Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/12/22
Area Forecast Discussion
National Weather Service Charleston SC
1023 PM EST Fri Mar 11 2022
.SYNOPSIS...
A strong cold front will cross the region tonight into Saturday
morning. Cold high pressure will build into the area through
early next week. Another storm system could affect the area by
mid-week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
The warm front was found roughly north of a line from Metter to
Beaufort to just off the Charleston coast, and this is a bit
slower than previously anticipated. As a result it may take
until 3 or 4 am before totally clearing the forecast counties.
For the most recent update given recent trends, we have backed
off on any t-storms until after midnight.
In advance of the front winds will be light or calm, and this
along with near zero dew point depressions will allow for patchy
fog to continue. As the front lifts through, winds will shift
to the south and continually increase through the night as a
50-60 kt low level jet moves through. Temps will be at their
min values prior to midnight, then slowly rise with the passage
of the warm front, climbing into the lower and middle 60s (maybe
even a few upper 60s near the Altamaha River.
Guidance of late has trended a bit slower with the convection
moving in overnight. While the instability is minimal as of
late Friday, it will increase some as it is drawn in from the
south-southwest in advance of the arctic cold front. Recent
runs of the HRRR show some SIG TOR values in excess of 1 or 2
units, with Supercell Composite of at least 3-5 units. This
keeps the risk of severe weather firmly in the forecast,
although timing could be a bit different depending upon how
trends go through the night. The main window for any severe
weather looks to be form 4 or 5 am through 9 or 10 am Saturday.
Previous discussion...
Light rains associated with the best overlap of moisture
transport and MLCAPE up to 250 J/kg will support light rains
either over the coastal corridor or just offshore early tonight.
There is then a lull in activity during the late evening and
early post-midnight period, before convection starts to arrive
from the south and southwest, and eventually as we get closer to
daybreak with the main line from the west. The chances of
severe weather will not occur until after 4 am, basing this off
the NAMNest, HRRR, RAP and to a lesser extent the NBM. However,
often times the guidance is a little slow with squall lines and
QLCS`s, such as this system. So this certainly bears close
watching.
Factors going for strong or severe convection will be the shear
and impressive wind fields that are 50+ knots as low in the
atmosphere as 1500-2000 ft, SRH on the order of 400-500 m2/sec2
and Supercell Composite values in excess of 4 or 5. Negative
factors for severe weather would be the unfavorable timing and
MLCAPE less than 500 J/kg. However, the strength of the
dynamical system could certainly be enough to compensate for
this.
Temps will hold fairly steady early tonight, then rise slowly
overnight as the warm front that is near Savannah to Claxton
early this evening, reaches northward into the Charleston quad-
county region by midnight, then north of the forecast area
overnight. With it will come a shifting of winds to the south,
increasing to 15-25 mph with gusts to 30 mph, which is enough
for a Lake Wind Advisory on Lake Moultrie late tonight.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
***Wind Advisory issued for all counties Saturday***
Based on sounding profiles that show winds tapping into 40+ or
greater within the mixed layer, and large isallobaric pressure
climbs on the order of 3-5 millibars every 3 hours, we opted to
raise a Wind Advisory from 7 am to 6 pm. For some places it
might not technically reach advisory thresholds, but rather for
impacts due to wet grounds and trees starting to leaf out.
However, for many places, wind gusts of 40 or 45 mph are
expected for at least a few hours throughout the day. Keep in
mind that winds on the bridges and overpasses will be even
stronger.
Previous discussion...
Saturday: By daybreak, a strong cold front will be moving swiftly
through the area. Along the front, instability will be lacking.
Although, there will be decent shear and helicity which will support
strong to severe thunderstorms. The main threats are damaging winds
and isolated tornadoes. By 7 am, SPC has the South Carolina coast
and slightly inland far east SC outlooked in an Enhanced Risk with
areas to the west lingering in Marginal/Slight Risk. In regards to
timing, the cold front should be mostly offshore by mid morning.
There could be isolated showers behind the front but high pressure
will push drier air into the area by the afternoon and cloud cover
will decrease, leading to a little bit of sunshine. Outside of
precip, winds are going to be quite gusty along and behind the
front. At this time, winds are below Wind Advisory criteria but one
could eventually be needed if winds become stronger than currently
forecast. High temperatures will max out in the upper 50s to mid 60s
and fall in the afternoon.
Saturday night through Monday: Surface high pressure will build into
the region and prevail through much of Monday. Overnight Saturday,
winds will be slightly elevated but will start to decrease. Sunday
will be sunny and then cloud cover will slightly increase on Monday.
The biggest concern of the period is low temperatures. Lows on
Sunday morning will be in the mid 20s to low 30s. A Freeze
Watch/Warning will eventually be needed. Another chilly morning is
then expected on Monday morning, although most areas could remain
above freezing. The bigger issue would be frost formation and have
mention in the gridded forecast for areas away from the coast.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
The forecast for mid-week is slightly complicated as the timing and
strength of a potential weak surface low moves out of the Gulf and
closer to the region. Overall though, the area will become more
conducive for showers as high pressure weakens and moves away from
the area. For Tuesday-early Thursday, at least sporadic showers will
be possible. The best chance for thunder will be late Tuesday and
into Wednesday so have maintained slight chance. High pressure will
then return late Thursday. Otherwise, temperatures will warm each
day.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
KCHS/KJZI/KSAV will remain IFR or LIFR through the night, with
no chance of any convection until late tonight and into
Saturday morning, mainly from about 08-14Z in association with a
strong Arctic front. This front will bring with it a QLCS and
strong to potentially severe TSRA, mainly around 10-13Z, before
conditions improve to MVFR by 13Z-14Z, then to VFR by 17Z.
Winds will definitely be a concern overnight and Saturday,
either in convection or outside of convection. Prior to the
heavier SHRA/TSRA moving in late tonight and Saturday, low
level wind shear will occur at all terminals, before stronger
surface winds occur as the QLCS approaches and within it.
