Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 221548
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
948 AM CST Wed Nov 22 2017

.UPDATE...

Fcst is in good shape this mrng. No significant changes were made. High
pressure will dominate the wx today with clear skies. Winds will
gradually shift to SW in advance of a weak clipper system that
will pass across N WI tonight with clouds increasing this aftn.

&&

.MARINE...

VFR conditions today with high pressure in control producing clear
skies and light NW breeze this mrng becoming SW this aftn. Winds
will pick up overnight as a weak storm system passes across N WI
but should diminish again through Thanksgiving remaining offshore
into Thursday night.

&&

.PREV DISCUSSION... (Issued 539 AM CST Wed Nov 22 2017)

UPDATE...The forecast is on track for today and tonight.

AVIATION(12Z TAFS)...

Mainly VFR conditions today and tonight. Flurries and very light
snow may occur for a few hours tnt, with the better chances
toward central WI. Thus, any restrictions in vsbys or possible
MVFR Cigs would occur toward central WI and would likely be brief.

PREV DISCUSSION... (Issued 315 AM CST Wed Nov 22 2017)

SHORT TERM...

Today And Tonight...Forecast Confidence Is Medium.

A ridge of high pressure will shift ewd across srn WI today, with
swly winds and weak warm advection beginning in the afternoon.
Full sunshine and the weak WAA should be able to boost temps into
the lower to middle 30s, before the high clouds arrive for late
afternoon.

A shortwave trough within nwly flow aloft will then move across
srn WI tnt. The associated low to mid level warm advection and PVA
will affect the region. Forecast soundings show the low levels of
the atmosphere remaining fairly dry in srn WI, with better
chances of saturation to the north. Thus, introduced slight
chances for light snow toward central WI, with sct flurries
elsewhere from this evening into the early morning hours. A
dusting of snow could occur toward central WI, including Fond du
Lac and Sheboygan.

Thanksgiving Day Through Friday Night...Forecast Confidence Is
Medium.

Models are in decent agreement with northwest flow at 500 mb on
Thanksgiving Day becoming more zonal by Friday morning. Quiet
weather is expected Thanksgiving Day, with temperatures near
seasonal normals. Warm air advection Thursday night into Friday on
increasing southwest winds should bring in warmer temperatures.
Highs should reach into the lower to middle 50s Friday, perhaps a
few degrees warmer.

Models then bring a cold front through the area later Friday into
Friday evening. There is modest low level frontogenesis response
during this time, along with fairly strong differential cyclonic
vorticity advection with a passing 500 mb shortwave trough.

Area forecast soundings are showing a good amount of air column
saturation for a brief period either late Friday or Friday
evening. The best is in the north and east portions of the area,
though the NAM is holding onto this saturation several hours
longer than the GFS.

For now, will continue with mainly low end PoPs, until more
confidence can be gained with moisture profiles between the
models. It will be warm enough for all rain during this period.

LONG TERM...

Saturday Through Tuesday...Forecast Confidence Is Medium.

Models in this period are showing a broad 500 mb ridge moving east
across the region Saturday into Monday, before sliding off to the
east by Tuesday. Brisk northwest winds Saturday should limit
temperatures to the upper 30s to lower 40s. High pressure should
then slide southeast from the northern Plains into the Middle
Mississippi River Valley Saturday night into Sunday. Quiet weather
should continue Saturday into Sunday. Temperatures should remain a
little below seasonal normals Saturday night into Sunday.

Fairly strong warm air advection should then move into the region
late Sunday into Tuesday. This should bring a warming trend into
the region, with highs reaching back into the 40s, perhaps a bit
warmer.

There are model differences with timing and placement of the low
track undergoing cyclogenesis for later Tuesday and beyond.
GFS/ECMWF are similar in bringing the deepening low northeast
across Wisconsin either Tuesday or Tuesday night, with a strong
cold front moving east through the region. The Canadian model does
not show much cyclogenesis with this low, and is quicker to move
it out of the region. For now, will use consensus blended PoPs and
temperatures for Tuesday.

AVIATION(09Z TAFS)...

Mainly VFR conditions today and tonight. Flurries and very light
snow may occur for a few hours tnt, with the better chances
toward central WI. Thus, any restrictions in vsbys or possible
MVFR Cigs would occur toward central WI and would likely be brief.

MARINE...

Light to moderate offshore flow and low wave heights for today
and Thu.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...BM
Today/Tonight and Aviation/Marine...BM
Thursday THROUGH Tuesday...Davis



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