Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 290911
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
411 AM CDT THU SEP 29 2016
.TODAY AND TONIGHT...Forecast confidence medium.
A low stratus deck has formed possibly from moisture rotating around
the low and lake to 850 mb temperature differences of 8C. Believe
south central WI can scatter out by late morning or early afternoon
but se WI may stay cloudy due to a higher moisture content. A lobe
of vorticity will rotate around the upper low and pass through srn
WI tonight. Thus small chances today in far se WI will increase from
east to west across srn WI tonight. Kept temps a little cooler for
today given more clouds.
FRIDAY THROUGH SATURDAY NIGHT...Forecast Confidence Is Medium.
The closed 500 mb low is shown by models to slowly shift
northwest from central Kentucky to southern Indiana on Friday. It
lingers in Indiana Friday night, before sliding northward into
northern Indiana Saturday. The 500 mb low then slides northeast
into southern lower Michigan Saturday night. Several vorticity
maxima rotate around the 500 mb low through the area during this
period, with differential cyclonic vorticity advection providing
upward vertical motion.
Area forecast soundings gradually moisten through a deep layer
Friday into Friday night, then show some drying Saturday into
Saturday night. Gusty onshore winds Friday into Friday evening are
expected, before the pressure gradient relaxes somewhat Saturday
into Saturday night. The onshore winds and favorable delta T
values suggest some lake effect clouds would be possible during
Spread likely PoPs into the eastern counties Friday, with higher
end chances elsewhere. May need higher PoPs for Friday into
Saturday night overall, with SREF model showing high
probabilities for showers during this period. Expected cloud cover
with the 500 mb low, and the showers, should keep temperatures
cool during this period.
.SUNDAY THROUGH WEDNESDAY...Forecast Confidence Is Medium.
ECMWF/GFS suggest some lower end PoPs for the far eastern counties
on Sunday, as the last effects of the cutoff 500 mb low affect the
area. This feature will continue to slide well east of the region
Sunday night into Monday, with the area out of the cyclonic flow
around the low.
Weak high pressure and a 500 mb ridge axis moving across the
region Sunday night into Tuesday suggest a period of quiet weather
is possible. The dry period may extend into Wednesday, as dry
southeast flow limits advance of next system. Temperatures look to
slowly warm during this period, with some sunshine each day.
.AVIATION/12Z TAFS/...The low stratus deck will likely continue
today over se WI given the closer proximity to the higher low level
moisture content that is associated with the stalled low over the
Ohio River valley. Over south central WI expect skies to become
partly cloudy by late morning or early afternoon. Until then Cigs of
600-1300 feet will prevail over much of srn WI. Cigs may rise to 2-3
kft over se WI this afternoon before falling to 1 kft this evening
and possible below 1 kft toward sunrise on Fri. The low cigs will
also spread wwd into south central WI late tnt. Small chances for
rain over far se WI this afternoon with chances for rain increasing
tonight from east to west as the low pressure area begins to move
toward the Great Lakes.
.MARINE...The Small Craft Advisory has been extended into
early Saturday morning due to a continuation of brisk nnely winds
and high waves. The brisk winds will continue as low pressure over
the Ohio River valley moves back north toward the Great Lakes.
LM...SMALL CRAFT ADVISORY until 4 AM CDT Saturday for LMZ643>646.
TODAY/TONIGHT AND AVIATION/MARINE...Gehring
Friday THROUGH Wednesday...Wood