Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/22
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
518 PM CST Fri Jan 14 2022
.SHORT TERM...(This Evening through Saturday)
Issued at 232 PM CST Fri Jan 14 2022
The winter storm will continue to wind down this evening. Warm
advection to the east of the inverted trough will continue late this
afternoon. As the low and upper wave continue to move southward,
ascent will gradually weaken and accumulating snow will be ending by
00Z around KHON and K9V9 and by 06Z in all by the Hwy 20 corridor
in northwestern Iowa. The heaviest snowfall amounts this evening
will be in northwestern Iowa where up to 2 inches additional snow
could fall. Over the remainder of the area additional snowfall
will be less than an inch. Another concern will be winds which
will be increasing as they back to the north behind the inverted
trough. The strongest winds will be in south central South Dakota
which will see gusts up to 45 mph through early evening. Winds
will gust from 30-40 mph over the remainder of the area with the
exception of areas east of the Buffalo Ridge in southwestern
Minnesota where winds aloft are closer to 25 kts, so gusts should
remain from 25 to 30 mph.
With this mind, we will be canceling the winter weather advisory in
south central South Dakota since the threat of any freezing drizzle
has ended. We will also allow the advisory in the James Valley from
Huron to Yankton to expire at 00Z since snowfall has been less than
2 inches and no additional freezing drizzle is expected. No other
changes are planned for advisories or warnings at this time.
With strong cold advection late this afternoon and tonight,
temperatures will be falling the next 18 h. 925 mb temperatures down
to -15 are expected over the area by 12Z Saturday. With fresh snow
cover in southwestern MN, lows will be from 0 to -5. Elsewhere,
lows will be in the single digits. The combination of wind and cold
temperatures will produce wind chills from -10 to -20 east of the
James River.
Otherwise, clouds are expected to remain over much of the area
overnight. There could be some clearing for a few hours in portions
of southeastern South Dakota as a small area of clearing moves
through overnight. Additional stratus is expected to follow
behind this clear patch within a few hours such that skies should be
mostly cloudy by Saturday morning. Many models, including the RAP
and GFS, are slow to move these clouds out as high pressure results
in a fairly strong inversion and light winds in the morning. As the
high moves south of the area, southwesterly winds should help to
erode the clouds and advect them to the northeast. Even if there is
sun, with very cold air centered over MN, highs will be from 10 to
15 east of I-29. Warmer air associated with the southwest winds
will allow temperatures to rise into the 20s to around 30 in the
James and Missouri Valleys.
.LONG TERM...(Saturday Night through Friday)
Issued at 232 PM CST Fri Jan 14 2022
Surface ridge slides east of the forecast area Saturday evening,
with increasing south-southwest flow at the surface and aloft. Model
soundings showing 40-50kt aloft, roughly 1-2kft AGL in southwest MN.
Given the higher elevation of the Buffalo Ridge, would anticipate
some stronger wind gusts along and east of the Ridge Saturday night,
and blended some higher-res wind guidance in with the NBM to bump up
speeds in this area. The gusty winds will bring the potential for
patchy blowing/drifting of the recent snowfall, primarily in these
higher elevations.
On a more widespread scale, the increasing winds along with an
increase in higher level clouds through the night, should also
result in rising temperatures through the latter half of the night.
This will lead into a more mild day on Sunday, with temps climbing
into the lower 40s west of the James River, where snowfall today has
been quite limited. Meanwhile the areas east of I-29, where snowfall
was heaviest, should be limited to highs right around freezing.
A mid-upper level trough slides southeast across the northern Plains
Sunday night, but upper ridging quickly builds back in, so the mild
conditions are expected to continue through the early part of next
week.
This pattern breaks down midweek, as a stronger trough drives an
arctic front south into the Plains. Especially given the recent
snowfall in eastern portions of the forecast area, expect to see
temperatures return to well below seasonal normals for a couple of
days, with highs Wednesday-Thursday in the single digits east, and
possibly even struggling to reach zero in some areas on Wednesday.
Likewise, nighttime lows will be back below zero early Wednesday
through Friday morning, with periods of wind chill readings in the
teens and 20s below zero.
The coldest air slides east of the forecast area by Friday, and we
may see a brief moderation in temperatures before another surge of
cold air pushes southward. However, models showing little consensus
on timing of the weak upper ridging and trailing wave, so confidence
in temperatures by Friday is on the low side.
As far as precipitation chances, cannot completely rule out some
light precip with any of the aforementioned waves, but the lack of
model consistency in timing/strength precludes including any mention
of precip in the mid-long range periods for now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 514 PM CST Fri Jan 14 2022
Snow continues to settle southward this evening. We`re gradually
seeing the back edge of snow move south of Highway 14 early this
evening. 1/2 to 1 1/2 mile visibility will remain in snow, with
gradually improving ceilings as dry air begins to filter
southward.
That said, anticipating at least a chance for MVFR ceilings to
continue into Saturday morning, and they could linger well into
the daytime hours. Northerly winds will relax through the night,
becoming light and variable by mid-morning Saturday.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 3 AM CST Saturday for SDZ070-071.
Winter Storm Warning until midnight CST tonight for SDZ039-040-
056.
Winter Weather Advisory until 6 PM CST this evening for SDZ038-
052>054-059>061-065-066-069.
Winter Weather Advisory until midnight CST tonight for SDZ055-
062-067.
MN...Winter Storm Warning until midnight CST tonight for MNZ071-072-
080-081-089-090-097-098.
IA...Winter Weather Advisory until 3 AM CST Saturday for IAZ020-031.
Winter Storm Warning until 3 AM CST Saturday for IAZ001>003-
012>014-021-022-032.
NE...Winter Weather Advisory until 3 AM CST Saturday for NEZ013-014.
