527 
fxus63 kgrb 181955 
afdgrb 


Area forecast discussion 
National Weather Service Green Bay WI 
255 PM CDT Friday Jul 18 2008 


Short term...main focus rest of this afternoon and evening is the 
precipitation potential with a weak boundary very slowly dropping south 
over the forecast area. At 1930z surface winds suggests the boundary extends 
from around isw to mtw. Isolated rain showers were developing along this 
boundary and will linger an isolated thunderstorms and rain/rain mention into the 
evening in this region. Do not expect this boundary to shift too 
much south due to a convective complex rotating into Iowa this 
afternoon and tonight. Radars to the west indicate a west to east 
band of rain showers may continue and affect the southern tier of counties at 
least through the evening and perhaps overnight. Will add scattered 
mention. 


Rest of the forecast area expected to remain dry with the lack of 
convergence and with the mostly clear skies anticipated and dewpoints 
in the 60s...fog development likely. On Saturday...will continue 
all day chance probability of precipitation for the south due to proximity to the 
boundary....but will confine any precipitation chances over the north half to 
the afternoon as warm air advection isent lift begins to affect the area. Typical 
with this pattern...foresee probability of precipitation needing adjustments for later 
periods as frontal positions become more evident. 


Long term...Sat night through next Thursday. Mdm range models in some 
agreement with a short wave trough over Montana this afternoon 
prognosticated to to work west toward the region toward Saturday night 
into Sunday. General isent lift Saturday night as warm air advection returns to 
the area. Models do divert on maximum rain potential due to location 
of surface boundary and deeper moisture as well as prognosticated surface 
low. Will continue high end chance probability of precipitation for Sat night into Sunday. 
Will attempt to put in a break in the precipitation for Sunday night with 
weak ridging ahead of the next short wave trough for Monday. Again 
will have higher end chance probability of precipitation with the upper height falls. Will 
shift toward a drier forecast after Tuesday with an upper ridge 
prognosticated to build into the Great Lakes region and surface high 
ridging from southern Canada. Confidence getting low with late 
next week as some trends back to a zonal flow. 


&& 


Aviation...VFR conditions will prevail this evening over the 
north half...but expect areas of LIFR visibilities/ceilings after 09z due to 
fog formation. For the south half...and especially south of a isw 
to mtw line...scattered MVFR ceilings/visibilities due to rain showers/thunderstorms and rain will linger 
into tonight. 
&& 


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


$$ 
Tdh/mg