Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/24/23
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
827 PM CST Thu Feb 23 2023
.UPDATE...
Issued at 820 PM CST Thu Feb 23 2023
Main overnight concern is low temperatures. Mostly clear skies,
light winds and a dry airmass should lead to some lows in the 20
below range. Dewpoints upstream are in the teens below zero
already, so will stick with current forecast.
&&
.SHORT TERM...(This Evening through Friday Night)
Issued at 244 PM CST Thu Feb 23 2023
After this multi-day winter storm, we will have nice quiet weather
heading into tonight. The main concern is the very cold
temperatures/low wind chill values overnight. There could also be
some flurries/light snow across the area Friday afternoon into the
evening but confidence remains low on that.
ECMWF/GEFS ensembles indicate a positive tilted trough/low over the
Northwest Coast bringing zonal flow to our area this evening. It
also indicates a slight neg tilted ridging pattern over the Rockies
bringing more of a west/southwest flow overnight into Friday midday.
A split flow pattern then occurs as this trough and low move south
with the low breaking off from the main flow through the day Friday.
A shortwave will also be moving across the upper US and Canada
Friday into early Saturday (flattening the ridge). A few CAMs, along
with Bufkit soundings, do indicate some possible spotty light
snow/flurries due to some low level moisture/lift in the DGZ zone
Friday afternoon and into the evening time. Deterministic
models/Cams really are not in sync with each other with this chance
of precip, location wise. NBM really does not show much in the form
of precip at all. So I went ahead and added in some slight chances
of Pops during this time frame, keeping it more widespread at this
time. At the surface, an elongated 1044mb high will be positioned
over Alberta around 00Z Friday and then pretty much overhead into
early Friday morning before pushing east/southeast early Saturday as
this trough moves in.
With the exiting low and incoming high, pressure gradients will
become lighter, with wind directions still out of the
north/northwest through the afternoon/evening, per Rap model, and
remain calm/light overnight. With the passing of the shortwave,
winds creep back up a bit Friday afternoon into Saturday morning up
to 20kts. Could see some higher gusts off the Coteau early morning
Saturday.
Even though 850mb low level winds will be out of the southwest, that
"warmer air" will stay aloft overnight due to the light winds at the
surface/850mb creating limited mixing, therefore temps will tank
overnight near the surface, especially with the new snow pack.
Models indicate 925mb temps at 12Z Friday will be around -21C to -
25C per ECMWF! Overnight lows will range from -15 to -25F with
windchill values as low as -35F. Due to this, a wind chill advisory
has been issued and will go into effect at 6PM this evening through
Friday morning. Chilly temps will continue Friday with highs around
-2 to 5F, with the exception of south central SD where temps could
be around 10 to 13F. Friday night will be cold once again (but not
as cold) with values ranging from -1 to -14F and wind chills as low
as -25F.
.LONG TERM...(Saturday through Thursday)
Issued at 244 PM CST Thu Feb 23 2023
Will see upper level ridging and warm air advection building across
the region Saturday into Sunday. Generally left inherited highs
alone for these days, but it will be interesting to see if/what
extent the fresh snow cover has on high temperatures. Focus then
shifts to a storm system moving northeast across the plains Sunday
night. Still appears to be some mild air associated with this, thus
bringing in precip type issues. Generally an eastern CWA issue it
would appear, which is where the highest POPs remain. Another
disturbance moving through possibly mid-week, but will wait for
better model agreement before POPs get any higher than 20/30 percent.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 511 PM CST Thu Feb 23 2023
Terminals KABR,KATY,KPIR,KMBG
VFR skies/vsbys are expected through tonight regionwide.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Chill Advisory until 10 AM CST /9 AM MST/ Friday for
SDZ003>011-015>023-033>037-045-048-051.
MN...Wind Chill Advisory until 10 AM CST Friday for MNZ039-046.
&&
$$
UPDATE...TDK
SHORT TERM...MMM
LONG TERM...TMT
AVIATION...TDK
AREA FORECAST DISCUSSION
National Weather Service Albany NY
1012 PM EST Thu Feb 23 2023
.SYNOPSIS...