&&
$$
SHORT TERM...Schumacher
LONG TERM...JH
AVIATION...Dux
Area Forecast Discussion
National Weather Service Wilmington NC
1002 PM EST Fri Jan 14 2022
.SYNOPSIS...
High pressure will extend in from the north tonight. Low
pressure approaching from the west late Saturday will deepen
rapidly by Sunday bringing heavy rain that will start as a
period of freezing rain away from the immediate coast. Breezy
and cool on Monday behind this system with the remainder of the
week remaining cool and dry.
&&
.UPDATE...
No big changes necessary from the ongoing forecast with this
update.
&&
.NEAR TERM /THROUGH SATURDAY/...
Gusty NW winds on the back end of deepening low pressure system
lifting off to the NE will diminish into this evening as the
gradient relaxes. High pressure over Canada will extend down
into the Carolinas as low pressure system develops and dives
down from the Midwest toward the Gulf coast states tonight
into Saturday. This will kick winds around from the N to NE
becoming more on shore as winds aloft increase out of the SW
ahead of approaching system. Moisture will increase through the
column with scattered mid to high clouds tonight increasing and
thickening through the day on Saturday. Overall, shallow cool
air will remain in place with fairly decent radiational cooling,
but increasing mid to high clouds will increase and should help
to level off temps inland toward morning. Should see lows near
freezing with highs tomorrow struggling to get through the 40s
inland in thickening clouds and continued cold air in place.
Temps near the coast should reach 50 and slightly warmer over
coastal SC.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Temperatures on Saturday night should drop rapidly after sunset due
to the building high pressure and cold air advection. Along with the
cold air advection, most of the area will see dew points drop into
the lower 20s (a few upper teens possible along our northern CWA
border). This dry air advection will be important to monitor as mid-
level and low-level moisture spreads across the area through 03-06Z.
Should start to see light radar returns between 03Z-06Z during the
early development of isentropic upglide. It is unlikely that any
precip will make it to the ground at this stage, but should be the
first step in saturation from south to north. Temperatures quickly
dropping as virga saturates the area, with the near-surface layer
dropping to below freezing across much of the CWA. Our first
observed precip should start in the form of freezing rain away
from the immediate coast. Points along the coast could see a
brief period of freezing rain, but we expect this quickly to
become all rain and confidence in this occurring is low (i.e.
all rain likely even from onset).
Models continue to vary greatly on the duration of freezing rain
across the area. The GFS continues to be the warmer solution while
other major global models are slightly further south with more cold
air available at the start of the event. Soundings do support this
given the dry air available and timing of precip arrival. High
pressure to the north also leaves some lingering questions. This
feature has been wavering in location and intensity and a slight
shift southward, as in the ECMWF/CMC, would lead to better cold/dry
air advection, potentially producing more ice accumulation along
and west of I-95.
As we get closer to the event, we are finally starting to see some
of our high-res model guidance pick up on system evolution. Given
its track-record with good handling of cold air damming, the NAM is
being heavily considered for this event. I have blended some of its
temperatures and dew points in this forecast update and this has
reflected a slight shift southward in overall freezing rain
potential. The vertical resolution of the NAM and HRRR are likely to
handle the physical low-level mechanisms that could prolong periods
of freezing rain. It is prudent to note that both show a stronger
low-level jet overtaking the area during the day with a faster low
overall.
For now the forecast reflects another southward shift with a wider
coverage of freezing rain to start and slow regression of the
freezing line through late Sunday morning, clearing the CWA by early
Sunday afternoon. This would produce around a quarter of an inch of
ice accrual along the I-95 corridor. Again, subtle changes could
lead to slightly larger or smaller amounts, bullseye still well
west of our area.
As the system transitions to all rain on Sunday afternoon, the
center of the low is likely to track near the Cape Fear region,
either just offshore or just inland. It is likely that a portion of
the area will exist within the warm sector of the deepening low.
Within this area, we could have our strongest land-based wind
speeds. Gusts of up to 35 mph are possible along the immediate
coastline with the NC coast having a shot at slightly higher wind
gusts. This could produce some minor impacts, especially with the
rain-soaked soils (e.g. branches or trees down, isolated power
outages, and misplaced outdoor items left unsecured).
Rain could be heavy at times and could create some travel headaches
in itself: reduced visibility, ponding on roadways, and slick
surfaces in general could be enough to cause some minor impacts.
Current storm total QPF shows between 2-3 inches of rain along the
coast and 1-2 inches of rain inland. It is important to mention that
this too will change with the track and observed p-type on Sunday.
While this will be welcomed for most of us, some low-lying and poor
drainage areas are likely to have some minor flooding issues
throughout the day.
Rain is likely to end across the area from south to north on Sunday
night. Winds on the back side of the system will continue to be
worthy of monitoring with some of our coastal areas seeing ongoing
gusts up to 30-35 mph late Sunday night into early Monday morning.
This is likely to be aided by a tongue of dry air progressing within
the hook of the deepening low by sunrise. The lack of moisture on
the back side of this system will also rob us of seeing any
lingering flurries on Sunday night or Monday morning.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
Low pressure moves away from the coast late Monday, remaining breezy
late in the day as high pressure builds into the area. Temperatures
on Monday remaining below normal with cold-advecting NW wind. Highs
only in the mid or upper 40s. Cold overnight Monday into Tuesday
morning with lows in the mid and upper 20s. High pressure will bring
a quiet Tuesday and below-normal temperatures. High pressure allows
for good radiational cooling Tuesday night into Wednesday morning,
lows again in the upper 20s to around freezing. Sunshine is able to
really have an impact on Wednesday high temperatures under clear
skies. Highs back to normal and could potentially rebound to a
couple degrees above normal. Cold front will move through the area
on Thursday and could bring some precip as it moves through. Much
colder air should follow with strong Canadian high pressure moving
into the central US.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
VFR through the 00Z TAF period. Just some high clouds tonight
with very light N/NW wind potentially becoming calm. Light NE
winds can be expected as we begin to mix on Saturday, up to 5
to 10 kts. Very dry air will keep fog potential low Saturday
morning, with clouds starting to thicken through the day ahead
of the next low pressure system.
