Area Forecast Discussion
Issued by NWS La Crosse, WI

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339
FXUS63 KARX 280752
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
252 AM CDT TUE JUN 28 2016

.SHORT TERM...(Today and tonight)
Issued at 252 AM CDT Tue Jun 28 2016

Latest water vapor satellite imagery shows shortwave trough over
northern Wisconsin and the Upper Peninsula of Michigan. This
shortwave trough is producing stratocumulus deck of clouds across
parts of eastern Minnesota and much of Wisconsin per latest
infrared satellite imagery.

Main forecast concerns today are cloud trends and the potential
for fog in river valleys tonight. The 28.00z GFS/NAM are in good
agreement in moving shortwave trough east of the forecast area and
digging upper level trough over the Great Lakes Region today. The
28.00z GFS/NAM suggest stratocumulus deck in association with
shortwave trough will erode by 15z today. However...next weak
impulse over the Northern Plains will track over the forecast area
today and allow for some clouds to develop across parts of the
forecast area. This will provide mostly/partly sunny skies across
the forecast area. The clouds are expected to dissipate
tonight...as surface ridge builds into the forecast area. With
light winds and clear skies...fog is possible to
develop...especially in river valleys. Have introduced patchy fog
in the Mississippi river valley and areas of fog in the Wisconsin
river valley after 08z Wednesday.

.LONG TERM...(Wednesday through Monday)
Issued at 252 AM CDT Tue Jun 28 2016

Focus then turns to Wednesday night into Thursday night. The
28.00z GFS/NAM/ECMWF models show differences in timing of weak
shortwave trough tracking into the forecast area after 00z
Thursday. The 28.00z GFS/NAM are faster and slightly stronger with
the forcing/moisture convergence than the 28.00z ECMWF. Due to
these differences...confidence in precipitation chances are low
and have continued trend with small shower/thunderstorm chances
across the forecast area Wednesday night.

The 28.00z models GFS/NAM/ECMWF are in better agreement with
placement and movement of cold front moving across the forecast area
during the daytime Thursday. With increasing moisture convergence
and forcing along cold front...showers and thunderstorms chances
will increase...especially after 18z Thursday. At this time severe
weather is not expected with the thunderstorms...as the 28.00z
GFS/NAM place the better shear behind surface cold front.

Main forecast concerns Friday through Sunday are temperatures...then
precipitation chances Monday. The 28.00z GFS/ECMWF/GEM are in good
agreement in digging upper level trough over the northeastern United
States and building upper level ridge over the Rocky Mountains
through the period. The GFS/ECMWF/GEM indicate slight differences on
the strength of the upper level ridge over the Rocky Mountains...as
the 28.00z GFS is weaker. However...the 28.00z long range
deterministic models are in good agreement with surface ridge
dominating the forecast area Friday into Sunday. This will
provide dry weather and temperatures near or slightly below
normal. Surface ridge builds east of forecast area and upper level
ridge flattens out and west to east zonal flow develops across the
northern tier United States Monday. This allows return southerly
moisture flow into the Upper Midwest. Due to timing differences of
shortwave troughs embedded in the west to east zonal flow
aloft...confidence of shower/thunderstorm chances is low. For now
continued trend of small precipitation chances Monday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1124 PM CDT Mon Jun 27 2016

Stratocumulus will linger at the TAF sites through the overnight
hours with cloud bases around 4 kft. These clouds will then exit
the TAF sites, mainly after sunrise, with VFR conditions expected
through the rest of the forecast period. Winds will be light as
high pressure builds in.


&&

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

$$

SHORT TERM...DTJ
LONG TERM...DTJ
AVIATION...WETENKAMP



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