Area Forecast Discussion
Issued by NWS Twin Cities, MN

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024
FXUS63 KMPX 241024
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
424 AM CST Sat Feb 24 2018

.SHORT TERM...(Today and tonight)
Issued at 422 AM CST Sat Feb 24 2018

Early morning water vapor imagery reveals the upper trough is moving
east over the four corners region as of 09Z.  The latest surface
analysis indicates surface cyclogenesis occurring near the
Colorado/New Mexico border.  Closer to home, we`re still under high
pressure early this morning with much of the area under a dense fog
advisory through 15Z.  We do recommend you exercise caution on the
roadways this morning, as fog at these cold temperatures may produce
slick conditions on area roads.

The forecast for the snow later today remains largely on track.  The
most notable change was to drop the snow amounts down around an
inch or so, mainly due to the relatively high speed of the system,
which limits the amount of time spent under moderate/heavy snow. The
placement of the heavies snow, which should be about 5-7", remains
in the Winter Storm Warning area.  Did not need to make any
adjustments to the warning or advisory issued yesterday.  There is
still some uncertainty with this event.  The QPF from the various
guidance does vary, so continued to stick with a blended approach.

The impressive shortwave will gain a negative tilt as it races
northeast toward our area later today.  Impressive forcing is
expected and there even looks to be some elevated instability with
the snow this afternoon and tonight.  Most of the accumulation will
come in a 4-6 hour period of moderate to heavy snow, with the timing
dependent on your exact location.  For the Twin Cities, the heaviest
snow will move through from about 3PM-9PM. Travel will quickly
become difficult as the snow spreads in from the southwest this
afternoon, as visibilities will crash very rapidly at the onset.  On
top of that, 1-2"/hr rates are likely, so the snow will pile up
quickly on the roads.  Alter travel plans if possible.

The snow will come to an abrupt end late tonight from southwest to
northeast.  The wind speeds will then increase overnight, especially
across far southern MN.  Winds of up to 30 MPH will lead to some
blowing and drifting snow overnight, hence travel will remain
difficult overnight.

.LONG TERM...(Sunday through Friday)
Issued at 422 AM CST Sat Feb 24 2018

Quiet weather expected for next week with temperatures near or
slightly above the seasonal average for late February. The storm
track will generally be to the south, so little if any precipitation
is expected.

There is a slight chance for a strong storm to develop and move
across the region Wednesday into Thursday, but this storm is
trending a bit further south. The origins of this storm are from a
positively tilted upper level trough off the coast of California,
and these systems generally are poorly handled by the numerical
models. The 24.00Z ECMWF is farther south than the GFS and GEM.
Given the uncertainty in both the large scale pattern, and the
spread in the forecast models, at this time feel there is a better
chance of it not happening than of it happening. In other words,
something to watch, but not something to hang your hat on since it
will likely end up south of the forecast area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1028 PM CST Fri Feb 23 2018

Fog/freezing fog is expected to continue developing overnight as
winds become light to calm and temperatures cool. LIFR
visibilities are expected to become widespread, with 1/4SM or less
the most likely from west central into south central MN. The fog
should improve Saturday morning, but low clouds will likely remain
until the onset of snow, which is expected after 20Z. Once the
snow begins rapid reductions to LIFR conditions are probable.
Easterly winds increase to around 10-12 knots on Saturday, then
shift to west/northwest on Saturday night.

KMSP...
Fog is the main concern overnight. Currently expecting winds to
go calm around 08Z, which will likely cause visibilities to drop
below 1SM. Conditions briefly improve Saturday morning, although
broken MVFR cigs will likely persist. Snow onset looks to be
around 22Z, with conditions LIFR conditions shortly after that. 1
to 2 inch per hour rates possible 23Z Saturday to 05Z Sunday.

/OUTLOOK FOR KMSP/
Sun...MVFR early, VFR during the afternoon. Wind W at 20G25kt.
Mon...VFR. Wind SW at 15G20kt.
Tue...MVFR with -SN possible. Wind NE at 05kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory until 9 AM CST this morning for WIZ014>016-
     023>028.

     Winter Storm Warning from 3 PM this afternoon to 6 AM CST Sunday
     for WIZ023-024-026.

     Winter Storm Warning from 6 PM this evening to 6 AM CST Sunday
     for WIZ014>016-025-027.

     Winter Weather Advisory from 6 PM this evening to 6 AM CST
     Sunday for WIZ028.

MN...Dense Fog Advisory until 9 AM CST this morning for MNZ054-056-
     064-065-067-070-073>078-082>085-091>093.

     Winter Storm Warning from 3 PM this afternoon to 6 AM CST Sunday
     for MNZ050-051-058>063-066>070-076>078-084-085.

     Winter Weather Advisory from 3 PM this afternoon to 6 AM CST
     Sunday for MNZ041>043-048-049-057.

     Winter Storm Warning from 6 PM this evening to 6 AM CST Sunday
     for MNZ044-045-052-053.

     Winter Weather Advisory from noon today to 3 AM CST Sunday for
     MNZ047-054>056-064-093.

     Winter Storm Warning from noon today to 3 AM CST Sunday for
     MNZ065-073>075-082-083-091-092.

&&

$$

SHORT TERM...SPD
LONG TERM...JRB
AVIATION...LS



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