Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
934 PM CDT Monday Oct 20 2014
Update...still a few sprinkles hanging on in the east as weak
short wave trough slides off to the east. Will be more pessimistic
regarding cloud cover tonight due to strenghtening thermal trough
over eastern WI and lingering cyclonic flow. Will hang onto clouds in
the east through Tuesday morning as well. Moist low level onshore flow may
result in the low clouds potentially lingering into Tuesday evening in
the east. Nudged overnight low temperatures up several degrees due to the
Aviation/06z tafs/...onshore flow likely to result in a period of
MVFR ceilings for a time later tonight and Tuesday in eastern taf sites.
Lower clouds may hang on for much of Tuesday.
Marine...winds beginnning to increase over the nearshore waters
as pressure gradient tightens and low level lapse rate steepens.
Will continue Small Craft Advisory with strongest winds anticipated
later tonight into Tuesday morning. Low level winds will turn
onshore creating longer fetch and higher waves on Tuesday before
pressure gradient weakens Tuesday night.
Previous discussion... /issued 329 PM CDT Monday Oct 20 2014/
Tonight and Tuesday...forecast confidence...high
Could see a few sprinkles in the east this evening as a middle-level
vortmax rotates through...but not enough confidence for probability of precipitation at
this point. Extensive cloud cover is expected to linger in the
northeast half of the forecast area into tonight under northwest
flow...likely hanging around in the east through at least Tuesday
morning. Western portions of the forecast area should see mostly
clear to partly cloudy conditions.
Colder temperatures aloft will advect into the area tonight. Should see
lows right near normal tonight...with highs a few degrees below
.Tuesday night through Wednesday night...Forecast confidence
A middle level ridge will slide through the center of the country which
will bring surface high pressure to southern Wisconsin. Models are
suggesting some weak low level Theta-E advection over southeast WI
on light easterly return flow early Wednesday morning which would produce
a few low clouds. Any clouds will keep min temperatures a little higher
than previously forecast. Expecting skies to remain clear for most
of the night well inland which will allow min temperatures to drop into the
lower 30s and also some patchy fog.
Plan on mostly sunny skies Wednesday with a few diurnal cumulus with a
lake breeze. Look for increasing clouds Wednesday night with an
Thursday and beyond...forecast confidence medium.
A vigorous shortwave trough will swing through the upper Midwest
Thursday. There is good agreement between the models that light showers
should move across southern WI during the day Thursday and taper off
overnight Thursday night. The GFS shows saturated low levels through the
night while the NAM dries it out quicker. If the GFS solution pans
out...then we can expect drizzle and low clouds lingering through
early Friday morning.
High pressure and mostly sunny skies will settle back into the
region over the weekend. A strong upper trough over Ontario Canada
could lead to some middle and high clouds as far south as southern
WI... but overall we should be in the warm air area. In fact...
forecast maximum temperatures in the lower 60s are little on the conservative
side and middle to upper 60s are not out of the question.
Will see VFR clouds linger across mainly the northeast
half of the forecast area into tonight. Could see a few showers
in the east this evening...but most places will remain dry.
Clouds will linger in the east Tuesday. Still some indication that
ceilings may be MVFR for a time...so opted to put MVFR into tafs.
Kept the Small Craft Advisory as is for later this evening into
Tuesday night. Best chance for gusts to 25 knots and waves greater
than 4 feet will be toward open waters.
Lm...Small Craft Advisory until 1 am CDT Wednesday for lmz643>646.