Finally, winds will remain elevated in wake of the SHRA/TSRA for
most of Saturday. Highest winds could be 40 kt or greater, as
they shift from S-SW late tonight to the W and NW on Saturday.
Saturday evening through Wednesday: VFR will prevail through at
least Monday. Thereafter, flight restrictions will be possible in
showers and thunderstorms. Overnight Saturday, gusty winds will
continue before dropping off early Sunday.
&&
.MARINE...
We did add mention of the potential for a Storm Warning on the
AMZ350 waters into the Hazardous Weather Outlook from about 5
am to 2 pm due to forecast soundings showing winds of 50+ kt
within the mixed layer, and the HREF depicting a 30-50% chance
of winds reaching 50 kt. It is possible that similar winds could
impact parts of AMZ352 and AMZ374, but for only a short period.
Previous discussion...
Southerly winds will increase significantly and turn to the
southwest ahead of an approaching cold front. Gusts to gale
force are likely early morning hours, and a Gale Warning has
been issued for all coastal waters including the Charleston
Harbor starting at 1 AM. Seas will quickly increase in
response, becoming 4-6 ft and trending upward around sunrise
Saturday. A line of thunderstorms will accompany the cold
front, moving over the coastal waters in the early morning
hours. Strong wind gusts are the primary threat, waterspouts
will also be possible.
Saturday through Wednesday: A strong cold front will move across the
waters on Saturday morning, leading to gusty winds and strong to
severe thunderstorms. There will be a chance for waterspouts in any
convection that forms. Gale Warnings will remain in effect through
late Saturday for the Charleston Harbor then early Sunday for the
nearshore and outer Georgia waters. High pressure will then build in
over the waters on Sunday, leading to better marine conditions.
Although, Small Craft Advisories could be needed due to lingering
elevated seas and winds. By Monday, no marine headlines are expected
through Wednesday.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Wind Advisory from 7 AM to 6 PM EST Saturday for GAZ087-088-
099>101-114>119-137>141.
SC...Wind Advisory from 7 AM to 6 PM EST Saturday for SCZ040-
042>045-047>052.
Lake Wind Advisory from 4 AM to 7 AM EST Saturday for SCZ045.
MARINE...Gale Warning until 1 AM EST Sunday for AMZ350-352-354.
Gale Warning until 5 AM EDT Sunday for AMZ374.
Gale Warning until 7 PM EST Saturday for AMZ330.
&&
$$
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
Area Forecast Discussion
National Weather Service Cleveland OH
1019 PM EST Fri Mar 11 2022
.SYNOPSIS...
A cold front continues to drift eastward across our region and will
exit to the east by this early evening. This will happen before
primary low pressure deepens and moves northeastward along the front
from the Gulf of Mexico to New England through early Saturday
afternoon. Behind the front, a high pressure ridge builds from the
central United States through Saturday night. On Sunday, a weak
trough of low pressure should overspread our area from the west as
its parent low moves eastward across southern Ontario.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
9:30 PM Update...
Still watching the burst of snow showers along the
secondary/arctic cold front approaching western Lake Erie.
Increased PoPs to chance in NW Ohio to cover this frontal
passage. This is a key feature in the phasing of the northern
and southern stream energy as the mid/upper trough swings into
the Ohio Valley over the next 7 to 9 hours. It still looks like
the northern and southern stream H3 jet coupling early tonight
will expand an area of moderate snow over the eastern half of
the CWA, but latest 700 mb frontogenesis analysis from the 00Z
NAM and RAP shows a sharp axis from SE Ohio through
western/central PA. The aforementioned strong lift from the jet
coupling is leading to a tight gradient along this mid-level
frontal zone, so adjusted the highest PoPs slightly farther east
overnight with the expectation that the snow shield will expand
up an axis generally from SE Ohio to east of Erie, PA. This is
supported by 850-700 mb Omega fields showing strong sinking
motion west of the mid-level frontogenesis band and strong lift
along and east of it. This all means that areas west of I-77
should not see much additional snow tonight except for the quick
burst along the arctic front. Still expecting lake enhancement
later tonight as the cold air deepens behind the arctic front,
especially after 06 to 08Z when 850 mb temps fall to -13 to -15C
with deep moisture remaining east of Cleveland and NW flow. This
could add an additional couple of inches in the hills SE of
Cleveland and through the primary snowbelt before the system
pulls away in the 12-15Z timeframe leaving some pure lake-effect
in its wake. See original discussion for details on the
leftover lake-effect Saturday.
6:30 PM Update...
The cold front is now east across western PA with all sites
seeing mainly snow across the region. Increased PoPs to
categorical the rest of the evening west of I-71 based on
observations of snowfall as far west as the Sandusky area. The
gradient is beginning to tighten as expected with no snow at all
west of I-75, so have the steadiest snow ending west of a
Lorain to Marion County line by 02Z. We continue to expect
heavier snow to move up the I-71 corridor and points east the
rest of the evening through about 09Z before shifting east and
transitioning to leftover lake- effect. This is in response to
fairly textbook H3 jet coupling with one jet streak over lower
Michigan and another over West Virginia coupling the right
entrance and left exit regions over the eastern third of our CWA
this evening through the first half of tonight. This will
result in an intense 180+ knot H3 jet over PA and NY by Saturday
morning as the mid/upper trough axis swings across Ohio with
the surface low bombing out over the Jersey shore. Radar mosaic
loops are showing the heavier snow filling in to our SW between
Cincinnati and Columbus, and this will progress NE the rest of
the evening. A secondary cold front currently moving across
lower Michigan tied to the northern stream surface low over
Ontario also has a burst of snow along it. Once this crosses
Lake Erie in the next few hours, 850 mb temps falling below -10
C and WNW flow across a mostly open lake will generate lake
enhancement across the hills SE of Cleveland through the primary
snowbelt of NE Ohio and NW PA. Still think our previous snow
amounts look reasonable based on snow spotter reports so far
this evening, but we will need to watch for some overachieving
areas as this lake enhancement gets going after 02 or 03Z.
