Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 112006
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
306 PM EST Wed Dec 11 2013
.SHORT TERM (Now through Thursday Night)...
Issued at 305 PM EST Wed Dec 11 2013
Mostly clear skies were noted across the forecast area this
afternoon. Surface map shows the next cold front just north of the
forecast area. Front was from near Poplar Bluff MO to near Muncie
Indiana and heading southeast. Based on the short term model
guidance, the front should approach the Ohio River in the next few
hours and sweep through Kentucky early this evening. Band of
mid-high level clouds will sweep through the region as the front
passes through. Some deeper moisture will pass just northeast of
the forecast area and perhaps a snow flurry or two may be possible
across our far NE sections this evening. Temperatures will then
take the plunge overnight as the new colder airmass spills into the
region and skies clear out.
Overnight lows look to be the coldest over our far
northwest/northern areas...where readings are likely to get near
zero or -1. Feel that best chances of this occurring would be north
of a line from near Jasper to Deputy Indiana. Readings in the
single digits will be found south of the area down to just a little
south of the Ohio River to where the southern edge of the snow pack
remains. Temperatures in the Louisville, Frankfort, and Lexington
areas will probably drop to the single digits. A sharp gradient in
temperatures is likely along and south of the I-64 corridor with
lower-middle teens expected across much of central and southern
Kentucky. These temperature forecasts are based on generally light
winds occurring tonight. If the surface winds stay up a little
higher than forecast, then readings may not get as cold. We will
continue to monitor that this evening. In addition to cold
temperatures, any wind will make it feel colder with wind chill
readings likely in the 0 to -5 range across southern IN with 0-5
wind chills across portions of north-central KY.
Mostly sunny conditions are expected on Thursday as high pressure
passes over the area. A gradient of temperature is likely to be
found across the area with highs only topping out in the lower 20s
across the snowpack in southern Indiana. Temperatures should really
ramp up along and south of the Ohio River along the southern edge of
the snowpack with readings in the mid-upper 20s in KY north of the
BG/WK parkways. South of the parkways, upper 20s to the lower 30s
Mostly clear and cold conditions look to continue into Thursday
night. Temperatures will likely drop back into the single digits to
lower teens in the snowpack regions of southern Indiana with
mid-upper teens across northern Kentucky and lower 20s across
.LONG TERM (Friday through Wednesday)...
Issued at 305 PM EST Wed Dec 11 2013
Friday - Saturday Night...
Another strong subtropical impulse will overspread the Ohio Valley
from the southwest CONUS as we head into the weekend. Meanwhile, a
weak shortwave embedded in the polar jet will dive across the
northern Plains, then through the Ohio Valley late Saturday.
This impulse will phase with the more dominant southern stream to
our east to end the weekend. At the surface, a lee side low develops
and strengthens over Texas on Friday, riding northeast toward the
Ohio Valley on Saturday. The low should be over the mid Atlantic
states by Sunday morning.
This setup will once again bring the possibility of transitioning
precipitation types across the Ohio Valley from late in the day on
Friday through Saturday night. At this point, it appears that a
light mix of rain, snow, or ice pellets will be possible on Friday
night as the column saturates and temp profiles wet bulb.
Precipitation type should transition to almost all rain on Saturday
as we warm to the upper 30s and lower 40s on steady southerly flow
ahead of the approaching low. We could hold on to a rain/snow mix
across the southern Indiana counties through the day. On Saturday
night, cold air will quickly come crashing in as the phasing H5
trough axis swings through and cold air aloft arrives quickly. We
will be losing deep moisture at this time, so could see a scenario
where the changeover to light snow is brief. A bit concerned about
potential for freezing drizzle on the back side as we lose ice
crystal growth when deep moisture exits.
Overall, don`t really think we`ll see many problems with the initial
batch of mixed precipitation on Friday night as temperatures will be
marginally around freezing and surfaces will be warm from earlier
in the day. Also think that the change over will be too brief on
Saturday night, with mainly light snow, flurries, and some patches
of freezing drizzle. Will continue to mention some minor snow
accumulations possible across our northern CWA in the HWO.
Sunday - Wednesday...
Will go with a prolonged period of dry weather as we head into the
next week. The pattern will be characterized by more zonal, if not
slightly shallow northwest, flow. Will watch as several moisture
starved waves dive through the flow across the Great Lakes, however
do not expect any precipitation from any of these disturbances at
this time. Expect an upward trend in temperatures from highs in the
upper 20s and low 30s on Sunday to highs in the low and mid 40s by
Tuesday. Lows will also trend milder, back to the mid and upper 20s
by Wednesday morning.
.AVIATION (18Z TAF Update)...
Updated at 1151 AM EST Wed Dec 11 2013
VFR conditions are expected through the upcoming TAF period.
Surface winds this afternoon will be out of the southwest this
afternoon in advance of an approaching cold front. Surface winds
are expected to be in the 8-11 knot range. Winds should veer to the
west late this afternoon and then shift to the northwest as the dry
front presses southward through the region. Frontal passage and
wind shift looks to occur between 11/23Z to 12/01Z at the
terminals. Northwest winds will continue overnight with speeds of