Area Forecast Discussion
Issued by NWS La Crosse, WI

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714
FXUS63 KARX 251750
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
1250 PM CDT MON JUL 25 2016

.SHORT TERM...(This evening through Tuesday)
Issued at 349 PM CDT Mon Jul 25 2016

At 3 AM, a 1018 mb surface high pressure area, centered near
Sioux Falls South Dakota, was producing clear skies across the
Upper Mississippi River Valley. This high also was bringing drier
air into the region. Dew points were in the lower and mid 60s.
This is about 10F lower than 24 hours ago.

Through tonight, the high pressure area will move slowly east
southeast into Iowa. This high will keep skies mostly clear. With
850 mb temperatures anywhere from 2 to 4C cooler than yesterday,
high temperatures will be up to 5F cooler than Sunday. In
addition, the diurnal mixing will bring drier air from aloft to
the surface. This will lower the surface dew points to around 60
degrees.

.LONG TERM...(Tuesday night through Monday)
Issued at 349 PM CDT Mon Jul 25 2016

On Tuesday night, there is good agreement that a mesoscale
convective complex will develop over eastern South Dakota and
eastern Nebraska on Tuesday night and this system will move
southeast across Iowa on Wednesday. Additional showers and storms
develop along a cold front across central Minnesota and northern
Wisconsin on Tuesday night. The ECMWF and NAM have this front
slightly further north as a result the area remains dry.
Meanwhile the GEM and GFS is a bit further south with this front
and they have some showers and storms north of Interstate 90.
Since the models have shown little run to run consistency for this
time period, just kept a small chance of rain along and north of
Interstate 90.

From Wednesday into Thursday, a surface cold front and short wave
trough will move slowly southeast and east through the region. The
combination of convergence from the trough and cold front and
modest instability (1-2 K 0-1 km CAPES) will result in the
development of showers and storms across the area. With very weak
0-3 mb and 0-6 km shear located across the region, not
anticipating any severe weather from this system. While
precipitable water values will be around 1.5 inches, both the 925
and 850 mb moisture transport looks rather weak. In addition, the
warm cloud layer depths remain less than 3K feet. As a result, not
anticipating a heavy rain threat at this time.

Another short wave trough will move through the region from Friday
night into Saturday. This system looks pretty similar to the one
that will be moving through the area from Wednesday into Thursday.
Due to this, not anticipating a severe or flooding threat from
this system.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1250 PM CDT Mon Jul 25 2016

After some scattered cumulus this afternoon with cloud bases
around 4 kft, high pressure will provide clear skies for the late
evening and overnight hours. Some areas of valley fog are possible
near KLSE but considering how high the temperature/dewpoint spreads
are this afternoon, current thinking is that it probably won`t
impact the TAF site. Have included a light visibility restriction
at KLSE, at 6SM, but will have to monitor temperature and dewpoint
trends closely this evening.

&&

.HYDROLOGY...
Issued at 349 AM CDT Mon Jul 25 2016

Runoff from the rains Saturday has caused some rises on area
rivers. The Turkey River at Elkader crested at 12.21 feet early
this morning. Flood stage is 12 feet. With a couple of dry days
expected, this river along with many other tributaries around the
region will likely fall quickly.

&&

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

$$

SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...WETENKAMP
HYDROLOGY...BOYNE



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