Original Discussion...
Predominantly SW`erly flow aloft persists through tonight as a
longwave trough approaches from the west. The axis of this
longwave trough should be located near James Bay and the Lower
OH Valley by daybreak Saturday. At the surface, a cold front has
accelerated eastward out of northeast OH into northwest PA and
should exit the rest of our CWA by this early evening. Behind
the front, a high pressure ridge builds from the northern and
central Great Plains. Periods of rain and/or snow are expected
along and ahead of the front due to a combination of lift along
the surface to 700 mb front and a corridor of pre-frontal
isentropic ascent tapping into appreciable moisture from the
Gulf of Mexico. Behind the surface cold front, rain should
change quickly to snow as the atmospheric column cools via CAA
and the wet-bulb effect. All widespread precip along and ahead
of the front should exit our CWA to the east by daybreak
Saturday. Precip is expected to remain light generally west of
I-71. Farther east, periods of moderate to heavy precip, mainly
in the form of snow, are expected this evening and overnight
tonight as the surface to 700 mb front strengthens, allowing
moderate to strong ascent to become maximized in a cloudy and
fairly deep DGZ, which will promote more efficient and heavier
snow production. The front will strengthen via low-level
temperature advection induced by a surface low that will develop
northeastward along the front from the north-central Gulf of
Mexico to the Mid- Atlantic region. In addition, favorable
interaction between coupled 500 mb jet-streaks will promote FGEN
aloft. Deep low to mid-level moisture/cloud cover and CAA
behind the cold front should allow a period of steady to heavy
lake-enhanced snow to occur generally east and southeast of Lake
Erie later this evening through the predawn hours of Saturday
morning, in and near the snowbelt. By daybreak Saturday,
lingering and primarily light lake-effect snow is expected
generally southeast of Lake Erie as a well-aligned northwesterly
low- level flow of unusually-cold air becomes established, yet
low-level dry air advection causes lake-induced CAPE to wane.
Fresh snow accumulations through daybreak Saturday are expected
to be 3-5 inches in northwest PA. In northeast OH, fresh snow
accumulations should reach 1-4 inches, with a tight westerly to
easterly gradient in snowfall expected along and near the PA
line. Elsewhere, fresh snowfall should average an inch or less.
The Winter WX Advisory and Winter Storm Warning remain
unchanged. Overnight lows should reach below-normal values in
the mid teens to lower 20`s tonight.
Primarily fair weather is expected Saturday through Saturday night
as surface high pressure ridging continues building eastward. Aloft,
the longwave trough traverses our region from west to east on
Saturday and is followed by ridging aloft Saturday night. Light to
perhaps occasionally moderate LES showers should continue generally
southeast of Lake Erie on Saturday. These LES showers should
eventually shift northeastward and offshore our CWA overnight
Saturday night as the mean low-level flow backs from NW`erly toward
SW`erly. Simultaneously, LES should weaken as lake-induced CAPE
wanes via dry air advection, and a lowering subsidence inversion.
Additional snow accumulations should be about an inch or less
in/near the secondary snowbelt and 1-3 inches in the primary
snowbelt. Daytime highs should reach only the low to mid 20`s on
Saturday amidst net CAA. For perspective, normal highs are near 45F.
Overnight lows should dip into the teens to near 10F Saturday night.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A weakening clipper system is forecast to cross the Upper Great
Lakes on Sunday. Warm advection precipitation with this system
is expected to be limited with just a low chance of mainly light
snow across Lake Erie and the snowbelt areas. Any accumulation
is expected to be half inch or less. Breezy southwest winds will
result in favorable warm advection through the remainder of the
day on Sunday with highs rebounding into the mid 30s(PA) and
into the 40`s in Ohio.
By Monday a split flow regime will develop with deep southwest flow
developing overhead as a trough moves into the southern Plains.
Warming will continue with partly cloudy skies and temperatures
solidly reaching the 50s area wide. A trough will move through the
northern stream on Monday night with a weak cold front crossing Lake
Erie. This front will be somewhat shallow and the southern reach of
it will have a large effect on temperatures. Currently the forecast
maintains highs in the 50s closer to Lake Erie with cooler flow off
Lake Erie dropping back into the low 40s, making for a large
gradient in temperatures across the forecast area. We did add a low
chance of rain/snow showers with the front but some models have only
a very weak surface reflection and limited forcing for
precipitation.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
Split flow pattern continues to start the long term with a ridge
building aloft while a closed upper low slowly crosses the
southeastern states. Warm advection is expected to continue through
Thursday with above normal temperatures in the mid and upper 60`s. A
poorly organized upper level trough will cross the Plains States
Thursday into Friday with southwest flow bringing an increase in
return moisture by Friday. Chances of rain look to return to the
area by Friday but can not rule out a few light showers as early as
Thursday evening.
&&
.AVIATION /00Z Saturday THROUGH Wednesday/...
Messy TAFs over the next 12 hours as a large area of moderate
snow moves through the eastern two thirds of the region bringing
prevailing MVFR and IFR cigs and vis. The heaviest snow and
lowest cigs and vis will be from about 01 to 07Z at MFD and CLE
and from 03 to 10Z at CAK, YNG, and ERI; perhaps a few hours
longer at ERI. Periods of LIFR are possible at times during
these windows. TOL and FDY will largely avoid the snow, so
expect very few issues there other than some MVFR at TOL
Saturday afternoon. Drier air working in Saturday morning will
lead to VFR returning from west to east at the TAF sites, but
scattered lake-effect snow showers will continue periods of MVFR
at ERI and YNG through midday. Some of these snow showers could
clip CLE into midday too, but not confident enough to include
in the TAF.