Extended Outlook...Mostly VFR outside of a high potential for
IFR Saturday night through Sunday with a developing low pressure
system to bring RA and FZRA to the area.
&&
.MARINE...
Through Saturday...Lingering gusts to 25 kts over waters N and E
of Cape Fear will come to an end this evening as exiting low
moves farther off to the northeast, allowing gradient to relax.
Offshore flow keeping highest seas well offshore with 2 to 4 ft
most waters and down less than 2 ft over nearshore SC waters. A
minimal easterly swell will mix in and become more dominant as
winds drop into Sat. Northwest winds will gradually veer to
northeast overnight. Speeds dip under 15 kt around midnight and
continue trending down through the early morning hours.
Saturday night through Tuesday...Rapid deterioration of
conditions is expected late Saturday night ahead of a surface
low over the southeastern US. Deepening low pressure will lead
to a quick increase of the gradient winds on Saturday night
through Sunday morning. Expecting sustained winds 25-30 knots,
gusts 35-40 knots through the majority of the day on Sunday.
Gale conditions are likely to develop with this system and a
Gale Watch has been issued for all of our nearshore coastal
waters. Conditions will be at their worst Sunday afternoon and
through the overnight period. Surface low will begin to exit the
region by Monday morning. Seas 6-10 feet late Sunday as the
center of this storm passes near the coastline. Conditions will
improve during the day on Monday and Monday night. Returning to
near normal by Tuesday with offshore winds 10-15 knots and seas
3-5 feet and decreasing. Clear and mostly calm on Wednesday with
southerly flow increasing ahead of a cold front later in the
week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Winter Storm Watch from late Saturday night through Sunday
afternoon for SCZ017-023-024-032-033.
NC...Winter Storm Watch from late Saturday night through Sunday
afternoon for NCZ087-096.
MARINE...Gale Watch from Sunday morning through Monday morning for
AMZ250-252-254-256.
&&
$$
SYNOPSIS...ILM
UPDATE...MAS
NEAR TERM...RGZ
SHORT TERM...21
LONG TERM...21
AVIATION...MAS
MARINE...RGZ/21
Area Forecast Discussion
National Weather Service Jackson MS
950 PM CST Fri Jan 14 2022
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
Plenty of high clouds streaming into the region on satellite
imagery this evening. For the most part, clouds remain above
12kft, but some of those are getting picked up on radar. Any
sprinkles that might be coming out of those clouds would never
make it to the ground given the deep dry boundary layer on the 00z
JAN sounding. Not much in the way of updates anticipated for the
overnight. Forecast on track for increasing clouds and lows mainly
in the 40s. Some showers may be encroaching on the Mississippi
Delta just before dawn in advance of the next storm system.
Prior discussion below:
Tonight through Tomorrow...
In the near-term, weather will remain quiet. Shortwave ridging over
our region has kept weather dry today, but the approaching upper-
level shortwave trough can be seen on water vapor satellite imagery
diving southward from the Northern High Plains this afternoon. High
clouds associated with this system are moving across our forecast
area, but increased low clouds and rain chances don`t arrive until
tomorrow morning time frame. As the trough dives southward, a
deepening low pressure system will close off from the flow aloft,
and the surface low pressure center will slide east from Texas
across Louisiana and Mississippi. The surface cold front should
enter northeast LA around sunrise tomorrow and pivot across our
forecast area through the afternoon hours. Forcing along the front
and enhanced lift through the upper-levels will support a good line
of showers as the front moves east. Some elevated instability will
also support a little thunder mixed in with this daytime activity.
Temperatures will warm into the mid 60s ahead of the cold front in
our southern areas, while temperatures in the Delta will warm only
to a more mild mid-50s range. Then attention quickly turns to our
winter weather potential. /NF/
Saturday night through next Thursday...
Sat night-Sun: Main focus remains on winter weather event likely
Sun. Cold core will continue diving to the E-SE, with center of
cold core over the central Plains by Sat morn, ArkLaTex by Sat
aftn & MS River to I-55 corridor by midnight Sun. This highly
dynamic system will bring a TROWL & wrap around moisture, broad
sfc low pressure/baroclinic zone centered off to the E-SE by
Sunday. Increasing isentropic ascent/convergence into strong
deformation zone & conditional symmetric instability (CSI) will be
present. Strong ascent will keep broad deformation axis of rain
changing over to snow generally along & W of MS River by midnight,
W of I-55 before daybreak & E of I-55 through Sun aftn, with some
lingering light snow psbl in E-NE MS into early Sun aftn. There
remains uncertainty on how much WAA in the TROWL will occur to
see some warmer low-level temps & rain lingering longer. There has
been a continual S trend to the center of the strong cold core in
recent global guid consensus. Strong dynamic cooling underneath &
some heavier QPF/snow are possible in areas of temps hovering
right around or just above freezing. Low-level thermal warmth
less than 1000ft could keep it just rain/snow & less precip type
issues. Heavier bands will remain difficult to pin down. However,
there remains enough confidence that areas in the N-N central MS,
far NE LA & SE AR remains probable for accumulating snow & some
potential of some approaching or possibly exceeding winter storm
criteria. HRRR has some small trends with some stronger WAA, less
totals along & E of the Natchez Trace. 12Z runs indicate some
higher end potential to easily exceed winter storm criteria. For
now, with limited probs > 2 inches into our NW, main adjustments
were to adjust the "Limited" graphic further S closer to the I-20
corridor & SW & somewhat to the E along the Hwy 82 corridor just
W of the AL state line. Lows that morning will only peak near or
just above freezing, with best snowfall potential areas only
falling near the freezing mark, then only climbing into the mid-
upper 30s in E to low 40s in SW. Leaned towards raw blend of guid
for highs. In addition, TROWL situations & with strong gradient,
efficient gradient winds could approach +30-35mph at times, with
some sustained near wind advisory possible Sunday. This could
bring visibilities down & create additional travel difficulties.
