated potent
shortwave is seen clearly on GOES WV and IR imagery over W NC, with
the RAP indicating the 1.5 PVU surface down to 600 mb. As expected
and suggested by CAMs, a batch of high-based showers have blossomed
ahead of this wave over the W Piedmont, progressing E within the
fast cyclonic steering flow. The existing forecast of chance pops
crossing the CWA through the next several hours remains valid.
Leaning toward the HRRR, which has been consistent and initialized
well, have brought shower chances further south, which aligns with
current radar trends. QPF should be limited by the lack of deep
moisture and fairly high cloud bases. However, given the presence of
decent low level lapse rates and strong, focused forcing for ascent
to make the most of the layers of moisture through the column
(including within the mixed phase region aloft), as indicated by the
00z soundings, have nudged pops up slightly and expanded them
areally. At any rate, most places should see just a few hundredths
of an inch. Current temps vary widely across the region (including
some uncomfortably low values in the mid 30s, ranging to the mid
40s). Once skies start to clear out over all but the NE sections
later tonight, temps areawide should eventually bottom out in the
mid 30s to lower 40s, with a few lower 30s in rural areas of the W
Piedmont. -GIH
Previous discussion from 1250 PM: Significant
amplification of the long wave trough in place across the Eastern US
trough will begin late today but especially tonight and Wednesday(H5
anomalies-2 to -3 SD) as an intense upper PV anomaly dives into the
SE US. Skies will remain sunny through the mid afternoon will clouds
starting to spread/fill in from NW during the late afternoon and
early evening. Central NC will experience seasonable to slightly
above normal temps, ranging from lower/mid 50s north to lower 60s
across southern NC.
The robust synoptic scale H5 falls of 120-130 meters coupled with
strengthening upper divergence from the merger of the PJ with the
STJ will be able to overcome modest moisture profiles to support
some scattered light rain showers and sprinkles, mainly across
central and northern portions of central NC, this evening and
tonight. The cloud cover and precip will keep it slighter warmer
than previously advertised. Lows 35 to 40.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 150 PM Tuesday...
The core of a deep mid/upper trough will be situated over the Mid-
Atlantic 12z Wed then shifting east and offshore by 00z Thurs with
NW to WNW flow directed over central NC through Thurs night. This
feature will provide deep layer forcing for ascent overspreading an
area over the northern/central Coastal Plain where a nearly
saturated layer up to 700mb will be in place as the 850mb front
provides some extra low-level forcing. This pattern will be
supportive of light rain and/or sprinkles during the early morning
into the early afternoon hours, which is hinted at by 12z CAM
guidance. Accumulations will likely be minimal, if any. Expansive
cloud cover will slowly collapse to the ESE throughout the day with
mostly clear conditions expected Wed night.
At the surface, a strong pressure gradient will be in place Wed as
an area of low pressure develops in the western Atlantic and high
pressure over the Mid MS Valley continues to build into the eastern
CONUS. A deep elevated mixed layer will quickly be tapped into Wed
morning as surface heating erodes the very shallow stable layer at
the surface. The result will lead to brisk NW winds gusting up to 20-
25 mph beginning shortly after sunrise and persisting throughout Wed
afternoon.
High pressure will briefly settle over GA and the Carolinas Thurs
morning and provide a few hours of optimal radiational cooling,
especially across the western/southern Piedmont, allowing
temperatures to dip into the mid 20s to low 30s. High pressure will
keep conditions dry and seasonably cool as it traverses across
central NC through Thurs afternoon before shifting offshore,
returning SW flow at the surface late Thurs into early Fri.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 150 PM Tuesday...