Winds will become more northwesterly tonight with gusts of 20-30
knots late tonight into Saturday afternoon. These winds will
begin to diminish at the very end of the TAF period.
Outlook...Non-VFR possible with periods of snow and/or rain
through Tuesday. This includes periods of lake-effect snow
showers that should persist generally southeast and then east of
Lake Erie Saturday afternoon through Sunday morning.
&&
.MARINE...
A cold front has settled south of Lake Erie with winds out of the
northwest. A stronger cold front will cross the lake overnight with
winds increasing to 20-25 knots across the Central Basin. A Small
Craft Advisory has been issued from the Islands to the Pennsylvania
state line where winds will increase after 11 PM and limited ice
coverage will allow waves of 5 to 8 feet. A Small Craft Advisory
will also be needed for the Pennsylvania nearshore waters by noon on
Saturday but thought we could wait a little while longer on the
issuance. In addition, given the northwest winds of 20-30 knots and
building waves, combined with a much colder airmass over Lake Erie
on Saturday, freezing spray is also likely to develop.
Conditions will improve by Sunday morning as high pressure builds
east across the Ohio Valley and winds back to southwest. Winds
during the day on Sunday will increase to 20-25 knots but will be
offshore flow. Small Craft Advisories may need to be expanded if
winds are strong enough. Southwest wind will continue on Monday
before a weak cold front settle south of the lake for Tuesday. A
gradual transition back to southerly winds will continue Wednesday
and Thursday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until noon EST Saturday for OHZ013-014-
023-033-089.
PA...Winter Weather Advisory until 7 PM EST Saturday for PAZ001-003.
Winter Storm Warning until 7 PM EST Saturday for PAZ002.
MARINE...Small Craft Advisory until 4 AM EDT Sunday for LEZ144>148.
Small Craft Advisory from 3 AM EST Saturday to 4 AM EDT Sunday
for LEZ149.
Small Craft Advisory until 10 PM EST Saturday for LEZ142-143.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Garuckas/Jaszka
SHORT TERM...KEC
LONG TERM...KEC
AVIATION...Garuckas
MARINE...KEC/Sullivan
Area Forecast Discussion
National Weather Service Green Bay WI
533 PM CST Fri Mar 11 2022
Updated aviation portion for 00Z TAF issuance
.SYNOPSIS...
Issued at 254 PM CST Fri Mar 11 2022
A brief shot of wintry weather for the start of the weekend and
early next week, then temperatures warming to above normal for the
middle to latter part of the week.
The upper pattern across North America was highly amplified, with
a deep trough over the middle of the continent. The westerlies
will quickly flatten back to a zonal regime early next week. Some
splitting of the flow is likely during the latter half of the
forecast period, with the forecast area primarily under the
influence of the dominant northern branch of the split.
A brief but intense (for mid-March) surge of cold will sweep
through the area during the next 36 hours. That will be followed
by a significant warm-up. Temperatures will reach considerably
above normal levels by the middle of next week, then remain mild
into the following weekend. Precipitation is likely to be AOB
normal for the period.
&&
.SHORT TERM...Tonight and Saturday
Issued at 254 PM CST Fri Mar 11 2022
The latest RAP analysis and satellite/radar imagery show scattered
snow showers along an arctic front exiting northeast Wisconsin
early this afternoon. A few snow showers briefly became rather
intense and dropped visibilities to a half mile or less for around 30
minutes and a couple tenths of accumulations. But most snow
shower activity has behaved so far today. Behind the front, winds
have shifted to the west and increased to between 30-35 kts at a
few locations. Daytime convective clouds have also developed
behind the front with only a few reports of flurries. As an arctic
airmass returns to the region, forecast concerns mainly revolve
around wind chill headlines, followed by the chance of lingering
snow showers this evening.
Tonight...Gusty northwest winds between 25-30 kts will usher a
much colder airmass into the region. With a very dry arctic airmass
arriving, think cloud cover is likely to be overdone in the
multi model blends. A few snow showers could linger near the U.P.
border which could get help from moisture fluxes off of frozen
western Lake Superior. Otherwise, skies will be clearing, but
northwest winds will remain breezy. Combined with falling temps
below zero over parts of central and most of north- central WI,
wind chill values of 20 to 25 below zero are likely for several
hours late tonight into Saturday morning. With coordination from
surrounding offices, issued a wind chill advisory from 08z to 15z
Saturday.
Saturday...After a very cold start, the surface ridge axis will be
sliding across the region through the day. Winds will diminish
further with the ridge axis under mostly sunny skies for most of
the daylight hours. Highs will be well be normal with highs
ranging from mid teens to low 20s.
.LONG TERM...Saturday Night Through Friday
Issued at 254 PM CST Fri Mar 11 2022
Changes to the long-term portion of the forecast were fairly
minor. It still looks like a 1-3 inch snowfall is likely Saturday
night, as a weak short-wave and strong isentropic lift sweep
through the area. The precipitation will taper off to flurries or
freezing drizzle as the mid-level moisture strips off to the
east. The highest snowfall totals will be across the north and far
northeast. Lows will probably occur before midnight, with rising
temperatures later in the night.
The next chance for precipitation will be late Sunday night into
Monday. Forcing for ascent will be rather complex, as a shortwave
propagating east across the CONUS begins to split as the southern
stream separates away from the main band of westerlies. The models
have had reasonable consistency with the placement of axis of the
heaviest the precipitation (especially for 3-4 days out). But the
precipitation band may be rather narrow, and precipitation type
may come into question as warmer air above the surface works into
the area from the south. The best estimate right now is for mainly
snow north with the heavier precip, and a rain/snow mix C/E-C WI
were precipitation will be lighter.
