Weather

900 
fxus63 karx 110804 
afdarx 


Area forecast discussion 
National Weather Service La Crosse WI 
304 am CDT Sat Oct 11 2008 


Short term...today through Monday night 


Main forecast concern is on temperatures next several days...then 
precipitation chances Sunday through Monday night. 


At 07z weak surface warm front resides just northwest of the 
forecast area...from southwest Minnesota into western Wisconsin. 
Infrared satellite imagery showing mainly high clouds across the 
forecast area with thicker cloud cover farther west across central 
and western Minnesota. 


11.00z models only show some minor differences in their solutions... 
with the NAM slighty faster beyond 48 hours with the surface cold 
front. No clear cut favorite so used a blend approach. Longwave 
trough digs into the southwest Continental U.S. Today with the closed 
circulation then lifting northeast into the northern rockies Sunday 
and into southern Canada by 12z Monday...then translates eastward 
toward the area pushing a surface cold front across the forecast 
area Monday. 


Upper ridging will remain in place across the region through Sunday 
as the forecast area remains on the warm side of the western 
trough. Continued low level warm/moisture advection will continue 
into Sunday. 850mb temperatures climb into the middle teens celsius 
for this afternoon and again on Sunday. BUFKIT soundings show 
atmosphere to mix to at least 875mb both days which will result in 
middle 70s to near 80 for afternoon highs in most locations. These 
should be tempered somewhat on Sunday by clouds so have went a few 
degrees cooler. Strongest moisture transport to remain well west of 
the area into Sunday...but by Sunday afternoon cold front pushes 
into western Minnesota. Convection ahead of it may reach the far 
western and northern area by late in the afternoon and have kept 
the low end probability of precipitation in these areas. 


As the middle level trough pushes east Sunday night and Monday... 
associated cold front will push toward and through the area on 
Monday. Moisture from the remnants of Norbert gets pulled northward 
ahead of boundary with models showing precipitable water values of 
1.5 inches Monday into Monday evening setting up a possible heavy 
rainfall scenario. 


Long term...Tuesday through Friday 


11.00z European model (ecmwf) and GFS differ somewhat in their solutions for this 
period. European model (ecmwf) continues its trend of lifting a second bundle of 
energy across the plains into the southern Great Lakes Wednesday.... 
while the GFS does not have this feature. Then later in the week the 
European model (ecmwf) shows a rather potent wave dropping out of Canada Thursday 
night...while the GFS is much weaker with this system. Will allow 
day shift to peruse the complete medium range data set for any 
needed changes. If the weakening European model (ecmwf) trend continues for the 
Tuesday system...probability of precipitation may have to be removed for this time frame. 
Temperatures look to be closer to seasonal normals for the middle 
part of October. 


&& 


Aviation...today and tonight 


Building high pressure aloft...warm air in the middle levels and a 
generally dry airmass over the middle/upper MS valley will result in 
good VFR conditions today...tonight and much of Sunday. Gradient 
will remain tight over the area through tonight as a wave of low 
pressure lifts northeast along the front/trough over eastern Nebraska 
through western Minnesota. Again expect south-southeast winds around 15kt 
g20-25kts in the 17z-23z time-frame...especially over the open and 
higher terrain areas /krst-kaum-ktob-kccy/. Parameters remain 
marginal for low level wind shear above klse through 14z...though winds 
increase to 30kts from the south at 3k feet mean sea level. 


&& 


Climate...Saturday night and Sunday night 


With southerly winds keeping the boundary layer well mixed and 
also bringing dew points close to 60 degrees...the minimum 
temperatures should remain rather warm overnight. Low temperatures 
are expected to range from the upper 50s to middle 60s both tonight and 
Sunday night. If this does indeed occur...we could break some warm 
minimum temperatures records. The following are the highest lows 
for La Crosse and Rochester for th next several days. 


La Crosse.....65 for October 12 and 68 for October 13. 
Rochester.....61 for October 12 and 60 for October 13. 


&& 


Arx watches/warnings/advisories... 
WI...none. 
Minnesota...none. 
Iowa...none. 
&& 


$$ 


Aviation - rrs 
short and long term - raberding 
climate - boyne/jlr