Scientific Forecaster Discussion
fxus63 kgrb 152014
Area forecast discussion
National Weather Service Green Bay WI
314 PM CDT Mon Jul 15 2019
Forecast discussion for routine afternoon forecast issuance
Short term...tonight and Tuesday
issued at 313 PM CDT Mon Jul 15 2019
Thunderstorms remain the primary concern during this part of the
Once morning convection departed the area skies cleared at most
locations. This allowed for plenty of sunshine and
destabilization. MUCAPE values exceeded 3,000 j/kg, with little
or no cin, across parts of central and north-central Wisconsin by
midday. Convection began east of the Twin Cities early this
afternoon and rapid development also began in central and north-
central Wisconsin shortly after 1830z. MUCAPE values in excess of
2,000 j/kg continued to spread east according to local
mesoanalysis graphics. As of 19z Door County and the far northeast
corner of the state were the only locations with any significant
cin and MUCAPE values below 1,000 j/kg. Any leftover boundaries
from this morning, outflows from current convection, or Lake/Bay
induced boundaries could help to initiate additional convection.
Activity should decrease some with loss of daytime heating, but an
approaching cold front will help keep things going overnight.
Once the front clears the area on Tuesday there should at least be
a lull in the activity until a mid level short wave trough
approaching from the west brings a chance for more convection.
High dew points should keep temperatures from dropping much below
70 tonight. Another very warm day is in store for Tuesday, with
highs mainly in the upper half of the 80s.
Long term...Tuesday night through Monday
issued at 313 PM CDT Mon Jul 15 2019
Heat, humidity, and various opportunities for storms remain the
focus in the extended forecast.
Tuesday evening, a frontal boundary continues to hang around the
northern part of Wisconsin. This remains the focus for any ongoing
convection. MLCAPE values around 1500 to 2500 j/kg with bulk
shear of 20 to 30 knots would initially support some stronger or
possibly severe storms with damaging winds or large hail.
Torrential rain is also a concern with pwats up to around 2.0
inches. This is near the daily Max based on Storm Prediction Center sounding
climatology for mid-July. Instability wanes as the evening GOES
on, which would limit the severe potential, but some isolated
thunder and heavy rain would remain possible through the night.
Latest model runs are currently in some agreement that dry
conditions would exist for much of Wednesday, however have not
completely removed pops due to inconsistent model performance as
of late. Storms would return Wednesday evening and overnight as
the low level jet increases across western WI and a mid-level shortwave
approaches from the west. Heavy rain remains a concern with the
amount of moisture present.
Beyond Wednesday night, low confidence in timing of any
storms/pcpn. Flow turns more southwesterly as a broad ridge
builds across the southeast Continental U.S.. this makes it hard to get much
upper level support for convection, but with lingering surface
boundaries it's hard to rule anything out on any particular day.
Forecast continues to feature chance pops through Thursday, and
slight chances through the weekend.
Warm and humid air will remain in place through the week and
likely the upcoming weekend. Daily high temps are still progged to
reach the mid 80s to low 90s each day, unless held back a bit by
prolonged cloud cover or rain. Right now, Friday looks to be the
warmest day of the week, then trends show temps and humidity
levels slowly returning to seasonal mid- July numbers by early
next week, which means highs in the low 80s.
Aviation...for 18z taf issuance
issued at 103 PM CDT Mon Jul 15 2019
There was a mix of VFR and MVFR ceilings at midday, but a few showers
and a thunderstorm across parts of east-central Wisconsin were
diminishing as they moved east. Thunderstorms are the main concern
but timing and exact location remain uncertain. Think there will
be development this afternoon, especially in central and north-
central Wisconsin where MUCAPE values were at least 2,000 j/kg
with little or no convective inhibition. Even if nothing manages
to develop during the afternoon, an approaching cold front should
provide the focus for convection during the night. Some low level wind shear is
likely with winds of 35 to 40 knots from the southwest.