Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 180410
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1110 PM CDT Thu Aug 17 2017

.SHORT TERM...(Tonight through Friday Night)
Issued at 144 PM CDT Thu Aug 17 2017

GOES satellite/surface analysis show deep 999mb low pinwheeling
northeast across northern WI. Still a few showers/patches of drizzle
rotating across the area mainly east of the Mississippi River under
the low. Otherwise, widespread cloud cover in place with breezy
westerly winds of 10-20 mph/gusting around 35 mph across the more
wind prone areas of northeast IA and southeast MN. Temperatures were
in the middle 60s to the lower 70s.

For tonight, the low will continue to pull northeast into southern
Ontario Canada with showers exiting, winds decreasing, and clearing
expected after midnight. A mid-level trough on the heels of the
departing low is expected to produce an increase in altocumulus
toward morning mainly west of the Mississippi River. Plan on lows
tonight in the middle 50s to lower 60s.

Altocumulus will continue to spread across the area Friday with a
few showers and a slight chance of thunderstorms as that mid-level
trough rotates through. Otherwise, it will be slightly cooler than
normal as highs top off in the 70s.

Mid-level trough and bulk of associated shower/isolated thunderstorm
chances exit the area by midnight with high pressure building in
early Saturday morning. Light winds and clearing skies toward
morning will set up the scenario for some fog development. For now
went with patchy/areas of fog but will have to be watched for
perhaps more widespread development if we can clear out earlier.
Otherwise, plan on overnight lows in the 50s.

.LONG TERM...(Saturday through Thursday)
Issued at 144 PM CDT Thu Aug 17 2017

High pressure will provide a dry Saturday with highs in the middle
and upper 70s. A cold front moves from the Northern Plains into far
northwest WI by late Sunday afternoon but appears any shower/thunder
chances remain north of the area. Otherwise, warm air advection
ahead of this boundary will push highs into the lower and middle 80s.

Shower and thunderstorm chances overspread the area Sunday night as
that cold front sinks southward into the area. Models show this
frontal boundary hanging up across the area Monday into Tuesday as a
weak wave of low pressure runs northeast along it. This will
continue shower/thunderstorm chances. This is not good news for
solar eclipse fans given cloud cover and precipitation chances. Plan
on highs Monday and Tuesday in the upper 70s/lower 80s.

High pressure builds in for Wednesday into Thursday for dry and
slightly cooler than normal conditions.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1110 PM CDT Thu Aug 17 2017

Lower stratus that has encompassed the area for the better part of
the past 24 hours continues to gradually diminish from west to
east late this evening. That trend will slowly continue through
the overnight hours, with mainly VFR conditions in stratus giving
way to just some increasing mid/high clouds from the west at RST
and LSE through the morning hours. A few weakening showers remain
possible at RST though with no impact to ceilings or visibility
expected, while LSE might see a sprinkle at worst through early
afternoon. Additional scattered showers and thunderstorms are
possible during the afternoon hours, though at this time, the
greatest risk looks to be west and south of the terminal sites.
Winds will remain from the northwest early this morning, shifting
westerly and then becoming light tonight. With that light flow,
some fog appears likely to develop, though mainly after the
current TAF period ends at 06Z.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...DAS
LONG TERM...DAS
AVIATION...Lawrence



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