Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 240441
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1141 PM CDT Wed Aug 23 2017

.UPDATE...


&&

.AVIATION(06Z TAFS)...Mid to high clouds will increase during the
early morning hours on Thu and decrease by late morning and early
afternoon. Patchy ground fog will form early Thu AM before the mid
level clouds arrive, but dissipate once the cloud cover thickens.
Broken cumulus of 3-4 kft will occur over the lake counties via
lake effect for a period Thu AM. There will be a clearing trend
from ne to sw through the afternoon as dry air moves into the
region. Patchy ground fog may occur late Thu night.


&&

.PREV DISCUSSION... (Issued 943 PM CDT Wed Aug 23 2017)

UPDATE...

MARINE...A cold front will accelerate down Lake MI late tonight
and Thu AM with winds becoming nely and gusting to 20 kts from
around 3-4 am near Sheboygan to Milwaukee around 7-8 am and
Kenosha around 10-11 am. Scattered lake effect showers will
develop along the front with a small potential for waterspouts
given the warm waters and cold air aloft. Waves up to 3 feet on
Thu. Otherwise light winds and low wave heights for Fri and the
weekend.

PREV DISCUSSION... (Issued 728 PM CDT Wed Aug 23 2017)

UPDATE...A strong shortwave trough currently moving into nw MN
will track to east central WI by 12z. Forecast soundings indicate
steep lapse rates and saturation from the mid levels upward
so introduced low PoPs over the nrn CWA. At the sfc, a surge of
nnely winds will move down Lake MI, possibly causing lake effect
showers given lake to 850 mb temp difference of 15-16C so
introduced low PoPs over the lake counties. The timing will be
from the early morning hours over the nrn CWA while the potential
for lake effect showers could linger into the early afternoon over
Kenosha and Racine.

AVIATION(00Z TAFS)...Mid to high clouds will increase during the
early morning hours on Thu and decrease by late morning and early
afternoon. Although, broken cumulus of 3-4 kft will occur over
the lake counties via lake effect for a period Thu AM. There will
be a clearing trend from ne to sw through the afternoon as dry air
moves into the region.

PREV DISCUSSION... (Issued 323 PM CDT Wed Aug 23 2017)

SHORT TERM...

Tonight and Thursday - Confidence...Medium

Overall dry and cool surface high will dominate this period. A
reinforcing cool front arrives later tonight into Thursday
morning. A potent mid level shortwave combined with this front
will try to fight the substantially dry column to kick off a few
showers. Bufkit soundings do show various depths to the mid level
moistening so have some small chances mainly in the western cwa.
Cyclonic flow and low level thermal trough in place for much of
Thursday so after any lingering mid clouds move off should see
some more in the way of CU formation.

LONG TERM...

Thursday night through Saturday...Forecast confidence is medium to
high:

High pressure will hold in place over the Great Lakes late week
into the weekend. Moisture will be increasing from the west on the
back side of the high during this time. This could allow for a few
showers at times as weak waves rotate through the northwest flow.
It will be a battle between the higher moisture west and the much
drier conditions toward the center of the high in the east.
Confined highest pops mainly to the west as a result, with
eastern areas possibly staying dry through this time period.

Below normal temps are expected during this forecast period.

Sunday through Wednesday...Forecast confidence is medium:

Models are developing a closed upper low in the area late weekend
into early next week. As is typical with these systems, models are
struggling a bit with the movement/strength of the upper low as
well as the resultant surface development. It does look like
showers and maybe a few storms are possible as this low moves
through the region, with Sunday and Monday having the higher
chances given the overlap among models. It should turn dry by
mid-week, though the ECMWF is slower to push the system out and
hangs on to shower chances through Wednesday.

Some uncertainty with exact temps given the different
possibilities with the low pressure system next week. Overall
though, temps should be near to a few degrees below normal.

AVIATION(21Z TAFS)...VFR cumulus field should dissipate within
the cooling/dry airmass this evening. Small chance of shra very
late tonight into Thursday morning with approaching vigorous
shortwave and southward sliding cold front.

MARINE...Arrival of potent mid level shortwave combined with
lower level CAA may still lead to an isolated waterspout or two
overnight into Thursday morning. Passing cold front late tonight
into Thursday morning will shift winds onshore though winds and
resultant waves are expected to remain below small craft criteria.

&&

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

$$

Update...Gehring
Tonight/Thursday and Aviation/Marine...Collar
Thursday Night through Wednesday...DDV



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