FXUS63 KLMK 241316
Area Forecast Discussion
National Weather Service Louisville KY
916 AM EDT Sat Mar 24 2018
Issued at 914 AM EDT Sat Mar 24 2018
The warm nose continues to progress slowly eastward. Area webcams
show that some areas that saw snow previously such as Frankfort are
seeing melting now. A mix of rain, snow, and sleet continues mainly
across areas in the Winter Weather Advisory with snow still likely
falling in much of the KY portions of the Winter Storm Warning area.
Jefferson, IN looks to be more of a mix. No changes to headlines are
planned at this time.
South central KY currently has a break in precipitation, but this
will fill back in over the next couple of hours as showers and
storms to the west move in.
Issued at 639 AM EDT Sat Mar 24 2018
850-700 mb warm nose had been progressing nicely to the east across
our CWA, however has recently stalled roughly along a line from
Scottsburg, IN down down through Richmond, KY due to dynamic
cooling. The stage is now set for a battle between the warm nose
aloft and undercutting cold advection at and near the surface. Areas
under the SPS and Winter Weather Advisory will likely see a mixture
of sleet, snow, rain, and even a bit of freezing rain this morning.
Some light accumulations mainly on grassy/elevated surfaces are
expected, although rates can be briefly strong enough to cover
roadways. Getting a few reports of heavy sleet mixing in over areas
where high reflectivities are occurring. So far, these areas are
covered under the Special Weather Statement and/or Winter Headlines.
The Winter Storm Warning area still looks good at this time as the
slower progression of the warm nose appears to be taking shape, and
longer residence time in mainly snow p-type appears to be setting up.
Ran some new numbers here in the last hour, and getting some
slightly higher totals in the Advisory and SPS counties. Not ready
to upgrade the SPS counties yet, but will consider one more tier of
Advisory counties if we start getting some accum reports.
.Short Term...(Today through Sunday)
Issued at 320 AM EDT Fri Mar 23 2018
...Another Round of Wintry Weather Expected For Some Today...
A surface low currently over east central Kansas will work its way
SE to the Ohio/Mississippi River confluence by this evening,
weakening slightly as it does so. Meanwhile, a warm front at the
surface will sneak into our far SW CWA near Bowling Green with a
large scale overrunning event occurring to the north and east of this
feature. The overrunning will be driven by a 850-700 mb SW-NE
oriented low level jet responding beneath the right entrance region
of an upper level jet.
This entire event will be driven by the location of the 850-700 mb
warm nose, and its role on P-type as we move into the morning and
afternoon hours. It should be noted that the warm nose is going to
be quite easy to track through the day as there should be a very
intense band of precipitation that sets up along it given a very
strong convergence zone along the elevated front. This band should
serve as the divider between rain on the SW side and heavy snow
along and on the NE side, with perhaps a period of sleet in between.
Currently the warm nose can be seen stretching from central IL down
through SW Indiana.
The big question with this forecast is exactly where the band of
snow is going to set up and persist the longest. The latest data
still supports our far NE CWA picking up the heaviest snow with
Warning criteria expected along and NE of a line from Madison, IN
down through Georgetown and Paris, KY. 3 to 5 inches is expected
across Jefferson County Indiana, and Scott/Bourbon counties KY, with
4 to 6 inches expected across Harrison/Nicholas counties. Will also
buffer these counties 1 tier to the SW where a tight 1 to 4"
gradient is possible across the counties. In coordination with IND,
will add Scott county to the Advisory where 1 to 2 inches could fall
in the NE parts of the county, but taper to nearly nothing in the SW
parts of the county. We're dealing with a very tight gradient here.
Did want to bring up the potential for some sleet and/or freezing
rain in the Advisory/Warning counties. The main wintry component
should be snow, but forecast soundings show a very deep isothermal
layer around 0-1C, and if enough melting occurs hydrometeors could
fall back into a re-freeze layer in the near-surface region.
Therefore, a brief but intense period of sleet is possible. In
addition, surface temps look to be just above freezing (~33F) in our
far NE, but if they are a degree or two cooler we could be dealing
with a period of freezing rain once the warm nose gets established
later this afternoon and evening. Don't think this is the likely
scenario, especially with precipitation rates being pretty intense
at times, but didn't want to mention as chances aren't zero for a
glaze of ice on some trees.
