Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/28/23
AREA FORECAST DISCUSSION
National Weather Service Albany NY
954 PM EST Wed Dec 27 2023
.SYNOPSIS...
Mild and overcast conditions persist with occasional showers
through sunset. A period of steadier rain returns tonight with
moderate rain mainly south of Interstate 90. Cloudy and mild
again tomorrow with occasional showers continuing. We stay mild
and cloudy through Friday before cooler and more seasonable
temperatures return this weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 945 PM EST, area of rain now advancing north and east from
the SE Catskills, mid Hudson Valley and NW CT into far SW
Herkimer County, and expanding northeast. Rain should spread
into the Capital Region and central/eastern Mohawk Valley over
the next 1-2 hours. Farther north and east, latest HRRR suggests
rain may erode as it expands north of I-90 for a few hours. So,
have trimmed back PoPs a bit across the SE Adirondacks into
upper Hudson Valley and SW VT. Rain should remain much lighter
in these areas, once it eventually begins well after midnight.
For areas mainly south of I-90, steady rain should be moderate
at times overnight, with perhaps even few heavier bursts across
portions of the SE Catskills, mid Hudson Valley into Litchfield
County, CT. Maximum rainfall rates upstream have been between
0.20-0.30/hour, some of which could eventually approach the I-84
corridor and southern Litchfield County, CT.
Areas of fog developed earlier, some locally dense, however
visibilities have trended upward over the last couple of hours.
Have an SPS for the areas of fog through much of the overnight
period.
Temps should hold fairly overnight, generally in the lower/mid
40s for most areas, except for some upper 30s across portions of
the southern Adirondacks.
[PREVIOUS 433 PM EST]...Temperatures remain mild today in the
40s throughout eastern NY and western New England with not much
of a diurnal range observed given ongoing scattered showers and
low clouds. It feels even milder out there thanks to the strong
southerly flow ahead of the cut-off low that the latest GOES16
water vapor clearly shows positioned out in the Midwest. 12 UTC
ALY sounding shows our freezing height over 7kft with PWATs
approaching 1 inch which is rather anomalous for late December.
Given the saturated column and continued upper level divergence
over the Northeast ahead of the parent cut-off low, scattered
showers have persisted through the day with NYS mesonet, ASOS
and other ground truth stations showing a few hundredths of an
inch of rain falling today up to two tenths in the southern
Adirondacks and parts of western New england where the terrain
enhanced the rainfall amounts.
Rain shower coverage increases as we approach sunset and
especially tonight with temperatures remaining steady and some
patchy fog lingering. GOES16 satellite imagery shows a coastal
low developing off the Carolina coast with a pronounced
baroclinic leaf and the southern jet directing a plume of rich
moisture from the western Gulf of Mexico into the system. PWATs
remain anomalously high tonight at or slightly above 1 inch and
guidance still indicates this low will strengthen and become
better organized as tracks it up the coast and remains in the
right exit region of a upper level jet tonight. An axis of
moderate to potentially even heavy rain develops on the
north/west side of the low within its deformation zone tonight
but the CAMs and high res guidance are in generally good
agreement that the heaviest rain remains to our south and east
closer to the I-95 corridor and closer to the coastal front. The
HREF shows 50-75% probabilities for 3-hourly rainfall rates to
meet or exceed 0.50" in Dutchess, Litchfield, and Ulster
Counties mainly 03 - 09 UTC so a period of moderate rain is
likely for these southern zones, especially given high freezing
levels seen on forecast soundings ranging 7-8kft and a strong
30-40kt southerly mid-level jet maintaining a fetch of moisture
out of the Gulf. Despite wetter antecedent conditions, 3-hourly
flash flood guidance values are greater than 2 inches and given
the progressive nature of the heavy rain, we should not have
flash flooding issues tonight. Expecting about 1 - 1.50 inches
south of I-90 which may result in some nuisance flooding in poor
drainage and low-lying areas tonight but widespread flooding
issues are not anticipated. Further north, expecting lower
rainfall amounts ranging 0.25 - 0.75 inches with lower amounts
expected in the Upper Hudson Valley and west of the southern
Greens in southern VT due to precipitation shadowing effects.
