Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

FXUS63 KGRB 110908

Area Forecast Discussion
National Weather Service Green Bay WI
408 AM CDT Sun Mar 11 2018

Forecast discussion for routine morning forecast issuance

Issued at 405 AM CDT Sun Mar 11 2018

Relatively quiet March weather to continue through most of the
upcoming week.

Amplification of the upper pattern is underway. Amplitude should
peak mid-week with strong troughs near 140W and 80W and a sharp
ridge around 110W. A slow progression of the features is expected
thereafter. The eastern trough will lift out into Canada, and the
ridge will flatten considerably as it shifts east. The western
trough will maintain its intensity better, likely reinforced with
additional shortwave energy at times.

The ongoing reamplification of the eastern trough will drive a
shot of colder air into the area early in the week, but the
downturn in temps will be moderated by higher mid-March sun angle
(compared with a month or two ago), a lack of substantial snow
accompanying the colder air into the area, and dwindling
snowcover over the southern part of the forecast area.
Temperatures will rebound for the latter half of the work week and
next weekend as the weakening upper ridge crosses the area.
Precipitation will be scattered/light for most of the period,
though the prospect for significant precipitation will increase
once the ridge shifts east and southwest upper flow develops late
in the period or beyond.

.SHORT TERM...Today...Tonight...and Monday
Issued at 405 AM CDT Sun Mar 11 2018

Continued generally quiet weather, but with a few more details to
sort out this morning.

Clouds slowly advancing across the area from the west were
resulting in a substantial temperature gradient across the area
this morning. At 08Z temps ranged from 28F at ISW to 1F at LNL.
Those areas that cloud over before daybreak will see temps warm
considerably. But the clouds aren`t going to reach the far east,
so that area will get off to a colder start. Precipitation (mainly
in the form of very light snow and some drizzle/freezing drizzle
will remain west of the area this morning.

An upper level speed max and mid-level shortwave digging southeast
from Canada may produce enough forcing to generate light
precipitation across the north this afternoon, and across the
north and east this evening. Precipitation type will primarily
depend on boundary layer temperature, so some liquid precip is
possible until evening. A secondary, smaller piece of energy will
wrap around the western flank of the digging trough Monday.
Combined with steepening low-level lapse rates during the
afternoon, that may lead to some light rain or snow showers, again
depending on boundary layer temperatures at the time.

Clouds and increasing winds tonight will not be favorable for
significant radiational cooling, so stayed close to a blend of top
performing guidance products for lows tonight as well as for
highs today and Monday.

.LONG TERM...Monday Night Through Saturday
Issued at 405 AM CDT Sun Mar 11 2018

500mb ridge across the western United States with downstream
closed upper low over the Great Lakes is expected at the beginning
of the forecast period. The ridge is expected to flatten while the
closed low opens up and moves east by the end of the work week.

Cyclonic flow expected Monday night with a weak upper level
disturbance moving across the western Great Lakes. Added or
increased chances of snow showers or flurries across the entire
area Monday night. The flurries should come to an end across
central Wisconsin towards daybreak. On Tuesday, the cold cyclonic
flow should lead to a chance of snow showers or flurries across
the north and across northeast Wisconsin before drier air moves
into the region by afternoon. Probably more notable is the
expected high temperatures on Tuesday. The latest EC numerical
guidance and the Canadian model surface temperatures are
considerably cooler than the mex guidance. Have lowered high
temperatures from the previous forecast on Tuesday which is now
considerably cooler than the mex guidance but not as cold as the
EC guidance and the Canadian surface temperatures.

High pressure dominates the weather pattern Tuesday night and
Wednesday. Some locations across the northwoods will drop into the
single digits above zero for low followed by afternoon highs
in the lower 40s. The diurnal range will be not as great across
the Fox Valley and lakeshore region.

The forecast wanes quickly Friday into the next weekend with the
next system. The EC/Canadian models were dry on the model run
tonight for Friday and that would have been my preferred
solutions. For now, removed the chances for precipitation across
the north to match up with Marquette and kept the small chances
across the south. No changes made to the Saturday forecast due to
the low confidence in the details of the forecast which should
move into the area by then.

.AVIATION...for 12Z TAF Issuance
Issued at 405 AM CDT Sun Mar 11 2018

Clouds with VFR bases will overspread the area today. Expect
ceilings to lower to MVFR from west to east during the afternoon
and evening. The top performing aviation guidance products were in
good agreement on this, and it seems reasonable. The departure
from guidance in the TAFs will be to hold with MVFR cloud bases
until skycon decreases, rather than bring bases up late tonight as
forecast by the majority of the guidance.



SHORT TERM.....Skowronski
LONG TERM......Eckberg
AVIATION.......Skowronski is the U.S. government's official web portal to all federal, state and local government web resources and services.