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Area forecast discussion 
National Weather Service Green Bay WI
353 am CDT Monday Jul 6 2015

Forecast discussion for routine morning forecast issuance

issued at 348 am CDT Monday Jul 6 2015

Thunderstorms spreading across the area today and tonight...some
of which will produce heavy rain and possibly some minor flooding.
Cooler and drier tomorrow.

Highly amplified upper flow over central and southern Canada will flatten
during the early part of the forecast period. That will allow some
separation of the westerlies...and the evolution of a southern branch
of the flow across the Continental U.S.. the southern stream will initially be
dominated by upper trough near the West Coast...but during the latter
part of the period an upper anticyclone is expected to form in vicinity of
the lower Mississippi Valley/southeastern Continental U.S..

It looks like we are heading back into a much wetter weather regime.
Cold front crossing the area will generate sig rainfall the next 24
hours. Then after a few dry days...the chance for sig rains will return
during the latter part of the period as the forecast area comes under
the influence of shortwaves in evolving southern stream. Cool temperatures
are expected mid-week...then readings will return to at or above normal
for late in the week and next weekend.

Short Tuesday
issued at 348 am CDT Monday Jul 6 2015

Fairly strong frontal system with increasing upper support will push across
the area today and tonight. In response to the upper level energy...
several waves are expected to ride newly along the front as it
crosses the region. Given the upper support...increasing moisture...and
waves riding along the boundary...this looks like it will be a sig
precipitation event. It/S been a little while since most areas had
substantial rains...and at this point it/S hard to pinpoint any
specific areas where heavy precipitation will focus. It/S likely we/ll need
some advisories for urban/minor flooding at some point later today.
It/S also not out of the question that a localized flash flood
sitn could develop...but without being able to delineate those
locations as of yet...will forego a watch and handle with the severe weather potential statement.

Even the details of the timing of the precipitation are elusive. Convection
got way ahead of where the models were forecasting it to be occurring
late yesterday evening...but now seems to have hit the wall. Expect
current rain band to make it into north-c WI this morning. Additional
development to the S could affect central WI by middle-late
morning...and even work into east-c WI. Those rains would be in
advance of the main rain band with the front...which is likely to
cross the area in the 18z-06z time frame. Very low confidence in
individual 1 hour pop forecast today...but confidence in 12 hour pop for
today with categoricals northwest 1/2 ranging down to chance in the far southeast
S...and an inverse of that for pretty high.

High clouds have already spread across the entire area. If breaks in
the clouds can develop...they would greatly increase the severe risk
this afternoon. But at this point that seems rather unlikely. Storm Prediction Center
maintained marginal risk across the entire area in their new day 1
convective outlook...and that seems right on target. Best chance for
severe may be from wet microbursts/localized damaging wind gusts.

Long term...Tuesday night through Sunday
issued at 348 am CDT Monday Jul 6 2015

The latest ensemble means continue to indicate flattened troughing
will persist through the end of the work week. But the ensembles
are now more aggressive building sub-tropical ridging into the
region by Friday and Saturday. This would put northern Wisconsin in
the so called ring of fire...or an area that is typically associated
with periods of showers and storms. The operational models show
this pattern...but have a large spread with moving shortwave energy
across the western Great Lakes during the weekend. Tough to have
much confidence in this sort of pattern. Regardless...will side
with the European model (ecmwf) through Friday and the extended initialization

Tuesday night through Wednesday night...high pressure will be moving
across the region Tuesday night and Wednesday. With clear skies and
light winds...will side with the coldest guidance for lows Tuesday
night. Some cold spots over north-c WI could see upper 30s for mins.
Highs on Wednesday mainly in the low to middle 70s. Will see an influx of
high clouds Wednesday night which should make for warmer temperatures.
Otherwise...still tranquil with lows in the 50s.

Rest of the forecast...yesterdays models were showing a weak
disturbance moving through on Thursday...but tonights runs have
waffled back to the dry side. Temperatures will start a warming trend back
into the middle to upper 70s. By Friday...a warm front will begin
surging northeast into the southwest Great Lakes. Though precipitation
will primarily reside south of region on Friday...better chances
will arrive by Friday night and continue right through the weekend.
Temperatures next weekend could be approaching 90 in many locales if
rainfall does not surpress temperatures. Best chance of rainfall appears
to be Sunday.

Aviation...for 12z taf issuance
issued at 348 am CDT Monday Jul 6 2015

Flight conditions will deteriorate today into tonight as thunderstorms and rain and lower
ceilings overspread the area. Will attempt to hit the most likely period
for thunder in the 12z tafs...though the actual period where
thunder is possible will probably be 12-18 hours at any point in the
forecast area.

Grb watches/warnings/advisories...
beach hazards statement from 10 am CDT this morning through this
evening for wiz022-040-050.


short term.....Skowronski
long term......mpc

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