Expect the warm nose to become established well enough over the CWA
for all rain by 5 PM EDT. The exception would be the northern halves
of Harrison and Nicholas county KY where snow could hang on through
sunset. This is the area where we have the highest snow totals
forecast. 4 to 6" with locally higher amounts not out of the
The event is mostly over by sunset, although the warm nose does look
to collapse later in the evening with mid level cold advection. So,
if there is any deeper moisture left by this point, we could see a
last round of light snow. Like the idea of keeping the far NE
headlines going until 06z.
Tough to be overly confident with this forecast given the marginal
temp profiles due to a surging warm nose, and a very narrow swath of
heavy snow. That being said, the data has been fairly consistent
over the past 24 hours with where the heaviest snow is expected.
Please keep in mind that a very subtle change in the warm nose
position either NE or SW will result in a different amount/p-type
...Rain and Thunder Chances Elsewhere...
South and west of the Warning/Advisory headlines, expecting all rain
with even some embedded thunderstorms as forecast soundings show a
notable amount of elevated instability above 700 mb. Expect a 100%
chance of rain today with an 80-100% chance of rain tonight.
Overall, rainfall totals should be between 1 to 1.5" in most spots,
with some localized areas possibly seeing up to 2". Can't rule out a
few nuisance flooding issues given recent snow melt contributing to
It should be noted that a stiff E wind between 15 and 20 mph,
gusting up around 25 mph combined with cold rain and temps in the
30s will make for quite a miserable day. Our southern tier or two of
counties will be a bit milder with highs in the low 50s as the
surface warm front noses into that area. Fully expect to see a 20
degree temperature difference between southern KY and northern KY
Precipitation should largely be gone by Sunday morning with temps
starting out around 30 north to 40 south. Look for a dry day with
temps only struggling into the mid and upper 40s in most spots due
to cloud cover and a steady NE surface wind. The south could touch
the low 50s.
.Long Term...(Sunday night through Friday)
Issued at 320 AM EDT Sat Mar 24 2018
Sunday Night - Monday Afternoon...
An elongated upper ridge axis will stretch from the Gulf of Mexico
up through eastern Canada to end the weekend. This will give us a
brief, but mostly dry stretch into early Monday afternoon before the
next stretch of wet weather begins later Monday. Sunday night lows
will be in the mid to upper 30s, likely in the low 40s down near
BWG. Monday highs will top out in the mid to upper 50s before rain
Monday Evening - Wednesday Night...
A wet period of weather looks to take shape for the remainder of the
work week as SW flow through a deep layer develops between western
CONUS trough and east CONUS ridging. Initial rainfall should be
fairly light although pretty widespread as a warm front lifts over
the area. Will continue mention of scattered to numerous showers in
most areas, with categorical pops along and north of the Ohio River
through Tuesday afternoon.
At this point, the best chances for heavy rainfall look to be later
Tuesday night into Wednesday night as a plume of deep moisture
characterized by PWATs approaching 1.5 inches through the column
works into the region ahead of the upper trough axis. Heavy rainfall
leading to some hydro problems is a concern considering the rainfall
we receive this weekend, plus the work week rain. Will have to
monitor this potential over the coming days both for a Flash/Areal
Flood as well as a River Flood threat. WPC has a large area of 3 to
4 inches over our region over the next 7 days, and with locally
higher amounts possible given the setup bringing attention to the
potential for flooding seems like a reasonable message to continue.
The early to mid week time frame should be a milder stretch with
highs mostly in the low to mid 60s. After Monday night lows in the
mid to upper 40s, look for lows in the 50s on Tuesday night.
Thursday - Friday...
The full latitude trough axis will slowly slide through the area to
end the work week, keeping lingering showers in the forecast, and
bringing slightly cooler temperatures. Coverage won't be as
widespread, but will still be scattered to numerous at times. After
highs Thursday in the upper 50s and low 60s, Friday highs will be
back in the mid to upper 50s. Lows find their way back into the low
40s by Thursday night.
.Aviation...(12Z TAF Issuance)
Issued at 645 AM EDT Sat Mar 24 2018
Warm frontal boundary continues to push eastward into the region
with a band of widespread precipitation extending from north-central
IL into eastern KY. Precipitation is in the form of rain across
much of the region. However, areas east of a KMDN to KLEX line are
likely seeing a wintry mix of SN/PL. KHNB/KSDF/KBWG will likely see
on and off rain showers for much of the day. Winds will be gusty
out of the east with speeds of 10-15kts and gusts up to 22-23kts at
times. A wintry mix is expected at KLEX with a period of snow being
possible for a few hours this morning. The warm nose looks to push
eastward later this morning changing KLEX precip over to mainly rain
by afternoon. Winds over at KLEX will remain out of the east at 10-
15kts with gusts to 20kts possible at times.
