Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
FXUS63 KARX 191737

Area Forecast Discussion
National Weather Service La Crosse WI
1237 PM CDT Wed Oct 19 2016

.SHORT TERM...(Today and tonight)
Issued at 335 AM CDT Wed Oct 19 2016

At 3 AM, a Canadian cold front was located across central
Minnesota. The 19.00z models are in general agreement that this
front will be located near the Interstate 90 corridor by noon and
moving out of the area by 6 PM. There is an extensive 2 to 4K deck
of clouds currently located behind this front. Both the GFS and
NAM suggest that these clouds will dissipate as diurnal mixing
occurs. However we will have to watch this trend throughout the
day. While there are some questions on the low clouds, it is
pretty clear from the water vapor and infrared imagery that we
will likely see a broken deck of mid and high clouds move into the
area this morning and then linger across areas south of
Interstate 94 through this evening. These clouds are associated
with a short wave trough moving east southeast across South

With moderate cold air advection developing earlier in the day
north of the Interstate 90 corridor, high temperatures will range
from the mid 50s to lower 60s. Meanwhile south of this
interstate, high temperatures will be in the mid-60s.

.LONG TERM...(Thursday through Tuesday)
Issued at 335 AM CDT Wed Oct 19 2016

On Thursday, soundings suggest that we will only mix up to 900 mb.
the temperatures at this level will be nearly 10C colder than they
will be today. Mixing these temperatures down to the surface would
result in highs about 2 to 5 degrees colder than the 19.00z MOS
temperatures. For now just stayed close to the model consensus and
will continue to monitor the trends over the next 24 hours.

On Thursday night, the models continue to suggest that the ridge
of high pressure will be overhead. This is typically results excellent
radiative conditions. However the GFS and ECMWF are suggesting
that there may be clouds trapped below this subsidence inversion.
This is similar to what happened in western Wisconsin on the
morning of October 13th. This may prevent the development of frost
for areas along the Mississippi and Wisconsin rivers (which are
the only counties that we are still issuing frost/freeze
headlines). At this time, kept the mention of frost in the
forecast, but the confidence that this frost will occur is a bit
lower than last night.

While the models continue to show that a warm front will move
through the region on Friday night, the models continue to back
away from producing scattered showers across the area. This is due
to the moisture depth in the soundings decreasing. At this time,
the only model still generating showers is the Canadian.

On Tuesday, the models are showing that a warm front will move
through the region. With surface-based CAPES climbing into the 500
to 1000 J/kg range, added the mention of isolated thunderstorms to
the forecast.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1236 PM CDT Wed Oct 19 2016

An expansive MVFR cloud deck was found over most of MN west of a
line from KDLH-KRWF. This area was slowly shifting east behind a
cold front with a more solid coverage of OVC south of KSTC.
Northwest flow in the lower levels behind the cold front will try
to usher this cloud deck in over the TAF sites. Sunshine has
allowed deeper mixing today at both KRST/KLSE and thus as the air
mass shifts southeast...the air mass will become a bit less-
saturated in the lowest levels.

Therefore it makes for a tough forecast if this layer will be
saturated enough to form clouds. Satellite over the past hours is
indicating some break up to more cellular clouds over SD/MN which
favors dissipation of the cloud. Have introduced an MVFR SCT cloud
layer to trend toward the clouds moving in later today and
tonight. Some MVFR cloud around overnight seems the way to go.




AVIATION...BAUMGARDT is the U.S. government's official web portal to all federal, state and local government web resources and services.