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Area forecast discussion 
National Weather Service La Crosse WI
548 PM CST Monday Nov 30 2015

Short term...(this evening through wednesday)
issued at 307 PM CST Monday Nov 30 2015

Still quite the challenging forecast heading into the evening and
overnight hours from a precipitation type standpoint...which
unfortunately will play into just how much snow falls in any given
area. As well discussed the past several days...the best risk for
significant accumulating snow remains over the western/far northern
County Warning Area while other spots south and east of there deal with an
encroaching warm nose. That feature is plainly evident on the 12z
quadrant cities radiosonde observation...with a nose of about +4c centered on 800mb. As is
usual in these developing negative tilt/trowal feature setups...
guidance continues to underplay the warm nose...with even the most
recent runs of the rap failing to capture the true degree of that
feature. We're only talking 1-2c of difference...but that makes a
huge difference when it comes to precipitation type across the County Warning Area tonight.

So...what's most likely to happen? Approach of the upper low and a
sharp uptick in middle level difluence/low level warm advection ascent
will swing another band or two of precipitation through the area from late
this afternoon through tonight...increasingly chased northward by
the approach of a pronounced middle level dry slot. As expected the
past few days...suspect this precipitation will largely fall as a cold rain
over the southeast half of the County Warning Area...perhaps mixed with some sleet
at times with enough of a cold dome around -2c below 850mb but with
surface temperatures above freezing mitigating any big impacts. Farther
north...say roughly north and west of a Neillsville WI to Winona Minnesota
to Dodge Center Iowa line...looking for more of a messy mix...with maximum
temperatures aloft ranging from about 1.5c to as low as -1c...with the
highest confidence for snow across the far west. Some convective
component to the precipitation may also throw a wrench into the
situation with hints of steep lapse rates crossing the area for a
time on the leading edge of the dry slot. All told...still expecting
another 1 to 4 inches of sloppy wet snow to fall where advisories
remain in place overnight with only a narrow dgz and quite "warm"
thermal profile.

Still have to wonder if there could be a narrow window on the
leading edge of the dry slot where enough cold air quickly wraps
back in to given a brief burst of snow to areas farther east.
However...we should trend quickly toward maybe a little drizzle or
even no precipitation at all within the dry slot with a lack of any ice in
the cloud but saturation hanging around up to 700mb before crashing
below 850mb over at least the southeast half of the County Warning Area. Then as
colder air continues to wrap in along with deeper moisture as the
closed low drifts overhead...we should see a batch of light snow
filter back in from the southwest...though really wonder if northern
areas see nothing much at all through the day given how wrapped up
the system is with the dry slow wrapping north along the I-94
corridor. A few batches of light lingering snow or flurries should
work back through the region right on through Tuesday night and
probably even Wednesday morning...with a trend toward much more
cloud cover sticking around through Wednesday as the upper low
slowly departs.

Long term...(wednesday night through monday)
issued at 307 PM CST Monday Nov 30 2015

A well-deserved break for US forecasters into late week and next
weekend...with some downright awesome weather for early December
expected across the region. Medium range guidance remains in
steadfast agreement with a return to building heights over the
plains/middle Continental U.S. Through late advance of the next piece of
shortwave energy working through the western states. That feature
may make a run at our area sometime later in the weekend or early
next week...but with a notable lack of moisture through the period
as the Gulf effectively remains closed. In the low levels...a broad
ridge of high pressure looks to very slowly traverse the entire
region right on through the weekend...setting up broadening return
flow toward Friday and especially Saturday.

Given the pattern setup...having a hard time finding any reason to
have any cloud cover in the forecast...with just some fantastic late
Fall weather as daily high temperatures gradually rebound through
the 30s and likely into the 40s for snow-free areas by Friday and
Saturday...and probably into Sunday as well. Overnight lows may
initially be on the chilly side where snow cover resides...but
should otherwise hold well above normal by the weekend with
southerly flow in place. About the only possible "fly in the
ointment" would be any pesky fog or stratus development overnight by
the weekend as we melt snow over western areas...but obviously
confidence this far out is very low.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 548 PM CST Monday Nov 30 2015

A wintry mix will continue at both taf sites this evening and into
the overnight hours...finally lifting to the north by early
Tuesday morning. Ceilings will drop into the IFR category with
generally MVFR visibility. Light easterly winds will gradually
shift to the south through the period. Should see some improvement
in ceilings/visibility Tuesday morning before another chance for
light snow at both taf airfields Tuesday afternoon. Given the
complexity of this system...multiple taf updates are possible
before the next regular forecast issuance.


Arx watches/warnings/advisories...
WI...Winter Weather Advisory until midnight CST Tuesday night for

Minnesota...Winter Weather Advisory until midnight CST Tuesday night for

Iowa...Winter Weather Advisory until midnight CST Tuesday night for



Short term...Lawrence
long term...Lawrence

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