Otherwise, temperatures remain steady tonight in the upper 30s
to low 40s with elevated dew points which will make it feel
mild. We may experience a record high minimum temperature for
December 27 at Glens Falls given mild temperatures last night
and tonight (current record is 40F set in 1949).
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
Steady rain lingers in western New England early tomorrow
morning before finally exiting further east by mid to late
morning. However, with our parent low still positioned to our
west over the Ohio Valley and the column saturated, upper level
divergence will support scattered rain showers through much of
the day. Skies remain cloudy and temperatures mild with highs
once again in the 40s to perhaps near 50 in the valley in some
spots, not changing much of their morning "lows." Dew points
will remain elevated in the 40s as well which will keep it
feeling mild.
Dreary conditions linger into Thursday night as the occluded front
finally tracks from west to east across the region. The enhanced
low-level convergence along the boundary should support a period of
more organized showers as winds shift from north-northwest to
west-southwest. We increased POPs to high chance and even likely
in the higher terrain where westerly flow against the terrain
should enhance rainfall chances. Overall precip amounts should
still be light with QPF amounts only ranging from a few
hundredths to up to a tenth or two.
While the boundary exits to our east by daytime Friday,
unsettled conditions continue as the upper level trough remains
overhead with westerly winds supporting a fetch off the lakes
and therefore cloudy skies. Temperatures remain mild on Friday
but the slightly breezy westerly winds should result in cold air
advection so temperatures should be a few degrees cooler than
previous days.
Breezy westerly wind will support cold air advection Friday
night into Saturday allowing temperatures to trend cooler and
closer to seasonable levels for the weekend. A secondary trough
axis tracks through the region during the day Saturday with
sufficient mid-level moisture as a potent shortwave pushes
through northern New England. This will support another cloudy
day with a period of rain showers for the valley and snow or
rain/snow showers for the higher terrain and hill towns. Lake
moisture may also enhance the coverage of rain and snow showers. Highs
will be cooler in comparison to recent days with temperatures
in the upper 30s to low to mid 40s and lower dew points so it
will feel cooler, especially with the breezy westerly winds.
We finally have a break for drier weather heading into Saturday
night as weak ridging builds into the Northeast, ending the lake
effect response, with subsidence supporting at least partial
clearing skies. Temperatures should drop below freezing for
once, falling into the 20s to low 30s just in time for the final
night of December. Breezy winds should prevent temperatures
from turning too chilly despite some radiational cooling.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Dry and seasonably cool conditions expected for New Year`s Eve
as high pressure builds over the Eastern CONUS. We may even see
some sunshine on Sunday, especially during the first half of the
day, which would be our first time seeing sun in multiple days.
However, clouds look to return the second half of the day as yet
another shortwave tracks eastward across the Great Lakes into
our region. Still uncertainty on its exact timing and intensity
but this could support some additional showers, especially for
areas west of the Hudson River. Temperatures are cool enough to
support snow and with some enhanced moisture off the lake, those
traveling for New Year`s Eve may experience some snow showers
overnight.
Some snow showers may linger into New Year`s Day, depending on
how quickly the upper level disturbance and trough axis tracks
eastward across the region. Temperatures remain seasonable for
New Year`s Day and the first few days of January with generally
dry conditions expected.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Widely varying flight conditions through early this evening,
with mainly LIFR/VLIFR at KGFL due to fog, IFR/LIFR at KPOU/KPSF
due to Vsbys/Cigs, and VFR at KALB. As rain overspreads the
region, expect IFR/LIFR conditions to become more widespread
(between 03Z-06Z/Thu), with IFR/LIFR conditions then most likely
prevailing through most of Thursday with low Cigs and areas of
mainly light rain/drizzle and some possible fog.
Light/variable winds overnight should trend into the north by
Thursday morning at 3-6 KT.
Outlook...
Thursday Night: High Operational Impact. Likely SHRA.
Friday: Moderate Operational Impact. Chance of SHRA.
Friday Night: Moderate Operational Impact. Chance of SHRA.
