Scientific Forecaster Discussion
fxus63 kmkx 290824
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
324 am CDT Mon may 29 2017
Today and tonight...forecast confidence is medium.
Models are in pretty good agreement with showing a 500 mb low
sliding southeast across portions of Lake Superior and Ontario
Canada today. This feature then shifts to the east tonight.
Cyclonic flow across the region is expected at 500 mb, which will
bring an initial vorticity maximum through the area early this
morning. There may be a few showers with this feature in southern
portions of the area.
Another vorticity maximum should then slide southeast toward the
area later this afternoon, moving through in the evening. Area
forecast soundings, adjusted for the expected temperatures and dew
points, support chances for showers and slight chances for
thunderstorms this afternoon. Mesoscale models may be overdone
with areal coverage, as they tend to be in these situations.
Area of clouds should slide southeast into the area later this
afternoon into this evening, before retreating to the north
tonight. Gusty west winds are expected today as well. Highs today
should reach the upper 60s, with lower 70s across far southeast
Wisconsin. Lows tonight should be in the upper 40s to lower 50s.
Tuesday...forecast confidence is medium
The mid level and surface lows will lift north across of Ontario.
Several waves of vorticity will move through the region and weak
frontogenesis and some instability results in shower and thunder
chances. It will be a tad cooler. 850 winds will be 25-30 knots and
steep low level lapse rates will promote mixing and breezy west
Wednesday and Thursday...forecast confidence is high.
Surface high pressure will slide south of the state bringing mainly
dry weather and sunny skies on Wednesday. Temperatures will rebound
slightly as the upper low loses its grip. Behind the high, southwest
flow will bring a push of warmer and more moist air. Precip and
thunder chances return Thursday night.
Friday and Saturday...forecast confidence is medium.
A frontal boundary looks to be over the region on Friday bringing
precip and thunder chances. As high pressure moves north of the
state a cold front will push south across the region. Precip chances
linger through Friday evening with convergence along the front. High
pressure will continue slides south across the Great Lakes on
Saturday. Another surge of cooler air looks possible with the cool,
Sunday and Monday...forecast confidence is low.
Models have been flip flopping for this period showing either high
pressure of or a surface low and precip. As a result, a lot of
uncertainty with temperatures too. Easterly flow will keep
temperatures cooler near the lake.
Sct mid level clouds will move across srn WI early Mon am while
sct-bkn040-050 is expected from late Mon am into Mon eve. Small
chances of showers and a slight chance of a tstorm from late Mon
am and through the afternoon. Gusty wly winds expected for Mon.
A Small Craft Advisory is in effect from 15z today to 00z Tuesday
across the nearshore waters of Lake Michigan. A tight pressure
gradient will develop during this period, along with robust low
level mixing. This will result in gusty westerly winds. Frequent
gusts to 25 knots are expected. Any high waves will be over the
open waters, given the offshore flow.
Gusty west southwest winds are possible on Tuesday, as the
pressure gradient remains tight, and low level mixing continues.
The gusts may not be as high as today, so there is some
uncertainty. A Small Craft Advisory may be needed for Tuesday. Any
high waves will remain over the open waters once again.
Lm...Small Craft Advisory from 10 am this morning to 7 PM CDT this
evening for lmz643>646.