A low pressure system and a cold front will bring a light
wintry mix tonight. Much colder and windy conditions will occur in
the wake of the cold front on Friday. High pressure briefly builds
in Friday night into early Saturday with cold conditions. A weak
disturbance will bring some light snow to eastern New York and
western New England mainly Saturday afternoon into early Saturday
night. A more significant winter storm may impact the region Monday
night through Tuesday with snow or mixed wintry precipitation.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A Winter Weather Advisory for the southern Adirondacks, Lake
George Saratoga Region, Mohawk Valley, Greater Capital Region,
northern Taconics, Schoharie Valley, the Helderbergs and
northern Catskills until 1 AM EST...
A Winter Weather Advisory for all of western New England until
4 am EST
UPDATE AS OF 10 PM...Convective rain and freezing rain showers
have overspread the region more heavily concentrated across the
Eastern Catskills, Upper-Hudson Valley, Mid-Hudson Valley,
Taconics, Southern Vermont and the Berkshires. With temperatures
on the rise for the next few hours, expect mainly rain south of
the Lake George-Saratoga region. Current Showalter Index values
are indicative of sufficient instability, therefore, added
isolated thunder to the weather grids for Albany and areas to
the south where a rumble or two is possible.
The forecast remains relatively on track for this update, though
low temperatures continue to present a challenge. With heavy
cloud cover throughout the area and southwest winds holding
warmer air at the surface, a non- diurnal effect on
temperatures will persist for the next couple of hours. However,
upon the full progression of the front later tonight, winds
will shift to the northwest, advecting cold air into the
region. Based on latest model runs, temperatures should drop
fairly quickly, though how quickly and to what degree remains
the question. The HRRR and FV3 were fairly aggressive where the
NAM3k and RGEM were a little more mild. So, went with a model
blend that kept lows at a fair compromise of upper teens to low
30s with pockets of low teens in the Adirondacks.
UPDATE AS OF 630 PM...KENX radar shows precipitation currently
overspreading the Southern Adirondacks and northern-most points
of the Upper-Hudson Valley. ASOS and NY MESONET obs are
reporting this precip as light freezing rain. Consequently, the
forecast remains on track as low pressure continues to push
eastward from the Great Lakes region. Temperatures were minorly
adjusted with this update to reflect current observations of
upper 20s to low 30s from the Capital District northward as well
as southern Vermont, the Berkshires and Litchfield Hills, and
mid to upper 30s in the lower Mid- Hudson Valley.
A southwest-northeast oriented band of more convective showers
is approaching from central NY/north-central PA is currently
moving just to the western boundary of the CWA. Within this band
are some more enhanced showers that could bring brief periods of
heavier freezing rain. However, this shouldn`t affect expected
ice accretions of less than 0.1".
PREVIOUS DISCUSSION...
As of 415 PM EST...Subtropical ridging continues to attempt to
build in from near Florida, the lower Mid Atlantic Region and
the western Atlantic. A potent mid and upper level jet stream
with multiple disturbances in the west/southwest flow will
continue to impact the forecast area into tonight. Low pressure
is approaching from Michigan and the eastern Great Lakes Region.
Freezing drizzle has been problematic north of the frontal
boundary over east-central PA into NJ and south of Long Island.
Temps have warmed above freezing in the mid Hudson River Valley,
southern Taconics and eastern Catskills, but have been stuck in
the 20s to below freezing elsewhere. We elected to raised
another Winter Weather Advisory flag now for the light freezing
drizzle for all of western New England and from the Capital
Region, Schoharie Valley and northern Taconics northward. This
will capture the freezing drizzle with any ice accretions and
the batch of light mixed pcpn coming tonight, especially before
1 am. Coating to a tenth of an inch of flat ice amounts are
possible.
Temps are likely going to rise tonight just above freezing into
the Capital Region, Taconics, and perhaps the Mohawk Valley,
southern reaches of the Lake George Region. This will be due to
the southeast/east flow ahead of the wave. Model soundings from
the NAM/GFS/3-km HRRR show mixed pcpn in the form of sleet and
freezing rain are likely along and north of I-90 due to lack of
ice in clouds and the elevated warm nose early on. Portions of
western New England including the Berkshires and Litchfield CTY
have been stuck in the subfreezing, shallow cold air. Additional
light ice accums are possible. We did keep the advisory going
until 4 am for the western New England zones, but this likely
can be dropped a little early as the wave and front zip through.
