Area Forecast Discussion
Issued by NWS La Crosse, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
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 44 45 46 47 48 49 50
FXUS63 KARX 182354

Area Forecast Discussion
National Weather Service La Crosse WI
554 PM CST Wed Jan 18 2017

.SHORT TERM...(This evening through Friday)
Issued at 303 PM CST Wed Jan 18 2017

Main forecast concerns in the short term on on dense fog potential
tonight into Thursday morning. Focus then quickly turns to a chance
for a wintry mix which could produce slippery travel conditions
for some Thursday night into Friday.

An active weather pattern sets up across the region the the next
several days as a broad trough sets up across the western conus.
First off tonight, relatively warm and moist air flowing over the
snowpack across the area could lead to the development of dense fog
in areas and to go along with this, some low clouds/stratus. The
first trough then lifts into the region Thursday night into
Friday pushing a warm front through the area. Precipitation will
develop along and ahead of the approaching front and will most
likely start out as a wintry mix before transitioning over to all
rain. Locations north of interstate 90 look to remain cold enough
Thursday night into Friday morning that we may have some freezing
rain and perhaps some sleet concerns. The big concern is how
quickly will surface temperatures warm above freezing. By early
afternoon, most locations should be above freezing with rain the
main precipitation type. The freezing rain may produce travel
problems, especially north of Interstate 90, and on any untreated
secondary roads, before temperatures warm above freezing.

.LONG TERM...(Friday night through Wednesday)
Issued at 303 PM CST Wed Jan 18 2017

We then lose forcing for precipitation for the bulk of Friday night
ahead of the next through moving in from the south. Given the nearly
saturated lower levels, from surface through around 5 kft, the
most likley precipitation outcome will be drizzle or very light
rain. Steadier rain should then set in during the day on Saturday
and continue into Saturday evening. Surface temperatures will be
warm enough that any precipitation that falls should be in the
form of rain. Chances for light rain continue into Sunday then we
look to cool enough Sunday night into Monday for possibly
rain/snow mix. We are seeing mixed signals for a potential system
late Tuesday into Wednesday. What looks like a potential impactful
weather system in the GFS is now pretty much absent in the ECWMF.
A lot of uncertainty out there on days 6-7 so will continue to
keep an eye on future model runs.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 554 PM CST Wed Jan 18 2017

Very challenging forecast throughout the period concerning low
stratus/fog potential. Confidence is low as short range forecast
guidance does not match reality; multiple updates are likely over
the next 6-12 hours. For this evening, there is a narrow band of
low stratus from 300 to 1000 ft agl, from just south and east of
KRST to the tri-state border area of northeast IA/northwest
IL/southwest WI. Despite poor handling of these clouds by the
models, satellite trends suggest a slow northward expansion
through the evening along light southerly surface flow. On their
current trajectory, these clouds should reach KLSE in the
19.02-19.03Z time frame, but may remain just east of KRST unless
there is a westward expansion with time. Once/if clouds impact TAF
airfields with IFR/LIFR ceilings, reductions in visibility from 2
to 5SM are also likely in mist. Cloud cover not likely to
dissipate through the night once over TAF airfields, but given low
confidence over the next 6 hours, did not make any changes to the
previous forecast Thursday morning and beyond.




SHORT TERM...Wetenkamp
LONG TERM...Wetenkamp
AVIATION...Rogers is the U.S. government's official web portal to all federal, state and local government web resources and services.