Later this afternoon, a period of showers with a few thunderstorms
may affect KHNB/KSDF/KBWG. Model proximity soundings show the LFC
hanging around 700 hPa with a bit of elevated instability. For now
will continue to carry some VCTS down at KBWG, but may need to add
it into KHNB and KSDF in later forecasts.
IN...Winter Weather Advisory until 2 PM EDT this afternoon for INZ078.
Winter Storm Warning until 2 AM EDT Sunday for INZ079.
KY...Winter Weather Advisory until 2 PM EDT this afternoon for KYZ032-
Winter Storm Warning until 2 AM EDT Sunday for KYZ036-037-042-
FXUS63 KJKL 241200
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
800 AM EDT Sat Mar 24 2018
Issued at 800 AM EDT SAT MAR 24 2018
Precipitation making steady headway east and northeast across
eastern Kentucky. Getting reports of moderate snow around Stanton
and Clay City, but accumulations remain confined to grassy
surfaces. Temperatures will continue to wet-bulb to right around
freezing along and north of roughly a Harlan to McKee line, with
precipitation transitioning to rain from south to north through
the morning into this afternoon.
.SHORT TERM...(Today through Sunday)
Issued at 413 AM EDT SAT MAR 24 2018
Light rain continues to push into the Lake Cumberland region this
morning as a warm front lifts northeast through the mid-Mississippi
Valley toward the Tennessee Valley. The parent surface low will
track from eastern Kansas across the Ozarks, allowing abundant
moisture to stream into eastern Kentucky. Temperatures largely
remain in the upper 30s to lower 40s throughout much of eastern
Kentucky, with a few locales across the Big Sandy region and far
eastern Kentucky sitting in the low 30s as a result of being farther
displaced from the warmer incoming air and still being under the
influence of a residual cold dome on the southwestern fringes of
high pressure. Dewpoints in the Bluegrass region still remain in the
mid 20s, so wet bulb processes will allow for cooling temperatures
this morning once virga/rainfall arrives. This should allow for a
mix of rain and snow with likely all snow for a period into this
afternoon from Fleming to Elliott Counties and perhaps a few points
south and west.
Snowfall accumulations will likely be dampened by antecedent warm
ground conditions and extremely wet snow, evidenced by isothermal
sounding profiles just below freezing. Stout omega profiles,
especially above the boundary layer and right in the dendritic
growth layer, suggest plenty of lift in tandem with forcing for
ascent associated with shortwave energy stretching from the Corn
Belt through the Ohio Valley. Expecting 1.25 to 1.75 inches of
precipitation south of Mountain Parkway with around an inch north
through tonight. River flooding concerns may arise across portions
of the Cumberland River basin as elevated convection may result in
periods of heavier rainfall this afternoon and evening. Snowfall
amounts still look to fall in the 3.5 to 5 inch range along and
north of a Mount Sterling to West Liberty line, with 1-3 inches
south of this and north of a Stanton to Jackson to Whitesburg line.
These will be refined through the day based on thermal profiles. It
is important to keep in mind that a degree or less difference in
temperature profiles could spell the difference between several
inches of heavy/wet snow and cold rain. Nonetheless, even a couple
of inches of snow today may be enough to produce scattered power
After transitioning to mostly rain this afternoon, the snow line
will shift back south this evening into tonight. Precipitation will
taper off from north to south as the upper shortwave trough shears
out and translates across eastern Kentucky before becoming absorbed
with energy across the northeastern CONUS. Surface ridging remaining
centered across Quebec along with rising upper heights locally
will negate a strong push of cold air into eastern Kentucky
tonight as the surface low shifts south and east. This should keep
ridgetops near the Virginia state line from seeing much in the
way if any additional snowfall accumulations this evening and
tonight as precipitation remains mostly liquid. Drier conditions
will prevail Sunday afternoon with temperatures topping out in the
mid 40s north to mid 50s south.
.LONG TERM...(Sunday night through Friday)
Issued at 453 AM EDT SAT MAR 24 2018
Upper level ridging will take hold early Monday through Tuesday,
bringing drier weather into the Commonwealth. A trough will
develop to the west as a surface low pressure system develops.
With the progression of this low pressure, a warm front will set
up over the Great Lakes into the Ohio Valley later on Tuesday.
