Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 241916

Area Forecast Discussion
National Weather Service La Crosse WI
216 PM CDT Thu May 24 2018

.SHORT TERM...(Tonight through Friday Night)
Issued at 216 PM CDT Thu May 24 2018

GOES-East Water Vapor this afternoon showing a closed upper Warm low
across northeast MT/southern Saskatchewan. Mid-level trough moving
northeast in advance of this low was producing scattered storms
across central into northern MN. However, across our forecast area,
warm air advection in full swing with temperatures well into the 80s
as of 2 pm under partly cloudy skies.

For tonight, that mid-level trough will continue pressing eastward
toward the region with a general uptick in 850mb moisture transport.
This could produce a few showers and storms mainly north of the I-
90/94 corridors where better nose of moisture transport will reside.

For Friday, the trough and attendant weak surface cold front will
continue pushing into the area for scattered showers and storms.
Plenty of CAPE (generally around 3000J/kg) will be in place along
with higher precipitable water values in the 1.5 to 1.8 inch range,
but bulk wind shear rather weak around 20kt. So, thinking any storms
will be pulse type in nature with heavy downpours and some stronger
wind gust/small hail -but expecting most storms to remain below
severe limits. Otherwise, look for warm and humid conditions with
highs in the 80s and dew points in the 60s. Scattered showers and
storms expected to continue into Friday evening, exiting south after

.LONG TERM...(Saturday through Thursday)
Issued at 216 PM CDT Thu May 24 2018

Saturday will be very warm, and quiet for the most part. A weak
secondary mid-level trough will drop through the U.P. and northern
WI. This could spark a few showers/isolated storms across northern
WI. Otherwise, look for highs topping off in the middle 80s to lower

Ridge amplification on Sunday will provide for a very warm, quiet
day with highs pushing into the upper 80s to the lower 90s.

Memorial Day looks continued very warm and quiet for the most part
with mid-level ridge in place. Will have to watch for possible
elevated convection though as a deep trough out west sends bits of
energy northeast into us.  For now, will carry very small-end
chances of this occurring. Plan on highs in the 85-90 degree range.

Look for a general uptick in shower/thunderstorm chances for Tuesday
through Thursday as a fairly strong trough ejects northeast out of
the Rockies into the Upper Mississippi River Valley region.
Otherwise, plan on temperatures to remain above normal with highs
expected to be in the 80s.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1250 PM CDT Thu May 24 2018

Gusty south/southwesterly winds expected through the afternoon along
with scattered cumulus with bases in the 4-5 kft agl range.
Forecast confidence for the remainder of the TAF period then becomes
fairly low. Showers and storms are expected to develop late this
evening/overnight in parts of southeast Minnesota into Wisconsin.
RST would be the more likely TAF site to be impacted, but latest
guidance suggests best chances will remain north and west, so
elected to leave TAFs dry overnight. That said, can`t completely
rule out a shower/storm sneaking into either TAF site tonight.
Storms could continue into Friday morning, pending evolution of the
storms tonight. In addition, a weak front approaching from the west
on Friday is expected to trigger additional showers and storms, but
timing/location is quite uncertain at this time. Currently thinking
both sites will see showers and/or storms at some point on Friday,
but thinking best chances will be after this TAF period and
confidence is too low to include mention for this issuance. Assuming
no showers/storms tonight and Friday, thinking winds will be more
southwesterly on Friday at around 10 kts with scattered to broken
clouds in the 10-15 kft agl layer.




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