Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 161353
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
953 AM EDT Wed Apr 16 2014
Issued at 950 PM EDT Wed Apr 16 2014
Cold dome of high pressure now shifting east of the region. Had
Bowling Green tie their record cold and Frankfort break their record
this morning. That high will shift east of the region today, with
winds picking up from the east and southeast. Under sunny skies we
should top out in the mid to upper 50s for most locations. As all
sites now are above freezing, have cancelled the freeze warning a
little early. Sent out a zone update to handle this headline change
and to trend toward current obs.
.SHORT TERM (Now through Thursday)...
Issued at 300 AM EDT Wed Apr 16 2014
Surface ridge is currently centered over the I-65 corridor this
morning. To the east of the ridge, a light northeast wind has kept
temperatures from falling as quickly as we would normally see in a
radiational cooling situation. However, as the ridge axis moves a
little more east this morning, we should see winds slacken off a bit
more allowing temperatures to fall. In general, temperatures this
morning were in the upper 20s to the lower 30s. The lower 20s were
confined to areas mainly north of the Bluegrass Parkway. The latest
guidance suggests that temperatures will fall several more degrees
before sunrise with most locations dropping into the mid-upper 20s.
Needless to say, temperatures below 29 degrees for several hours
this morning will be particularly damaging to unprotected plants and
fruit trees across the region. We will continue the freeze warning
through the morning hours.
For today, axis of high pressure at the surface will move eastward
and away from the Ohio Valley. Other than some high clouds passing
through, we expect a mostly sunny, but a cooler than normal day.
Afternoon highs will range from the lower 50s in the north to the
mid-upper 50s across the south. A few areas along the KY/TN border
region may get close to 60 this afternoon.
For Tonight, another mostly clear night is expected. With the high
pressure ridge to the east of the region, we`ll see a more
pronounced southerly wind flow develop this evening and into the
overnight hours. In fact, winds are likely to go more southwesterly
across the western areas late tonight. This will likely result in a
gradient of temperature across the forecast area with lower 30s in
the east and middle 30s along and west of I-65. In areas east of
I-65, there is a very good possibility for several hours of
temperature readings below 35 degrees. In coordination with
surrounding offices, we will be going with a Frost Advisory for our
eastern half of the forecast area tonight. Should later guidance
suggest cooler temperatures a bit more west, an additional expansion
to the west could be required in future forecasts.
.LONG TERM (Thursday night through Tuesday)...
Issued at 245 AM EDT Wed Apr 16 2014
Well...the long term is characterized by seasonal temperatures and 2
frontal systems. No major hazardous weather systems in site for the
7 day period. According to the GFS the long range extended has a
large ridge moving in which could bring the Ohio Valley back above
normal into spring like mercury readings.
The Nrn stream system coming out of the Show Me State and Hawkeye
State pivots across the Land of Lincoln and into the Nrn Ohio
Valley. Meanwhile the srn stream will pivot out of the Crimson State
and move into Ern KY. The models sure try to come together but never
quite seem to phase. Quite honestly, there is a distinct possibility
that the CWA might be gapped by the precip. Agree with day shift
long term fcstr that there is still a modicum of forcing to squeeze
out scattered light showers. Looking at the model soundings, there
is hint of some isolated elevated convection, but will limit the
mention of thunder and the QPF looks rather meager. System will
move out on Good Friday and clouds will decrease and will move
Fri Ngt through Easter Sunday
Behind the front, shortwave upper ridging will keep areas nice and
dry over the weekend. Saturday will be on the cool side with N-NE
low-level flow, but rising heights will put Sunday back above
Sunday night and Monday...
A progressive southern stream system will bring the next round of
precip to the Ohio Valley around Monday, but confidence in the exact
timing is limited. The GFS and Euro are quite divergent next week on
the timing and extent of this system, so will only be making minor
tweaks to the previous fcst. The timing is too uncertain to put more
than a chance POP in any given time period.
Tuesday and beyond...
The eastern extent of the central US upper ridge diverges in the
long range models. For now looks like normal to above normal temps
looks prudent at this juncture.
.AVIATION (12Z TAF Update)...
Issued at 630 AM EDT Wed Apr 16 2014
High pressure will continue to work eastward across the region this
morning. This will result in VFR conditions at all the terminals
for the upcoming TAF period. Light and variable winds this morning
will give way to east to east-southeasterly winds by mid-morning and
into the afternoon hours with speeds of 8-10kts. Some high level
cirrus will move through the region today, but will have no impact
on aviation at the terminals.
KY...FROST ADVISORY from 2 AM EDT /1 AM CDT/ to 9 AM EDT /8 AM CDT/
Thursday FOR KYZ033>043-045>049-053>057-063>067-073>078-081-