Area forecast discussion
National Weather Service Green Bay WI
352 am CDT Wednesday Jun 19 2013
Forecast discussion for routine morning forecast issuance
Short term...today...tonight...and Thursday
issued at 350 am CDT Wednesday Jun 19 2013
Tonight and Wednesday
Another nice day expected today as high pressure remains over
the western lakes. Will see increasing southerly flow bringing
warmer and more humid air north into the state today and Thursday.
Sat imagery showing mostly clear skies over northeast WI...with
few clouds moving into central WI..mainly associated with pocket
of moisture around 5k. Given rather dry grb sounding last evening
will stay with mostly sunny wording for much of the day. Another
area of middle level clouds over northern Minnesota associated with weak
disturbance may bring some clouds into north central WI later this
afternoon. Temperatures to run near normal.
Low pressure moving through central Canada to drag cold front east
and south to vicinity Lake Superior tonight...vicinity WI/Michigan border by
Thursday evening. Will continue low probability of precipitation north for day period Thursday
with front in vicinity...modest instability with convective available potential energy around 1k Thursday
afternoon. Models not showing any cin...though also showing no
upper support for initiation of convection with low level jet also
still focused over Minnesota through day period Thursday. Main change was to
back off a bit on clouds and probability of precipitation from previous forecast.
Long term...Thursday night through Tuesday
issued at 350 am CDT Wednesday Jun 19 2013
Upper ridge will build across the eastern United States late this
week into the weekend before retrograding into The Rockies by the
middle of next week. Position of 500mb ridge on the 00z models
tonight put US in the ring of fire during the period. However...
it will turn much warmer and more humid into the weekend as moist
southerly flow develops.
As always the case with these scenarios...when and where complexes
set up always difficult to pinpoint this far out. Also...maximum
temperatures each day complicated on timing of these systems if
they should hold off later in the day or even into the evening
hours.
Will have a chance of showers and thunderstorms Thursday night
with weak boundary dropping southward across the north and expected
complex moving into the west late. Increasing low level jet and
steepening middle level lapse rates would suggest that strong or
severe storms are possible Friday afternoon and Friday night...
although exact timing still somewhat uncertain. Middle level lapse
rates are around 7 c/km and wet bulb heights are just over 10000
feet. Modified soundings also did show convective available potential energy of 1000 to 2000 j/kg
and windex values of 45 to 50 knots. First complex of storms
should move through the area Friday night/possibly linger into
Saturday morning. Although not shown in the grids...do suspect
there will be a lull or no activity for awhile late Saturday
morning due to departing complex/cloud cover. Atmosphere should
become unstable again later Saturday afternoon with another
complex of thunderstorms Saturday night/linger Sunday morning
across the east. Would suspect based on the models...more storms
will reform Sunday afternoon. With the heat and humidity around...
damaging winds and locally heavy rain are the primary threat with
these storms.
Boundary will be lurking around Monday and Tuesday...along with
the heat and humidity. Some of the storms could become strong or
severe...but it is too early to determine if or when organized
severe weather would occur.
Did raise maximum temperatures a few degrees most days. If more sunshine
than expected does occur...maximum temperatures may need to raised even
a few more degrees.
&&
Aviation...for 06z taf issuance
issued at 1236 am CDT Wednesday Jun 19 2013
Satellite and surface observation showed some 6500-12000ft
moving into northwest Minnesota. Expect clear skies to remain that
way overnight with unrestricted visibility and light and variable/calm
winds. Model time/height plots were showing some moisture around
4000-5000ft during the day on Wednesday...so have some VFR ceilings
going during the day. Have keep clouds in the north as a surface
front approaches northern Wisconsin and models show increased
moisture there during the evening.
&&
Marine...
issued at 350 am CDT Wednesday Jun 19 2013
A warm and humid air mass will overspread the cooler waters of the
Bay of Green Bay and Lake Michigan Thursday night or Friday...
leading to the formation of dense marine fog. Dense marine fog
will continue at times into early next week as the warm and humid
air mass remains firmly entrenched across the region. Several
complexes of thunderstorms are expected from time to time Friday
into early next week. These storms will pose a significant risk
for mariners with strong winds...locally higher waves... large
hail and torrential rains which will reduce visibilities below one
mile.
&&
Hydrology...
issued at 350 am CDT Wednesday Jun 19 2013
Several complexes of thunderstorms are expected between Friday
into early next week. A very warm and humid air mass will become
entrenched across the region late this week and continue into
early next week. Precipitable water values should run 150 to 200
percent of normal...leading the likelihood on torrential rains and
potential for urban flooding due to the intense rainfall rates.
Any training or slow moving thunderstorms will increase the risk
of flooding.
&&
Grb watches/warnings/advisories...
none.
&&
$$
Short term.....Te
long term......eckberg
aviation.......mg
marine.........Eckberg
hydrology......eckberg
