Area forecast discussion
National Weather Service La Crosse WI
641 PM CDT Sat may 25 2013
Short term...(this evening through sunday)
issued at 341 PM CDT Sat may 25 2013
At 3 PM...a dying mesoscale convective complex was located over
central Illinois. This system produced up to 4 inches of rain
across parts of story...Marshall...and Jasper counties in central
Iowa. Meanwhile northeast Iowa and Mower County in southeast
Minnesota...received up to a third of an inch /karx radar was
overestimating by up to 300 percent in some locations/. The rain
and clouds from this system kept temperatures in the lower and middle
50s in these areas which is very close to the record coldest
maximum temperatures for the date. The record cold maximum for the
date is 46 in 1992 for Austin Minnesota...48 in 1943 in Charles City
Iowa...and 53 in 1992 in Decorah Iowa. The Decorah record is the only
one that could possibly be broken or tied. Meanwhile areas north
of Interstate 94 saw a bit of sunshine and they were able to warm
into the middle 60s.
For tonight and Sunday...the main concern is the track of the
mesoscale convective complex over western North Dakota. Corfidi
vectors suggest that this system will move east across the Dakotas
this evening...and then it will move southeast across the eastern
third of South Dakota...southern and western Minnesota and northern
Iowa tonight. Overall...the 25.18z hrrr has the best handle on this
system and it has this system over southwest Minnesota by 26.06z.
With that speed...it should move into northeast Iowa and parts of
southeast Minnesota by 26... then linger across these areas
through much of Sunday morning. Ahead of this system...the
rap...GFS...NAM/WRF...and European model (ecmwf) show that scattered showers and
thunderstorms will develop north of a warm front from northwest
Iowa to southeast Iowa. This precipitation is associated with
moderate 925 to 850 mb moisture transport and 310k isentropic
lift.
Like today...expect the low clouds and precipitation to keep
temperatures in the middle and upper 50s across southeast
Minnesota...northeast Iowa...and southwest Wisconsin on Sunday.
Meanwhile some sun north of Interstate 94 will allow temperatures
to warm into the middle 60s.
Long term...(sunday night through saturday)
issued at 341 PM CDT Sat may 25 2013
On Sunday night and Monday...the warm front will move into north
southwest Iowa. Weak to moderate 925 and 850 mb moisture transport
will result in the development of showers and thunderstorms north
of the warm front from north central Iowa southeast into southeast
Iowa. The GFS...ECMWF...and Gem suggest that a mesoscale
convective complex will develop across eastern South Dakota late
Sunday night...and the dying system moves east through our area
Monday.
From Monday night into Tuesday...the models are continuing to
struggle with the location of the warm front. The NAM/WRF stalls
the warm front near the Minnesota and Iowa border. This makes a
lot of sense if a lot of convection develops north of this front
and its cold pool prevents this warm front moving any further
north. Meanwhile the GFS and European model (ecmwf) would synoptically favor that
the warm front would move northward through the area. However the
cap in the warm sector remains southwest of the forecast
area...thus there would be the potential for a series of mesoscale
convective systems to move through the area. So in either
scenario...it looks like the forecast area will remain wet. With
precipitable water values around 1.5 inches and warm cloud layer
depths up to 4km...there will be the potential for heavy rain from
any showers and thunderstorms that develop. In addition...will
have to watch for the potential of severe weather...but this is
highly dependent upon the location of the warm front.
From Tuesday night into Saturday...it continues to look like a
series of short wave troughs will move through the region. However
the timing of these waves is uncertain...thus kept precipitation
chances in the 40 to 60 percent range through this time period.
&&
Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 641 PM CDT Sat may 25 2013
Prevailing southeasterly flow will keep feed of of drier air in
place through the evening and overnight...allowing ceilings to
remain VFR krst/klse. As showers and thunderstorms erupt across the
Dakotas...this should form into an organized system and move
toward the region. There remains some uncertainty where this will
exactly track...but the favored areas are west central Minnesota
to central Iowa. This could possibly clip krst with some showers
in the early morning hours...lasting until late morning. Ceilings
will likely start off as VFR once showers commence...but then drop
to MVFR after a few hours. At klse...confidence in a dry forecast
is higher so have kept VFR conditions through most of the period.
Finally...confidence for Sunday afternoon lowers at both taf
sites...as there could be showers around...but again the higher
chances for a longer period of precipitation is south and west of
the taf sites so have kept forecast dry at this point.
&&
Arx watches/warnings/advisories...
WI...none.
Minnesota...none.
Iowa...none.
&&
$$
Short term...boyne
long term...boyne
aviation...zt