This southerly flow will usher in warmer, moist air up from the
Gulf of Mexico. As the surface low continues to progress eastward,
a fairly slow moving cold front will move over eastern Kentucky
Thursday. This system will be the main source of precipitation for
the extended period. One thing to note is that the precip for the
forecast period will be all rain due to the increase in
temperatures from the southerly Gulf flow.
There is fairly good agreement in the upper level pattern in the
models, especially early on in the forecast period. But, the GFS
shows higher QPF to the west of the CWA by Wednesday morning
compared to the ECMWF. The GFS QPF ranges from 0.1 to 1 inch,
with higher amounts to the north and west of the CWA. The ECMWF
shows QPF of 0.25 inches in the northernmost portion of the CWA at
this time. The latest trends in the model runs then show the
track of the system southward over the Appalachians as the upper
level trough deepens and progresses eastward. The GFS track is
more southerly than the ECMWF, though, since the upper level
trough is more amplified. This also correlates with the higher QPF
shown in the GFS run. Therefore, confidence is low for the later
portion of the extended. Opted for the Blend for the most part,
with little adjustments in the PoPs moreso for the later portion
of the extended.
Temperatures will be on the increase with the advancement of the
southerly, warm Gulf air. High temps will be in the 60s for the
majority of the period until the passage of the cold front later
Thursday, bringing a decrease in temperatures to end the work
.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
ISSUED AT 800 AM EDT SAT MAR 24 2018
MVFR conditions unfolding across the Lake Cumberland region will
continue to progress northeastward this morning. These will
further lower toward IFR levels this morning as rain moves in from
the west, also subsequently reducing visibilities to IFR/MVFR
levels. Farther north, will see snow impact SYM, SJS, and JKL,
leading to slushy/slippery tarmacs this morning and possibly into
this afternoon. Should see a changeover to mostly rain this
afternoon with some snow continuing to mix in along and north of
an IOB to PBX line. The snow line will gradually work back south
this evening and tonight as precipitation tapers off from north to
south, while ceilings and visibilities remain IFR/MVFR through
much of the night. Additionally, the terminals across southern to
southeast Kentucky, including EKQ/SME/LOZ may see a few bolts of
lightning this afternoon and evening as elevated thunderstorms
will be possible. Winds off the deck will quickly veer from
easterly to westerly within the lowest few thousand feet. May see
speeds approach 30-40 knots at times, but have kept low level wind
shear out of the forecast for now as the greatest impact from
this may be just above FL020.
Winter Storm Warning until 2 AM EDT Sunday for KYZ044-050>052-
Winter Weather Advisory until 2 AM EDT Sunday for KYZ059-107>110-
FXUS63 KPAH 241126
Area Forecast Discussion
National Weather Service Paducah KY
626 AM CDT Sat Mar 24 2018
.SHORT TERM...(Today through Monday night)
Issued at 313 AM CDT Sat Mar 24 2018
Elevated warm advection showers will continue to gradually drift
from southwest to northeast this morning. A secondary mid-level
shortwave is currently rotating around a trough in eastern
Nebraska/western Iowa at this time, adding lift near a low west of
Kansas City this morning. This should help fill in new convective
activity across south central/southeast Missouri through
daybreak, working east across the rest of the WFO PAH forecast
area by late morning.
The 13km RAP seems to have a good handle on elevated instability
this morning, with most of the lightning activity developing with
a gradient of 100-200 J/KG in the 700-650 mb layer. Backed off
with the initial elevated thunder mention over southeast
Missouri/southwest Illinois until daybreak.
As the surface low rapidly develops southeastward near Perryville
by 4 pm this afternoon, surface-based warm sector showers and
thunderstorms will develop east of the weak cold front/weak dry
line. Dewpoints within the warm sector will range from 50 to 60
degrees Fahrenheit, providing amble fuel for convection as the
upper trough/mid-level slow slides southeast across the area
Temperatures will be in the upper 50s along and just south of the
warm front to lower 70s in the foothills of southeast Missouri
prior to the frontal passage. With more scattered convection
expected south of the warm front, rainfall amounts should remain
less than 0.5". Rainfall amounts will kick up north of a
Pinckneyville and Eddyville Illinois line onward to Princeton and
Elkton Kentucky. With elevated thunderstorms expected further to
the northeast, rainfall totals near 1.25" will not be out of the
question near a Petersburg and Dale Indiana.
