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Area forecast discussion 
National Weather Service Green Bay WI
1202 PM CDT sun Mar 29 2015

Updated aviation portion for 18z taf issuance

Short Monday
issued at 422 am CDT sun Mar 29 2015

The left exit region of an upper jet streak combined with low
level warm advection and convergence was producing an area of rain
mixed with snow across eastern Minnesota at 09z. It should move
fast across the forecast area with the primary area of precipitation
east of here by midday. The air is very dry ahead of this system
so precipitation amounts will be modest. Precipitation type is
tricky. Forecast soundings suggest that mostly wet snow will fall
across the north with a mixture of snow...sleet and rain further
south. Middle level lapse rates are somewhat unstable so some
elevated thunder is not out of the question. Whatever wet snow is
able to fall should melt this afternoon as temperatures climb to
near 40 in most areas. Gusty surface winds expected along and
behind the area of precipitation.

Sprinkles or flurries possible in northcentral parts of the area
during the early evening hours then there should be clearing. Lows
will be fairly mild due to a steady wind and lack of cold air
behind this front. Another upper jet will approach the area from
the northern plains Monday afternoon. The best upper support is to
our southwest but it might be able to produce some light rain or
sprinkles. Highs will be pretty close to normal for this time of
the year.

Long term...Monday night through Saturday
issued at 422 am CDT sun Mar 29 2015

There were still location issues among the 00z models with the
system that is forecast to move southeast across the western Great
Lakes region Monday through Monday night. The NAM and GFS remained
similar to each other and to previous versions...while the European model (ecmwf)
and Gem-New Hampshire were generally farther southwest with the quantitative precipitation forecast and
showed more differences from their previous runs. For this reason
the NAM/GFS solution was followed more closely...along with HPC
guidance. This placed the highest quantitative precipitation forecast values along the
Wisconsin/Upper Michigan border. Have some likely probability of precipitation along the
border but there is at least some uncertainty due to model
differences. Rain will take a little while to change to snow as
boundary layer temperatures drop. Have an inch or two of
accumulation in far northeast Wisconsin.

A more potent looking system is expected to move into the region
from the west and bring showers to the forecast area starting on
Wednesday. Temperatures are expected to be warm enough to keep
precipitation in liquid form.

There was not quite as much of a difference between the GFS and ec
later in the week than there was in the recent past. However...the
GFS was more progressive a cold front pushing southeast after
exiting Wisconsin...while the ec showed a surface low from the
Southern Plains moving along the front and into the region. The
GFS solution would have quantitative precipitation forecast out of southeast of Wisconsin while
the ec solution had quantitative precipitation forecast remaining in east central Wisconsin
thought at least Thursday evening.

Aviation...for 18z taf issuance
issued at 1158 am CDT sun Mar 29 2015

Continued MVFR and IFR ceilings and precipitation are expected through
this afternoon and early evening as a frontal system swings
through the area. Any linger freezing precipitation should come to
end early this afternoon...with snow and freezing rain continuing
the longest in northern Wisconsin. After The Rounds of precipitation come
to an end...much better flying weather is expected as rain ends
and clouds scatter out then clear overnight. Gusty south winds
this afternoon will continue before veer west behind the front
early this evening...then diminish overnight. Monday should be
much nicer with mostly sunny skies and warmer temperatures...with
lighter west to northwest winds.


Grb watches/warnings/advisories...


Short term.....Rdm

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