Saturday: Low Operational Impact. Slight Chance of SHRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
New Years Day: Low Operational Impact. Slight Chance of SHRA...SHSN.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Speciale
NEAR TERM...KL/Speciale
SHORT TERM...Speciale
LONG TERM...Speciale
AVIATION...KL
Area Forecast Discussion
National Weather Service Bismarck ND
914 PM CST Wed Dec 27 2023
.KEY MESSAGES...
- Areas of fog will likely continue through tonight in the James
River Valley, although there could be improvements in
visibility at times.
- Seasonably warm and dry conditions are expected Thursday and
Friday.
- Mostly dry conditions will persist through the weekend and
into early next week, with more seasonable temperatures
expected.
&&
.UPDATE...
Issued at 912 PM CST Wed Dec 27 2023
Outside of an area of mid level clouds moving southwest into
south central North Dakota, the forecast remains on track for
tonight. Low stratus remains across the James River Valley,
though any impactful fog remains off to our east across the Red
River Valley region.
&&
&&
.UPDATE...
Issued at 547 PM CST Wed Dec 27 2023
The forecast for tonight remains on track. Low stratus and fog
will linger through most of tonight across the James River
Valley, and just made a few minor tweaks to sky cover for this
evening based on latest satellite imagery, and it seems the
latest RAP may have the best depiction of the low clouds. Area
web cams show some fog in my southeast, though visibility seems
OK at the moment so let the Special Weather Statement expire
earlier. Will continue to monitor this evening in case any
elevated wording/products become needed once again.
&&
.DISCUSSION...
Issued at 312 PM CST Wed Dec 27 2023
This afternoon, a deep stacked low was placed over Missouri, slowly
moving off to the east and taking our wintry weather with it. Low
stratus extends well to the north of the low, with the northern
edge located from Strasburg, to Wishek, to Montpelier. Areas of
fog have been persistent under this stratus deck across the
southern James River Valley, so we did put out a Special Weather
Statement through the rest of the afternoon for this area.
The remainder of the forecast area is sunny and mild, with only a
few stray high clouds exiting the south central. Temperatures
have warmed up nicely, with forecast highs mainly in the mid 30s
to lower 40s. Interestingly, the Turtle Mountains area is one
of the warmest spots, with 21 UTC obs in the lower 40s at Rolla
and the International Peace Garden (NDAWN sensor). This is
likely from a combination of downsloping winds, sunny skies with
very limited snow/ice cover, and lower albedo from tree cover
compared to surrounding areas.
With forecast soundings showing modest saturation, expected
persistent low stratus, and knowing there is surface saturation
with fresh snow/ice, we continued patchy to areas of fog in the
James River Valley through tonight. Will have to monitor for
more significantly reduced visibilities, since for now obs have
been generally in the 1/2 to 1 mile range, and DOT webcams paint
a similar picture.
The deep low to our south is becoming the eastern portion of an
Omega block, with the secondary upper low well off the coast of
the Pacific Northwest. The tilted central ridge will continue
building into the Rockies Mountains and Northern Plains regions,
leading to dry and seasonably mild conditions Thursday and
Friday. Expect plenty of sunshine and temperatures peaking on
Friday in the mid 30s to mid 40s.
As the upper flow pattern begins to collapse this weekend, a compact
shortwave is projected to drop south from the Canadian Prairies in
northerly flow aloft. Blended guidance continues to keep the
forecast dry on Saturday and Sunday, although with this wave coming
through, can`t rule out some light precipitation from the Turtle
Mountains through the James River Valley. What is more certain is
this shortwave bringing a cold front with it, with temperatures
cooling down on Saturday and then further still on Sunday, bringing
high temperatures closer to normal.
