Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 251731

Area Forecast Discussion
National Weather Service La Crosse WI
1231 PM CDT Tue Oct 25 2016

.SHORT TERM...(Today through Wednesday night)
Issued at 308 AM CDT Tue Oct 25 2016

Surface to mid-level ridge of high pressure over the region early
this morning with increasing mid/high level clouds streaming in per
IR satellite imagery. This mid/high level cloud was in response to
increasing 850-700mb isentropic lift/moisture transport ahead of low
pressure moving out of the Northern Rockies.

Mid-level trough/surface low move out of the Rockies into the Plains
this afternoon. This increases isentropic lift/moisture transport
into the region. A dry lower level airmass will be in place as the
ridge of high pressure shifts slowly east, so a lot of this lift
will go into cloud production  with perhaps a few showers mainly
west of the Mississippi River.

For tonight...the mid-level trough/surface low continues to track
out of the Plains into Iowa. 850mb moisture transport amps up quite
a bit in response to increasing nocturnal jet/tap of Gulf moisture.
As a result, precipitable water values rapidly increase into the 1-
1.3 inch range which in turn ramps up rain production over the area.
Heaviest rainfall looking to occur from around midnight through mid-
Wednesday morning. Although Cape is not very impressive tonight
through Wednesday morning with 0-3km MUCAPE less than 500J/kg south
of I-90, still thinking enough forcing will be present for a few
embedded thunderstorms.

Look for the rain rate to be on a slow diminishing trend Wednesday
afternoon as 850mb moisture transport/higher precipitable water
value plume shifts east as low moves through northern IL. Rain moves
out Wednesday night as the low pulls toward lower MI/Indiana.

All in all, looks like 1-2 inches of rain is likely, heaviest
along/south of I-90. However, due to rather spread out nature of the
rain and the rather dry October thus far, feel flooding will not be
an issue. However, we could see some localized ponding of water in
roadways where drainages may be poor due to fallen leaves.

Look for temperatures today in the upper 40s to the middle 50s under
cloud cover and then mainly in the 40s on Wednesday due to
widespread rain and cloud cover.

.LONG TERM...(Thursday through Monday)
Issued at 308 AM CDT Tue Oct 25 2016

High pressure builds in on Thursday but Bufkit soundings show
lingering stratus behind the departing low. Looks like at least some
partial sunshine going into the afternoon. Otherwise...look for
highs in the upper 40s to middle 50s.

Northwest flow aloft ushers in low pressure from central Canada into
the region Friday. With the track of the low, appears better forcing
and saturation for showers will be east of the Mississippi. Latest
models even indicating showers could be confined northeast of I-94.
Rest of the area looks to be in the warm sector with highs pushing
into the 60s.

Cold air advection takes place on Saturday behind the departing
low...otherwise dry with highs in the 50s.

Sunday looks like a pleasant autumn day as a ridge of high pressure
builds over the region. This looks to be short-lived through as
models show low pressure and threat for showers moving back in for


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1231 PM CDT Tue Oct 25 2016

Main taf concerns are LIFR conditions at RST and IFR conditions
at LSE taf sites after 06z Wednesday. Low pressure tracking into
the Midwest this evening into Wednesday morning will spread
showers...possibly a thunderstorm...across the region. With the
showers moving into the region...ceilings are expected to lower
into the LIFR after 06z Wednesday at RST and IFR at the
better forcing associated with the low pressure system moves into
the area. Pressure gradient tightens this evening and allows winds
to gust to 25 to 30 knots at both RST/LSE taf sites by 06z
Wednesday. The precipitation should exit the RST taf site around
15z...however LIFR conditions will prevail through 18z Wednesday
and precipitation/IFR conditions will continue at LSE taf site
through 18z Wednesday. Limited instability across the area will
inhibit widespread coverage of thunderstorms...will continue to
leave mention of thunder out of the tafs.




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