Speaking of the front, it is a strong one with a decent theta-e
gradient and some elevated instability is present with the wave
and boundary. Showalter values get close to 0 to +1C on the NAM,
and some of the CAMs have a narrow convective line from roughly
the Capital Region south moving through just before or just
midnight. A rumble of thunder is possible over the southern most
zones. Colder air rushes into the forecast area in the early to
mid morning hours. It will become windy prior to daybreak. Some
spotty outages may occur with ice on some tree limbs being
downed especially across portions of western New England, the
Capital Region and the the Taconics. The winds will shift from
the south/southeast at 10-20 mph to west/northwest at 10-20 mph
with gusts 30-40 mph. Lows will be in the upper teens to upper
20s with a few lower 30s in the mid Hudson valley, and single
digits over the southern Dacks. Some surfaces may be slick in
the wake of the front. Light snow accums of a dusting to less
than an inch are possible across the western Dacks, western
Mohawk Valley, and the eastern and northern Catskills in the
wake of the wave. Some upslope snow showers may yield some light
snow accums along the southern Greens and northern Berkshires.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Wind Advisory for Berkshires County 5 am EST to 7 pm EST
Friday...
Tomorrow...Blustery and cold conditions engulf the forecast area
with temps steady or falling through the day. The latest NAEFs
has 850 hPa temps tumbling to -1 to -2 STDEVs below normal.
Strong cold advection occurs in the wake of the front. The
actual H850 temps fall to -15C to -20C from the Capital Region
north and west during the day, and -10C to -15C to the south and
east. Any wet surfaces will become encased and crusted into
ice. Additional multi-banded lake effect and upslope snow
showers and flurries continues west of the Hudson River Valley
during the early morning and early pm, and also along the spine
of the southern Greens. Gusty winds will persist through the
morning into the early afternoon. The latest 12-km NAM 925 hPa
jet is about 30-35 KT from the west/northwest. Bufkit soundings
show some potential for momentum transfer to 2-3 kft AGL with
gusts possibly reaching 35-40 KT at KALY. We weren`t confident
for widespread gusts of 46-57 mph for an advisory. We believe
gusts 35-45 mph are possible across eastern NY. As the wave
deepens and intensifies moving towards Nova Scotia/Canadian
maritimes strong winds may persist near the western New England
higher terrain. The best gusts mid morning into the early-mid
afternoon will occur over the Berkshires. We stayed with the
advisory there. Northwest of 15-25 mph with gusts 30-40 mph
will be more common again. Temps will fall from the mid 20s and
mid 30s outside the southern Adirondacks/western Mohawk Valley
where temps will fall from the teens and lower 20s. Wind chills
will be in the single digits to below zero in the afternoon.
Wind chill values may flirt with advisory levels over the
southern Adirondacks and the southern Greens Friday night, as
they will be close to -20F. Elsewhere, wind chills will be in
the single numbers to 10 to 15 degrees below zero. High pressure
will be building in from Great Lakes over NY and New England
Friday night with diminishing winds and very cold conditions. We
went below the NBM mins and closer to a blend of the GFS/NAM
MOS guidance. Lows will be in the single digits to lower teens
along and south of the I-90 corridor, and zero to 10 below to
the north in most areas.
Sat-Sat night...A short-wave trough and clipper like low
approaches from southeast Ontario and the Great Lakes Region
Sat morning into the afternoon. The warm front associated with
the disturbance will increase some isentropic lift with clouds
thickening and lowering with initially isolated to scattered
snow showers by the late morning/early pm becoming a period of
light snow. Light snow amounts of a dusting to half inch are
possible with some half inch to inch plus amounts over the
higher terrain. Some slick spots will be possible. The snow
tapers off early Saturday evening with cold and dry weather
returning. Highs on Saturday will be below normal with teens and
20s and lows with be in the single digits and teens.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
The extended forecast period begins with the eastward progression of
an upper-level, weak shortwave and parent surface clipper just
overhead of the forecast area. This disturbance, aided by sufficient
lift along its surface warm front and requisite moisture transport
off Lake Ontario will pose the chance for snow showers to form
especially in the Southern Adirondacks. Scattered snow showers
cannot be ruled out in the Valleys, Eastern Catskills, Southern
Vermont, and Berkshires as this weak system pushes eastward during
the day Sunday. Accumulations above an inch are unlikely, though
points in the Adirondacks could see up to an inch.
This weak system will continue to push eastward until it moves fully
off the New England coast by Monday morning, allowing narrow, upper
level ridging and surface high pressure to build in in its wake.
Tranquil conditions will then persist through Monday evening/early
Tuesday morning ahead of the next opportunity for wintery
precipitation to overspread the region.
