Area Forecast Discussion
Issued by NWS La Crosse, WI

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FXUS63 KARX 201904
AFDARX

Area Forecast Discussion
National Weather Service La Crosse WI
200 PM CDT Mon Mar 20 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 200 PM CDT Mon Mar 20 2017

Weak west-east running mid level frontogenetic boundary sinking
southeast across WI this afternoon, leading to some returns on the
radar but little if any ground truth via sfc obs. Meso models trends
quickly weaken the forcing, thus diminish any potential pcpn, by
00z. Won`t carry any small pcpn chances past late afternoon as a
result.

A weak ripple in the upper level flow will slip southeast from the
northern plains to across ia/il on Tue. Weak mid level frontogenetic
forcing/warming will help this system trigger a thin line of
showers. Current track/trends favoring keeping any threat well south
of the area at this time.

Its going to be cooler the next few days as colder low level air
flows southward behind that departing front from today. Temps should
return to (or be a bit cooler than) the seasonable normals.

.LONG TERM...(Thursday through Monday)
Issued at 200 PM CDT Mon Mar 20 2017

GFS/EC remain consistent with their wet pattern heading into the
weekend, a bit more in step with each other in placement/timing of
the upper level trough/sfc low expected to impact the region Thu-
Sat.

500 mb trough slated to move east from the southern CA coast into
the southern plains by 00z Sat, then lifting northeast across the oh
river valley for the weekend. A fetch of relatively warm/moist air
will lead this system into the local area, with the low level
thermodynamics and west-east running frontogenetic forcing likely
resulting in bands of rain starting thu afternoon. Both the GFS and
EC take the associated sfc low into central IL by 00z sun, keeping
the local area on the north side, deformation region. Likely get
some aid in the lift Fri from the right entrance region of a 300 mb
jet streak moving across the Upper Mississippi River valley.
Precipitation remains likely from late Thu through Sat.

Airmass looks rather juicy for late March with NAEFS pw anomalies
now up to +2 to +3 for the period. GEFS qpf plumes suggest around an
inch on average, but show a good amount of spread (mostly due to
differences in shifting the main band north or south). 1 to 2 inches
looks reasonable.

All said, still some potential for a shift in the system north or
south, impacting more the amounts moreso then if there is a rain or
not.

As for precipitation type, keep talking about rain as the sfc/near
temps are progged to be warm. In addition, some potential for loss
of ice in cloud from time to time over that 2-3 day period, keeping
pcpn type as liquid also. Can`t rule out a shot for a rain/snow mix
if the pcpn moves in earlier on Thu, with some snow (freezing pcpn?)
possible on the backside of the exiting system Saturday. Overall
though, it should be rain.

Another west coast trough slated to move east and bring more rain to
the area Mon-Tue. Some differences in positioning/timing, but both
the GFS/EC suggest some wet conditions to start the new work week.
Quicker moving system, and not as strong of a low level moisture
surge, so qpf is less.

Overall, getting into a wetter pattern starting Thu, and with much
of the rainfall likely making its way in the area waterways, expect
some impacts to the local river systems. In bank rises for sure, but
can`t rule out some flooding concerns. Something to watch.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1220 PM CDT Mon Mar 20 2017

VFR conditions expected through the period as dry Canadian surface
high pressure gradually builds southward from Canada. Northerly
winds of 5-15 kts will diminish tonight before increasing to 10-15
kts by late morning Tuesday. Only some mid/high cloud cover is
expected at times through the period.

&&

.FIRE WEATHER...Today through Wednesday
Issued at 254 AM CDT Mon Mar 20 2017

Dry Canadian high pressure builds into the region late today into
tonight and remains over the region through Wednesday. Red Flag
weather conditions are not expected due to lighter winds.

This afternoon look for relative humidity values to drop into the 25
to 35 percent range across portions of central into northern
Wisconsin. Plan on north winds of 10 to 14 mph today.

Tuesday will be another dry day across the area with afternoon
relative humidity values falling into the 25 to 35 percent range
along and east of the Mississippi River. Winds on Tuesday will be
out of the north/northwest at 10 to 15 mph.

Wednesday is expected to be the driest day when afternoon
relative humidity values look to drop into the 20 to 25 percent
range along and east of the Mississippi River. Central and
northern Wisconsin could see values fall into the teens. The good
news is that winds will be light out of the east/southeast at 5
to 10 mph. Precipitation chances return late Wednesday night into
Thursday and higher humidity values will move back into the
region.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM.....Rieck
LONG TERM......Rieck
AVIATION.......JM
FIRE WEATHER...Wetenkamp


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