Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 050605
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
105 AM EST Thu Mar 5 2015
Issued at 100 AM EST Thu Mar 5 2015
SPC Mesoanalysis page still has a good band of frontogenesis at 700
mb with EPV colocated and this region is where the heaviest returns
are on radar. Initial two band structure has morphed into one
broader and slightly weaker band. Still getting plenty of heavy snow
reports in that band with a foot likely in several spots. Louisville
may yet see a little more snow as another surge of moisture comes in
here from southern Illinois.
Issued at 1130 PM EST Wed Mar 4 2015
Intense mesoscale band of snow up to 1.5 inches per hour continues
at 1130 pm EST from Hardinsburg through just south of Fort Knox
through Shelbyville through Frankfort. This band is only very slowly
moving southeast. It is under this band and across the Bluegrass
Region that some storm total snowfall amounts of a foot or more are
Snow is beginning to lessen over southern Indiana and only an inch
or so of additional snow is likely from Dubois through northern
Scott County. The edge of the very heavy snow is right along the
Ohio River and will slowly sag southeast through 1am EST.
Issued at 1040 pm EST Wed Mar 4 2015
At 1040 pm...a band of intense snow is setting up from Breckinridge
through Fort Knox through Frankfort. Snowfall rates of over one inch
per hour will be experienced under this band as it sags southeast
towards Bardstown and Lexington. Heavy snow continue along and south
of the Ohio River. Heavy snow along the Ohio will likely continue
through at least midnight and probably longer.
Issued at 940 pm EST Wed Mar 4 2015
Freezing rain and sleet continues along a line along the Cumberland
Parkway. Snow has had a difficult time moving south of a Bowling
Green to Madison County line. Eventually, mixed precipitation will
change over to snow. Sleet accumulations along the Bluegrass Parkway
may exceed 1/2 inch before changing over to snow towards midnight.
Issued at 820 PM EST Wed Mar 4 2015
Will let the areal flood warnings and flood advisories expire. Rain
has changed over to snow across much of the advised area. Main stem
rivers such as the Kentucky and Green will still rise over the next
.SHORT TERM (Now through Thursday Night)...
Issued at 301 PM EST Wed Mar 4 2015
...Winter Storm Still on Track Tonight...
...Bitter Cold Friday Morning...
First, though, will likely go ahead and let the Flood Watch expire
on time at 7pm EST/6pm CST. Only light rainfall amounts are
expected for the rest of the afternoon/evening and any ongoing minor
flooding can be handled with short term products.
Cold air is coming into the region as arctic high pressure enters
the from the northwest. The rain changed to sleet and then snow
earlier this afternoon north of the Ohio River, with the changeover
continuing to move to the southeast late this afternoon and this
evening. Frontogenetical forcing, our location near the right
entrance region of the upper jet, deep moisture, significant
isothermal layer and good dendritic growth on soundings, and some
weak low level instability all point to widespread snow tonight.
Snow amounts are never easy to nail down, but in general, after
chatting with neighboring offices, we have remained fairly
consistent with the amounts we`ve been advertising since last night.
There will be some banding with this event, and anyone getting
caught under a band will see strong snowfall rates and, as a result,
higher amounts. The best chance for heavy banding appears to be
roughly from the northern Blue Grass through the Nolin and Rough
River Lake areas.
We have pulled back a bit on glaze in the south tonight. In
southern Indiana the changeover has been primarily from rain to
sleet to snow, and model progs in southern Kentucky this evening
support that idea. Some ice will still be possible, but should be
less than a tenth of an inch.
Low temperatures tonight will generally be in the teens...perhaps
around 20 in the Lake Cumberland region.
On Thursday the storm system will pull off as the arctic high
advances from Iowa to Illinois. In southern Indiana significant
snow should be done before the sun rises, with snow tapering off
from northwest to southeast during the early and mid morning hours
in Kentucky. Could see a few lingering flurries into the afternoon
as clouds slowly break up. With clouds in the sky and snow on the
ground, and northerly surface winds, went cooler than guidance for
highs. Didn`t goo *too* cool, though, since we could get some
partial March sunshine in the afternoon. Given this, temps landed
in the lower and middle 20s for highs.
Tomorrow night that high will continue to invade, and will be
centered right over the Ohio River at 12Z. This will lead to calm
winds and mostly clear skies. With those factors plus deep fresh
snowcover, went well below guidance for lows, keeping in line with
previous forecasts in the single digits either side of 0. That`s
about 30 degrees colder than normal.
.LONG TERM (Friday through Wednesday)...
Issued at 230 PM EST Wed Mar 4 2015
...Spring-like Temperatures On the Way...
Friday - Saturday...
Sfc high pressure will settle into the region for Friday/Saturday
resulting in dry conditions. The main forecast challenge will then
be temperatures over the snowpack. After a potentially record
setting cold Fri morning, temperatures will struggle to reach the
mid to upper 20s Friday afternoon with perhaps some locations over
far south central KY in the Lake Cumberland region reaching lower
30s. If the Lake Cumberland region receives a thicker snowfall,
they may not make it out of the upper 20s Fri afternoon either.
Friday night into Saturday, temperatures look to moderate some as
troughing/NW flow flattens over the Ohio Valley. Expect low temps
Sat to range between 10-17 degrees and highs on Sat afternoon to
rise above freezing into the mid and upper 30s with some locations
potentially reaching 40 degrees.
Although sunshine on Friday should help melt snow off of dark
surfaces like pavement, Saturday should be a better melting day area
wide as temps rise above freezing.
Sunday - Wednesday...
The GFS tries to bring a very small amount of precip into our area
from a disturbance passing to our north on Sunday, but moisture
profiles seem too shallow for precipitation. Thus, will continue
with increased clouds and no POPs.
The bigger story for next week is a big warm up for the Ohio Valley
taking temperatures back to around normal. The upper level pattern
will flatten over the CONUS early next week helping temps to
moderate over our region as thicknesses steadily rise. In addition
a more active southern stream should help push warm air into the
Ohio Valley starting Tues. Some rain chances look to occur in the
Tues-Thurs time frame next week although models are in disagreement
as to when and how much rain we will receive mid week next week.
Therefore will continue 20% POPs in that time frame. One thing that
long range models are in agreement with is high temperatures
reaching the 50s and perhaps low 60s Tues-Thurs next week!
.AVIATION (06Z TAF Update)...
Issued at 1240 AM EST Thu Mar 5 2015
Impactful winter storm ongoing across the TAF sites. Persistent
moderate to heavy snow continues to slide NE under a powerful upper
level jet. Visibilities have mostly been around 1/4 to 1/2 mile
range in heavy snow, with ceilings below the IFR threshold.
SDF will be the first to see improvement, and will likely waffle in
and out of 1/2 to 2 miles as it lingers on the northern edge of the
precipitation shield. Expect to improve to low MVFR by 08z with a
continued steady north wind. Have light snow ending just after
daybreak, with a return to higher MVFR ceilings. Expect to go VFR
by early this evening.
LEX and BWG still have several more hours of 1/2-1 SM moderate to
heavy snow and IFR ceilings before conditions improve to light snow
around daybreak. Expect snow to end around early to mid afternoon
with MVFR conditions persisting at least through sunset. Steady
north winds will persist through the forecast period.
KY...WINTER STORM WARNING until 1 PM EST /Noon CST/ this afternoon
IN...WINTER STORM WARNING until 1 PM EST /Noon CST/ this afternoon