A potent low pressure system will move northeastward from the
southern Plains to the Great Lakes region Monday afternoon through
early Tuesday. This system, with its embedded occluded front looks
to bring widespread snow, and possibly a rain/snow mix in the Mid-
Hudson Valley, to the forecast area Tuesday night through at least
Wednesday morning. At this time, models still show uncertainty
surrounding expected snowfall amounts as well as precipitation type.
While snow looks to be the main precipitation type for most of the
CWA, models suggest that there may be some areas that experience a
rain/snow mix or even just plain rain at times with this storm. We
will continue to monitor conditions as lead time decreases.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 18Z Sat...Low conditions will continue through the first
part of the TAF period. Patches of freezing drizzle continue at
KALB/KGFL at the start of the TAF period with (L)IFR conditions.
Unclear at this time how long the FZDZ will persist, but there are
some signals that it will tend to dissipate around 20Z as low-level
winds may turn southeasterly and erode some of the very low level
moisture. That said, would not be surprised to see it persist into
the evening hours. There is a slight chance that cigs pop up to MVFR
levels briefly this afternoon, but this TAF cycle was more
pessimistic (except at KPSF where an easterly flow has deepened the
boundary layer).
Another round of showers is expected this evening into early tonight
ahead of a frontal boundary. Thermal profiles suggest this will be
rain for KPOU, likely freezing rain at KALB/KPSF (although
temperatures may edge just about freezing at KALB, turning it to
plain rain), and a mixture of freezing rain and sleet at KGFL. The
showers could be briefly heavy, and a rumble of thunder cannot be
ruled out. The time frame is 00-04Z at KGFL, 01-05Z at KALB, and 02-
06Z at KPSF/KPOU. After this boundary passes, cigs will rise to MVFR
and eventually VFR as cold advection takes hold and strong westerly
winds mix out some of the low level moisture.
Winds will be light and variable this afternoon, becoming southerly
at 5 to 10 kt this evening just ahead of the frontal boundary. The
winds will turn westerly and northwesterly, becoming strong late
tonight through the end of the TAF period, with gusts of 25-35 kt
possible. A brief period of low level wind shear is possible at KPSF
02-06Z.
Outlook...
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Moderate Operational Impact. Chance of SHSN...SN.
Saturday Night: Low Operational Impact. Slight Chance of SHSN.
Sunday: Low Operational Impact. Slight Chance of SHSN.
Sunday Night: Low Operational Impact. Slight Chance of SHRA...SHSN.
Monday: Moderate Operational Impact. Chance of SHRA...SHSN.
Monday Night: High Operational Impact. Definite SHSN.
Tuesday: High Operational Impact. Definite SHRA...SHSN.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 4 AM EST Friday for CTZ001-013.
NY...Winter Weather Advisory until 1 AM EST Friday for NYZ032-033-
038>043-047>054-082>084.
MA...Winter Weather Advisory until 4 AM EST Friday for MAZ001-025.
Wind Advisory from 5 AM to 7 PM EST Friday for MAZ001-025.
VT...Winter Weather Advisory until 4 AM EST Friday for VTZ013>015.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...Gant/Wasula
SHORT TERM...Wasula
LONG TERM...Gant
AVIATION...MSE
Area Forecast Discussion
National Weather Service La Crosse WI
539 PM CST Thu Feb 23 2023
.DISCUSSION...(This evening through Thursday)
Issued at 256 PM CST Thu Feb 23 2023
Key Messages:
- Storm winding down with lingering light snow and flurries early.
Turning cold tonight and Friday; coldest wind chills 0 to -20.
- Minor light snow Friday afternoon and Friday night.
- Confidence continues to increase for another significant
precipitation event Sunday night and Monday for a combination of
wintry precipitation and rain, however the details are yet to be
resolved.
.DISCUSSION...
Winter Storm Wrap Up:
The latest WSR-88D shows a little light lingering snow and flurries
as the last vestiges of the 500mb trough/vorticity advection push
through the Upper Mississippi Valley and into the Great Lakes. In
its wake, the prolonged snow/wintry mix event left a band of heavy
snow 6 to 15" across the Midwest from South Dakota, across the
southern half Minnesota and into central and northern Wisconsin.
