Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 291739
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
139 PM EDT SUN MAY 29 2016

...Updated Aviation Discussion...

...Forecast Update...
Issued at 1155 AM EDT Sun May 29 2016

The showers across the Bluegrass region of KY have mostly moved off
to the east. Dry conditions are expected for at least the next few
hours. Thereafter, storms should begin to develop across southern IN
by mid afternoon along a cold front pushing into the region. Models
have quite a bit of instability developing across the region this
afternoon. Wind fields will be weak, but some stronger pulse storms
are possible along the front as it pushes through the region this
afternoon and evening. The forecast was updated to reflect the
current thinking with regard to pops.

.SHORT TERM (Now through Monday)...
Issued at 244 AM EDT Sun May 29 2016

Well...muggy airmass will continue for another day across the Ohio
Valley with a break in the humidity levels on Memorial Day into Tue.

Forecast Challenge...POPS today...

Metwatch...

Currently PPINE on radar with high level clouds streaming from far
outer spiral feeder bands from TS Bonnie just off CHS. Temps in the
upper 60s with dew points in the low to mid 60s and light SE winds.
Herculean backbuilding MCS (2) over TX is something to behold, some
folks are getting copious rain in the Lone Star State.

Today and This Evening...

There are two areas to watch for convection...the first is the weak
outflow from Bonnie in the higher moisture channels. The water vapor
channel imagery shows the deeper moisture transport swinging north
thru GA thru the Cumberland Plateau and into the I 75 corridor. The
HRR has been trying to develop convection as early as 08-09z, but
not buying it that timeframe, but after daybreak this should be a
focusing mechanism.

The second area will be ahead and along a weak front making its trek
through the Ohio Valley. Isolated Showers and storms are expected to
develop ahead of the front by lunchtime and increase to scattered
during the mid and late afternoon. So 20-40% pops for this afternoon
look fairly reasonable. No organized severe weather is expected, but
isolated stronger storms with gusty winds and heavy rainfall are not
out of the question. The MUCAPE climbs to 1000 j/kg but wind fields
are weak. PWATs are lower than yesterday but still 1.25 inches will
be a factor with such weak mid level steering currents.

The one odd model is the NAM which develops nothing on the front
until 00Z and then explodes the entire line over the CWA. For now am
following the SREF and then will be in mesoscale model mode for the
first 12-18 hours.

Highs will top out in the mid 80s with dew points climbing into the
mid 60s, and for a 3-4 hour timeframe ahead of the front into the
upper 60s in some spots before falling.

Tonight thru Mon Night...

The front is not expected to bring much cooler air with it, but
Monday will see a slight drop in dewpoints. As high pressure builds
in, these should bring dry weather and clearing skies. Plan to
have a dry forecast.

Lows will be in the mid 60s and Highs on Memorial Day in the mid 80s.

.LONG TERM (Monday Night through Saturday)...
Issued at 245 AM EDT Sun May 29 2016

...Dry 1st half of the week...
...Nrn trough and meandering upper lows bringing unsettled wx
pattern Thu-Sat...

Tue-Wed...

Well...the upper level pattern has weak sw zonal flow with potent
low over the Dakotas and a weaker upper low moving out of AZ/NM.
This will maintain a dry forecast and bring lots of daytime cerulean
sky and star gazing Tue night.  The forecast soundings show strong
daytime mixing each afternoon with steep llvl lapse rates and nearly
dry adiabatic up to 8k.  Plan to raise high temps on Tue to 85-90
across the CWA. 90 is my pick number for SDF on Tue. Lows will be in
the low to mid 60s.

Wed night and Thu

Clouds start really increasing ahead of deep closed low over Isle
Royale NP MI of Lake Superior. Lots of energy will form an elongated
trough axis and push it eastward toward the Ohio Valley.
This feature could act to funnel better moisture up from the GLFMEX
and the from the SSW and sweep a surface front across the area. This
is the type of pattern which will produce very heavy rain, such as
in TX/LA as the low meanders.  Like the Superblend of likely POPs on
Thu with good moisture and forcing. Could be a stormy day.

Thu Night-Weekend

GFS and ECM developing large scale ridge over the 4 Corners and
almost an unusual Omega Blocking pattern with low off of srn CA and
another off of SE TX.  This will keep CWA under a NW flow pattern
which will yield cooler temps, more cloud cover, and sporadic
precip. Temps will be near normal to slightly below normal during
parts of next weekend.

&&

.AVIATION (18Z TAF Update)...
Issued at 125 PM EDT Sun May 29 2016

Cumulus clouds around 4 kft have developed over central KY north
thru IN, with a modest SW surface wind of 4-8 kt. As a weak cold
front from the Great Lakes through central IL moves southeast this
afternoon and evening, isolated to scattered convective cells should
develop from OH to southern IN and north-central and northern KY.
With weak forcing but unstable air, coverage should be limited but
any storm could cause brief, isolated wind gusts around 30 kts. SDF
appears to have the best chance given the timing of the front and
best instability, although even here, coverage should be limited and
no more than VCTS. At LEX, any cells may wait til a bit later as
cells begin to weaken, so will carry VCSH for now. Looks like any
activity should remain north and east of BWG. Nevertheless,
conditions will remain VFR except briefly lower in any storm.

For tonight, winds become light NW at SDF and eventually LEX and
light and variable at BWG. By early Tuesday morning, there will
still be residual surface-based moisture as dewpoints remain up.
Thus, at least tempo MVFR fog is possible at BWG and LEX. Conditions
become VFR quickly thereafter on Tuesday with a NNW breeze 5-10 kts.

&&

.LMK Watches/Warnings/Advisories...
KY...NONE.
IN...NONE.
&&

$$

Update.........EER
Short Term.....JDG
Long Term......JDG
Aviation.......TWF



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