High Pressure will briefly develop into the area late tonight and
through the daytime hours on Sunday, as another ridge builds in
at mid/upper levels through Sunday evening.
This ridge will move out early Monday morning, with ample warm
advection again moving moisture back northeast at lower levels
Monday morning, with another warm front working northeast through
afternoon and evening. Another round of showers will develop along
a warm front will mostly impact southwest Indiana and the
Pennyrile region of West Kentucky.
By Monday night, as the upper level flow begins to become
southwest flow the bulk of the moisture advection and lift will
switch westward into southwest/south central Missouri and West
The Canadian guidance seemed to initialize well and was in line
with the ECWMF and NAM-WRF guidance in the short term. Forecast
confidence is fair to good (up to 65%) today through Monday night.
.LONG TERM...(Tuesday through Friday)
Issued at 313 AM CDT Sat Mar 24 2018
Forecast confidence is well above normal through Wednesday and then
decreases heading into the end of the week and next weekend.
Tuesday will begin with an upper-level ridge extending from the Gulf
northeast up the Appalachians and a complex trough extending from
the northern Plains to the Four Corners. At the surface a cold front
will extend from Oklahoma northeast into Wisconsin. Our region will
be under southwest flow aloft, with strong and gusty south winds
advecting Gulf moisture northward toward the boundary. Convection
will be ongoing along or just southeast of the cold front, generally
just to the northwest of our area.
As the northern portion of the upper trough pushes eastward into the
Great Lakes through Wednesday, the front and primary band of
precipitation will push southeast into and most likely through our
area. The ECMWF continues to be stronger with the upper ridge in the
east, and is a bit slower with the frontal passage. It leaves open
the possibility of the boundary stalling out over or just southeast
of west Kentucky, but even it has trended faster and ultimately
drier for our region. The bottom line is that Tuesday and Tuesday
night look wet, but much of the area should be dry Wednesday and
With the faster progression of the boundary through the region,
precipitation totals have trended down significantly from
yesterday's levels. Totals from Sunday night through Thursday night
now range from 1.25" over southwest Indiana to 2.5"-3" along the far
western and southern border regions. This is still quite a bit of
rain, but over a 4-5 day period it should not cause to much trouble,
especially with the mainstem rivers starting out well below flood
stage. Instability is still hard to find, but some elevated
instability does exist mainly over southeast Missouri and southern
Illinois as the main band of rain begins to move into the area
The 00Z models diverge a bit Thursday with the upper trough, in some
form, moving east through the Quad State. The ECMWF develops a wave
along the surface boundary, which is just to our southeast, and
brings a quarter to a half inch of rain over the entire area
Thursday. The GFS has the boundary farther southeast, and has
scattered showers moving east across the region Thursday night, with
only some light precipitation in the southeast during the day. The
GEM/CMC has a much weaker trough and keeps our area dry Thursday and
Thursday night. We will leave chance PoPs over the entire area both
periods to acknowledge the possibility, but not fully endorse the
wetter ECMWF just yet.
All indications are that the area will clear quickly behind the
upper trough passage, and there should be plenty of sunshine next
Friday. However, surface high pressure will hold temperatures down
about 5 degrees below normal with highs only in the middle 50s.
The flow aloft will really relax and become nearly zonal early next
weekend. At the surface a warm front will be moving through the
region Saturday into Saturday night. The ECWMF and GFS agree on
these basics, but differ in the specific timing and
coverage/intensity of the precipitation. For now we will lean toward
the GFS and have just small chances of showers over the northern
half of the forecast area, mainly Saturday morning. The GEM/CMC is
much wetter and is a definite outlier at this point, so it was
ignored for this forecast.
Looking another day out for Easter Sunday, it looks like the entire
area should be in the warm sector with stout south winds and
generally mild conditions. A few showers cannot be ruled out, but we
should be mostly dry.
Issued at 627 AM CDT Sat Mar 24 2018
Although KCGI and KPAH will start out in VFR and MVFR category
ceilings, these ceilings will drop sharply to IFR and LIFR
category as the surface low between Kansas City and Springfield
Missouri moves east-southeast through the WFO PAH TAF sites. The
frontal boundary appears to be initalizing a little further south
than previously forecast for KCGI and KPAH, which will keep them
in IFR category alot longer. In addition, with a warm frontal zone
nearby, low level wind shear will be a concern through at least
14z for KCGI and KPAH.
For KEVV and KOWB, well entrenched on the cold side of the warm
frontal boundary, IFR ceilings will dominate through the forecast