With potential for heavy wet snow banding at times, combined with
gusty gradient winds, some power outages could be possible as
well. Held off for now in the HWO, but a "Limited" gradient wind
will likely be needed. Lastly, some areas in E-NE MS could see
some convective rain prior, with some QPF totals in excess of 1-2
inches. For now, something to monitor but will hold off in the
HWO.
Next week (Mon-Thurs)...
Mon: As sfc high builds off to the W & clouds clear & winds
lighten, efficient rad cooling is psbl with lows falling near or
below freezing. This will especially be the case in any areas of
snowpack. This could cause any lingering snow on elevated sfc,
including bridges or overpasses, & could keep slick travel
conditions through early Mon morning, mainly through 7-8AM. Highs
will warm & some of that will go into melting of the lingering
snow, so high temp fcst could be in flux to start the week. Highs
will generally be near climo in the upper 40s in NE to low-mid
50s in the S.
Tues-Thurs...As sfc high builds E & broad blocking pattern persists,
expect any quick zonal flow to give way to another amplifying mean
trough out of the NW by late week. This will help some increasing
WAA & temps moderating above climo into the low 60s N to low 70s S
by mid-week, before rain & some storm chances move through by Wed
aftn & move out through Thurs. Highs will fall back near climo into
the low-mid 40s N to mid 50s S. /DC/
&&
.AVIATION...
00Z TAF discussion:
VFR conditions overnight with light southeasterly winds.
Conditions will start to deteriorate tomorrow mid morning as a
cold front move into the region ahead of the next storm system.
Models persist on dropping to MVFR conditions around midday with
showers...and then to IFR cigs and/or vis in most locations before
sunset. Towards the end of the fcst pd and behind the front, the
winds become more westerly and brisk, gusting to 20-25kts.
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 47 60 33 39 / 4 92 63 16
Meridian 43 60 35 38 / 3 95 83 37
Vicksburg 49 59 33 43 / 7 82 54 8
Hattiesburg 44 65 34 41 / 1 95 46 6
Natchez 51 61 33 45 / 6 79 33 3
Greenville 47 55 31 40 / 11 89 80 16
Greenwood 47 56 32 38 / 8 93 83 46
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
HJS
Area Forecast Discussion
National Weather Service New Orleans LA
938 PM CST Fri Jan 14 2022
.EVENING UPDATE...No adjustments made to tonight`s forecast but
we did adjust tomorrow and tomorrow nights forecast. Timing is
still similar with tomorrow`s activity. First round of convection
appears to be associated with waa possibly a warm front sliding
north. One thing to watch will be how far east that can move and
how fast. If that activity is slower to move out or is anchored
closer to the coast then we will struggle to recover and the
amount of convection that will be associated with the cold front
tomorrow afternoon will be far lower than currently forecasting.
On the other hand of that activity moves to the east and northeast
a little faster it will allow for better destabilization and
perhaps a few strong storms...can`t rule out one or two severe but
the most likely risk of strong/severe weather will be quick weak
tornadoes early in the afternoon. These could very well develop on
showers, so yeah no lighting with some of these is possible. The
best directional shear will be from morning and into the early
afternoon but winds quickly become unidirectional mid afternoon
and ahead of the cold front.
As for Winter Weather, the key will be the path of the mid level
low. The trend had been a little south so we shall see if that
continues. If the low can get a touch farther south then light
snow would be possible in southwest MS, not just flurries.
Flurries do look likely in southwest MS and the adjacent LA
parishes but could even be possible down to I-12. The next thing
to watch which we wont see till tomorrow evening will be how much
moisture can wrap around it. All indications suggest there could
be a rather decent amount of moisture wrapping around, probably
due to what looks like an impressive TROWAL ahead of it across MS
and AL. We did bring flurries a little farther south with this
update but holding off on any real accumulating snow at this time.
Grids and zones will be out shortly.
One thing to mention...confidence is low and there is a chance
that Winter weather could over preform. The key again is that
wrap around moisture. Numerous forecast soundings over the last
12-18 hours has indicated there could be a brief window of rather
decent waa/lift in the dendritic zone. At the same time the column
looks pretty well saturated from the sfc and perhaps all the way
to h7. If, and this is a big IF, that happens we could be see a
window of moderate snow possibly leading to some light
accumulations. If that happens it would most likely be in
southwest MS. At this time the potential for any meaningful snow
is rather low in SELA and coastal MS but southwest MS will need to
be monitored. This could make travel along I-55 from the LA/MS
border north through the state rather dangerous to drive on. /CAB/
.AVIATION...06z TAF Package...VFR conditions will likely continue
through the night but shortly after 12z look for conditions to
begin to deteriorate with most terminals likely seeing MVFR
conditions near 18z and then IFR conditions later in the afternoon
and early evening. Winds will also begin to pick up tomorrow out
of the southwest but the strongest winds will likely hold off
until later into the evening behind the cold front and out of the
northwest. Strongest winds will as always be along the southshore
of Lake Pontchartrain and perhaps along the MS coast. /CAB/
PREV DISCUSSION... /issued 406 PM CST Fri Jan 14 2022/
NEAR TERM (This evening and Tonight)...
