Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 160807

Area Forecast Discussion
National Weather Service La Crosse WI
307 AM CDT Mon Oct 16 2017

.SHORT TERM...(Today and tonight)
Issued at 307 AM CDT Mon Oct 16 2017

At 3 AM, a short wave trough was moving into Michigan. This system
brought some mid clouds to the area during the evening and early
overnight. As these clouds pulled away from the region, skies
cleared and they should remain at the way through the remainder of
the early morning. The combination of light winds and clear skies
will allow temperatures to fall into the upper 20s in central
Wisconsin and into the 30s elsewhere. There will be widespread
frost in central Wisconsin and areas of frost elsewhere.

For this afternoon, soundings show that we will be mixing to
around 900 mb. This will allow temperatures to warm into the mid
and upper 50s north of Interstate 94 and into the lower to mid 60s
elsewhere. The soundings also showed that plenty of dry air will
mix to the surface. The model dew points looked too high, so
lowered them into the lower and mid 30s.

For tonight, south and southwest winds of 5 to 10 mph will bring
slightly warmer air into the region. As a result, low temperatures
on Tuesday morning will be in the mid and upper 30s in central
Wisconsin and in the lower and mid 40s elsewhere.

.LONG TERM...(Tuesday through Sunday)
Issued at 307 AM CDT Mon Oct 16 2017

On Tuesday, the MOS temperatures looked too cool considering the
temperatures below 900 mb. Due to this, used the mix down tool to
raise them up some. In addition like today, the soundings show
that there will plenty of dry air to mix down, so lowered the dew
points into the lower 40s.

On Wednesday afternoon and evening, a weak cold front will move
southeast through the region. With very little moisture across the
region and much of the forcing north of the Canadian border, only
expecting a wind shift with this front. With 925 mb temperatures
warming to around 15C ahead of this front, high temperatures will
warm to around 70 north of Interstate 94 and into the lower to mid
70s elsewhere.

On Thursday, the 925 mb temperatures will be slightly cooler
(around 12C) than Wednesday afternoon; thus, the high temperatures
will be mainly confined to the 60s.

With a strong southerly gradient ahead of ahead of an approaching
long wave trough, it looks like Friday will be another warm one.
High temperatures will likely warm into the lower and mid 70s.

The next chance of rain will be this upcoming weekend. The highest
rain chances will likely be on Saturday and Saturday night.
However, the GEM does develop a deformation band of precipitation
and this band moves through the Upper Mississippi River Valley on
Sunday. With most unstable CAPES up to 700 J/kg, there will be a
chance of thunderstorms ahead of the approaching cold front. These
were added to the forecast. With the shear weak ahead of the
front, not anticipating any of these storms to become severe.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1145 PM CDT Sun Oct 15 2017

The mid level clouds continue to move east and will be past both
airports by or shortly after 16.06Z and plan to start both
forecast with just some remaining scattered clouds. Skies will
clear out by sunrise Monday with southwest wind under 10 knots for
much of the day with surface high pressure centered over Missouri
and Arkansas. As the high moves off to the east Monday evening as
a cold front advances onto the High Plains, forecast soundings
from the 16.00Z NAM suggest the potential for some low level wind
shear. Winds above the surface ahead of front look to increase
into the 40 to 45 knot range with surface winds of 10 knots or
less. This looks to be very late in the forecast period so will
not include it for now, but this will be needed if later model
runs continue to show this trend.


WI...Frost Advisory until 9 AM CDT this morning for WIZ017-029-034-



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