Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 270814
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
314 AM EST Sat Dec 27 2014
.SHORT TERM (Now through Sunday)...
Issued at 300 AM EST Sat Dec 27 2014
Rainy short-term period set up by a slow-moving cold front now
stretching from a surface low over eastern Iowa southwest through
central Missouri. Flow aloft will remain southwesterly even as the
front passes us tonight. Disturbances within this flow should bring
periods of rain, given ample moisture streaming in here along with
forcing in the vicinity of the front. The best chances today will be
west of the I-65 corridor through early afternoon, then they pick up
quickly as the day wears on. Rainfall totals of a half inch to an
inch should be common by the end of the day Sunday. Rains should
taper off from west to east as the day goes on Sunday.
Temperatures will be above normal both today and tonight, then with
the front clearing the region around daybreak Sunday, we should see
a near normal day for highs.
.LONG TERM (Sunday night through Friday)...
Issued at 310 AM EST Sat Dec 27 2014
By Sunday evening, the cold front will be nearly parallel to the
flow aloft and therefore would take its time exiting to the south
and east. Will carry chance POPs south and east of a BWG-LEX line
Sunday night to account for this. Temps are warm enough to keep it
all rain. Bubble of high pressure will build in on Monday, with dry
conditions and temps near or just above climo. Cloud cover will
limit diurnal temp recovery, so max temp forecast is a couple
degrees below most of the guidance.
A moisture-starved upper shortwave trof will move into the Great
Lakes Monday night, opening the door for a sprawling Canadian high.
Will close out 2014 and begin 2015 with temps solidly below normal,
but by no means bitterly cold as the upper flow is still fairly
zonal. Coldest part of the week will be New Years Eve into New Years
Day, with afternoon highs Wednesday struggling to crack the freezing
mark, and lows Thursday morning in the teens and lower 20s.
The next chance for precipitation will come Thursday night into
Friday as a system moves in from the southwest. ECMWF is currently
12-18 hrs faster than GFS with onset of precip, so confidence is
limited and the models will likely waffle over the coming days with
most of the details. This will impact p-type as the low crosses the
Ohio Valley. If precip begins Thursday night, it could start off as
a wintry mix before transitioning to rain on Friday. This system
will therefore need to be watched closely in the coming days.
.AVIATION (06Z TAF Update)...
Issued at 1230 AM EST Sat Dec 27 2014
A cold front currently moving slowly eastward across Missouri will
bring increasing moisture into the region through the morning hours.
We should start to see some rains form ahead of it by early
afternoon, with cigs lowering through the afternoon hours. The front
likely will not clear the terminals until very late in the period,
but the rains will stick around, with IFR conditions likely tonight.