Near the MPX metro, there were a few 16 to 19 inch reports and
locally, we had some higher 15 to 20" reports, however it is likely
the the drifting made it tough to get accurate totals. The heavier
snow amounts locally were across southeast MN into western and north
central Wisconsin. Farther south, 1 to 5" were reported from
northeast Iowa into southwest Wisconsin. Icing of a glaze to 0.3"
were common for Clayton, Fayette, and Grant counties, however there
were reports of freezing rain as far north as Monroe County with
sleet as well. Locally, our the storm total snow accumulations
through noon were: Rochester had 11.5"-La Crosse airport 9.8"-NWS La
Crosse 8.9".
Water vapor satellite imagery/heights show the trough over the Upper
Mississippi Valley, but it is part of a much larger trough that is
centered off the Pacific Northwest Coast and covers all over the
western U.S. The 500mb trough locally will push east tonight while
the large trough and closed low out west drops south off the
California coast Friday. This potent storm has prompted blizzard
warnings for Los Angeles County for the first time since 1989. While
the low remains closed off to the west, energy moving through Canada
will bring a weaker trough into the region Friday night and Saturday
with another weak ripple Saturday night. Ridging occurs Saturday
into Sunday the the storm system over the Four Corners region.
Sunday night into Monday, the closed low/trough pivots east into
the Plains and Mid-Mississippi with widespread precipitation for
the region. A wintry mix of precipitation
Winter storm winding down-cold tonight-light snow Friday night
The mid-tropospheric wave will continue to exit the area into the
Great Lakes this evening with the surface low off to the east and a
surface trough swinging through. Northwest winds will remain
elevated this evening, however later tonight...the winds lessen and
the colder air and lower dewpoints will filter in. The HREF
synthetic cloud forecast tonight shows the low clouds breaking up
with mid clouds increasing from the southwest late tonight into
Friday. With the fresh snow, did lower low temperatures, however
never sure how low to go. We currently have -5 to -10 below for our
lowest temps near and north of I90. The RAP has some dewpoints -10
to -20, so theoretically, if cloud-free, some spots could drop to
this range north of I90. The HREF shows a 10 to 40% probability of
seeing temperatures colder than -10. Coldest wind chills are zero to
-20, but these could go lower if temps are lowered further.
We remain cold Friday with highs in the single digits and teens
with variable mid clouds. A shortwave trough in the westerly flow
brings a chance for light snow and flurries. There is an isothermal
layer around - 10 deg C. At this time, the precipitation looks to
be light and fast moving. Snow amounts from a trace to 1/2 or 1"
possible Friday night. Currently the higher amounts are north of
I94.
Widespread precipitation Sunday night and Monday:
We continue to watch the significant storm system for Sunday night
and Monday. Widespread precipitation looks likely and a mix of rain
and a wintry mix are forecast. There are still some significant
differences in the track and evolution of the storm. The 23/00z
mean long range grandensemble QPF has 0.5 to 1.25" of liquid/melted
precipitation with higher amounts for northeast Iowa and southern
WI. The highest probabilities for impactful snowfall with the grand
ensemble is from central into northeast Wisconsin with 4" or more of
snow. There will be a transition zone from rain to freezing rain
with the cold temperatures in place. The 23/12Z GFS/EC have come
into better agreement with the surface low track across Iowa,
however there are still thermal/strength differences. Liquid/melted
precipitation remain significant between .5 and 2". It will be
hard to lose our 6 to 14" of snow in a short time, thus there will
be additional impacts due to the intact snowcover and re-freeze.
Stay tuned over the next few days as we iron out the details.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 540 PM CST Thu Feb 23 2023
Flurries, associated lower visibilities, and lower cigs expected
to exit the forecast area tonight with the surface low. High
pressure shifts in, relaxing winds. While saturation-prone high
resolution soundings want to saturate low levels and bring in fog,
dewpoints are very low and winds off deck should mix lowest
levels. Upstream wind profiles exhibit off deck mixing winds well.
Therefore, have not introduced restrictions overnight (i.e., fog). Light
snow chances increase post 24.00Z TAF period. VFR conditions
primarily expected throughout the period. May waiver into MVFR
cigs towards end of the period at KRST, too low of confidence to
include or introduce at this time however.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
DISCUSSION...Zapotocny
AVIATION...JAR
Area Forecast Discussion
National Weather Service Charleston SC
958 PM EST Thu Feb 23 2023
.SYNOPSIS...
High pressure will prevail through tonight, before a cold front
drops in from the northwest Friday and stalls to our south.
