Area Forecast Discussion
Issued by NWS Louisville, KY

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KLMK 191648
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1248 PM EDT Sat Apr 19 2014

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1147 AM EDT Sat Apr 19 2014

Forecast is on track for this afternoon. Northeast winds will gain a
little more strength as the pressure gradient tightens between high
pressure of the Great Lakes and low pressure over Florida. We`ll
basically see cloudless sky this afternoon except for a few puffs of
Cu possible in the afternoon, and some thin upper level clouds near
the Lake Cumberland region. Otherwise, temperatures look on their
way to the low and mid 70s across the region, with the steady NE
flow only slightly hindering perfect heating conditions.

Did have to nudge expected afternoon dew points down a few degrees
as the steady NE flow advects slightly drier air into the region,
and we mix into a dry layer aloft. These lower dew points will take
minimum relative humidity values closer to the 25 percent range,
however 20 foot winds are expected to stay well below any critical
thresholds.

.SHORT TERM (Now through Sunday)...
Issued at 245 AM EDT Sat Apr 19 2014

A very pleasant weekend is in store for the Ohio Valley as
upper-level ridging establishes itself across the region.

Surface high pressure centered to the northeast of the region will
bring mostly sunny skies today (after some high cirrus clouds this
morning).  The orientation of the surface ridge will bring ENE winds
to the Ohio Valley today.  While this wind direction is not
typically conducive to warming, guidance has been running a cool
bias in recent weeks under mostly sunny conditions.  Given this fact
and drier air being advected in on these ENE winds (dewpoints in the
upper 30s to lower 40s by this afternoon), will bump temperatures up
a degree or two above guidance which puts highs in the low to mid
70s.

Overnight, skies will remain clear and winds will die down.  This
will allow for a quick drop off in temperatures after sunset given
the good radiational cooling conditions.  Lows will fall into the
mid 40s (perhaps lower 40s or even some upper 30s in sheltered
locations).

Easter Sunday is shaping up to be an incredibly pleasant day across
the Ohio Valley.  850mb temps will rise to near 10C, which coupled
with ample sunshine and dry low-levels, should allow temperatures to
climb into the upper 70s and lower 80s (a few degrees above
guidance).  These temperatures along with light winds should make
for a great day to be outdoors.

.LONG TERM (Sunday night through Friday)...
Issued at 300 AM EDT Sat Apr 19 2014

Surface and upper ridge axes near the Appalachians will shift
eastward Sunday night and Monday, giving way to deepening return
flow ahead of the next weak cold front. Gulf never really opens up,
so moisture return will be quite limited, with dewpoints struggling
into the 50s. Normal model bias in this pattern would suggest that
guidance is too cool, but low-level thickness progs actually support
the cooler NAM MOS for Monday`s max temps. Sunday night mins close
to consensus, as the pre-frontal SW flow is still a bit too weak.

Best chance for precip is Monday night as PWATs jump neatly above
75th percentile values, and at least some elevated instability
develops. Will carry at least a high-end chance POP Monday night
into Tuesday morning, and later shifts will likely bump one of those
periods into likely once confidence increases in the timing.

Look for increasing heights Tuesday night on through Thursday, as a
shortwave upper ridge builds in again. Expect mainly dry weather and
near-normal temps as we`ll be on the southern periphery of the main
surface high. ECMWF spits out some QPF Wednesday night as a warm
front lifts through, but will not jump on that yet as the GFS does
not agree.

Next wave will push a cold front through the Ohio Valley on Friday,
give or take a half a day. Will carry low-end chance POP, mainly
during the day, owing to the uncertainty in the exact timing. Either
way, it`s a low-amplitude wave aloft with no strong Canadian surface
high following, so temps will remain at or above climo even into
Saturday.

&&

.AVIATION (18Z TAF Update)...
Issued at 1247 PM EDT Sat Apr 19 2014

VFR conditions will prevail through this TAF period with high
pressure in control at the surface and aloft. A steady NE surface
flow has developed today with the tightening pressure gradient
between high pressure over the Great Lakes and a low over Florida.
These winds will peak early to mid afternoon between 10-15 mph,
becoming light and variable shortly after sunset. Expect skies to be
sunny the remainder of the afternoon, and clear overnight. Could see
a brief period of visibilities around 6 SM at BWG toward dawn.
Otherwise, expect VFR Sunday with winds light out of the SE on
Sunday. Expect a few Cu around 4 k feet and a few upper level
clouds.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Update.........BJS
Short Term.....KJD
Long Term......RAS
Aviation.......BJS




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.