Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
274
FXUS63 KMKX 281455 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
955 AM CDT WED SEP 28 2016

.UPDATE...

No change to the forecast for this fall day. Scattered showers are
expected across southeast WI, with isolated showers or sprinkles in
south central WI. Clouds will keep us cool today- high temperatures
will be in the upper 50s to lower 60s. Winds will be breezy out of
the north-northeast.

&&

.AVIATION/18Z TAFS/...

Ceilings of 700-1900 feet will continue this morning over south
central WI while farther to east over se WI, ceilings of 1000-3000
ft will continue. Visibility will be VFR through the afternoon,
with the exception of within brief showers.

Although scattered showers will continue through the afternoon,
cloud bases/ceilings are expected to rise to 3500-4500 ft during the
afternoon and then become partly cloudy to mostly clear tonight.
MVFR lake effect clouds will be possible over ern WI along with
slight chances of showers over far se WI through the overnight hours.

&&

.MARINE...

Current wind observations and short range guidance support starting
the small craft advisory a few hours early. So opted to start it at
the 930 am marine forecast issuance.  We are stuck within a tight
pressure gradient between high pressure nosing south out of Canada
and low pressure holding fairly stationary over the Ohio Valley with
an inverted trof axis stretching into the southern Great Lakes. This
will bring a rather prolonged period of brisk northerly winds and
large waves to the nearshore and open waters through Thursday night.

A large delta-t over the lake...water temp - 850 temp in C...
combined with rather deep convective cloud depths will bring
favorable waterspout conditions to southern Lake Michigan today. The
low level wind convergence axis over the lake is also helping. The
International Center for Waterspout Research model is highlighting
southern Lake Michigan for a WP threat, but the focus is clearly in
the far southern basin. Any decent convective cells over the lake
could develop a WP.  So mariners are cautioned to remain alert if on
the water today.

&&

.PREV DISCUSSION... /Issued 434 AM CDT WED SEP 28 2016/

TODAY AND TONIGHT...Forecast Confidence Is Medium.

The organized area of light rain is diminishing across far se WI
as the sfc-850 mb frontogenesis moves swd. The upper low over Lake
MI will slowly move swd across IN today and tonight. A broad sfc
low will move from IN to the central Appalachians, but with an
inverted sfc trough extending back to srn Lake MI and lower MI.
The inverted sfc trough, along with a passing lobe of PVA today,
will continue scattered showers over srn WI with best chances in
the east via additional instability from the warm Lake MI waters.

For tonight, slight warm advection and drying on the back side of
the upper low may result in partly cloudy to mostly clear skies.
The onshore flow from Lake MI may result in some lake clouds via
lake to 850 mb temp differences of 8C. Low temps will range from
the upper 40s over south central WI, to the upper 50s near Lake
MI.

THURSDAY THROUGH FRIDAY NIGHT...Forecast Confidence Is Medium.

The models are in fairly good agreement with trends with the
closed 500 mb low during this period. They take it from far
southern Indiana at 12Z Thursday into east central Kentucky by 00Z
Friday. This keeps the system far enough to the southeast to keep
dry air in place over most of the area Thursday, except in the far
southeast counties where the best low level moisture resides. Kept
small PoPs in this area Thursday. At least partial sunshine should
allow for mid 60s near Lake Michigan, to around 70 well inland.
Gusty northeast winds will bring a chill to the air, and onshore
flow over the mild waters may maintain clouds near the lake.

The closed 500 mb low then stalls over east central Kentucky
Thursday night, before retrograding northwestward into either
northern or southern Indiana by 12Z Saturday. This track of the
closed 500 mb low will bring various vorticity maxima westward
through the area Thursday night into Friday night. Area forecast
soundings suggest moisture will increase through the air column
into Friday in the eastern portions of the area, spreading
westward into Friday night.

Thus, will continue to bring in higher PoPs for showers westward
into the forecast area during this period. Best PoPs will remain
in the lakeshore counties. Persistent northeast winds Thursday
night into Friday night, with increasing clouds, should keep
temperatures in the 60s Friday, with lows in the 50s Thursday
night and Friday night.

SATURDAY THROUGH TUESDAY...Forecast Confidence Is Medium.

GFS/ECMWF models generally take the 500 mb closed low northeast
from Indiana into southern lower Michigan Saturday, then shifts
further northeast into Ontario Canada Saturday night and Sunday.
Enough moisture lingers in the low levels within the cyclonic
circulation of the 500 mb closed low to continue to mention
showers in forecast. Cool highs in the 60s, with lows in the 50s,
are forecast during this period.

Models are then indicating a switch to south or southwest flow at
500 mb early next week. There are still some big timing
differences with the surface and upper air features between the
models. Used consensus PoPs and temperatures for this later
period.

AVIATION/12Z TAFS/...

Cigs of 700-1900 feet will continue this morning over south central
WI while farther to east over se WI, cigs of 1-3 kft will continue.
Areas of mvfr vsbys via light fog and drizzle will also be found.
Although scattered showers will continue through the afternoon, cigs
are expected to rise to 3.5-4.0 kft during the afternoon and become
partly cloudy to mostly clear tonight. Lake effect clouds will be
possible over ern WI along with slight chances of showers over far
se WI.

MARINE...

A Small Craft Advisory is in effect from 18z today into Thu
night. Brisk and gusty nnely winds are expected with high waves of
4-7 feet. The brisk nnely winds is the result of low pressure
stalling over the Ohio River valley. Waterspouts will be possible
today as the upper low passes across Lake MI and to the south.

&&

.MKX Watches/Warnings/Advisories...
WI...None.
LM...SMALL CRAFT ADVISORY until 7 AM CDT Friday for LMZ646.

     SMALL CRAFT ADVISORY until 1 AM CDT Friday for LMZ643>645.

&&

$$

UPDATE...MRC/Davis
TODAY/TONIGHT AND AVIATION/MARINE...Gehring
Thursday THROUGH Tuesday...Wood



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.