Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 221650
AFDLMK

Area Forecast Discussion
National Weather Service Louisville KY
1250 PM EDT Wed Mar 22 2017

...Updated Aviation Discussion...

.Forecast Update...
Issued at 1015 AM EDT Wed Mar 22 2017

Updated the forecast to remove the Freeze Warning wording from this
morning and go ahead and issue another Freeze Warning for late
tonight into Thu morning as portions of southern Indiana and east
central KY will again drop into the 28-31 degree range.  Other than
that, today looks mostly sunny and chilly.  High temps look to range
from the mid 40s to mid 50s.

&&

.Short Term...(This afternoon through Thursday evening)
Issued at 250 AM EDT Wed Mar 22 2017

...Moderate temperature swing for next 36 hours...

For this morning NPW will continue for a narrow line of counties but
borderline freeze warning is fighting brisk nly winds of 10-18 mph.
As of 2 am...temps are in the low to mid 40s.

Well...Cool Canadian high pressure (1040 mb) over Lake Winnipeg will
be ushering in some decent CAA today. NE winds of 10-15 mph drop or
hold steady 1000-850 mb thicknesses throughout the day except across
the srn 1/3 of CWA.  So upper 40s across NE CWA looks plausible and
low to mid 50s down near the TN state line.

Model soundings show extremely dry air (-40F dewpoints!) between 4-
5kft above the ground, but generally keep mixing heights just below
this dry air. Current thinking is that RH this afternoon will
generally be in the 20-25% range, but should mixing heights be
higher than forecast and the drier air aloft mixes down, we could
see RH plummet into the teens this afternoon. Not expecting RFW
criteria as 20ft winds will generally be under 15mph and 10hr fuels
should remain above 8%.

For Wed night lows mid and high clouds will be streaming in from the
west after 23z and keeping skies mostly cloudy overnight which will
offset good radiational cooling. In addition enough of a easterly
wind gradient for 4-8 mph.  The sfc high moves to between lake Huron
and Erie so very cold night will be near PIT, CLE, BUF etc. So ALL
OH Valley offices agreed to NOT issued a freeze warning for tonight
and will let day shift look this over. Have raised lows 2-4 degrees
for tonight period.

Srn transitory ridge will push thru and bringing substantial height
rises. Sfc temps will climb some 15-20 degrees for zeniths on
Thu, with low to mid 60s.

.Long Term...(After midnight Thursday night through Tuesday)
Issued at 259 AM EDT Wed Mar 22 2017

...Above normal temps thru the medium and long range...
...Wet Sat PM into Sun...then another wet system Monday...

Well...deep synoptic scale system low moving from Arches NP in the
Beehive State Thursday morning to Wrn Sunflower State Friday morning
to the OK/AR/KS/MO border Sat morning. This will bring a substantial
rain event from Saturday pm into Sunday. One big factor of the
evolution of the pcpn field is the sfc high near Bermuda and SE 582m
ridge over SE Atlantic, which will impede the progress of the
frontal system on Sat.

Thu Ngt-Fri Ngt...

Ridging and warmer temps are the theme with 20-25 kts of 925 mb ssw
flow.  This will bump temps up into the upper 60s and low 70s. Rough
River to BWG area should easily climb into the 70s.  One fly in the
ointment is warm front swinging thru Thu night.  Models hinting at
isolated shra when this swings thru so keeping theme of slgt chance
shra across NE CWA, along ILN/IND border region.  Going above
guidance on temps Fri and Fri ngt.

Sat-Sun...

Weakening low pressure will progress from SGF/JLN Sat morning to
Quad Cities region Sun AM and on to the Lake Huron Mon AM. Most
significantly coordinated with BNA and IND and delaying majority of
the all precip shield east of I 65 until Sat afternoon. This system
will bring widespread showers and scattered thunderstorms to the
region Sat aftn and night.  Enough instability to warrant tsra in
grids.

Being in the warm sector of the system continued the theme of going
close to and above guidance for highs Saturday...well into the 70s.

The surface trof that the weekend low traveled along will still be
in place early next week, with another low following roughly the
same path Monday-Tuesday bringing us additional showers and
scattered thunderstorms. Highs in the 70s should continue. Looks
like another srn stream low mid to late week too.  Bottom line,
above normal with series of srn stream systems to contend with.

&&

.Aviation...(18Z TAF Issuance)
Issued at 1247 PM EDT Wed Mar 22 2017

VFR conditions are expected through this TAF period. Mainly thin
cirrus is expected through the afternoon with some mid level clouds
moving in overnight. Gusty winds out of the NNE will continue
through the afternoon. Winds will shift to more easterly by tomorrow
morning and southeasterly by mid day Thursday as high pressure
shifts off to the east.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...Freeze Warning from 1 AM to 10 AM EDT Thursday for INZ077>079-
     092.

KY...Freeze Warning from 1 AM to 10 AM EDT Thursday for KYZ031>037-
     039>043-047>049-055>057-066-067.

&&

$$

Update...AMS/EER
Short Term...JDG/DM
Long Term...JDG
Aviation...EER



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