Splitting up the short-range discussion between the near term and
weekend system to allow better focus on both. For a detailed
analysis on the weekend system divided by potential hazard, scroll
down. As far as the near term goes, all is quiet. Continuing to
see thin upper-level cirrus advecting in from the northwest within
a pocket of H2 to H3 moisture ahead of an amplifying positive
tilt trough pushing south along the eastern Rockies/central
Plains. Upper-level clouds will continue tonight, becoming
thicker with time into daybreak Saturday. No major adjustments
performed to minimum temperatures, just a slight nudge down for
drainage basins as winds could remain light (just enough) early
Saturday morning. Based on trends this afternoon, also slightly
slowed the increase in dewpoints as there appears there may be a
slight lag due to southeasterly winds persisting overnight. KLG
WEEKEND SYSTEM (Saturday morning through Sunday Night)...
Synopsis... A shortwave trough axis originating from the PacNW
continues to phase with a lead shortwave trough across the
northern Plains, diving southeast into central US. The PacNW
trough/remnant energy aloft and evolution of the upstream ridge
axis building east into the northern Plains will act to
enhance/deepen the trough axis, eventually closing off as an
upper-level low diving southeast into the Arklatex Region Saturday
afternoon and evening. NAEFS Mean Geopotential height and
Climatology Percentiles analyzed per layer reveals an overall
extremely low height anomaly associated with this deep 5460m H5
center, progressing east just barely to the north of the area late
Saturday and into Sunday. Meanwhile at the surface, an elongated
surface trough axis extending from central TX, northeast into MO
will progress east along a strengthening baroclinic zone/frontal
boundary. We are already seeing surface low cyclogenesis along
this trough over northern Texas, with this low expected to
progress east just to the north of the CWA and an attendant strong
cold front swinging through the northern Gulf coast Saturday
through Sunday. Upper-low position and orientation does not
typically favor a severe weather or notable winter weather risk
for our location, however each contain a non-zero chance. Each
potential hazard is discussed in more detail below.
Convection... Any threat of strong or severe storms will be hard
to come by with the lack of deep Gulf moist return flow. Seems
like recent frontal boundaries over the past weeks have pressed
dry, continental air deep into the Gulf with very little
opportunity for us to build back deep enough moisture ahead of the
eastward surging low to our north. Keeping this in mind, there
are some features to mention. There is some weak reflection of a
subtle impulse riding along strengthening WSW to ENE flow aloft,
which CAMs depict as a cluster of showers mid to late Saturday
morning across the area, with the potential for deeper convection
across coastal SE LA (within somewhat better Gulf
moisture/instability). Can`t rule out a strong storm or two over
marine areas generally confined to what could be a weak warm front
surging north. Anything further north would likely be elevated,
with barely any thunder to come by.
Stronger forcing arrives just barely with the frontal boundary,
entering our NW CWA late Saturday morning/early afternoon.
Noticing CAMs have been trending slightly higher with surface
dewpoints (low 60 Td`s) to the north ahead of this boundary
matched with stronger low to mid-level winds. However, should
coastal convection/stratiform precip be more widespread early on,
this could starve necessary deep moisture to support convection
along the boundary. Recent synoptic hour 18Z run of the HRRR shows
very little activity along the front early in the afternoon, but
intensifying dynamic ascent attempts to overcome by producing
individual cells near or north of I-10/12. Modest shear within
limited instability... taking into consideration so many struggles
here... really going to be difficult to get any severe weather,
but the two areas to monitor may be for coastal convection earlier
on, and for any shallow cells that could try to develop along or
near the front within a thin zone of combined better forcing and
thin, skinny return of MLCAPE ~250-700J/kg meaning, will advertise
a non-zero isolated tornado risk. What is left of this threat
fades into nothing as we lose sunlight later into the afternoon.
Winds... Largest concern for winds will be primarily associated
with CAA on the back side of the front. Continuing to confidently
introduce the 90th percentile NBM into the forecast for all
areas.. with a slight nudge even above for marine zones. This will
present gale conditions beginning Saturday evening, lasting
through Sunday afternoon. Per our local Wind Advisory criteria,
even pulling sustained winds well above deterministic guidance,
still am coming in shy of advisory highlights. This may change,
but due to low confidence, will let subsequent shifts re-analyze
and issue should need be. Areas with the strongest winds will
likely be along the southshore and parts of coastal SE LA,
especially across marine areas and any north-facing shorelines
from Saturday night through the day on Sunday, finally tapering
off as the system pulls away and attendant SLP weakens with
surface high building in from the west Sunday night.
Temperatures... No question about it, temperatures will drop like
a rock following the front. Aimed at the lower end of NBM
ensemble guidance for lows Sunday morning, but not too cold as
winds will remain very much elevated with cloud cover. Did take a
close look at the possibility of clouds lingering during the day
on Sunday, which is looking more likely with plenty of wrap-around
925mb moisture behind the surface low. Given persistent CAA and
low-level stratus/stratocu... highs will struggle to reach out of
the mid to upper 40`s. Felt more confident as this has been an
ongoing trend, but cloud thickness will not be deep only a few
thousand feet thick meaning, if clouds break up early or erode
west to east earlier than anticipated, there could be further
adjustments but for now, confidence is high enough to aim lower
than blended guidance.