The general pattern expectation is for a sharp, narrow ridge to
build in over the Northern Rockies later in the weekend as the
previously mentioned shortwave moves east. From here, cluster
analysis is broadly in agreement on split flow developing, with the
southern stream focused over the southern CONUS, while the northern
stream keeps very broad ridging over the Canadian Prairies. This
keeps the forecast dry to start next week, with temperatures
moderating again. The focus then turns to precipitation potential
mid next week as split flow condenses and we end up with broadly
northwest flow. NBM temperatures are beginning to advertise a
cooling trend after the first of the year as well.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 552 PM CST Wed Dec 27 2023
Winter storm system continues to move out of the area, with
lingering effects still impacting KJMS. IFR to LIFR stratus
lingers across the James River Valley, with some fog also in the
same general area. Ceilings for KJMS will fluctuate through
tonight from MVFR to IFR, along with some VFR conditions also
mixed in. There also remains potential for fog redeveloping
overnight tonight for KJMS through about 12Z, so did include
this in the TAF. VFR conditions through the TAF period at
KBIS/KMOT/KDIK/KXWA with a mostly clear sky.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...NH
DISCUSSION...Jones
AVIATION...NH
Area Forecast Discussion
National Weather Service Grand Rapids MI
837 PM EST Wed Dec 27 2023
LATEST UPDATE...
Update
.UPDATE...
Issued at 837 PM EST Wed Dec 27 2023
No changes from the previous discussion.
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 218 PM EST Wed Dec 27 2023
- Light rain will increase tonight
The main area of low pressure sets up over the southeast part of
the state later tonight. This system is then shown to retrograde
westward into Thursday night. Moisture deepens up over the CWA this
evening and that will support an increasing potential for
showers. Overall the forcing looks weak. Also the DGZ will be
marginally saturated through Thursday night but moist above and
below. As a result, this will be a light rain/drizzle event with
most locations seeing under a quarter inch of rain, but the
Muskegon basin could have some values over a quarter inch. Most
ensemble members from the various models have measurable qpf for
Grand Rapids and as a result we will feature higher POPs for this
event.
The latest HRRR is generating some fog later tonight and Thursday
morning, especially for southeast parts of the CWA, which we will
feature in the forecast. There is good agreement on this scenario.
All this cloud cover, light precipitation and areas of fog will
act to tighten up the diurnal temperature values into Thursday
night.
.LONG TERM...(Friday through Wednesday)
Issued at 218 PM EST Wed Dec 27 2023
- Rain through the end of the week
The mid to long term period begins with the models in fair agreement
on the location and nature of the upper level pattern on Friday.
The large upper level low will dominate the weather pattern as it
moves through the lower midwest and the Ohio river valley. Showers
will linger through Friday as a band of showers moves on the
backside of the exiting low. The temperatures continue to be mild
into the weekend so any precipitation will remain rain. Highs will
continue to be upwards of 10 to 15 degrees above normal.
- Next chance of snow late in the weekend
As the upper level pattern shifts the models begin to diverge on
the placement of the positively tilted ridge that will build over
Michigan. Drier air will move into the region Saturday. However
another large upper level low will drop down from Canada and through
the Upper midwest Saturday into Sunday. Cold air will accompany this
low. Temperatures will drop down to near normal and that system will
bring the next chance for snow Sunday into Monday. Given how far out
the system is and given the timing issues, are unsure on
precipitation amounts. The northerly pattern does show a signal it
will be lake enhanced and probably strongest along the lakeshore.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 630 PM EST Wed Dec 27 2023
MVFR to IFR ceilings continue with any MVFR ceilings falling to
IFR around 6Z. Toward LAN and JXN LIFR ceilings are expected into
Thursday. Off and on rain showers tonight persist through
Thursday with visibilities mainly around 3 to 5 SM. Toward LAN and
JXN visibilities could drop around 1 SM Thursday morning. North to
northwest winds become more northeasterly during the day Thursday.
&&
.MARINE...
Issued at 218 PM EST Wed Dec 27 2023
The pressure gradient will tighten up over the nearshore waters
tonight and remain relatively tight into Thursday. North winds
will increase as a result and gusts will likely top 20 knots at
times. Thus a small craft advisory will be issued. The highest
waves will be off of Little and Big Sable points and on down
towards the South Haven region. Values may reach 5 feet there.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 4 PM EST Thursday for LMZ844>849.
