Area Forecast Discussion
Issued by NWS Louisville, KY
FXUS63 KLMK 290648
Area Forecast Discussion
National Weather Service Louisville KY
248 AM EDT SUN MAY 29 2016
.SHORT TERM (Now through Sunday)...
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...
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
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 (Sunday night through Friday)...
Issued at 245 AM EDT Sun May 29 2016
...Dry 1st half of the week...
...Nrn trough and meandering upper lows bringing unsettled wx
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.
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 (06Z TAF Update)...
Issued at 105 AM EDT Sun May 29 2016
TAF weather will remain quiet with VFR conditions and winds under 10
knots expected through the period. A broken area of showers and a
few embedded thunderstorms will be possible late this afternoon and
early this evening coincident with a weak surface front, upper level
divergence, and diurnal instability. The front will bring winds
around to the northwest but at low speeds.