Another cold front will move through early Tuesday, followed by
high pressure into Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The forecast area will remain between a backdoor cold front to
the north and high pressure over Florida. This pattern should
support light and steady southwest winds. The steady winds and
thickening high clouds should keep cooling limited through the
night. It is possible, that temperatures will remain record-
breaking high minimum temps (see Climate section below). Minimum
temperatures should favor values in the mid 60s. Guidance
continues to indicate that sea fog will expand off the GA coast
during the pre-dawn hours. The forecast will continue to feature
patchy fog across a portions of the marine zones.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
Friday: The day will begin with some patchy fog south of I-16 in
Georgia, but this potentially quickly ends by 8 or 9 AM with rapid
warming. Meanwhile, high pressure extends from the southwest
Atlantic across Florida and into the eastern Gulf of Mexico, a cold
front sags south into the local counties. The fronts progression
into and across the area is rather slow due to the front aligned
parallel to the flow aloft. There is sufficient moisture transport
across the region with PWat approaching 1.50 inches across South
Carolina, and with the proximity to the front and decent upward
vertical velocities, we look for the development of isolated to
scattered showers, mainly in the afternoon. There is even enough
instability/CAPE to allow for isolated t-storms to occur. But no
risk for severe weather. Compressional heating in advance of the
front with a deep westerly flow through the vertical allows for
another unusually warm day and close to record levels (see CLIMATE
below).
Friday night: The front eventually makes it near or south of the
Altamaha River. While instability/CAPE diminishes forcing from the
front, and also with isentropic ascent developing atop a low level
easterly flow behind the front, we maintain mention of isolated to
scattered showers through the night, especially in South Carolina.
The thunderstorms risk drops off with sunset. There is a slightly
cooler air mass in wake of the front, so most places look to drip
into the 50s.
Saturday: The front looks to become more diffuse, with the
development of a weak wave of low pressure or coastal trough not
far offshore. There remains enough moisture and lift to keep the
risk for isolated or scattered showers in the forecast. Guidance
provides mixed signals regarding temps, and is dependent upon how
extensive the low cloud cover is, and the strength and southern push
of the inland high pressure wedge. It`s likely one of the events
where we have close to a 20 degree spread from locations near the
Santee River to those close to the Altamaha River. For now we have a
spread of mid 60s in Berkeley County to as high as 80-82 degrees in
some places south of I-16 in Georgia.
Sunday: The wave of low pressure over the Atlantic lifts northeast
and slowly starts to deepen as short wave energy arrives aloft.
Across the immediate counties there is a band of moisture that
persists, but with isentropic downglide and the lack of forcing, we
have a rainfree forecast. If there is enough insolation, with a deep
westerly flow and 850 mb temps as high as 11-13C, max temps will be
far above climo, with many places of 80-85 degrees over Georgia and
away from the coast.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Much of this period features zonal flow or flat ridging aloft, with
the passage of fast moving cold front late Monday or early Tuesday,
followed by high pressure into mid week, before it pulls offshore
Thursday. There is some forcing from a short wave aloft with the
cold front, but due to little to no low level convergence and only
limited moisture, the prospects for rain look low. We have just
slight chance PoPs Monday night as a result. temps remain well above
climo through the entire period as meteorological winter comes to an
end Tuesday, and meteorological spring begins on Wednesday.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR conditions with light SW winds is forecast to continue
across KCHS/KJZI/KSAV into the early daylight hours Friday
morning. A backdoor cold front will approach KCHS/KJZI during
the morning hours, timed to reach the SC terminals by the
afternoon. Forecast soundings and MOS indicate that MVFR
ceilings will develop at KCHS/KJZI, starting at 15Z and ending
before 22Z. In addition, a round of light showers is expected to
accompany the backdoor cold front, highlighted with a TEMPO
between 18-22Z for KCHS/KJZI. KSAV is expected to observe MVFR
ceilings between 11-15Z. Winds are forecast to turn from the NNE
by late Friday afternoon.
Extended Aviation Outlook: Flight restrictions are possible at times
for all terminals Friday afternoon into Saturday, mainly with
showers and perhaps isolated thunderstorms associated with a
passing cold front, then with a coastal trough/low developing
nearby. VFR conditions should then prevail through Monday before
a second front and maybe isolated to scattered showers are
possible late Monday/early Tuesday.
&&
.MARINE...
Tonight: Southwest flow will prevail across the local waters through
the period. However, the pressure gradient will relax, causing winds
to gradually weaken while tipping slightly more west late. In
general, wind speeds should range between 10-15 kt. Seas should also
gradually subside to 2-3 ft. Although westerly winds are not
favorable for sea fog development, they will become light and when
combined with low 60 dewpts crossing over slightly cooler waters
could result in patches of sea fog developing across southern South
Carolina and Georgia nearshore waters approaching daybreak.