&&
$$
UPDATE...RAH
SHORT TERM...MJS
LONG TERM...Ceru
AVIATION...RAH
MARINE...MJS
Area Forecast Discussion
National Weather Service Indianapolis IN
934 PM EST Wed Dec 27 2023
.Key Messages...
- Patchy dense fog over northeast portions of central Indiana
tonight
- Rain transitioning to snow over SW central Indiana tonight.
Minimal accumltions on elevated and grassy surfaces
- Snow chances once again Friday night; highest risk of a dusting
are over western central Indiana
- Seasonable temperatures persist through the weekend
&&
.Forecast Update...
Issued at 934 PM EST Wed Dec 27 2023
- Cloudy and mild
- Scattered rain showers, possibly mixed with snow late tonight
Surface analysis this evening showed low pressure in place over
eastern MO. This low was associated with a cut off upper level low
pressure system, also found over SE MO. GOES16 shows a classic
cyclone cloud formation over the middle Mississippi Valley, nudging
eastward toward Indiana. An area of light showers were found pushing
into southwest Central Indiana, flowing north, influenced by the
cyclone to the west. Skies were cloudy across Central Indiana and
temperatures were mainly in the lower 40s with dew points in the
middle 30s.
Models overnight suggest a slow SE progression of the upper low.
This will slowly spread the stronger cyclonic flow into Central
Indiana, along with scattered showers, HRRR suggests the showers
will remain mainly within the Wabash Valley through the night. Some
additional development will be possible across the northern parts of
the forecast area as cyclonic flow increases. Still overall
available moisture remains minimal and precipitation amounts will be
light.
Forecast soundings keep much of the column above freezing within the
lower levels of the column, promoting a change over to rain as any
frozen precipitation falls. Also current dew points across the area
remain in the mid 30s. Thus a few snowflakes are possible, but any
accumulations will be very limited. Overall we will aim for cloudy
skies with chances for rain, a few snowflakes possible and lows in
the mid 30s. Overall, the ongoing forecast handles this quite well.
&&
.Short Term...(This evening through Thursday)
Issued at 254 PM EST Wed Dec 27 2023
The short term period will be largely influenced by a large broad
mid-upper level low slowly tracking through the region. Currently at
the surface, ridging across the region has allowed for a nice mild
winter day today. Expect clouds to continue increasing through the
overnight hours as the system approaches from the west. Much of the
area will likely remain dry through tonight, but most high-res
models are in good agreement that a band of precipitation will
develop near far southwest portions of central Indiana late tonight
towards daybreak Thursday. Thermal profiles may be just cold enough
for snow to mix in. Accumulating snow is unlikely due to warm ground
temperatures, but light accumulations on grassy surfaces cannot be
ruled out if precip rates are high enough.
The aforementioned band of precipitation, likely induced by
deformation, will begin to weaken after daybreak. Additional showers
are then possible as PVA and diffluence aloft promotes cyclogenesis.
Coverage will likely be greatest from Thursday afternoon through the
overnight hours. Thermal profiles suggest precip type will
predominately be rain during the day, but snow is expected to mix in
once temperatures begin to gradually fall after sunset. Light
accumulation will be possible on grassy surfaces. However, impacts
are unlikely due to marginal surface temperatures. Patchy fog will
be possible again tonight, especially across the eastern half of the
area where surface ridging should help keep winds very light.
&&
.Long Term...(Thursday night through Wednesday)
Issued at 254 PM EST Wed Dec 27 2023
Thursday night and Friday...
The aforementioned low will sill be
centered over Indiana on Friday with scattered rain/snow showers
possible. No impacts are expected with this. Gloomy conditions for
much of the period will greatly limit diurnal temperatures
swings. Look for highs in the upper 30s to low 40s and overnight
temperatures in the low-mid 30s.
Friday night through Tuesday...
Following the low passage on Friday, high pressure will build within
AVA leading to broad subsidence over the region. Without a strong
baroclinic zone, resulting temperatures this weekend will trend
towards seasonal; highs near 40 and lows in the mid to upper 20s.
There are some hints towards a mostly dry frontal passage late
Sunday attached with a back door low pressure system over Quebec.
