Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 260722

Area Forecast Discussion
National Weather Service La Crosse WI
220 AM CDT Sun Mar 26 2017

.SHORT TERM...(Today through Tuesday)
Issued at 220 AM CDT Sun Mar 26 2017

Upper level trough/500 mb low spinning over the mid mississippi
river valley early this morning, per latest water vapor satellite
imagery. The trough will continue to lift northeast today-tonight,
with the low filling as it moves over the eastern great lakes.
Spokes of energy will fragment and slip across the forecast area
today into tonight, with some weak reflection frontogenetically on a
few pressure sfcs. Most of the saturation is confined under 600 mb -
per time/height x-sections and bufkit soundings. The combo of
lift/moisture should be enough to keep scattered, light showers
going today into tonight.

GFS/NAM then favor bringing a weak ripple along the 500 mb flow from
the northern plains to across northern portions of the upper
mississippi river valley tue. Decent frontogenetic response in the
800-600 mb layer, and with enough saturation present, expect a few
more showers to develop across central MN and northern WI.

Farther south, models want to slip a shortwave in the southern
branch of the flow from the southern plains to across the oh/tn
river valleys. Some variances with how far north this shortwave
makes, and the potential for rain chances across the far south. At
this time, most models trend keeping the bulk of any pcpn chances
just south...although with small chances across the far south. Looks
reasonable at this time.

.LONG TERM...(Wednesday through Saturday)
Issued at 220 AM CDT Sun Mar 26 2017

Forecast confidence remains shaky for the mid to later part of the
new week as the GFS and EC remain at odds with their handling of the
various upper level shortwaves that could (would?) impact the local

First point of contention is with a shortwave trough slated to roll
out of the desert southwest Wed, tracking east north-east toward the
oh river valley and eastern great lakes. The EC takes a more
northeast track with the trough, with a large swath of associated
pcpn (low level warming, deformation region) ahead and north of its
associated sfc low. This has been a consistent signal in the EC over
its past several runs. The GFS has the same trough, but holds it
farther south, with little if any pcpn threat locally. This has been
a consistent signal in the GFS. Meanwhile, the latest Canadian is
more on board with the EC, giving that solution a bit more weight.
With this in mind, will lean toward the wetter solution in Thu-Fri
time frame.

The second point would be a shortwave in the northern stream slated
to drop across the Upper Mississippi River Valley least
if you believe the GFS. A swath of pcpn would accompany the trough.
A consistent signal in the GFS. Meanwhile the EC is slower and not
as strong with this feature. Rather, it eventually merges it with
another trough moving out of the southwest that would bring another
round of pcpn Mon (ala what the EC expects for Thu-Fri). With
confidence low, going to let consensus blend detail any pcpn chances.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1150 PM CDT Sat Mar 25 2017

IFR ceilings and visibility will be the rule through the night and
likely through much of Sunday morning as a moist air mass lifts
northward across TAF airfields. Will have to watch for visibility
reductions below 1SM in fog at KRST given lower visibilities across
much of IA, but not enough confidence at this time to include in 06Z
TAFs. Expect gradual improvement in visibility by late Sunday
morning and early afternoon. However, ceilings likely to remain at
or below 1000 ft agl at both TAF sites through the period.




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