As winds taper going into Monday morning and clouds break up/pull
out of the area, still anticipating Monday morning to be the
coldest morning due to strong radiational cooling promoted by
nearby surface high pressure. Again, well below the NBM placing
many areas in the low 30`s to some upper 20`s which will bring
widespread frost. Southshore/NOLA and surrounding areas still
looking likely in the mid 30`s even with this colder nudge. KLG
Winter Weather... Since it has been a bit of a discussion lately,
and since we rarely get to analyze the potential for winter
weather here... sure let`s analyze it! As the low presses east, as
mentioned with plenty of wrap around low-level moisture sliding
behind the low (prominent TROWAL looking at 700 and 500mb
ThetaE). This has been a very interesting trend closely looking at
the CAMs trying to pull precipitation deeper into our CWA (12 and
18Z HRRR really standing out). Model soundings for SW MS
illustrate enough deep moisture within the DGZ pulling atleast
into parts of the northern Florida parishes. Temperatures will be
falling, but question will be how fast will they fall and how far
will they go. Even with the re-adjustment in colder temperatures
daybreak Sunday, we generally see temperatures in the 34-37 degree
range for northern areas. With dynamic lift in place (850-500mb
PVA), combined with DGZ/ice crystal growth all within wrap around
low- level moisture/TROWAL... that could very well be enough to
get some wet snowflakes to the surface, perhaps mixed with rain in
some spots further south. This may be a brief window only for a
few hours spanning somewhere between 09 to 15Z, with the greater
potential along the northern parts of the Florida Parishes and SW
MS. For now, have introduced Rain/Snow for parts of SW MS to
flurries just barely farther south (lower confidence).
Yes, this does have the potential to over (or under) perform...
so confidence is low at this time and am NOT advertising
measurable accumulations at this time. However, a light dusting
could be possible especially on elevated surfaces. This will be
something we will have to closely monitor should anything change
as the system develops and evolves. KLG
LONG TERM (Monday through Thursday)...
After a very cold morning, we warm up into the upper 50`s to
nearing 60 for a few. This moderation trend persists into mid-week
before the next cold front swings through late Wednesday/early
Thursday. Large disagreement in late-week guidance at this time
with a large ensemble spread in temperatures, likely due to
frontal speed and where it may stall near the area. But, not going
to get too caught into details this far out in advance. Will take
a closer look once guidance aligns better after we pass this
weekend system. KLG
AVIATION (18Z TAF DISCUSSION)...
VFR conditions will prevail this afternoon, evening and portions
of overnight tonight with only patchy upper-level cirrus and light
surface winds expected. Low clouds build back in early Saturday
morning as return southeasterly flow develops leading to primarily
MVFR flight categories beyond after daybreak. Light showers will
increase in coverage across coastal SE LA early to mid-morning
Saturday, with a strong cold front swinging west to east across
the area thereafter Saturday afternoon and evening. At this time,
mentioning SHRA ahead of the front to a few western and central
terminals where guidance is in better agreement. There is the
potential for TSRA for central and southern terminals after 18Z,
but chances remain low. Will revisit this in subsequent TAF
updates. KLG
MARINE...
Light winds and calm wave/seas will continue this evening. Winds
will steadily increase out of the south during the morning hours
on Saturday. Showers and a few strong storms may be possible mid
to late morning Saturday, before a strong cold front swings
through Saturday afternoon and evening. Behind this front, strong
winds will be building to gale force, with all Gale Watch
headlines now upgraded to Gale Warning. Additionally, waves/seas
will be quickly building behind the front, reaching 10-15ft+ for
outer 20-60nm zones to 3-6ft for lakes/sounds. Gale Warning
headlines will remain in effect through Sunday evening, likely
being transitioned into a Small Craft Advisory to follow due to
linger winds and waves/seas. Thereafter, high pressure builds into
the region with conditions becoming more calm. The next front
will be possible mid to late-week either passing through coastal
waters or stalling near or potentially south of marine zones. KLG
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 48 64 33 43 / 0 80 30 10
BTR 51 66 35 48 / 0 70 10 0
ASD 48 70 36 46 / 0 90 40 0
MSY 54 71 38 48 / 0 90 20 0
GPT 50 68 36 46 / 0 90 60 10
PQL 47 70 35 45 / 0 90 70 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Small Craft Advisory from noon to 6 PM CST Saturday for GMZ530-
532-534-536-538-550-552-555-557-570-572-575-577.
Gale Warning from 6 PM Saturday to 6 PM CST Sunday for GMZ530-
532-534-536-538-550-552-555-557-570-572-575-577.
MS...None.
GM...Small Craft Advisory from noon to 6 PM CST Saturday for GMZ532-
534-536-538-550-552-555-557-570-572-575-577.
Gale Warning from 6 PM Saturday to 6 PM CST Sunday for GMZ532-
534-536-538-550-552-555-557-570-572-575-577.
&&
$$
Area Forecast Discussion
National Weather Service Louisville KY
925 PM EST Fri Jan 14 2022
.Forecast Update...
Issued at 924 PM EST Fri Jan 14 2022
Evening satellite and observations reveal mostly cloudy skies across
southern Indiana and much of northern Kentucky with low overcast
hanging on strong. Further south over southern KY skies were clear
to partly cloudy with some light mist/fog being reported.
Temperatures across the region were generally in the lower 30s,
though some lower-mid 40s were noted over far southwestern KY.
Current forecast remains on track for the overnight period. We will
continue to see clouds increase across the region. The clouds will
likely keep temperatures in the lower 30s for much of the night. As
well advertised weekend system approaches off to the west, still
think we`ll have some light snow showers and/or flurries develop
across southwest Indiana and the western part of KY (mainly west of
I-65). Amounts still look to be very light and with temps staying
at or above freezing, the impacts here still look limited at this
time.
As for the rest of the forecast, no headline changes will be made
this evening. The afternoon data from the NAM, HRRR, and Canadian
GEM continue to be on the south edge of the model guidance keeping
much of the region dry on Saturday and Saturday night before
bringing wintry weather back to east-central and southeastern KY on
Sunday. The 18Z GFS and the 18Z Euro runs continued to support our
wintry mess within the current watch area for Sunday.
Looking at the 00Z upper air obs and comparing them to the earlier
GFS/Euro runs, the mid-level heights from the northern Plains down
through the east-central Plains remain higher than the GFS forecast,
meaning that the ridge out to our west remains a little stronger,
or, it could also mean that the lead wave is weaker than forecast.