This may lower temperatures slightly for Monday, but they should
quickly moderate to seasonal during the middle of the week.
&&
.Aviation...(00Z TAF Issuance)
Issued at 610 PM EST Wed Dec 27 2023
Impacts:
- VFR Conditions expected through this evening
- MVFR/IFR ceilings with isolated showers possible late tonight into
Thursday
- IFR/LIFR ceilings likely during the day Thursday
Discussion:
Little change in the ongoing forecast.
VFR Conditions are expected to continue for the next 6-10 hours as
the cut-off cyclone over SE Missouri slowly pushes southeast. As
the low arrives, flying conditions will deteriorate toward MVFR and
IFR for much of Thursday.
Cigs are expected to fall to IFR late tonight as the low arrives.
Models show saturation in the lower levels arriving late tonight,
and this persists through Thursday. Thus have trended here toward
IFR cigs with fog possible. This will persist through much of
Thursday as the low remains in the vicinity of the TAF sites.
Confidence on timing for any precipitation at any specific location
is low. Thus have used large windows of VCSH to account for the
light stray showers rotating around the low.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...Melo
Long Term...Updike/Melo
Aviation...Puma
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
902 PM CST Wed Dec 27 2023
.UPDATE...
Issued at 858 PM CST Wed Dec 27 2023
Observed temperatures so far this evening have either tracked with
the forecast or a degree or two warmer, maintaining high confidence
that snow will have trouble sticking to paved surfaces. Even beneath
more intense pockets of snowfall this evening, both live camera
feeds and reports have shown that accumulation has been limited to
elevated and grassy surfaces. Furthermore, DOT travel maps continue
to show clear roads and flowing traffic across a majority of the
area. Recent radar imagery from both the KLSX and KILX WSR-88Ds show
a weakening and contraction of the primary band of more intense
snowfall currently stretching across southwestern Illinois into
eastern Missouri. This is coincident with eastward moving and weakening
frontogenesis and lift seen in recent RAP analysis. Therefore,
while I still can`t rule out a pocket of relatively higher
accumulations (1-3") over portions of eastern Missouri where
colder temperatures and higher snowfall rates overlap, my
confidence is lower now (30% down from 50-70%) in this occurring.
In general, light snow will continue overnight as the core of the
upper-level low shifts eastward, coming to an end from north to
south through the early morning hours as drier air moves in.
Upstream trends show that precipitation may end as mostly rain as
the colder temperatures move eastward with the low and the
dendritic growth zone dries.
Elmore
&&
.KEY MESSAGES...
- Light snow will continue through Thursday morning around sunrise.
A band of higher snowfall rates is developing across east-
central Missouri and locations under this band could see upwards
to 2 inches of snow accumulations by Thursday morning.
- Largely unimpactful light snow is forecast to begin Thursday afternoon
through Friday morning.
- Dry weather with near normal temperatures expected Friday through
early next week.
&&
.SHORT TERM... (Through Friday)
Issued at 238 PM CST Wed Dec 27 2023
The latest regional surface analysis shows a surface low pressure
system located over central Missouri with an occluded front
extending across northern Missouri and south along the
Mississippi River. Temperatures west of this occluded front are
in the low- to mid- 30s with temperatures east of the front being
in the upper 30s to low 40s. Where temperatures are near in the
low to mid 30s, precipitation has fallen as snow or a rain/snow
mix in a south to north direction.
A frontogenetical band is developing across east-central
Missouri, near the I-70 corridor in Missouri. Within this band is
where the highest snow accumulations are forecast despite the
relatively warm grounds. This is due to higher snowfall rates
within the band being able to overcome the warmer surfaces. Snow
accumulations within this banded area of snow are forecast to be
upwards to 2.0 inches, with the greatest accumulations being on
grassy and elevated surfaces and with some slush possible on
roads. Locations outside of this band will continue to have wintry
precipitation (where temperatures are cold enough).
