Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 280404
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1004 PM CST Mon Feb 27 2017
.UPDATE...Showers will be increasing in coverage and intensity
from the state of IA for tonight as a vorticity maximum moves
into srn WI. 850-700 mb warm, moist advection and frontogenesis
will accompany the upper wave. Lowered thunder threat to slight
chance given very little elevated CAPE on forecast soundings.
Another round of showers may then occur from sw to ne across srn
WI between 13-17z as a nose of the LLJ pushes north. A stronger
round of showers and sct thunderstorms are then forecast for late
afternoon and evening as a wave of low pressure and surface to 850
mb frontogenesis moves across se WI. CAPE values remain low but
good lift and shear should support sct thunderstorms and possibly
A fairly strong shortwave trough will then bring accumulating snow
to the region for Wed.
.AVIATION/06Z TAFS/...Rain during the early morning hours and
moisture transport will eventually bring the CIGS to below 1 kft
before sunrise. A couple more rounds of showers and possible
thunderstorms are expected for Tue into Tue night followed by
rain changing to snow on Wed. CIGS will remain low and vsbys will
range from 2-5sm due to precipitation and/or light fog.
.MARINE...Brisk nly winds and high waves will develop late Tue nt.
and through Wed in the wake of a strong cold front. A Small Craft
Advisory will likely be needed.
.PREV DISCUSSION... /Issued 336 PM CST Mon Feb 27 2017/
TONIGHT AND TUESDAY... Forecast confidence is medium.
A warm front will bring an area of showers with a chance of elevated
thunderstorms to southern WI tonight on the nose of a low level jet.
It looks like there will be a back edge to these showers so there
should be a lull during the mid to late morning. Expect patchy fog
and low clouds to linger. Despite the clouds, temperatures should
rise into the 50s with a good push of warm air on southerly winds.
A coupled upper jet and another nose of the low level jet just ahead
of the surface low will bring another round of showers and scattered
thunderstorms midday. These will be elevated, but could produce some
SPC pushed the Day 2 marginal risk all the way up to Sheboygan now.
This is to cover the hail threat. The surface low and associated
cold front is forecast to track right through far northeast IL, but
it could clip southeast WI during the late afternoon and early
evening hours. This would allow for potential surface-based
convection. There is high shear but low instability, so a small
chance for severe storms.
TUESDAY night AND WEDNESDAY...Forecast Confidence...Medium
Low pressure will exit far southeast Wisconsin Thursday early
evening. There would still be a marginal risk of severe
thunderstorms far southeast early in the evening before the cold
The low is forecast to intensify over Lower Michigan with strong
cold air advection across southern Wisconsin. Precipitation will
be in the form of rain before midnight, slowly transitioning to
a mix of snow northwest Tuesday night, then to mainly snow across
the area by Wednesday afternoon. GFS has come in line with the
NAM/ECMWF showing the potential for 1 to 2 inches of snow on
Wednesday. A few 3 inch totals not out of the question if the
THURSDAY THROUGH SUNDAY...Forecast Confidence...Medium
Could see a little snow Thursday as a low moves across southern
Wisconsin. The GFS/NAM would indicate a 1 to 2 inch snow
potential, but the ECMWF is much less.
Decent agreement among models for Friday, showing high pressure
and near normal temperatures. South winds on the back side of the
high begins a moderation in temperatures Friday evening and
GFS and ECMWF show a little snow Fri night due to lift with the warm
Another trough may bring light rain/sprinkles Saturday evening
before south winds and warming begin again sunday.
As low pressure approaches rain may develop Sunday night into
Monday. The ECMWF and DGEX are quicker and deepen a low over Lower
Michigan. The GFS is slower, and has a more northern track.
A warm front will bring a surge of rain into southern WI after
midnight tonight. There is a small chance of thunderstorms with this
round. Another round of showers and a few storms is possible midday.
The better chance of showers and scattered storms is expected along
a cold front late Tue afternoon into the evening.
Ceilings should lower to MVFR after the rain arrives tonight with
some IFR conditions expected toward 12z Tuesday. Ceilings may rise
above IFR for a time on Tuesday, then go back down Tuesday night.
Southeast winds will approach small craft advisory levels very late
tonight into early Tuesday morning as low pressure approaches from
the west. Once the low passes by, northerly winds will again
approach small craft advisory levels on Wednesday. Small craft
should exercise caution during these periods.
TONIGHT/Tuesday AND AVIATION/MARINE...MRC
Tuesday NIGHT THROUGH Monday...Hentz