Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 281522
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1022 AM CDT FRI OCT 28 2016
.AVIATION/18Z TAFS/...Strong west/east 500-300 millibar flow
carrying any vorts to our north this period. Potent waa regime
continues into tonight ahead of surface/850 boundary. Areas of IFR
stratus persist in sc WI with VFR conditions more prevalent
elsewhere. SREF Cig progs suggest this stratus will not increase
in coverage but hard to clearly latch onto trends with CI
streaming overhead. Surface boundary proggd to sag through srn WI
later tonight into early Saturday with 850 boundary lagging a bit.
Main aviation concern tonight will be low level wind shear as
strong 850 jet translates across srn WI. Progd suggest some more
stratus potential along and ahead of the surface front.
.MARINE...An area of low pressure tracking across lake Superior
tonight, will bring a tight pressure gradient to the nearshore
waters, resulting in strong south winds. Latest high resolution
models show frequent wind gusts over gale force levels for areas
north of Port Washington today with a few Gale Gusts early this
evening to the south. A small craft advisory is in effect, with a
Gale warning north of Port Washington after 4 pm. Highest waves
will be north of Port Washington.
Another low pressure system moving through the area will bring small
craft advisory conditions for Monday and Monday night due to strong
.PREV DISCUSSION... /Issued 307 AM CDT FRI OCT 28 2016/
TODAY AND TONIGHT...Forecast Confidence Is High.
Surface low pressure will track from North Dakota this morning to
Lake Superior by late this evening. We are well south and east of
the low, but will be within the leading tightening pressure
gradient. We`ll see southerly winds pick up and get rather gusty
today, though it looks like they may not be as strong as expected
earlier. The model soundings are showing a rather strong low level
inversion through the windiest period, limiting our ability to mix
up into the stronger winds. We should still see a few gusts
pushing 30 mph at times, but generally around 15 to 25 mph. The
southerly winds will pump a seasonably warm airmass up here, so a
breezy mild day expected with highs in the lower to mid 60s.
As the low heads east of Lake Superior overnight, a trailing cold
front will be knocking on our doorstep toward sunrise Saturday.
The atmosphere is exceptionally dry through a deep layer, so no
rain expected through tonight. However, there is an increase in
low level moisture and this will likely result in increasing lower
clouds toward sunrise. The elevated southerly flow tonight will
keep temps very mild for late October.
SATURDAY THROUGH SUNDAY NIGHT...Forecast Confidence Is Medium.
Models are in decent agreement with trends during this period. A
cold front slides southward through the area on Saturday, then
into northern Illinois Saturday night. There is not much upward
vertical motion associated with the front itself. Kept low PoPs in
the north during the afternoon for now. Despite the mostly cloudy
skies expected Saturday, highs should still rise into the middle
to upper 60s.
The best QPF over the area comes Saturday night, as modest 850 mb
to 700 mb frontogenesis response moves through the area. There is
also a modest 500 mb vorticity maximum that shifts east through
the area. These features interact with a fairly moist air column
over the area to bring a decent shot at rain showers Saturday
Went with higher end chance to low end likely PoPs for Saturday
night. May need to go with higher PoPs in later forecasts, as the
models have trended higher with QPF over the area. Area forecast
soundings show very little elevated CAPE, so will leave out
thunder wording for now. Lows should drop into the mid 40s in most
High pressure builds into the area for Sunday, then shifts to the
east Sunday night. Kept small PoPs in the far southeast Sunday
morning, until precipitation can move out of that area. Otherwise,
skies should become partly cloudy by afternoon, as drier air moves
into the area. Highs should be limited to the mid 50s in most
areas. Cooler lows in the mid 40s are forecast for Sunday night.
MONDAY THROUGH THURSDAY...Forecast Confidence Is Medium.
The GFS takes the surface low for early next week further to the
south than the ECMWF, brushing the northern portions of the area
with light QPF. However, both models keep the best upward
vertical motion with this system north of the area Monday into
Monday night. They bring a cold front east through the area on
Tuesday. The relatively dry air over the region should limit any
precipitation chances with this passing system.
A tight pressure gradient should bring gusty southeast to south
winds on Monday, veering west and decreasing on Tuesday. This
should bring warmer temperatures back into the area. Highs Monday
and Tuesday should reach into the lower to mid 60s each day.
GFS/ECMWF then show a warm front to the south of the area later
Tuesday night into Wednesday, with a weak low pressure system and
cold front sliding southeast through the area Wednesday
afternoon and evening. They show an amplified shortwave trough at
500 mb moving through the region later Wednesday night. The GFS is
a bit faster with the movement of the system than the ECMWF.
Still, it looks to be trending toward a wet Wednesday at least.
Kept PoPs for later Tuesday night into Wednesday night for now,
and can refine timing with later forecasts. May need higher PoPs
for this system as well, if models remain in decent agreement.
Temperatures look to remain near seasonal normals Wednesday into
Some MVFR cigs may be stubbornly hanging around for a few hours
after the start of the 12z TAFs this morning, but an increasing
southerly flow should push those lower clouds north of the area
and eventually mixing them out. We should then remain VFR through
12z Saturday. One caveat...there is a possibility of MVFR cigs
developing around KMSN at around 12z Saturday, as a cold front
approaches the area and winds becoming very light.
A tightening pressure gradient ahead of low pressure passing
north of Wisconsin will bring gusty southerly winds later this
morning and into this evening. Moderate to strong low level wind
shear around 1500-2000ft is expected with winds at that level
reaching 50-55kts from the southwest. There is an inversion at
this level, resulting much lighter winds at the surface. The
strongest LLWS will run from about 19z Friday through 10z
An area of low pressure tracking north of Wisconsin through
tonight will bring a tight pressure gradient to the nearshore
waters, resulting in strong and gusty southerly winds. It looks
like we will generally remain below gale force levels, so dropped
the Gale Warning for areas north of Port Washington today.
However, we`ll still see winds in the 20 to 30kt range, so expect
large waves to build rapidly later this morning. A Small Craft
Advisory goes into effect at 11 am and will run through 7am
Saturday. With southerly winds, the highest waves will be north of
Another low pressure system moving through the area will bring
Small Craft Advisory conditions for Monday and Monday night, due
to strong southerly winds.
LM...SMALL CRAFT ADVISORY until 7 AM CDT Saturday for LMZ644>646.
SMALL CRAFT ADVISORY until 4 PM CDT this afternoon for LMZ643.
GALE WARNING from 4 PM this afternoon to 1 AM CDT Saturday for
TODAY/TONIGHT AND AVIATION/MARINE...Davis
Saturday THROUGH Thursday...Wood