Wintry precipitation will continue as the surface low treks east-
southeastward through Thursday morning. Temperatures area-wide will
drop into the low- to mid- 30s after sundown this evening, so areas
across western Illinois where rain or a rain/snow mix is will switch
to primarily snow. Snow accumulations are expected to be low with
the light nature of the snow and relatively warm ground surfaces.
Locations that have greater snowfall rates may see upwards of
0.5 inches of snow accumulation by Thursday morning.
Once the surface low is east of the region deep northerly flow will
take over with much of the late morning and early afternoon hours on
Thursday are forecast to be cloudy and dry. An upper-level low
(latest water vapor imagery shows this upper-low over central
Missouri) will be east of the CWA. Deterministic guidances show that
multiple areas of of positive vorticity advection (PVA) will
round the back side of this upper-level low Thursday afternoon and
provide another chance (50-80%) of widespread light snow Thursday
afternoon through Friday morning. Model soundings are showing
that lift within the dendritic growth zone will be marginal and a
slot of more unsaturated air will be present in the low levels,
furthering confidence that snowfall rates will be light. Given the
expected light snowfall rates, lower QPF, and warm grounds, this
event looks largely unimpactful.
MMG/Britt
&&
.LONG TERM... (Friday Night through Next Wednesday)
Issued at 238 PM CST Wed Dec 27 2023
Expect generally dry weather over the area from Friday night through
next Tuesday. The latest run of ensemble guidance is showing that
the upper low will shift east of the area by Friday night followed
by a shortwave ridge that will move over the Midwest early in the
weekend. There will be another trough that will move across the
Great Lakes on Sunday which will keep the best moisture and lift
northeast of the CWA. Then another ridge will move across the area
Monday and Tuesday before the next trough brings a slight chance
(20%) of precipitation to the area by next Wednesday.
High temperatures are going to be at or just below normal as 850mb
temperatures will be in the 0 to -10C range through the period.
Temperatures will cool down a bit on Sunday and Monday behind an
attendant cold front associated with the aforementioned trough that
will move through the Great Lakes.
Britt
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 528 PM CST Wed Dec 27 2023
Impacts are expected through much of tonight and tomorrow morning
at all local terminals as a weather system spins over the area.
This system is producing an arcing band of light rain and snow
that is currently impacting all local terminals. Through tonight,
this band will begin to slowly drop south and intensify along the
Mississippi River, impacting KSUS, KSTL, and KCPS. It currently
remains uncertain where the heaviest snow will be in proximity to
these three terminals as the band moves overhead, and while I`ve
only gone with a TEMPO to address impacts, impacts could be more
consistent with the band. As precipitation comes to an end through
late tonight and tomorrow morning, rain may mix in with the snow.
Overall, warm ground temperatures and air temperatures hovering
right above or at freezing is expected to limit accumulation on
paved surfaces.
Conditions will improve gradually through the day tomorrow ahead
of our next system that will move in from the north and begin
impacting local terminals at the end or just beyond the end of the current
TAF period.
Elmore
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Raleigh NC
925 PM EST Wed Dec 27 2023
.SYNOPSIS...
Surface low pressure will track from the Outer Banks northward along
the Mid Atlantic coast through tonight. Weak high pressure will
build briefly over the Southeast states on Thursday. A large upper
level low will track slowly east southeast from the Midwest across
the Ohio Valley to the Mid Atlantic region through Friday night.
&&
.NEAR TERM /TONIGHT/...
As of 925 PM Wednesday...
