Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 280147
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
847 PM CDT WED JUL 27 2016
Satellite cloud features and regional radar clearly show the mid
level circulation pushing into Wisconsin this evening. The
weakening diurnal trends, weak flow regime are resulting in a slow
diminishment of the activity upstream. However, there is recent,
isolated, pulse convection developing over south central Wisconsin
and northern Illinois at mid evening. But, with the lack of
shear, they are struggling, quickly choking themselves out. If
you get under one, you`ll get a quick, decent rain, but most
people will miss out on beneficial rainfall.
With the trough moving overhead, and a lower level inverted trough
lingering over western Wisconsin into Thursday, will keep the chance
of showers and storms going. Nothing serious, just nuisance stuff.
A trough of low pressure will continue to push into the area
overnight. We will continue to see small chances of showers and
thunderstorms through most of the period with the best chance
likely staying out toward KMSN. There is a deck of MVFR cigs over
northwest Wisconsin and east central MN that could drift south
southeast into the area late tonight, toward 10-12z Thursday, and
bring MVFR cigs to KMSN Thursday morning. It appears they wouldn`t
make it to the southeast WI TAF sites. There will also be some
light fog late tonight with VSBYS dropping to 3 to 5 miles in the
weak flow, moist environment. Conditions should improve by late
morning on Thursday with VFR conditions returning.
Light NE winds will increase later Thursday into Thursday night
and persist into Friday. Waves will build to 3 to 5 feet Thu ngt
into Fri AM. Winds are expected to stay below criteria. A small
craft advisory may be needed for wave heights.
.PREV DISCUSSION... /Issued 332 PM CDT WED JUL 27 2016/
REST OF THIS AFTERNOON AND TONIGHT - Confidence...Medium
Water vapor/RAP animation shows mid level shortwave approaching from
MN and IA. Pronounced outflow boundary shifting south through cwa.
Lake breeze boundary intersecting outflow may spawn a shower as
well. Outflow boundary triggering new convection vcnty Sauk county.
So boundaries and instability enough to keep things going for a while
Then meso models show a lot of this wiping out or at least becoming
more isolated in nature as the night wears on. May see a bit
more activity arrive later in the night as influence of upper
THURSDAY - Confidence...Medium
Inverted trough axis is proggd to be situated across the wrn CWA
with some flattening of this feature into the afternoon hours. Mid
level flow remains cyclonic across srn WI with embedded vorticity
maxima traversing across or just south of WI. Will keep highest
pops in the southern and western cwa. 925 flow turns more to the
northeast so a cooler thermal profile takes hold. MOS guide and llvl
rh progs keep quite a bit of cloud cover locked in.
Thursday night through Saturday...Forecast Confidence Medium.
A shortwave trough and cold front will be moving away over nrn IL
by early Thu eve but will maintain small chances of tstorms to
handle any lingering precipitation. Another shortwave trough will
then slowly move across IA and nrn IL Fri-Sat with a weak inverted
sfc trough possibly extending nwd into srn WI. Thus will maintain
small chances of showers and tstorms for that period. Nely winds
and pleasant temps and dewpoints will prevail with high pressure
centered over the nrn Great Lakes.
LONG TERM...Sunday through Wednesday...Forecast Confidence
An upper ridge will build toward the western Great Lakes for Sun-
Mon with dry conditions and a warming trend. Shortwave troughs
will then roll the ridge over to the east bringing a return of hot
and humid conditions for Tue-Wed with at least small chances of
AVIATION/00Z TAFS/...Band of convection associated with surface
boundary affecting areas north of TAF sites. With outflow boundary
sagging south and lake breeze boundary could certainly see more
shra/tsra pop up. Wind shift to the northeast accompanies the
southward moving outflow boundary. Could see some more development
as the night wears on with mid level energy though latest HRRR not
showing much coverage to this. SREF cig/vsbys prog shows axis of
some higher probs for lower cigs/vsbys later tonight into early
Thursday as post-frontal cooler airmass/low level thermal trough
starts to exert itself across srn WI. There continues to be precip
chances into Thursday as mid level wave rides southeast across the
area with some hints of weak surface cyclogenesis south of WI.
MARINE...Nely winds will develop this evening and last into Fri.
Waves will build to 3 to 5 feet Thu ngt into Fri AM. Winds are
expected to stay below criteria. A small craft advisory may be
needed for wave heights.
TONIGHT/Thursday AND AVIATION/MARINE...Collar
Thursday NIGHT THROUGH Wednesday...Gehring