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Area forecast discussion 
National Weather Service La Crosse WI
214 PM CST Friday Nov 27 2015

Short term...(tonight through Sunday night)
issued at 214 PM CST Friday Nov 27 2015

This weekend's forecast is brought to you by the letter "h" in
sprawling high pressure expected to slowly drift across the region
right on through Sunday. That feature is analyzed early this
afternoon nosing down through the Central Plains and extending east
toward the North Shore of Lake Superior...and will only very slowly
meander east this weekend...all as upper heights build in response
to the arrival of shortwave ridging aloft. That whole setup spells
just a really nice stretch of late November weather...with the slow
clearing trend today continuing tonight but giving way to plenty of
sunshine on Saturday...with perhaps some thicker middle level clouds
encroaching on the area later Sunday. As alluded to by the overnight
shift...have a suspicion that guidance is a touch too cool on
daytime highs given our lack of snow cover and plenty of unfrozen
ground at the moment...though still looking for readings to be
within a few degrees of "normal"...mainly into the 30s with maybe a
few spots pushing the lower 40s by Sunday. Overnight lows down into
the teens to low 20s look just fine with the ridge axis overhead
both tonight and again Saturday night.

Long term...(monday through friday)
issued at 214 PM CST Friday Nov 27 2015

A tricky system to start the work week...with at least some
potential for accumulating snowfall in spots. The current closed
low meandering over the southwest states/central Great Basin is
expected to get a nudge eastward as additional northern stream
energy cuts south of the Gulf of Alaska...helping dissolve the Rex
block over the western Continental U.S.. there remains pretty good agreement
among medium range guidance suggesting the upper low will pinwheel
eastward to a position pretty much over the Iowa/WI/IL border later
Tuesday...with a surface low lifting through the region Tuesday

From a pattern recognition standpoint...there should be a round of
precipitation crossing the area late Monday afternon into Monday
night...within a zone of modest warm advection ascent along a
developing trowal axis north of an approaching elevated warm front.
Moisture availability with this system actually looks pretty good
with some connection to the remnants of Sandra being drawn through
the Tennessee Valley...and a period of enhanced middle level difluence
helping broaden lift into Monday night. However...the biggest
question remains precipitation type. Have seen a trend the past 24
hours toward a bit more wound up system...suggesting more of a warm
nose may be drawn into the area - definitely not a good thing if
you're a snow fan given a lack of significant cold air already
intact ahead of this system.

Starting to get the feeling at least western Wisconsin is in for
nothing more than just a period of cold rain Monday night where the
warm nose is maximized up around 2-3c per forecast profiles and
surface temperatures should hold above freezing. Wouldn't be shocked to see
that warm nose shunted even farther west (as they typically
are)...suggesting more of a rain scenario even into parts of
southeast Minnesota and northeast Iowa...though likely with a small
area on the western fringe where we may remain cold enough to
maintain an all snow scenario. For the moment...the most likely area
for that to occur looks to be along and west of Highway 63...where
several inches of snow accumulation are certainly possible.

Passage of the upper low into Tuesday should drive enough cold air
to switch any remaining precipitation back over to snow for most
areas...but not so sure how much we will have left with weakening
middle level deformation forcing. Still Worth watching however as there
could be a sneaky inch or two in spots...most likely into Minnesota/Iowa

Thereafter...just not much to talk about as the flow aloft really
flattens out over the lower 48...allowing milder Pacific air to take
hold...all while high pressure slowly traverses much of the central
portions of the Continental U.S. Through Friday. After any remaining cloud
cover Wednesday...don't see much at all for clouds through Friday...
minus maybe a little passing cirrus. As such...expect temperatures to
rebound nicely through the 30s and 40s...with current blended
numbers likely too low given the setup...barring any snow cover on
the ground of course.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1139 am CST Friday Nov 27 2015

Main concern today is MVFR ceilings trapped under inversion with
cold air advection. Usual dilemma of how long will clouds persist
today but continue to slow clearing progress in forecast updates.
Some short term model hints that moisture remains there with
inversion but still think high building in should progress this
cloud deck far enough southeast to clear gradually today. We will
see so will continue to track short term updates and may need to
adjust back in time even still.

Once clouds clear...stretch of VFR weather expected through
weekend with light winds.


Arx watches/warnings/advisories...


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

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