Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
333 am CDT Thursday may 28 2015
Today and tonight...forecast confidence high.
Shortwave ridging aloft is expected this morning but will move eastward
for the afternoon with some weak positive vorticity advection aloft. Some models attempt to
produce convection along the lake breeze front and over central
WI...but dewpoints and cape appear overdone. Will maintain a dry
forecast with few-scattered cumulus expected. The west-east surface ridge that extends from
Illinois to Ohio will retreat eastward for the afternoon which will aid in lake
breeze development but also southerly flow inland as the pressure gradient
increases with the surface trough over the plains. 925 mb temperatures warm to
20-21c which yields lower 80s for high temperatures.
For late tonight the shortwave trough currently over NE and Kansas will lift
northeastward into west central and northwest WI. The 925-850 mb flow turns to the
SW with moisture return but very little warm advection. Precipitable waters increase
to 1.5 inches and elevated convective available potential energy of several hundred j/kg over the
western County Warning Area by 12z Friday. The moisture flux convergence remains weak with
the most focused lift closer to the MS river. Thus went with high
chance probability of precipitation west of kmsn to slight chance in eastern WI.
Showers and storms are expected Friday into Friday night as a
weak embedded wave or two moves through while a cold front drops
southward into the area. Some stronger storms are
possible...though overall flow and shear are pretty marginal.
Additionally...some question as to how much instability there will
be given ongoing showers/storms in the morning...along with
lingering clouds cover much of the day. Does seem like a
respectable chance for some destabilization and Storm Prediction Center has
maintained the area in a marginal risk for severe storms.
925 mb temperatures will be in the 19-22c range Friday. Even with the
possibility of convection/clouds...it will not take much sun at
all for highs to shoot up to around 80...so maintained warm temperatures.
Saturday through Wednesday...forecast confidence...medium
The surface cold front should be down to about the Illinois border
by daybreak Saturday...with showers and a few storms lingering
into the morning hours as the main shortwave moves through. Mainly
dry weather is then expected for the afternoon. Temperatures will be
much cooler Saturday behind the cold front...especially near Lake
Michigan where gusty north to northeast winds will bring in
chillier air off of Lake Michigan.
High pressure overhead Sunday will slowly head eastward early
next week...but should hold on long enough for dry weather Monday
and Tuesday. Temperatures should recover to near normal
Monday...climbing back a bit above normal Tuesday. Cooler temperatures
will persist near Lake Michigan under onshore winds.
Even milder temperatures along with a return of moisture is expected for
Wednesday...bringing a slight chance of storms.
VFR conditions today and tonight. A few fair weather cumulus today with
clouds increasing late tonight as moist and unstable air returns to the
region on a southwesterly low level jet stream. There will be small chances
of thunderstorms around sunrise on Friday with much better chances of thunderstorms
later in the day.
Today/tonight and aviation...gehring
Friday through Wednesday...ddv