Warmer air will surge into the area by mid-week. Highs Wednesday
and Thursday will be 10-20F degrees above normal. Readings may
settle back a little late in the week, but should still be well
above normal.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 526 PM CST Fri Mar 11 2022
BKN ceilings (mainly VFR) and isolated light snow showers or
flurries over northern WI will dissipate early this evening as an
upper level disturbance shifts east of the region. Clearing is
anticipated over most of the area tonight, though a few
stratocumulus may continue through the TAF period.
Gusty northwest winds to 25 to 30 kts will persist into early
this evening, then gradually diminish through the overnight hours.
The winds will drop off considerably as a ridge of high pressure
arrives Saturday afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 2 AM to 9 AM CST Saturday for WIZ005-
010>012-018-019-030-035.
&&
$$
SYNOPSIS.......Skowronski
SHORT TERM.....MPC
LONG TERM......Skowronski
AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1030 PM EST Fri Mar 11 2022
.SYNOPSIS...
Cool and damp weather will linger as the region remains north of a
stationary front. Abundant rainfall returns to the region tonight
ahead of a strong cold front, with mountain snow expected Saturday
as colder air moves in behind the front. Expect windy conditions on
Saturday and very cold conditions Saturday night.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1000 PM...The forecast continues to look on track. No
changes to any of the headlines with this update. The cold front
was analyzed pushing across the Great TN Valley, and should start
pushing into the NC mountains around 1 or 2 AM. Radar mosaic shows
precip filling in along and behind the front, with some deeper
convection across AL. Meanwhile, areas of light rain and showers
with patchy fog is developing across the forecast area. No real
change in thinking, based on latest guidance. The HRRR wind gusts
look scary along the Eastern Escarpment, with 50+ kts Saturday
morning. But think confidence is too low to upgrade to a High
Wind Warning anywhere at this time. The 00z HREF is coming in
with a few updraft helicity swaths over the Lakelands after 06z,
which weren`t in previous runs. I still think convection will
be elevated, limiting any tor or convective wind threat, but the
environment and radar trends will be closely monitored until the
cold front passes thru.
Otherwise, full-latitude upper trough will swing across the central
CONUS with a strong cold front, which will impact the CFWA overnight
and through the first half of Saturday. Sfc low will ride along
the boundary and induce cyclogenesis as the core of the low enters
the vicinity of the area and the best upper dynamics overlap near
the CFWA. The first of many weather hazards will be the heavy
rain threat as PWAT values range between 1.00`-1.50" as the cold
front encroaches the region tonight. With great upper forcing
and stout southerly flow, expect for widespread heavy rain with
QPF amounts between 0.5" to 2.0" for most locations with locally
higher amounts and this could produce a hydro threat for portions
of the CFWA. Expect for scattered showers to push in from the
south this evening and the main frontal zone along the cold font
with push in overnight. A potent nocturnal LLJ (40-60 kts) will
be the driving force for elevated instability to form, especially
in locations along and southeast of the I-85 corridor. With stout
deep layer shear and strong lifting mechanism, a marginal severe
risk will be in store. Damaging winds will be the primary threat,
but an isolated tornado can`t be ruled out near the intersection
of the cold and warm front where SRH values will be the highest.
As the cold front slides through the CFWA overnight, very rapid
height falls and intense CAA will filter in behind the front. This
will support a 10 degree C drop in 850mb temps in less than two
hours across the mountains with rapidly falling snow levels. Expect
a quick transition to snow across the mountains just after
midnight starting in the Smokies and ridgetops, with the valleys
getting in on the action later overnight as snow levels continue
to drop. Northwest flow regime will set up shop early Saturday
morning and should last well into the afternoon hours along the
TN border. With very good saturation through the dendritic growth
zone, frontogenetic forcing, and decent duration of snow, elected
to continue the Winter Storm Warning above 3500` and Winter Weather
Advisory below 3500` over the mountain zones. As the core of the
low enters the CFWA overnight, high-res models continue to produce
small CAPE which could produce thundersnow with 1-2" per hour snow
rates at times. With what looks like a Great Lakes connection and
the CAPE potential, wouldn`t be surprised if a few streamers across
the mountains developed snow squall characteristics. Temperatures
will rapidly drop behind the front due to the very stout CAA,
with temperatures dropping throughout the day Saturday. Expect
high temperatures to be recorded at midnight tonight as some of
the coldest air of the season filters in overnight through Saturday
and into the beginning portions of the short term period.
Due to very stout CAA, very gusty winds will enter the region
with a very tight pressure gradient setting up over the CFWA
tonight through much of the day Saturday. 30-40 kt 850mb and a
deep boundary layer during the day Saturday east of the mountains
will mix Wind Advisory level gusts down to the surface. Values
are borderline Wind Advisory level criteria, but with the current
antecedent conditions, including very saturated soil moisture and
the expectation of long duration gusty winds, decided to issue an
area-wide Wind Advisory for the potential of scattered trees and
powerlines to come down, especially in the High Country starting
tonight. With very cold temperatures and ongoing gusty winds in
place, wind chill temperatures will be borderline advisory level
across the mountains Saturday evening and into the nighttime
period. Decided to issue a Wind Chill Advisory for the mountains,
mainly for elevations above 3500`. Temperatures will be 15-30
degrees F below normal for mid March.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 225 PM Friday: High pressure building into the region and
drying from the top down will put an end to any lingering snow
shower activity near the Tennessee border by midnight. Relaxing
surface pressure gradients and a gradual loss of upper support will
support weakening winds, likely falling below advisory level across
the entire region during this time frame. The arctic airmass with
light winds late, especially east of the mountains will support
overnight lows in teens in the mountains to I-40 corridor to low to
mid 20s elsewhere. Where complete decoupling of the boundary layer
occurs and winds go calm overnight temperatures could be up to 5
degrees colder than forecast. If and where this happens, both winter
21/22 and daily min temperatures could be challenged.
