Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 270750
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
250 AM CDT SAT AUG 27 2016
.TODAY AND TONIGHT...Forecast Confidence Is Medium.
A strong shortwave exiting the northern plains will reach the lake
Superior and southern canada region late tonight. The entrance
region of a 100 knot 250 mb upper jet with southern and central
Wisconsin in the right entrance region today. This results in
upper divergence and mainly weak upward motion. A 700 mb wind max of
35 knots moves through this morning before moving off to the
northeast by early afternoon. The 850 mb wind max of around 25 to
30 knots also moves across southern Wisconsin this morning. The
resulting moisture convergence was setting off the area of showers
and thunderstorms. These should move off by afternoon south
central, and later this afternoon southeast. The high resolution
HRRR and the GFS are similar.
Precipitable water values get favorable, and mesoscale models
suggest some training of storms are possible. Heavy rainfall is
expected in some of the storms. However, think these storms will be
moving quick enough to limit any mainly urban flooding potential.
Precipitation chances Saturday afternoon are still rather murky, as
forcing weakens, but a surface boundary is expected to first push
north this morning, then back south across the area later
this afternoon and evening.
Zero to 1 km mixed layer CAPE is around 1100 Joules/kg with little
cap. Zero to 6 km shear is around 30 knots during the afternoon.
Will maintain the chance POPs for the afternoon hours. A marginal
severe risk exists across the area today and early this evening.
.SUNDAY - Confidence...Medium
Weak mid level ridging sets up with all models showing a weak wave
across nrn WI. The NAM also shows a wave riding across nrn IL though
this is an outlier and within an area of anticyclonic curvature.
Surface/850 ridging also noted so will go with quiet POPS. 925 temps
around 20c though a smidge warmer in the western CWA.
.MONDAY - Confidence...Medium
Surface/850 ridge axes shift a bit to the east though still some
lingering low level anticyclonic flow evident. The mid level ridge
collapses with some weak shortwave activity in place. Will have some
POPS in place with models keying more in the western and southern
CWA. 925 temps rise just a smidge into the lower 20s celsius with a
better hint of a return flow.
.TUESDAY - Confidence...Medium
Surface/850 boundary expected to focus a little better chance of
shra/tsra. Mid level flow becomes more cyclonic from the northwest
though better vorticity resides to the northeast and southwest of
the CWA. Main cool push arrives Tuesday evening as 925 temps turn
.WEDNESDAY THROUGH FRIDAY - Confidence...Medium
Shaping up to be a quiet and cooler period with low level thermal
trough in place. Per collab with LOT decided to trim Superblend a
few degrees in the east. Surface high pressure takes hold and sticks
around into Friday. Any return flow type precip is expected to hold
off to our west.
.AVIATION/12Z TAFS/...Expect MVRF and a period of IFR cigs with warm
front passage during the morning hours, with the area of showers
and thunderstorms. Should see a break in the precipitation late
morning into the early afternoon especially south central. Expect
VFR conditions once the warm front lifts north with MVFR cigs/vsbys
with any of the scattered showers and storms late this afternoon.
.MARINE...Weak gradient keeps winds, and thus waves, relatively low
through the weekend and into next week. Wind direction will go from
east and southeast early this morning, to southeast and south today
with passage of a warm front, then west tonight behind a weak surface
wave of low pressure. Showers and scattered thunderstorms likely
with the warm front and subsequent passage of the surface low but
only scattered coverage thunderstorms late this afternoon and this
TODAY/TONIGHT AND AVIATION/MARINE...Hentz
Sunday THROUGH Friday...Collar