Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 182008

Area Forecast Discussion
National Weather Service La Crosse WI
308 PM CDT Sun Mar 18 2018

.SHORT TERM...(This evening through Monday)
Issued at 308 PM CDT Sun Mar 18 2018

Upper-level ridging and surface high pressure were in place over the
Upper Mississippi River Valley this afternoon, with an upper-level
longwave trough over the Rockies. Low clouds over northern Iowa into
southern Minnesota have been more persistent than expected, keeping
temperatures a bit cooler in these areas. The western longwave
trough is forecast to break down tonight, with a southern stream
stacked-low approaching the Ozarks Monday morning and a northern
stream weaker disturbance/surface trough sliding through the
Dakotas. Strong surface high pressure over northern Manitoba/Ontario
will help steer these systems to the south and east, keeping
precipitation away from our area through Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 308 PM CDT Sun Mar 18 2018

Main forecast concerns in the long term are on chances for light
rain and snow Monday night into Tuesday. Focus then turns to the
continued dry weather through Thursday then onto the potential
rain and accumulating snow Friday into Saturday.

A trough edges east into the Upper Mississippi River Valley from the
northern Plains Monday night into Tuesday morning. Meanwhile,
surface high pressure attempts to hold strong across the western
Great Lakes, centered near over Hudson Bay.  This will result in a
persistent dry east/northeast flow. The trough will be slamming into
this drier air and it appears any precipitation will struggle to get
east of the Mississippi River. Will continue low chances for rain
and snow across southeast Minnesota, northeast Iowa, and west
central Wisconsin on Tuesday.  Any snow or rainfall amounts will be
on the light side thanks to that feed of dry air into the region.
The Hudson Bay surface high looks to be the dominant weather feature
from Tuesday night through Thursday providing dry weather across the
region. Thursday looks to be the warmest day with highs climbing
into the mid 40s at many locations. The good news is winds look to
remain on the lighter side across the area limiting any fire
weather concerns. Afternoon relative humidity values will need to
be watched closely.

A baroclinic zone then sets up over the area late Thursday through
Saturday as a trough moves across the central conus and low pressure
deepens over the Central Plains into the mid Mississippi River
Valley. Precipitation is looking very likely across the area in
the Friday through Saturday timeframe. Depending on the storm
track, a band of significant snowfall is possible. There is a lot
of uncertainty with the storm track and resulting thermal
profiles so it`s difficult to nail down where snow would fall at
this point. This system will have to be watched very closely this


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1234 PM CDT Sun Mar 18 2018

VFR conditions are expected at both TAF sites through this
forecast period. Cloud cover will increase at KRST by mid-
afternoon. However, expect ceilings to remain above 3 kft. Winds
will remain light and variable until becoming east-northeast
around 10 kt late Monday morning.




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