A quick transition from zonal to weak southwesterly flow and rapidly
rising heights and thickness will allow temperatures to warm into
the 50s Sunday afternoon and 60s for most into Monday. Sunny skies
may give way to partly cloudy skies later Monday as low level
moisture gradually rebounds.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 235 PM Friday: We have increasing confidence that active
weather will continue through much of next week. A couple of closed
low pressure systems will impact the region. The first appears to be
weaker, further south and may cut-off briefly, which could lead to
slow meandering movement. The second is stronger but more likely to
pass overhead or just to our north next Friday or Saturday. At least
scattered showers are expected with each system with isolated
thunder also possible, mainly south of I-85. The second system is
colder, so the ridgetops could see a wintry mix or snow. Regardless
temperatures will likely remain at or above normal through the
period save for perhaps Wednesday or Friday/Saturday should cloud
cover and precipitation keep us socked in.
&&
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: MVFR stratus and spotty light showers
continue to spread north into the area. Cigs are expected to lower
IFR and possibly LIFR levels through daybreak Saturday as a cold
front approaches the area from the west. Shower coverage will
increase ahead of the front, but the main band of convection will
be right along the front as it passes thru during the 05z to 11z
time frame. Cannot rule out embedded TSRA across the Piedmont,
but instability will be very limited. Gusty winds possible with
the convection, but the main gustiness will start behind the front
just before or right around daybreak Saturday, then continue thru
the period, except diminishing at KCLT Saturday evening in the
30-hour TAF. Lingering snow showers expected near the TN/NC border
Saturday, with a few possibly affecting KAVL Saturday morning,
but otherwise, clouds should scatter out and lift to VFR level by
late morning/midday, with further clearing in the aftn.
Outlook: Dry high pressure builds in Saturday night, and keeps
dry conditions across the area thru at least Tuesday. The next
low pressure system to affect the region may bring moisture in by
early Wednesday.
&&
.CLIMATE...
RECORDS FOR 03-12
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 83 1911 28 1960 57 1923 14 1998
KCLT 86 1990 38 1914 61 2016 19 1969
KGSP 83 1990 38 1960 59 1955 18 1934
RECORDS FOR 03-13
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 79 1990 29 1932 55 1927 14 1998
1960
1932
KCLT 86 1990 35 1940 61 2016 18 1960
KGSP 84 1990 34 1993 60 2006 20 1998
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Wind Advisory until 1 AM EST Sunday for GAZ010-017.
Wind Advisory until 7 PM EST Saturday for GAZ018-026-028-029.
NC...Wind Advisory until 1 AM EST Sunday for NCZ033-048>053-058-059-
062>065-501-503-505-507-509.
Wind Advisory until 7 PM EST Saturday for NCZ035>037-056-057-
068>072-082-502-504-506-508-510.
Winter Storm Warning above 3500 feet until 7 PM EST Saturday
for NCZ033-048>052-058.
Winter Weather Advisory below 3500 feet until 7 PM EST
Saturday for NCZ033-048>052-058.
Wind Chill Advisory from 3 PM EST Saturday to 8 AM EDT Sunday
for NCZ033-049-050.
Wind Chill Advisory above 3500 feet from 3 PM EST Saturday to
8 AM EDT Sunday for NCZ048-051-052-058-059-062-063.
Winter Weather Advisory until 7 PM EST Saturday for NCZ053-059-
062-065.
Winter Weather Advisory above 3500 feet until 7 PM EST
Saturday for NCZ063-064.
SC...Wind Advisory until 1 AM EST Sunday for SCZ001>003.
Wind Advisory until 7 PM EST Saturday for SCZ004>014-019.
&&
$$
SYNOPSIS...Munroe
NEAR TERM...ARK/CAC
SHORT TERM...Munroe
LONG TERM...Munroe
AVIATION...ARK
CLIMATE...
Area Forecast Discussion
National Weather Service Louisville KY
745 PM EST Fri Mar 11 2022
.Forecast Update...
Issued at 743 PM EST Fri Mar 11 2022
...Winter Storm Warning Expanded...
After reviewing some of the latest observational data upstream, as
well as near term models like the RAP/HRRR and watching those
trends, have decided to upgrade a section of the CWA to a winter
storm warning from the winter weather advisory. The winter storm
warning now stretches roughly from the BWG to LEX metro areas.
Models seem to be keying in on very heavy and concentrated snow
bands setting up within this area, and there is a good potential
that we see +4 inches of snow on grassy/elevated surfaces by the
time it wraps up tomorrow morning.
&&
.Short Term...(This evening through Saturday)
Issued at 315 PM EST Fri Mar 11 2022
...WINTER STORM TO IMPACT THE REGION TONIGHT...
======================================
Near Term (now through 7 PM Eastern)
Risks: Wintry mix across southern IN
Confidence: Medium-High
======================================
Afternoon satellite imagery shows mostly cloudy skies across western
Kentucky and southern Indiana. Across much of central and east-
central Kentucky, partly to mostly sunny skies were noted. There
was a strong temperature gradient across the region with readings in
the mid-upper 30s across portions of southwest Indiana and far
western KY. In the I-65 corridor, temperatures were in the upper
40s to the lower 50s and out in the I-75 corridor, temperatures were
in the lower 60s.
We expect highs on the day to occur within the hour and then
temperatures will start to fall from west to east as well advertised
baroclinic zone rolls eastward. By evening, we expect temperatures
to drop into the low-mid 30s across southern Indiana and western KY
(west of I-65) with lower-mid 40s across much of central-east KY.
Precipitation to the north and west of the region is expected to
increase in coverage as the right entrance region of the northern
branch of the jet works into the area. Through the late afternoon,
the highest risk of precipitation will be north of the Ohio River.
