Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 072005
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
305 PM EST Fri Mar 7 2014
.SHORT TERM (Now through Saturday Night)...
Issued at 300 PM EST Fri Mar 7 2014
Weak ridging at the sfc and aloft will result in dry conditions
tonight with only few-sct upper level clouds in the area. We should
see a decent rad cooling night with low temps in the low to mid 30s.
For Saturday, expect increasing clouds and increasing southwest
winds ahead of an approaching weak cold front. Temps should warm
nicely ahead of the front Sat afternoon into the upper 50s to lower
For Sat night, expect the cold front to push through the region
during the evening hours with some light rain following and then a
weak surge of cold air late Sat night. At most, some locations may
see up to a tenth of an inch of rain Sat night. After the rain
passes through, the colder airmass and clearing skies should help
temps drop during the early morning hours into the upper 20s to
lower 30s across much of the area. South central KY will probably
still stay in the mid 30s to around 40 by around sunrise Sun
.LONG TERM (Sunday through Friday)...
Issued at 255 PM EST Fri Mar 7 2014
The synoptic pattern at the start of the long term period will
feature northwest flow aloft, which will transition quickly into
more of a zonal pattern by the middle of next week. This will make
for a marked warming trend through the first part of the extended,
before yet another trough builds into the eastern CONUS by the
second half of next week.
The first part of the long term period will be characterized by
relatively benign weather, with a warmup coming. Behind the system
mentioned in the short term section below, temperatures will be a
bit cooler Sunday, with highs in the upper 40s and 50s. On Monday,
a surface low passing well to the north of the region will help
tighten the pressure gradient across the Ohio Valley. This will
help strengthen surface southwesterly flow, allowing for a nice
warmup. Given good turbulent mixing, the expected sunshine,
and warming temperatures aloft (850mb temps climbing to around 10C),
have bumped temperatures up quite a bit from the previous forecast
for Monday, which puts highs in the low to mid 60s.
On Tuesday, a PV anomaly will scoot across the western CONUS into
the central U.S., helping to induce a surface low across the Central
Plains. This will help tighten a frontal boundary somewhere near
the Ohio Valley. Where exactly this boundary sets up will determine
highs on Tuesday, but at this time it appears it will sharpen to the
north of the region, putting us in the warm sector which will allow
highs to climb into the mid 60s!
Guidance diverges a bit with the handling of the approaching system
Tuesday night into Wednesday. The latest 07/12Z ECMWF continues to
show a bit more phasing of this system with another strong anomaly
diving south out of Manitoba (a Manitoba mauler), which produces a
stronger overall system with better access to colder air. The GFS
and it`s ensemble are less phased with this system, leading to a
warmer solution. Either way, this appears to mainly be a rain event
for the region, with perhaps some light snow working in on the
backside (if the ECMWF were to verify). If this system were to
phase a bit earlier, then the colder air would work in a bit sooner
and winter precipitation could become more of a player, but that
scenario looks rather unlikely at this time.
After the mild temperatures Tuesday, highs will drop into the 40s
and 50s on Wednesday. The real cool air will work in for Thursday
behind the aforementioned system, as temperatures will struggle to
climb in the upper 30s and lower 40s.
.AVIATION (18Z TAF Update)...
Updated at 1230 PM EST Fri Mar 7 2014
VFR conditions are expected for this TAF period as sfc high pressure
and upper level ridging dominate the region. We will see upper
level clouds gradually increase tonight and tomorrow morning ahead
of an approaching cold front progged to cross the area Sat night.
Winds will be primarily from the WSW through the TAF period under 7
kts today and tonight. Tomorrow afternoon they could be stronger
ahead of the fropa. Debated adding a tempo group for fog at BWG,
but decided to hold off for now due to increasing cloud cover