The extended forecast will start and end on the quiet side, but be
rather active in the Sun-Mon period. Ridging at mid-levels will
continue to expand eastward from the central US Fri into Sat. In
contrast, a strong shortwave will dig into the central/southern
Plains and will be our weather maker for Sun-Mon. At the surface,
high pressure over the western Atlantic will bring return southerly
flow Fri-Sat and bring our highs back to above seasonal normal in
the upper 50s/low 60s Fri to the mid/upper 60s to near 70 Sat. Some
high clouds will be around Fri into Sat with a southern system
tracking into the SE US but we should be dry with limited moisture.
The main story in the extended in the vigorous shortwave trough
discussed previously over the central/southern Plains Sat that is
forecast in the guidance to track into the OH valley/Great Lakes Sun
evening and into eastern Canada Mon. The system becomes negatively
tilted as it tracks to the NE. Accompanying this mid-level wave is a
surface low that is forecast to track into the Mid-Atlantic, with a
trailing cold front moving through sometime late Sun night. Nearly
all ensemble guidance indicates a high likelihood of precipitation
Sun given anomalous moisture (PW`s 200+ percent of normal at 1.5-1.6
inches), strong lift from the trough/jet streak, and even some
instability. One area where models still differ is in regards to
timing. The latest GFS is the fastest solution, ending precipitation
early Sunday evening, while the GEFS/NAEFS/ECMWF are about 6-12
hours slower, ending rainfall late Sun night to early Mon. An
ensemble approach would favor these slower solutions, with the GFS
an outlier on timing. Precipitation could start as early as late Sat
night to early Sun associated with isentropic ascent with a warm
front. The the main batch of showers appears favored Sun afternoon
into the evening, ending from west to east late Sun night. It could
be rather gusty Sun as well with southerly winds gusting to 25-35
mph and highs still above normal in the mid/upper 60s. As for
rainfall amounts, the range in expected amounts varies from a
quarter inch to three quarters of an inch based on ensemble data,
though higher amounts up to an inch is possible. As for storm
potential, the dynamics support strong shear but the instability is
somewhat lacking. We introduced a chance of thunder on Sun, however,
given a strong fetch of moisture with low to mid 60s dewpoints
advecting into the area. The CIPS/CSU analog severe probabilities
suggest a signal across NC/VA, so the threat of storms will continue
to be monitored as we get closer to the event.
Drier and more seasonal weather is forecast Mon and Tue as zonal
flow takes over at mid-levels and high pressure builds into the area
from the lower Mississippi Valley. Highs should range from the low
to mid/upper 50s and lows in the upper 20s to mid 30s.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 611 PM Tuesday...
VFR conditions are expected at all terminals to start the 24 hr TAF
period. A potent short wave currently moving over the mountains will
move east across central NC tonight. As it moves east, it may
generate a few showers near KRDU between ~02 and 06Z. If showers do
develop, they will likely be light in nature and thus will likely
not produce any sub-VFR conditions at KRDU or elsewhere. These
showers will dissipate with time overnight. A stratocu deck is
expected to develop late Wednesday morning and move from north to
south across the Piedmont/northern Coastal Plain tomorrow. Enough
guidance is hinting at the potential for a brief period of MVFR
ceilings at both KRDU and KRWI to warrant at least some mention.
Thus, have added a TEMPO group for MVFR ceilings at both KRDU and
KRWI from ~14 to 18Z Wednesday with this TAF package. Additional
scattered showers may accompany the lower cloud deck, but should
remain light enough to preclude any sub-VFR reductions in
visibility. Any lingering MVFR stratocu should scatter and lift to
VFR by mid to late Wednesday afternoon. Lastly, nwly gusts of 20 to
25 kts appear likely at all terminals starting mid to late Wednesday
morning, before tapering off near sunset.
Outlook: Dry VFR conditions are expected to dominate through
Saturday. A strong cold front crossing the region will bring likely
to categorical rain chances, strong gusty winds and associated sub-
VFR restrictions to all of central NC late Saturday night and
Sunday.
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Blaes/Hartfield
NEAR TERM...Hartfield/CBL
SHORT TERM...Swiggett
LONG TERM...Kren
AVIATION...Luchetti/CBL