The overall speed of the system seems to be on track, perhaps ever
so slightly slower. However, if the lead wave is actually a bit
weaker, I would suspect that the 00Z models may drift a bit back to
the north with their runs this evening. This is already evident in
the 00Z HRRR runs with a more northward precipitation shield being
depicted across TN and into southern KY. The snow amounts from the
HRRR are lower, likely due to snow accumulation loss to expected
mixed precipitation cutting into those totals.
I suspect we`ll see a northward trend in the NAM guidance as well,
but I also suspect that we may see a bit more mixed precipitation
initially with the band lifting into east-central and SE KY which may
cut into snow totals. Overall, we should cool fairly rapidly late
Sunday afternoon changing everything back to snow. The westward
expansion of the precipitation shield as it comes northward remains
problematic as there are indications it could go back as far as the
I-65 corridor. Given the current spread in the guidance and the
lack of new 00Z guidance, confidence remains limited and no headline
changes will be made with this evening`s update.
&&
.Short Term...(This evening through Sunday Night)
Issued at 330 PM EST Fri Jan 14 2022
...Winter Storm Potential Still Carries Much Uncertainty...
...No Changes To Current Headlines Planned At This Time...
Currently, our region is bisected by a deck of stratus that has been
slow to erode today. South central KY is under clear skies with
temps in the 40s. Even seeing some upper 40s near the KY/TN border.
Farther north, we are seeing some signs of the deck eroding across
southern IN and north central KY, however by the time these clouds
give way we will likely be past any chance to "warm". So, have gone
pretty pessimistic with the temps heading into this evening/night.
Current values are in the mid to upper 30s under the persistent
cloud deck.
As we move into tonight, temps are expected to fall into the upper
20s and low 30s under a steady NE surface wind/cool advection. We`ll
see increasing upper sky cover tonight ahead of the clipper that
will be diving into the mid Mississippi River Valley. However, any
light precipitation expected with a lead band of moisture is likely
to hold off until early to mid Saturday now. No changes with that
expected snowfall (perhaps a rain/snow mix with marginal low level
temps) as only a dusting to half an inch at most west of I-65 would
be expected. Models have been trying to warm temps up into the mid
and upper 30s for much of the area on Saturday, however given steady
NE surface flow and heavy cloud cover those temps might be too
aggressive. We might very stay confined to the low to mid 30s during
that time. So, any precipitation (not much expected) will have a
chance to be rain/snow. Little to no accum expected.
Saturday night now looks mostly dry across our area as the much
anticipated storm system closes off over the lower Mississippi River
Valley. The farther south solution that has been trending in the
models is also translating to a slower onset time. So, Saturday
night should now be mostly dry outside of areas right along the
KY/TN border. Snow will be the main p-type, with a possible mix of
sleet at times, thanks to a marginal warm nose hovering right around
the 0 C line through a fairly deep layer above the surface. Surface
temps will be at or just below freezing in this area, so some light
accums around 1 to 2 inches along the state line are possible by
sunrise Sunday.
The main show is then expected mainly along and south of the
Parkways from around sunrise through around Midnight EST on Sunday
as the storm traverses the Gulf Coast states and heads up the
Appalachian spine to the mid Atlantic. We`ll be in a favorable
region of the storm such that mid level deformation will have some
residence time over our southern and eastern CWA, more specifically
the general Winter Storm Watch area. Here, look for widespread line
snowfall, with the potential to develop a moderate to occasionally
heavy band of snow thanks to a frontogenetical component producing
good lift through a saturated DGZ. Here, 1 to 2" per hour rates will
be possible, which is most likely to occur somewhere along and
southeast of a Scottsville, to Campbellsville, to Lexington, to
Carlisle line. In the Watch area, expect a wide range of 3 to 6 inch
amounts possible, however a locally higher/narrower band of 6 to 8"
is possible, likely somewhere closer to the I-75 corridor. Outside
of the watch area, expect only light snow, although it will persist
for a good portion of Sunday into Sunday evening. So, a broad area
of 1 to 3" is still possible south of the Ohio River. Areas closer
to the Watch will have the better chance at the higher totals, and
will likely need to be in a Winter Weather Advisory should the
current forecast hold. Across southern Indiana, very little if any
snow is expected with this system. The event ends late Sunday night
into Monday morning across our far east.
Confidence:
Overall confidence remains quite low with this system due to several
factors. 1.) the complexity and evolution of the system has been
giving forecast models trouble, and while overall trends are noted,
run to run inconsistencies are hurting confidence. For instance, the
18z HRRR is a complete miss and dry for our entire CWA, while other
models show a significant event still occurring in the Watch area.
Even ensemble members still show a pretty wide spread at this point
in the game. 2.) Precipitation type is a bit more in question with
this system given the aforementioned marginal warm nose across our
south and east. This is also where our highest totals/larges QPF
reside so any mixes in p-type could really put a dent in expected
snow totals.
Perhaps confidence will improve if a more clear trend begins to show
itself, but for now expect that confidence will remain low if we
don`t get good model consistency or some clarity on the potential
warm nose across the SE CWA where the Watch is.
The Watch:
At this time, plan no changes to the current headline other than to
freshen up the wording. It looks pretty well placed and give a
continued steady SE trend in the models, it could even be overdone
if that trend continues. It should be noted that if the current
forecast holds areas outside of the Watch will likely still need to
be in an Advisory with lesser totals. However, since the main event
isn`t until Sunday we`ll still have time to make that decision.
Could This Storm Still Be Significant?
Absolutely. Right now, the current sentiment is a little more
pessimistic due to recent model runs trending drier, however a
slight shift in the track, or if the deformation band really does
get going could still bring some higher totals. One thing worth
noting is that even though the models are struggling with p-type, a
healthy snow band could easily overcome any marginal thermal profile
to keep it all heavy, wet snow.
