Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 232138
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
338 PM CST Fri Feb 23 2018

.SHORT TERM...

Tonight and Saturday... Forecast Confidence is High.

The clouds are scattering out west of Madison this afternoon and
the trend will continue to the east through early evening. Skies
should mostly clear out for a period tonight, but expect high
clouds to begin streaming into the area toward morning as the next
system approaches from the southwest. The breezy west winds will
diminish around sunset. Light winds tonight will veer to the east
and increase Saturday morning. Skies should mostly clear out for
a period tonight, but expect high clouds to begin streaming into
the area toward morning as the next system approaches from the
southwest. There should be some patchy light fog inland overnight
under those clear skies.

A digging trough out west will approach the Midwest tomorrow.
Warm air advection and vorticity advection will cause precip to
develop over southern WI Saturday afternoon. The 12Z models
delayed the precip onset from prior runs since they`re picking up
on drier air it will have to overcome. Precip will spread in
quickly by late afternoon, but the type may start out as snow
initially before changing to all rain, depending on the rate of
the WAA and the temp profile. Not expecting snow accumulation.

Saturday night through Tuesday...Forecast confidence high.

Strong cyclogenesis will track from N MO to just east of
Marquette, MI for Sat nt. Strong and deep Q-vector convergence
will accompany this system via warm, moist advection on the nose
of a LLJ and PVA. The upper trough passage and cold frontal
passage will occur Sat nt. Fcst soundings are still indicating PWs
around 0.75 inches and enough elevated instability for a mention
of tstorms. Rainfall totals will range from 0.25-0.40 inches. This
should remain minimal enough to prevent another round of
flooding.

The deepening low will lead to windy conditions especially with
the passage of the cold front as lapse rates steepen. There may be
an initial burst of winds with the frontal passage that could
reach Wind Advisory criteria, but still remain close afterward
through Sun AM. The winds will be weakening through Sun PM as the
deep low moves to James Bay, Canada. The dry wly winds, eventual
sunshine, and lack of snow cover should result in temps reaching
the lower 40s for Sun. A weak sfc ridge will then pass late Sun
nt into Mon AM followed by swly winds and warm advection for the
remainder of Mon. Continued sunshine and warm advection should
boost temps to upper 40s to lower 50s. A repeat performance may
occur for Tue although lighter winds may lead to a Lake MI lake
breeze.



.LONG TERM...Wednesday through Friday...Forecast confidence medium.

Confidence lessens for this period due to the uncertain
interaction of upper waves in the nrn and srn streams of a split
flow jet stream. Weak or fairly strong cyclogenesis may occur and
bring rain and snow to srn WI for Tue nt-Thu. Polar high pressure
may then return for Fri unless the low pressure area lingers.


&&

.AVIATION(21Z TAFS)...

Ceilings are on the rise there will be a clearing trend with the
clouds from west to east late this afternoon/early evening. Gusty
west winds that developed in the wake of a surface trough this
morning will diminish around sunset. Light winds tonight will veer
to the east and increase Saturday morning. There should be some
patchy light fog inland overnight under some clear skies.

There is a chance for some low lake clouds to spread inland
Saturday morning as winds become easterly, but not a lot of
confidence in this yet, so left it out of the TAFs. Look for the
main batch of air to saturate from the top down which means the
rain should be delayed until late afternoon or early evening.
There is a slight chance for thunderstorms Saturday evening.


&&

.MARINE...

It`s still looking like a gale event for Saturday night into
Sunday as a strong, compact low pressure system tracks across
southern MN, central/northern WI, and Lake Superior. Highest winds
should be along the leading edge of the cold front early Sunday
morning.


&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Watch from Saturday evening through late Sunday night for
     LMZ643>646.

&&

$$

Tonight/Saturday and Aviation/Marine...Cronce
Saturday Night through Friday...Gehring



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