Friday: A backdoor cold front dips into the northern waters late,
while high pressure holds to the south. Not much in the way of wind
or wave action, but there is the risk of isolated t-storms due to
the nearby front.
Friday night and Saturday: Conditions will dramatically change as
the cold front continues to drop south across the local waters,
clearing the South Carolina zones by around midnight or a bit later,
with the front to maybe make it near or just south of the Georgia
waters by early Saturday. The front then washes out while an
inverted trough forms over or nearby Saturday. There is a
considerable surge of NE winds behind the front Friday night into
early Saturday with a tightening of the gradient and some cold
advection to mix some of the 30-35 kt winds just off the surface.
This will result in solid Small Craft Advisory conditions for
AMZ350, and maybe for AMZ352. After coordination with WFO ILM, since
this is a 3rd and 4th period concern, we opted not to raise the
advisory just yet. But it will happen.
Sunday through Tuesday night: We might have another risk for Small
Craft Advisories ahead of a cold front Monday night, otherwise winds
and seas remain below advisory thresholds.
Sea fog: Given somewhat favorable conditions, we have added mention
of patchy fog to the waters out 20 nm and to the south of Edisto on
Friday. The HREF actually has probabilities of less than 2 nm as
high as 70-75%, while the SREF shows 40-60% chances of less than 3
nm. With both the NBM and HRRR showing visibilities down near 1/2,
we`ll need to certainly keep watch for a Marine Dense Fog Advisory.
&&
.CLIMATE...
Record High Temperatures:
A record high temperature of 85 was set at Savannah GA today.
This broke the old record of 84 last set in 2022.
February 24:
KCHS: 84/2022
KCXM: 81/1930
KSAV: 86/2012
Record High Minimum Temperatures:
February 23:
KCHS: 62/2012
KCXM: 62/2022 and previous
KSAV: 65/2012
February 24:
KCHS: 61/2018
KCXM: 63/2018
KSAV: 64/1980
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...DPB
CLIMATE...
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
508 PM CST Thu Feb 23 2023
...AVIATION UPDATE...
.DISCUSSION...(This evening through Thursday)
Issued at 215 PM CST Thu Feb 23 2023
Key Messages:
* A quick passing upper level disturbance should bring a dusting
of snow to much of the local area late this evening and through
the overnight hours, but less than one inch of total snowfall
accumulation is expected.
* Wind chills of 10 to near 20 degrees below zero expected to
start the day on Friday.
* Warmer this weekend with a chance of Thunderstorms expected
Sunday evening.
* An active weather pattern continues with seasonably warm and dry
weather to start next week, with yet another upper level
disturbance expected to impact the local area late week.
After a very cold and blustery start to they day, temperatures
have "warmed" a bit this afternoon, although they remain 20 to 30
degrees below seasonal norms. Expect one more extremely cold
night tonight, with the saving grace being the lighter winds and
increasing cloud cover late in the evening, which should keep wind
chill values from reaching more dangerously cold levels again to
start the day Friday. Even so, it will be a cold and potentially
white start to the day tomorrow, as a quick moving disturbance
overnight will bring a chance for some light accumulating snowfall
by daybreak Friday. Most of the mesoscale models are picking up
on a light band of snow forming just before midnight tonight, with
a few tenths to just under one inch of total snowfall
accumulation possible. Nothing significant is expected given the
quick moving nature of this disturbance and the limited moisture.
As skies clear during the morning hours Friday, expect light
south to southeasterly winds to help advect warmer air our way,
although highs are still expected to be well below normal (in the
20s and lower 30s) for most locations tomorrow afternoon. After
the passing disturbance tonight, expect the upper level flow to
become more amplified with pronounced ridging aloft expected for
Saturday as temperatures soar back above normal, potentially to
near 50 across portions of north central Kansas. These warm
temperatures should then continue into Sunday, as a closed upper
level low across the southwest lifts into the plains. This low
will bring with it forcing for some shower and potential
thunderstorm activity Sunday into Sunday night, as a bit of
instability builds across most of the local area by Sunday
afternoon. At this time, severe potential looks limited given the
fairly weak instability across the area and modest shear, and not
surprisingly, the local area is now outside the 15% probability
line for severe weather from the SPC today.
