Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 150848

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
348 AM CDT Thu Mar 15 2018

...Update to Marine Section...


Today and Tonight...Forecast Confidence is High...

Clear skies and light north winds are being observed across
southern Wisconsin this morning. Northerly flow will continue
through the day today, with high temperatures ranging from the mid
40s over southwestern Wisconsin to the mid to upper 30s near Lake

Temperatures tonight will fall into the upper teens and low 20s.


Friday and Saturday...Forecast confidence is medium.

A shortwave trough will lose amplitude while progressing from the
central High Plains to the Ohio River valley. Rapid cyclogenesis
will commence along the Colorado Front Range on Friday, with the
occluding surface cyclone reaching the mid Mississippi and Ohio
Valleys by late Saturday. Forecast models are in good agreement with
keeping the low, and its associated tight baroclinic zone, to our
south. However, there is a window Friday night where column moisture
increases (Precipitable Water values ~ 0.5" in southwest Wisconsin),
juxtaposed with robust lift and modest moisture within the dendritic
(snow) growth zone. The GFS ensemble members are now in better
agreement with the surface low track, with most solutions bringing
measurable precipitation into southwest Wisconsin on Friday night.
This compares favorably with the latest ECMWF and Canadian
deterministic runs, which suggest the same. The NAM appears a rather
wet outlier (with > 0.25" of QPF southwest of Madison) and is
discounted for now. All of this is to say that we`re seeing enough
model consistency to increase rain/snow chances on Friday night,
particularly for areas southwest of Madison and towards the
Illinois border where light snow accumulations are possible.

Sunday through Thursday...Forecast confidence is medium.

Shortwave troughing ejects out of the Four Corers region on Sunday,
before reaching the lower Missouri and Ohio Valleys by Monday night.
The associated surface low passes through the mid Mississippi
valley on Monday, with southern Wisconsin once again on the
northern periphery of the associated moisture. There is still a
decent amount of model spread with regards to precipitation
timing/placement with this system, with the greatest odds
remaining generally south of our area. For now will maintain PoPs
(precipitation chances) for early next week with a rain-snow mix
possible. Near to slightly below normal temperatures are expected.


AVIATION(09Z TAF Update)...

VFR conditions will continue today. Winds will be from the north
today, generally remaining around 10 knots or less. Light
northeasterly winds are then expected tonight.



Northerly flow will continue across the lake today, becoming
northeasterly tonight, and then easterly Friday and Saturday.
Waves are expected to increase to 2 to 5 feet this afternoon, and
may approach 6 feet off of Wind Point tonight. As a result, went
ahead with a Small Craft Advisory starting at 1 PM today.  Any
higher wave action is expected to diminish Friday, with just 1-2
foot waves expected Saturday and Sunday.


LM...Small Craft Advisory from 1 PM this afternoon to 10 AM CDT
     Friday for LMZ643>646.



Today/Tonight and Aviation/Marine...Boxell
Friday THROUGH Wednesday...SPM is the U.S. government's official web portal to all federal, state and local government web resources and services.