Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 230910
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
310 AM CST Fri Feb 23 2018

.SHORT TERM...(Today and tonight)
Issued at 310 AM CST Fri Feb 23 2018

23.09Z water vapor loop shows a short-wave lifting northeastward,
resulting in a broad area of wintry precipitation across the
forecast area. The surface freezing line stretches from near Austin
to La Crosse to Richland Center and may nudge a bit south through
through sunrise, but overall should remain nearly stationary.
Precipitation south of this line is expected to fall as rain, but
cold ground temperatures could still result in some additional light
icing. North of this line, higher cloud ice and colder surface
temperatures should allow for a wintry mix or all snow. Warmer
temperatures last evening put a dent in snow amounts, so event snow
totals are likely to be a bit less than originally forecast.

Whether due to snow, light icing, or a mix, this morning`s
commute will likely be difficult for many areas, especially on
untreated rural roads. The good news is that the back edge of
precipitation is currently across northeast IA and this will
rapidly move across the forecast area through sunrise. With the
exception of some lingering freezing rain/drizzle, most
precipitation should be north of the forecast area by 8 AM.
Current Winter Weather Advisories look good with no changes at
this time.

The rest of today will see gradually clearing skies with
temperatures rising above freezing for areas mainly along and east
of the MS River. This will help to melt any icing from overnight.
Farther west across MN/IA, highs in the upper 20s to lower 30s will
be the general rule, prolonging slick travel conditions until roads
are treated and plowed.

.LONG TERM...(Saturday through Thursday)
Issued at 310 AM CST Fri Feb 23 2018

The next winter storm is set to take aim on the region Saturday
afternoon into Saturday night. 23.00Z GFS/ECMWF surface low tracks
are in good overall agreement, but the NAM is a bit faster and
farther north. The GEFS/SREF mean surface low track is from central
MO through central WI on Saturday. This will allow for warmer/drier
air to move into eastern portions of the forecast area, complicating
the precipitation type forecast. That said, areas that see a loss of
cloud ice are generally also on the warmer side of the system and
the freezing isotherm at the surface seems to move in tandem with
the colder air aloft. These two things combined should limit the
overall icing threat. Snow will be the dominant precipitation type
from north central IA into southeast MN and into north central WI.
Farther south across far northeast IA into southern WI looks to be
mainly rain with a wintry mix somewhere in-between.

Model ensembles suggest that if the surface low track is to deviate
from its current mean, it would take a slightly more northern route.
This would introduce even warmer/drier air across the forecast area
and cut-down on snow totals. Model QPF also differs with the GFS the
wettest, NAM the driest, and the ECMWF somewhere in-between. Right
now, there is still the potential for 6 or more inches of snow
within the current Winter Storm Watch area, but considerable spread
remains. For these reasons, will maintain the current watch and
decide on possible warning/advisories later today or tonight.

Remaining precipitation moves out of the area quickly on Sunday with
dry conditions then continuing into Wednesday as high pressure
generally dominates the regional weather pattern. GFS/ECMWF are then
in agreement showing another stronger system Wednesday night into
Thursday. Still lots of details to work out, but right now thermal
profiles support snow. Temperatures for much of next week look to be
near or above normal with zonal flow or ridging aloft. Daily highs
through Wednesday look to be in the 30s to mid 40s. Tuesday in
particular could be very warm with a model consensus hinting that
some spots across the south could approach 50 degrees.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1105 PM CST Thu Feb 22 2018

Cigs: mostly LIFR/IFR overnight. Should see some increase Fri
morning, with gradually breakout into sct conditions by/during the
afternoon.

WX/vsby: snow, freezing rain/drizzle and/or wintry mix into the
overnight, with most of the pcpn done by 12z. Warm air a loft and
ice in cloud making pcpn type tricky, but trends favoring more
snow for KRST and more freezing rain for KLSE. Both could flip to
-fzdz for 1-2 hours before it ends. vsbys mostly 1-2sm in the
snow, although some mvfr possible at the outset.

Winds: winds will go from the east to the west Fri morning as the
low pressure system responsible for the wintry mix slides northeast
across the region.


&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until 6 AM CST early this morning for
     WIZ032-033-041-053>055-061.

     Winter Weather Advisory until 9 AM CST this morning for WIZ017-
     029-034-042>044.

     Winter Storm Watch from Saturday afternoon through late Saturday
     night for WIZ032.

     Winter Storm Watch from Saturday evening through late Saturday
     night for WIZ017-029.

MN...Winter Weather Advisory until 6 AM CST early this morning for
     MNZ079-086>088-094>096.

     Winter Storm Watch from Saturday afternoon through late Saturday
     night for MNZ079-086-087-094.

IA...Winter Weather Advisory until 6 AM CST early this morning for
     IAZ008>011-018-019-029-030.

     Winter Storm Watch from Saturday afternoon through late Saturday
     night for IAZ008.

&&

$$

SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...Rieck


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