Not mentioned in the actual forecast is the small chance for a
little fog and possibly some drizzle to start the day Sunday ahead
of the main upper level low, as moisture surges from the south.
Both decent SREF probs for fog as well as a slight signature for
drizzle are apparent in this afternoons model data, but confidence
was too low to insert this into the forecast at the moment.
Behind this system, west southwesterly flow aloft will continue
across the local area for much of the week with generally mild
temperatures and dry weather through mid-week ahead of yet another
upper level system which could reach the local area towards the
end of next week. Model consensus on the intensity of this system
is low, but most models pick up on a disturbance crossing the
plains late in the week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 455 PM CST Thu Feb 23 2023
A weak disturbance will move over northern NE which could give the
TAF sites flurries to a little -SN overnight. Visby will be the
main issue with -SN, have kept it 6sm due to the small chances for
it, but if snow rates pickup a little then expect 1-2sm until -SN
moves off. The models are in agreement for a MVFR ceiling, but
what height it moves in they are all over the place. The short
range HRRR and RAP is what I decided to use and they gradually
lower and hold the lower ceilings through most of the afternoon
before afternoon heating lifts and scatter them out some.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION...Rossi
AVIATION...Beda
Area Forecast Discussion
National Weather Service Nashville TN
607 PM CST Thu Feb 23 2023
...New AVIATION...
.SHORT TERM...
(This afternoon through Friday Night)
Issued at 136 PM CST Thu Feb 23 2023
The temperature at BNA has already reached 84 degrees, which
breaks the record high for February 23 and ties the record high
for the month of February. If we`re going to squeeze out one more
degrees for a new monthly record, we`re going to have to do it
soon, as a long-awaited cold front has almost made it to
Clarksville. Although the cold front won`t bring freezing
temperatures to Middle Tennessee, it will cool us off
considerably. Tomorrow`s highs will actually be several degrees
cooler than this morning`s lows. Although there are currently no
radar echoes in Middle Tennessee, the HRRR does suggest the
development of isolated cells later in the afternoon and into the
evening. But these won`t be of much consequence. POP`s look to
return in earnest by tomorrow as the aforementioned cold front
becomes quasi-stationary to our south and showers begin to form
on the cool side of the front.
&&
.LONG TERM...
(Saturday through next Thursday)
Issued at 136 PM CST Thu Feb 23 2023
Rain chances will linger through the weekend, then look for
temperatures to make a nice recovery beginning on Sunday. A much
more progressive cold front will race across the mid state on
Monday, but the impact will be minimal -- mainly just showers and
a slight cool-down. Monday`s fropa will at least dry us out for a
couple of days before the next active weather system brings more
showers to the mid state from mid to late week. Temperatures
throughout next week will remain spring-like but not the record-
breaking warmth we`ve experienced the past couple of days. At
this time, we are not outlooked for any severe storms through day
8.
&&
.AVIATION...
(00Z TAFS)
Issued at 607 PM CST Thu Feb 23 2023
CKV/BNA/MQY/CSV...VFR conditions to prevail with iso/sct shwrs
possible thru 24/24Z. Quandary centers around if shwrs will
impact terminals/be in vcnty or not. At this time don`t have
enough confidence in location development and movement to mention
at terminal locations, but certainly can not rule out in vcnty.
Believe best potential vcnty generally 24/11Z-24/24Z as moisture
spreads W to E across entire mid state region. Sfc front currently
moving rather progressively thru area with all terminals expected
to have prevailing NW winds by no later than 24/05Z. With strong
sfc pressure gradient influences building in behind sfc frontal
passage per strong sfc high pressure influences building and
pushing SWD out of central Canada, gusts 20-25kts possible
24/01Z-24/23Z. Slow veering from initial NW winds to ENE by
24/24Z. VFR ceilings should generally range 4 Kft to 10 Kft thru
24/24Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 43 54 46 57 / 10 40 50 50
Clarksville 38 52 43 59 / 20 20 30 30
Crossville 43 52 44 56 / 20 40 60 70
Columbia 43 52 46 57 / 10 50 50 50
Cookeville 44 53 46 55 / 20 30 60 60
Jamestown 41 52 42 54 / 20 20 50 50
Lawrenceburg 44 53 47 58 / 10 50 60 60
Murfreesboro 43 54 46 57 / 10 40 60 60
Waverly 38 51 43 55 / 20 40 40 40
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Rose
LONG TERM....Rose
AVIATION.....JB Wright