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afdgrb

Area forecast discussion
National Weather Service Green Bay WI
1019 PM CDT Wed Oct 16 2019

Updated aviation portion for 06z taf issuance

Synopsis...
issued at 237 PM CDT Wed Oct 16 2019

Less windy and a little cooler tomorrow, then temperatures
returning to modestly above normal for the upcoming weekend.

A pretty typical energetic mid-autumn upper pattern is in place
across North America. The pattern will remain slowly progressive
into next week. Temperatures will undergo modest variations with
the passage of individual weather systems, but are unlikely to
have any prolonged significant departures from normal. The pattern
is likely to support at or above normal precipitation amounts.
&&

Short term...tonight and Thursday
issued at 237 PM CDT Wed Oct 16 2019

Strong north winds on the western side of the departing cyclone
generated numerous gusts at or above 40 kts across Door County today,
resulting in some power outages. Winds aloft will slowly diminish
late this afternoon and this evening, but cold air flowing across
the warm waters of the Bay of Green Bay will continue to
destabilize low-levels, so winds will remain gusty. The current
00z expiration times for the Wind Advisory and Gale Warning still
look on track. Otherwise, the flow across Lake Superior is likely
to continue to result in mostly cloudy conditions across the area.
Sprinkles will linger in the east through late afternoon. Stayed
close to a blend of recent top performing guidance products for
low temperatures.

A sharp low-level ridge will be across the area tomorrow. That
will result in more sunshine than today, but temperatures will
probably be a little cooler. The most noticeable difference will
be much lighter winds.

Long term...Thursday night through Wednesday
issued at 237 PM CDT Wed Oct 16 2019

Models show an amplified, but progressive pattern to persist
across the Continental U.S. Well into next week. A series of mid-level
shortwave troughs and cold fronts are expected to March through
the Continental U.S. On a regular basis and bring a chance of precipitation
to northeast WI just about every other day. The wettest system is
forecast to hit WI late Sunday night through Monday night as Gulf
moisture to be plentiful and the particular shortwave trough to be
the strongest. While temperatures go above normal through Monday,
readings drop below normal headed toward the middle of next week.
We will have to watch precipitation type issues across the north
behind the main system Monday night.

The surface ridge axis slides to the east Thursday night, allowing
for a return flow to develop across WI. Skies will be mostly clear
through the evening, however as warm air advection begins to overspread the
region, look for high clouds to begin moving in as well during the
overnight hours. Min temperatures to drop into the upper 20s to
lower 30s north, middle to upper 30s south. The pressure gradient
is expected to tighten across the area on Friday between the
retreating high pressure over the eastern Great Lakes and a pair
of low pressure areas over south-central Canada and Southern
Plains. South-southeast winds could gust in the 20-30 mph range by
the afternoon. A mix of clouds and sun with decent mixing to
around 850mb, should provide a boost to temperatures with readings
in the middle 50s along lake mi, upper 50s to lower 60s for inland
locations.

The approach of a Pacific cold front and trailing mid-level
shortwave trough will bring northeast WI its next chance for rain
showers late Friday night. Gulf moisture to be lacking initially,
thus any rainfall would be on the light side. Thickening clouds
with a persistent south wind of 5-15 mph, should provide for a
much more mild night temperature-wise. Look for readings to mainly
be in the middle to upper 40s. This cold front quickly pushes
across WI on Saturday with a narrow band of rain showers to
accompany the front. Highest pops to be placed across central WI
in the morning and eastern WI in the afternoon. Rain chances
should come to an end across central WI with some mixed sunshine
in the afternoon as drier air starts to advect into the area. Max
temperatures to range from the middle 50s to around 60 degrees.

A weak area of high pressure drifts into the western Great Lakes
region Saturday night, allowing for clearing skies and a light/
variable wind. Quiet conditions are forecast for Sunday as the
high pressure pushes east and the next system of interest to be
situated over northern/Central Plains. Anticipate some clouds to
gradually increase later on Sunday with Max temperatures in the
middle to upper 50s near lake mi, upper 50s to lower 60s inland.
This system, in the form of a cold front and a nearly vertically-
stacked area of low pressure, will begin to influence northeast WI
primarily after midnight Sunday night. Despite a lack of
instability, more than sufficient shear to arrive to bring at
least a minimal chance of thunder to the region. While the
surface/upper low track northeast from Minnesota toward Western Lake
Superior on Monday, the cold front will move east into WI. There
are timing issues with regards to the cold front and how far east
the front will get by 00z Tuesday. While this is a nuisance, it
does not stop the likelihood of seeing rain showers across
northeast WI, along with a chance of thunderstorms with minor
instability (mucapes < 500 j/kg) and 0-6km bulk shear of 50-70
knots. Some of this precipitation may be locally heavy as precipitable water
values surpass 1.0". Max temperatures Monday to be in the lower to
middle 50s central WI, middle 50s to around 60 degrees eastern WI.

Cyclonic flow to keep at least a chance of rain showers in the
forecast Monday night. It appears that temperatures would remain
warm enough to keep the precipitation as all rain through the
night. The rain chances could even linger through at least Tuesday
morning until the cyclonic flow weakens. Otherwise, a good amount
of clouds are expected on Tuesday with Max temperatures only
reaching the middle to upper 40s north, upper 40s to lower 50s
south.

Northeast WI to get a brief respite from the precipitation chances
Tuesday night before questions arise as to the timing of the next
system (wednesday or thursday). Have little confidence on any
particular model at this point, but may place a minimal pop across
the forecast area for now. Max temperatures on Wednesday appear to
be similar to Tuesday which would be a touch below normal.
&&

Aviation...for 06z taf issuance
issued at 1019 PM CDT Wed Oct 16 2019

Continued cyclonic flow across the area along with some low to
mid level moisture will lead to continued cloudy skies through
Thursday morning. Ceilings will likely continue to linger in the
low end VFR to high end MVFR range through this time period before
steady improving conditions occur by Thursday afternoon. The lower
ceilings will linger longest near the rhi taf site, where
upslope/lake effect clouds will be in place. Winds will steadily
decrease tonight as the pressure gradient weakens and mixing
decreases. Much better flying conditions can then be expected
Thursday afternoon through the rest of the work week.
&&

Grb watches/warnings/advisories...
none.
&&

$$

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