Area Forecast Discussion Issued by NWS Green Bay, WI
000
FXUS63 KGRB 130821
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
321 AM CDT Wed Mar 13 2024
Forecast discussion for routine morning forecast issuance
.KEY MESSAGES...
- Precipitation chances arrive this evening and last through
Thursday night. Precip likely to start as rain, then transition
to a mix of rain and snow or wet snow Thursday night. The best
chance for precipitation will be across central and east-central
Wisconsin.
- Temperatures begin a slight downward trend Thursday while still
remaining around 5 to 10 degrees above average through Saturday.
More seasonal temperatures expected Sunday and Monday.
- A system dropping south out of Canada Saturday will bring
another chance for rain transitioning to snow this weekend.
&&
.DISCUSSION...
Issued at 321 AM CDT Wed Mar 13 2024
Short Term...Today...Tonight...and Thursday
Mostly sunny skies are expected this morning as zonal upper level
flow continues across the western Great Lakes region. Clouds will
increase this afternoon as the cold front that passed through
yesterday lifts north as a warm front over the southern Great
Lakes region today. Dry weather is expected today as highs are
cooler than yesterday, but still expected to be well above normal
for this time of year. Highs this afternoon are expected to range
from the upper 50s across the far north, to the lower 60s along
and west of the Fox Valley and near 50 along the Lake Michigan
shoreline.
Precipitation chances will increase from south to north tonight as
a shortwave rides north of the surface front along with mid level
frontogenesis and isentropic lift. Precipitation is then slated to
continue on Thursday as additional shortwaves track through
central Wisconsin with continued isentropic lift and frontogenesis
at 700 and 850 mb. The main question is how far north the
precipitation will make it given the dry air in place across the
western Great Lakes region. The NAM is the most aggressive and
farthest north of all of the models, while the Canadian keeps the
region relatively dry for the duration of the event. Given the
dynamics in place the dry Canadian does not seem appropriate nor
does the aggressive NAM given the dry air feeding in from the
northeast. Therefore, will lean on the NBM POPs given these
factors with a chance for the far north to stay dry and the best
chance for precipitation across central and east-central Wisconsin
under the aforementioned dynamics. Although model soundings
indicate some snow could mix in at times, the predominant
precipitation type is expected to be rain as boundary layer
temperatures will be fairly warm during the event. If
precipitation does make it farther north, there will be a higher
chance for snow to mix in across that area, particularly tonight.
Lows tonight are expected to range from around 30 across the
north, to the middle 30s across central and east-central
Wisconsin. Highs on Thursday are expected to range from the lower
40s near the lakeshore, to the middle to upper 40s inland.
Long Term...Thursday Night Through Tuesday
Focus of the extended period continues to be a shift to a cooler
and more wet pattern. A wintry mix will come to an end Friday
morning north to south, but dry conditions are not expected to
remain long as a system driving south out of Canada brings another
chance for rain and snow this weekend into early next week.
Precipitation...With diurnal cooling Thursday night into Friday
morning rain is expected to transition to snow across much of
central WI on the back side of a departing low pressure system.
As upper and mid-level dry air wrap in behind this system the
precipitation is expected to end from north to south early Friday
morning. Snow accumulations are expected to be minimal with the
highest chances for over 1" (10-15%) being across central and
east-central WI. A brief period of upper level ridging is expected
to keep the remained of Friday dry. Ensemble guidance is in good
general agreement regarding an upper-level trough and associated
low pressure system dropping south out of central Canada Saturday.
The initial cold front and upper-level jet energy will likely
bring a period of rain for much of the CWA Saturday afternoon,
with only far northern WI seeing much in the way of snow chances.
More widespread snow chances may then come Sunday as a CAA regime
sets up and a trailing cold front and second wave of jet energy
drop southward across the region. There is still a lot of
uncertainty with what snow accumulations may be, but probabilistic
guidance is showing a 40-60% for over 1" across northern WI
Sunday. Locally higher amounts may be possible in Vilas County
with periods of lake effect snow possible Sunday into Monday as
the CAA increases surface to 850mb delta Ts and favorable
northwest winds set up. As this system moves off to the east high
pressure is forecast to build back over the region for the middle
of next week returning dry conditions to the area.
Temperatures...With increased cloud cover and north winds backing
westerly temperatures Friday and Saturday look cooler than what
the area has seen over recent days, but still about 10-15 degrees
warmer than normal with highs in the mid 40s to low 50s. Behind
the cold front temperatures for Sunday and Monday look more
seasonal with highs dropping back into the upper 20s to near 40
degrees. However, doesn`t look like those seasonal temperatues
will last long with another warming trend likely during the middle
of next week.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 726 PM CDT Tue Mar 12 2024
VFR conditions are expected for the TAF period. Wind gusts will
diminish early in the period, keeping light winds in the region
through tomorrow morning.
&&
.FIRE WEATHER...
Issued at 321 AM CDT Wed Mar 13 2024
Cooler temperatures and lighter sustained winds under 10 kts will
alleviate fire weather concerns some today, but afternoon minimum
humidities will again fall to the 20 to 30 pct range west of the
Fox Valley and Bayshore areas. Fine fuels continue to dry out as
evident by increasing FFMC values to around 90. Will continue to
highlight fire weather conditions in the HWO. Cooler temperatures
and precipitation on Thursday will provide a break in the warm and
dry conditions across the area.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION.....Kurimski/GK
AVIATION.......Uhlmann
FIRE WEATHER...Kurimski