In the last several hours, the surface low has made its way slowly
northward to the southern Outer Banks, in tandem with the movement
of the 925-850 mb trough, oriented WNW-to-ESE across north-central
and eastern NC. The rain has mostly exited our area with the slow
lifting-out of the low level low/trough and exit of weak mid level
perturbation rotating around the E side of the larger mid-upper low
centered over E MO. However, some very patchy drizzle will persist
until the gradual arrival of drier surface-based air from the west
later tonight, although the low clouds will slowly disperse
overnight, esp across the S and W. High clouds will continue to
streak across the region tonight with the 150+ kt upper jet coming
out of the NE Gulf, although this will shift E overnight, and our W
sections will see some thinning at sunrise. Overall, most of the
area will stay mostly cloudy to cloudy overnight, with any precip
will be extremely light and fleeting, although some patchy fog will
linger overnight over the N and NE. Temps will stay mild, with
current readings in the mid 50s to lower 60s dropping to lows in the
mid 40s to lower 50s. -GIH
Earlier discussion from 215 PM: As of 2pm, the RAP showed a surface
low just off the coast of Wilmington moving to the northeast, which
is now the primary weather-maker for the region. The bulk of
rainfall with the low remains near the coastline, although there is
a narrow band of rain extending from Virginia south into Roxboro,
Durham, and Fayetteville. The central portion of the forecast area
appears to be the focal point of rain over the next few hours,
although have kept some higher chances of rain to the east as well
through the evening hours. The surface low should be near Cape
Hatteras by this evening and off the Delmarva Peninsula by morning.
Despite the low moving away, low overcast skies are expected to
continue through the night. Afternoon highs will peak in the 60s,
but as heights fall aloft, overnight lows should fall into the 40s
everywhere.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 215 PM Wednesday...
Upper energy associated with cyclonic flow will likely produce some
offshore showers Thursday afternoon. Here locally, cloudy conditions
will accompany this upper feature. However, the overall sub-cloud
layer appears too dry in forecast soundings to support any
precipitation on Thursday for central NC (sans maybe a stray shower
in Sampson county Thursday afternoon). Light swly sfc winds will
pick up a bit in the afternoon which will help to maintain
unseasonably warm daytime highs in upper 50s to lower 60s (overnight
lows in the mid 30s).
As we pivot to Friday, a strong vorticity anomaly and associated
upper low will start to exert influence on our area. Recent guidance
has trended more sheared with this upper feature, and remains quite
moisture starved (only a few ensemble members squeeze out any
precipitation over our area). Conceptually, this type of setup
typically leads to very little in measurable precipitation. Decided
to maintain an area of just slight chance POPs for those generally
along and north of I-85 Friday afternoon. Daytime highs will be a
bit cooler (near normal) on Friday in the upper 40s (NW) to mid 50s
(SE).
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY...
As of 310 PM Wednesday...
Former closed upstream cyclone will traverse the area as a vigorous
shortwave trough between 12 to 18z Saturday. Enhanced cloudiness and
virga will be the mostly likely sensible weather impacts with this
system, but still can`t rule out a passing sprinkle/light rain
through midday/early afternoon. Thereafter, strong subsidence will
promote clearing during the second half of the day. Otherwise,
continental airmass from a parent high centered over the southern
CONUS will result in seasonable temperatures over the weekend.
Model spread in both timing and magnitude remains high involving
potential phasing of a weak southern stream energy with a more
dominate northern stream trough diving into the region late New
Year`s Day and into Tuesday. This looks like a classic case of the
cold air chasing the moisture and highly contingent on how far
east/offshore the associated surface low develops. While the latest
12z/27 superensemble probabilities for liquid precip chances have
increased late New Year`s day and New Year`s night, the
probabilities for snow/winter precip remain incredibly low(less than
5%). Thus, will leave precip as all rain/liquid for now. The system
will bring a reinforcement of cold air into the area with seasonable
temps continuing through early next week.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
As of 645 PM Wednesday...
LIFR/IFR cigs remain socked in over RDU/RWI in the vicinity of a
thin band of light rain slowly moving east into the Coastal Plain,
with IFR cigs at GSO/INT and MVFR at FAY. Clearing of the low clouds
is being observed over SC and expected to slowly clear from SW to NE
through tonight into tomorrow morning. 00z forecast slows the
departure of IFR restrictions based on trends and latest guidance.
There is a low chance for a development of VLIFR fog/stratus after
06z at GSO/INT, but confidence was too low to include at this time.
To highlight this potential, 00z TAFs included a TEMPO for a more
optimistic fog/stratus layer development during this time.
Outlook: A passing area of light rain falling out of VFR cloud bases
will be possible Fri afternoon/evening, mainly at GSO/INT.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield/Green
SHORT TERM...Luchetti
LONG TERM...CBL
AVIATION...Swiggett