063 
fxus63 kmkx 072024 
afdmkx 


Area forecast discussion 
National Weather Service Milwaukee/Sullivan WI 
324 PM CDT sun Sep 7 2008 


Scattered showers and thunderstorms firing ahead of surface cold front 
that extends from near Ashland...through msp to near Spencer Iowa. 
More widespread convection along front over northern WI in area of 
better surface instability (-2c to -4c) aided by differential cva 
from 500 mb vorticity maximum. Second band that developed along front 
in north cnrtl Iowa/S central Minnesota ahead of 110kt 300 mb jet streak marked 
by enhanced band of clouds over S Dakota on infrared satellite loops. 


Tonight...surface trough will Cross County warning area this evening...exiting 
the southeast corner by 06z. With frontal passage occurring after sunset chances 
for precipitation will diminish ahead of the front. Will keep isolated 
thunder in western County Warning Area for early evening as frontogenetic forcing in 
low and middle layers and lingering meager Cape May still trigger an 
isolated thunderstorm...and only slght chance of a shower in the 
east with all precipitation out by 06z. With cloudiness over region offsetting 
cold air advection some...tweaked warmer mav guidance numbers up a bit. 


Monday...models still on track with stronger shortwave moving 
through upper lakes. Current infrared loops of jet streak clouds show a northward 
shift to the jet...forecast by the models...that will place County Warning Area 
in right rear quadrant of jet maximum by 18z Monday. New 18z NAM in line 
with 12z GFS through 00z Tuesday with strength and track of surface low. 
Sloped frontogenetic forcing and precipitable waters  of 1 to 1.5 inches still 
available though a bit of shift to the southeast with the higher 
precipitable waters  from earlier runs. Still worthy of categorical probability of precipitation. 


Rain exits by Tuesday morning...with cool +3 to +5c 850 temperatures 
bringing hi temperatures in the middle 60s and lows Tuesday night into the low to 
middle 40s. Warm air advection ahead of next wave begins on Wednesday...with highs 
returning to the low 70s in the west. 


Long term...high chance probability of precipitation with next deep 500 mb wave as it moves 
through region Thursday/Thursday night. European model (ecmwf) and GFS part ways 
after this wave with 500mb features so trended with blended solution 
of HPC which leans toward more progressive European model (ecmwf). This keeps 
Friday dry...with the next chance of precipitation on Saturday...with a 
lingering chance Sunday. 




&& 


Aviation...frontal boundary over western Wisconsin to move across 
region tonight and exit area by 12z Monday. Although dynamics decent 
with this boundary...moisture is marginal so will stay with VFR 
conditions through forecast period. Expect scattered convection due 
to destabilizing airmass with bulk of convection along and north 
of a kmke to kmsn line and lesser chance of convection near kenw. 
Due to nature of scattered convection will opt to wait until 
development before introducing timing at Airport sites. West 
surface winds around 10 knots will become around 5 knots or less 
by midnight as baggy surface features follow frontal passage. 


&& 


Marine...northeast winds and waves may reach Small Craft Advisory 
conditions Monday night into Tuesday as strengthening low pressure 
develops along baroclinic zone and tracks from eastern Illinois into 
lower Michigan. 




&& 


Mkx watches/warnings/advisories... 
WI...none. 
Lm...none. 
&& 


$$ 


Short/long term...09 
aviation/marine...17