Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

FXUS63 KARX 251755

Area Forecast Discussion
National Weather Service La Crosse WI
1255 PM CDT Tue Jul 25 2017

.SHORT TERM...(Today and Tonight)
Issued at 341 AM CDT Tue Jul 25 2017

At 3 AM, warm air advection ahead of a short wave trough has
result in showers and storms across central Minnesota and west
central Wisconsin. The models are in general agreement that this
area of strong warm air adection will move east across the area
through early this afternoon. This will result in a band a couple
bands of showers and isolated thunderstorms moving across the
Upper Mississippi River Valley. With limited instability and shear
this morning, not anticipating any severe weather.

For tonight, a cold front will move slowly southeast into the
region. However, by the time this front arrives, instability will
be waning. With this said, will have to watch out, because this
will be the time period in which we will see the best deep shear.

.LONG TERM...(Wednesday through Monday)
Issued at 341 AM CDT Tue Jul 25 2017

On Wednesday and Wednesday night, a cold front will move southeast
through the Upper Mississippi River Valley. The models continue to
show that the moisture transport will increase across eastern
Iowa during the afternoon and evening as a weak surface low moves
along this front. While these have been consistent signals, there
is still much uncertainty on how much instability will be located
across the region. At this time, it looks like the 0-1 km mixed
layer CAPES will range from 1500 to 2500 J/kg. This is similar to
what the NAM has been forecasting the past 2 days. Meanwhile, it
is 1-2 K J/kg less than previous runs of the GFS. Like the past
couple of days, the 0-3 km and 0-6 km appear weak. However, with
this said, will have to watch where the low tracks. This could
potentially increase the shear enough that there could potentially
be some supercells.

In addition to severe weather, we will have to watch for the
potential of heavy rain. Precipitable water values along the front
climb into the 2 to 2.25 inch range and warm cloud layer depths
are in the 4 to 4.5 K foot range. However, the moisture
convergence along the front remains weak and this will greatly
affect the areal coverage of precipitation across the region. Due
to this opted, not to issue a Flash Flood Watch at this time.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1231 PM CDT Tue Jul 25 2017

Showers and embedded storms continue to push off to the
southeast, with a few additional showers and storms expected to
impact KLSE through the early afternoon. VFR conditions then
expected through the overnight hours, though a low level jet looks
to set up over the area tonight, so included LLWS from 05Z to 12Z
at both TAF sites. Increasing cloud cover and decreasing ceilings
(though still at VFR levels) are expected through the day on
Wednesday. Showers and storms are expected to move through the
entire area, with both TAF sites possibly being impacted toward
the end of the TAF period, but confidence on timing is not high
enough to include at this time. Should these showers and storms
arrive prior to 18Z, MVFR ceilings and visibilities would be
possible if a storm directly impacts either site.


.HYDROLOGY...through Wednesday night
Issued at 341 AM CDT Tue Jul 25 2017

Flood Warnings continue along the Kickapoo River from Soldiers
Grove to Steuben and along the Trempealeau River at Dodge. Despite
some rain through early this afternoon, these levels will
continue to slowly fall.

From tonight into Wednesday night, additional rain is expected
across the region. Some of these storms may produce locally heavy
rainfall that could result in some additional river rises and
perhaps minor flooding.

Thursday into the weekend will be dry.




HYDROLOGY...Boyne is the U.S. government's official web portal to all federal, state and local government web resources and services.