Precipitation will initially start off as a cold rain, but as the
column rapidly cools, we expect this precipitation to change over to
snow fairly quickly. At this time, only very minor accumulations of
snow are expected, mainly out toward the Jasper/French Lick areas
and that will likely be limited to grassy and elevated surfaces.
=======================================
Tonight (7PM - 7AM Eastern)
Risks: Snow and hazardous travel
P-type confidence: High
Societal Impacts Confidence: High
Snowfall Amounts Confidence: Medium-High
=======================================
Early this evening, combination of isentropic lift and strong
synoptic scale lift due to the region being underneath the favorable
entrance region of the jet will lead to widespread precipitation
development. Initially, the precipitation may start off as a very
brief period of rain, but as temperatures quickly crash and the
column cools, we expect snow to become the predominant precipitation
type rather quickly. Snow accumulation may be a bit slow at first
with rather light rates and warm ground. However, as the
precipitation intensity picks up, the rates will quickly overwhelm
the warmer ground and accumulations should pick up by mid-late
evening. Initially grassy and elevated surfaces (bridges/overpasses)
will be the first to experience problems. As the night wears on,
expect road conditions to become hazardous. Temperatures this
evening will start off in the lower-mid 30s over southern IN and in
the mid-upper 40s across much of central-eastern KY. These temps
will quickly crash and we expect most areas to be below freezing
prior to midnight.
As we get later into the evening, stronger synoptic scale lift is
expected across the region as not only will we be under the right
entrance region of the polar jet, but we will also be located within
the left exit region of the approaching sub-tropical jet. Model
cross sections still suggest that we`ll have a bit of weak symmetric
instability and a bit of conditional symmetric instability in parts
of the region. Much of this instability will be located in an area
east of I-65 and along and southeast of the Bluegrass Parkway.
Within a large band of snowfall, we expect some narrower bands of
moderate to heavy snowfall. The best combination of moisture and
lift with this instability looks to occur within the 12/03-08Z time
frame. Quite a bit of this lift and instability is co-incident
within the DGZ suggesting bouts of heavy snow will be possible.
Predicting exactly where this occurs is still uncertain, but the
overall guidance from this morning is still suggesting the highest
risk of heavy snow will reside within our current Winter Storm
Warning area.
With this forecast issuance, we have increased our snowfall amounts
slightly across portions of the advisory area and in the warning
area. Within the warning area, a general 3-6 inches of snow is
likely with locally higher amounts. To the west of the warning
area, we will continue to with a two segment Winter Weather
Advisory. In the eastern section (roughly from I-65 east to the
warning area), we are forecasting 2-4 inches of snowfall. In the
western sections of the advisory area, a general 1-2 inches is
expected. In areas north and northwest of the Ohio River, amounts
are expected to average around an inch or less.
In terms of confidence, we have high confidence that this will be an
impactful event late this evening and into Saturday morning. Our
confidence in amounts is medium-high. Overall, we have high
confidence in our warning area as deterministic and ensemble output
support warning level snows here. Within the advisory area, we have
a bit more uncertainty with amounts, especially over the eastern
sections of the advisory area. The data suggests we could see a
rather strong gradient of snowfall and even with the event this
close, these are really hard to determine. Some of the higher
resolution data has ticked slightly upward as well. Looking at
upstream obs, we noted that the HRRR did better with snowfall out
across the southwest this morning than the NAM runs. Hard to say if
this trend will continue with the storm moving east this evening. In
any event, we`ll continue to monitor data and observations this
evening. It is possible that we may have to expand the warning a
little further to the west if data and/or observations support it.
In terms of societal impacts, travel across the region is expected
to become hazardous overnight. With crashing temperatures, roads
will become slick with bridges and overpasses being the first to
freeze up. In general, if you do not have to travel this evening or
overnight, strongly consider delaying your travel plans until this
storm passes. If you must travel, check the road conditions before
traveling and make sure you have an emergency kit in your car just
in case. Motorists should take it easy on area roadways and reduce
your speeds and increase your distance between you and other
drivers. Additionally, please give local county and state road
crews appreciable distance as they will be out trying to clear the
roads.
Low temperatures tonight will drop into the mid teens to the lower
20s with wind chill values dropping into the single digits given
that we`ll have gusty northwest winds of 10-20 mph.
======================================
Saturday (7AM - 7 PM Eastern)
Risks: Hazardous Travel Early
Confidence: Medium-High
======================================
Snow is expected to be ending rather quickly across the eastern
portions of our forecast area early in the period. Temperatures in
the morning will remain cold with readings staying in the upper
teens to the lower 20s. Clearing will work into the region from the
west during the day, but strong cold advection will keep temps down
in the 20s for the entire day. Strong north to northwesterly flow
will be seen across the region. A fetch of moisture off the Great
Lakes may provide some additional snow showers across far
southeastern Indiana and into portions of the Bluegrass region. This
could bring some additional minor accumulations over the far
northeastern Bluegrass region.
Travel is expected to remain hazardous in the morning hours with
improvement expected in many areas by afternoon. This will be true
for the main roads, however, secondary and back roads within the
heavy snowfall band may remain slick through Sunday.
.Long Term...(Saturday night through Friday)
Issued at 305 PM EST Fri Mar 11 2022
Saturday Night - Sunday...
Anomalously deep low pressure system will quickly exit New England
off to the northeast Saturday night. A weaker shortwave trough zips
across southern Ontario through Sunday, but we`ll see increasingly
zonal flow aloft over southern IN and central KY. The weak wave to
the north will bring a brief uptick in cloud cover early Sunday over
southern IN and far northern KY. The pressure gradient does tighten
substantially early Sunday between the Canadian low and strong high
pressure over Alabama. Increasing southerly winds will result in
wind chills as cold as the single digits to teens Sunday morning,
but temperatures will also quickly warm after sunrise. After the
frigid Saturday night, temperatures jump back into the mid 40s to
lower 50s by Sunday afternoon. However, the wind will make it feel
cooler with gusts over 30 mph possible.
