Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 301047

Area Forecast Discussion
National Weather Service Louisville KY
647 AM EDT SAT JUL 30 2016

...Updated Aviation Discussion...

.SHORT TERM (Now through Sunday)...
Issued at 255 AM EDT Sat Jul 30 2016

Super Short Term...

Well...Isolated convection is ongoing mainly east of I 65 with broad
upper level troughing pattern. With high PWATs and weak mid level
flow the any storms could produce localized flooding. Storms on
Friday afternoon evening produced copious rainfall and intense
lightning.  One area of convection across Srn IL continues to push E-
SE. The HRRR continues to push that activity to the east and weaken
it slightly before igniting it during the peak heating of the
afternoon. The local WRF pushes it east and maintains it through
most of the day increasing its areal coverage during the peak
heating. Will be adjusting the first 12 hr POPs up until press time.


Several features are worth noting. Very weak boundary based on
latest sfc map from south of STL to near CVG.  Secondly, broad upper
trough over Ohio Valley with a juicy airmass.

Have focused precip from 16z onward along and east of I 65 for the
greatest coverage. PWATs are slightly less than yda with the main
threat still localized heavy rainfall and flooding. None of the high
mesoscale models doing that great with the convection, but am
leaning on having ISOL POPs through 16z, then low sct pops (best
chance across the Blue Grass region). Given the low convective temps
in this air mass, expect max temps to run near or just below climo,
but with limited cooling at night.

Sat Night...

Pops will ramp down after 03z, with no major trigger to continue
them overnight.  Patchy fog to even areas of fog if the cloud cover
can thin out, especially in areas that get hit hard with rainfall.


No major focus and less PWATS.  Looks like Isol POPs mainly in the
afternoon hours.  Elongated ridge stretched from St Augustine to
White Sands NM to Joshua Tree NP CA.  We should be near climo for

.LONG TERM (Sunday night through Friday)...
Issued at 255 PM EDT SAT JUL 30 2016

...Pattern Change with Amplifying Ridge brings MCS into the

Pattern/Sensible Weather...

Elongated high pressure ridge from the Golden State to the Peach
State will amplify significantly with large scale ridge of 594m from
the Cornhusker State to the Pelican State. This will set up a
series of perturbations flowing up and over the ridge from Sunday
night through Wednesday. It appears one will form across IA/MO and
slide southeast into western Kentucky on Monday morning. Will
coordinate with PAH on POPs for late Sunday night/Monday morning,
but will likely be chance POPs in far western counties.

The next more substantial MCS will form near the SD/MN/IA border
Monday evening and take the Nestea plunge southeastward into IL/IN
and perhaps across our entire area on Tuesday night into Wednesday.
For now, will keep chance POPs for possible MCS activity. However,
it would not surprise me if we need to upgrade to likely or even
categorical POPs if the MCS can maintain itself like several MCSs
did two weeks ago.

Late in the week, a cold front will try to move south into the
northern Ohio Valley looking more like a back door cold front along
I-70 on Saturday. I am not sure it has enough push to get all the
way into the CWA, but there will be much cooler air across the Great

Temps/Dew Points...

The real hot and sultry air will move into NE/IA/MO with H8 and H9
temps 3 SD above normal by midweek for OMA. For the Ohio Valley,
temps will be predicated on MCS cloud debris. For now, will be
slowly raising the temps with low 90s the target number until MCS
precip chances become more clear. It would not surprise me for temps
to be in the mid 80s on Wednesday based on the pattern recognition.

Dew points will primarily be around 70 until late in the week where
mid 70s will creep back in ahead of the cold front across central IN.


.AVIATION (12Z TAF Update)...
Issued at 645 AM EDT Sat Jul 30 2016

Plenty of low-level moisture out there this hour, creating low
stratus and IFR conditions. Expect a slow rise in heights through
the  morning hours. Line of storms that earlier was across southern
Illinois has dissipated, so have shifted the storm chance to this
afternoon in the SDF/LEX corridor, once we are able to get some
heating. Coverage of storms should be less than Friday. Chance for
fog comes in overnight.


.LMK Watches/Warnings/Advisories...


Short Term........JDG/MED/CRG
Long Term.........JDG/MED/CRG
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