Area Forecast Discussion
Issued by NWS La Crosse, WI

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198
FXUS63 KARX 311730
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1230 PM CDT WED AUG 31 2016

.SHORT TERM...(Today through Saturday)
Issued at 245 AM CDT Wed Aug 31 2016

Not sure September can get off to a better start. Models remain in
very good agreement with building an amplified upper level ridge
from the Plains to across the Upper Mississippi River Valley over
the next few days, while at the sfc its associated high moves
overhead Thu afternoon. Cooler and much less humid air is funneling
southward post the cold front that moved through yesterday, and will
hold across the area through Saturday. Highs mostly in the 70s with
lows in the 50s are expected.

River valley fog looks like a good bet for some of the local
waterways Thu and Fri mornings. Wind fields probably keep any fog
confined to the tributaries of the Mississippi Thu morning (low
level wind fields look a bit too breezy just off the deck). Much
lighter for Fri morning, which would support more spreading out
within the main stem.

.LONG TERM...(Sunday through Tuesday)
Issued at 245 AM CDT Wed Aug 31 2016

GFS/ECMWF remain in good agreement with shifting east/bending the
ridge over this weekend as an upper level trough drives from the PAC
NW into southern Canada. A relatively strong southerly fetch sets up
across the Plains, shifting over the local area Sun-Tue. While the
bulk of the upper level energy holds in the trough, the models
suggest a few ripples in the flow could work across the region. More
importantly, the trough`s associated sfc front will slide over the
Upper Mississippi River Valley in the Sun-Tue time frame - and
linger. A pretty good setup for shower/storm production. While the
details aren/t clear, the models have been suggesting a slow down in
the eastward advancement of this system - with Sat now looking dry.
All said, after what should be some real pleasant days, the area
will get under an unsettled weather pattern with shower/storm
chances. Will let consensus solution handle the chances.

Of note is the potential for heavy rain. If the GFS is right, PWs
for early next week could climb to near 2 inches, while warm cloud
depths approach 4 kft. Both very favorable for efficient rain
producers and heavy rain. Its a long ways out, but bears a close
watch.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1230 PM CDT Wed Aug 31 2016

Main taf concern is fog formation in river valleys tonight. High
pressure over the Upper Midwest and Great Lakes Region will remain
in control of the area this afternoon into Thursday. The latest
31.12z GFS/NAM/RAP Bufkit soundings show inversion developing
tonight and the combination of light winds...will result in the
formation of fog in river valleys after 06z Thursday. At this
time...VFR conditions will prevail at both RST/LSE taf sites.
However...a few or scattered deck of clouds with heights at or
around 200-300 feet could form at LSE taf site after 10z
Thursday...due to fog formation over the Mississippi River.

&&

.ARX Watches/Warnings/Advisories...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...DTJ



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