Monday - Thursday...
Monday looks dry and warmer with highs around 60. Low pressure moves
southeast near the TX/OK border, and deep southwest flow will remain
in place locally. Low pressure then drifts east across the Deep
South through the middle of next week, and most of the rain should
stay south of KY. Will hold on to a Slight Chance along the TN
border for now. But it looks mostly dry for now and quite pleasant.
Temperatures even look to approach/exceed 70 degrees Wednesday and
Thursday.
&&
.Aviation...(00Z TAF Issuance)
Issued at 601 PM EST Fri Mar 11 2022
Snow has developed and is impacting southern Indiana and portions of
central Kentucky at this hour. Cigs/Vis have generally been in the
IFR to MVFR range within the snow, and expect those types of
conditions for a part of the night for all sites. Cigs/Vis will
improve quickly to VFR behind the snow showers as drier air works in
from the northwest, with KLEX being the last site to dry out toward
dawn tomorrow morning. Winds will remain gusty out of the northwest
tonight and tomorrow.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 7 AM EST /6 AM CST/ Saturday for
INZ076>079-083-084-089>092.
KY...Winter Weather Advisory until 7 AM EST /6 AM CST/ Saturday for
KYZ023>039-045-061-070.
Winter Storm Warning until 10 AM EST /9 AM CST/ Saturday for
KYZ040>043-046>049-053>057-062>067-071>078-081-082.
&&
$$
Update...DM
Short Term...MJ
Long Term....EBW
Aviation...DM
Area Forecast Discussion
National Weather Service Memphis TN
902 PM CST Fri Mar 11 2022
.DISCUSSION...
Skies remain cloudy across the Mid-South this evening with
temperatures ranging from the upper 20s to upper 30s. A large area
of snow covers much of the region at this time. Many locations
have picked up 2 to 3 inches of snow with some isolated reports of
4 inches. Snow will start to taper off from west to east starting
around midnight and ending before sunrise. Will update forecast to
remove some early evening wording.
ARS
&&
.PREV DISCUSSION... /issued 310 PM CST Fri Mar 11 2022/
DISCUSSION...
Temperatures across the Midsouth range from the mid 30s in
portions of northeast Arkansas and the Missouri Bootheel to the
low 70s in far northeast Mississippi. A cold front front has moved
through Memphis and is approaching Oxford, MS and Savannah, TN.
Some very light rain or sleet may occur along or ahead of the
front, but most of the precipitation is post frontal and will fall
as snow tonight. Winter headlines have been issued for the entire
Midsouth. The large majority of the Midsouth is under a Winter
Weather Advisory with a small Winter Storm Warning in far
northeast Mississippi.
Latest guidance has trended faster with the overall system,
moving all of the snow into Alabama and Middle Tennessee before
sunrise. As a result, the Advisory and Warning will likely be
canceled before the current expiration time of 6 am. Most of the
Midsouth can expect to see a quick 1-3 inches of accumulation
though if a convective band sets up over any particular area, up
to 4 inches may accumulate. For now the most likely region for
this scenario looks to be in far northeast Mississippi or near the
Tennessee River in west Tennessee. The duration of snow at any
location across the Midsouth is likely only to be 3-4 hours but it
may become heavy at times.
Morning lows Saturday will be in the upper teens to mid 20`s with
a blustery north wind of 10-15mph. Sunrise wind chills will range
from the single digits to middle teens. We should see plenty of
sunshine tomorrow, however much of the Midsouth will remain in
the 30s.
Saturday through Monday should be mostly dry with significantly
warmer temperatures Sunday into Monday. High temperatures Monday
should be back in the 60s.
Another cold front is expected Monday night along with rain
showers. For now an upper low and weak surface low is expected to
track from south Arkansas across north Mississippi keeping most of
the Midsouth in the cool sector. This should keep any threat of
strong to severe thunderstorms to our south. Showers should
continue Tuesday and taper off by Wednesday morning.
Ridging behind the early week system will boost temperatures into
the 70s Wednesday and Thursday and provide dry conditions. Rain
showers are expected to return Friday as a more robust trough
moves out of the Plains.
30
&&
.AVIATION...
00Z TAFs
KNQA and METARs over east AR show some bands of +SN, with surface
VIS briefly dipping to 1/4SM. These bands appear likely to affect
MEM TRACON through 0115Z or so, before SN tapers off with drier
lifting CIGs to VFR and VIS to MVFR. HRRR has remained consistent
in tapering off snow in MEM by 06Z and see little reason to
disagree. VFR thereafter, with dry Arctic air prevailing
overnight and on Saturday.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Winter Weather Advisory until 6 AM CST Saturday for Crittenden-
Lee AR-Mississippi-Phillips.
Winter Weather Advisory until 3 AM CST Saturday for Clay-
Craighead-Cross-Greene-Poinsett-St. Francis.
MO...Winter Weather Advisory until 6 AM CST Saturday for Pemiscot.
Winter Weather Advisory until 3 AM CST Saturday for Dunklin.
MS...Winter Weather Advisory until 6 AM CST Saturday for Alcorn-
Benton MS-Calhoun-Chickasaw-Coahoma-DeSoto-Lafayette-
Marshall-Monroe-Panola-Pontotoc-Quitman-Tallahatchie-Tate-
Tippah-Tunica-Union-Yalobusha.
Winter Storm Warning until 6 AM CST Saturday for Itawamba-Lee MS-
Prentiss-Tishomingo.
TN...Winter Weather Advisory until 6 AM CST Saturday for Benton TN-
Carroll-Chester-Crockett-Decatur-Dyer-Fayette-Gibson-
Hardeman-Hardin-Haywood-Henderson-Henry-Lake-Lauderdale-
Madison-McNairy-Obion-Shelby-Tipton-Weakley.
&&
$$