Could This Storm Be A Bust?
Yep. In fact, some of the shorter term/higher res models coming in
this afternoon are keeping our entire area dry and storm free. It is
entirely possible that the current Winter Storm Watch could be
dropped with little fanfare if the latest trends hold in the coming
shifts.
Bottom Line:
Pay attention to the latest forecasts through this holiday weekend
as we gain more confidence. Sometimes it is easy to be confident in
a storm. Other times it is not due to the complexity of how the
storm forms, and/or interacts with other atmospheric disturbances.
This could still go either way.
.Long Term...(Monday Morning through Friday)
Issued at 245 PM EST Fri Jan 14 2022
Long term period begins Monday morning, where the primary winter low
will be pushing up the Appalachians and impacting the northeast. A
mid-level vort max associated with the thermal shortwave will track
across the region, which looks to spark an additional light round of
snow for areas east of I-65 Monday morning. Flurries to a very light
dusting is possible, with the highest 6-hr snow accumulation (a few
tenths) forecast for our Bluegrass region. With northwesterly flow
taking over, temperatures will struggle to get out of the 30s for
Monday.
Drier air and low level ridging sets up for Tuesday, with a broad
sfc high located across the Gulf Coast. We`ll see cloud cover
decrease through the day as temperatures return to near normal
(generally in the 40s). It`s not until Wednesday that the forecast
introduces our next shot at wet weather. A shortwave will pivot
across the northern US border, bringing the associated sfc low
across the Great Lakes region. A trailing cold front will connect to
a secondary low over the ArkLaTex region. Temperatures ahead of the
front look to be above freezing, resulting in light rain showers for
our region. Some model spread on timing limits confidence, but cold
air will quickly rush in behind the frontal passage. Lingering
precip just along or behind the front may mix with colder air,
resulting in a possibility of light snow Wednesday evening and
night.
&&
.Aviation...(00Z TAF Issuance)
Issued at 616 PM EST Fri Jan 13 2022
IMPACTS:
- MVFR/IFR cigs this evening
- Some snow flurries and light snow showers possible overnight
DISCUSSION:
MVFR cigs are in place at KSDF/KLEX and will likely become
prevailing at KHNB this evening. VFR conditions are likely at KBWG
this evening, but we expect their cigs to come down after midnight
into the MVFR range. Northeast winds will be seen this evening with
speeds of 5-10 knots. Overnight, some light isentropic lift may
produce a few light snow showers and/or snow flurries at the sites.
Higher confidence on snow flurries/showers at KBWG/KHNB, but lower
at KSDF and KLEX. Generally overcast conditions are expected on
Saturday with northeast winds of 10-15kts.
Confidence:
Medium on cigs and winds
Low-medium on snow flurries/showers overnight
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Winter Storm Watch from Sunday morning through late Sunday night
for KYZ055>057-064>067-074-076>078.
Winter Storm Watch from Sunday morning through late Sunday night
for KYZ041>043-048-049.
Winter Storm Watch from late Saturday night through Sunday
evening for KYZ073-075-081-082.
&&
$$
Update.......MJ
Short Term...BJS
Long Term....CJP
Aviation.....MJ
Area Forecast Discussion
National Weather Service Nashville TN
841 PM CST Fri Jan 14 2022
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Cool and cloudy at update time. Pretty quiet out there. We`ll take
it because the next couple of days are going to be hectic. I`m not
going to go into a bunch of in-depth analysis here, mainly because
the 00Z model suite hasn`t come in yet. I`ll leave that to the
overnight crew. What I will say is that several places in Middle
TN look like they`re going to get more snow than they bargained
for Saturday night and Sunday. Yes, models are all over the place
as far as positioning where the heaviest snow is going to fall,
but if there`s anything they agree on, someone (or a large swath
of someones) is gonna get hammered. Of note, the 00Z HRRR has
finally started to show heavy snow accumulation. I mention this,
because arguably, the HRRR did the best with the last two snow
events across the mid-state. That said, I have also seen evidence
of forecast soundings showing strong Omega signs in the dendritic
growth layer across a good swath of I-40 and south. How`s that
for scientific? Basically, it means heavy snow for a period of
time.
All of this is leading to potentially 4-8 inches of snow across a
good portion of the area and I wouldn`t be surprised to see a
couple of spots see more and even a few spots (probably our far
northwest counties) see something closer to an inch.
I think the bottom line is: be prepared. Many places are going to
get a bunch of snow and everyone knows how even an inch of snow
can cripple TN when it comes to travel and traffic. Be prepared
for major travel impacts by late Sunday morning, lasting through
the night and probably even worse Monday morning in the aftermath
as temperatures in the morning should bottom out in the 20s,
freezing over anything liquid on the roads. Afternoon
temperatures Monday will try to inch towards 40 but I`m seeing a
lot of clouds Monday, so the sun may not be out to help melt
anything on area roadways. Hopefully by Tuesday, we can start
getting things back towards normal.
&&
.AVIATION...
00Z TAF DISCUSSION.
VFR conditions continue currently with conditions expected to
begin deteriorating beginning with CKV ~14Z, BNA/MQY ~17Z, and
CSV ~19Z. MVFR vis and cigs expected as SHRA/VCSH moves through
the area mainly after 18Z through the remainder of the TAF period.
Winds will remain from the NE, with winds increasing by mid-
morning. Gusts upwards of 15 to 25 kts can be expected at CKV
after 18Z and BNA/MQY after 22Z.
I will note, there is a small chance that a few flurries could mix
in with SHRA mainly at CKV between 10Z and 14Z. Confidence is low
which is why it was not included in the TAF, but worth mentioning.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Saturday evening through Sunday
afternoon for all of Middle TN.
&&
$$
DISCUSSION......Unger
AVIATION........Adcock