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Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
658 am CDT Wednesday Apr 16 2014
Short term...(today and tonight)
issued at 415 am CDT Wednesday Apr 16 2014
Upper trough was entering the western Dakotas this morning with
increasing moisture as evident via water vapor imagery. Main
changes to the short term package was to slightly slow the system
down. Hi-res models and NAM came in with a slower progression of
this wave. Due to this slow down...the deformation zone will be
oriented slightly further back to the west so snow amounts were
increased southwest of Alexandria. The northern portion of these
counties will see significant accumulation today...so went ahead and
expanded the Winter Weather Advisory south from Madison through
Willmar and Buffalo. In addition...the heaviest precipitation band
still matches up well with the warning area...but northeastern
Stearns and northern Benton counties snow amounts were increased
given more moisture and additional quantitative precipitation forecast pushing these areas into
warning criteria. These two counties have been upgraded to a Winter
Storm Warning. For the Twin Cities metropolitan...low level dry air will
push well north of the Iowa border and keep the metropolitan relatively
quiet through the morning. By the time saturation is achieved...it
will be warm enough for purely rain to fall. With the deformation
zone taking more of a tilt toward the west...it will push through
the metropolitan this afternoon/evening and cause a changeover to snow once
surface temperatures begin to cool. A quick burst of snow for the
metropolitan could impact the evening commute in...but Road surfaces may
remain mostly wet. In western Wisconsin...temperatures appear
slightly warmer in the low levels...but enough to make a difference
in rain/snow placement. Snow ratios look lower than previously in
this area...especially given the warmer surface temperatures this
afternoon. So...snow amounts were decreased somewhat...but the
counties in the warning still look to see six or more inches of
snow. The snow wont come to an end in western Wisconsin until
Thursday morning given the speed of the system slowing down.
Long term...(thursday through tuesday)
issued at 415 am CDT Wednesday Apr 16 2014
The long term will start off rather quiet aside from a few
flurries or lingering light snow across the central Wisconsin
counties early Thursday morning. By afternoon...ridge of high
pressure will build in with the axis located across eastern
Minnesota and western Wisconsin Thursday night and early Friday.
Should be another night of well below average temperatures...especially
in areas with several inches of snow on the ground. Lowered temperatures
a bit across central Minnesota and northwestern WI for this likelihood. On the
southwestern periphery of the ridge...models disagree on the
existence of a fast moving short wave that brings with it a narrow
swath of precipitation across South Dakota and far southern Minnesota/northern
Iowa. GFS and NAM seem much too bullish on amounts considering the
large ridge just to the north and the amount of dry air
accompanying it. Gem and European model (ecmwf) Don/T acknowledge this feature.
Figured it was at least Worth a slight chance near the Iowa border.
A system will propagate across the northern plains and southern
Canada Saturday with the cold front traversing the County Warning Area Saturday
night. Moisture return ahead of this front appears sufficient
enough for precipitation to accompany the front...but not enough to bring
much threat of thunder.
A pattern shift will be underway come early next week. Troughiness
emerging across The Rockies/West Coast will result in building
heights to the east across the central Continental U.S.. temperatures will
trend above average levels during this time with highs likely
reaching the 60s and 70s on a number of days next week. Will need
to keep an eye on a storm system developing midweek across the
western High Plains in response to the digging trough. It may
bring some potential of severe weather across the northern plains
and Mississippi Valley depending on its evolution.
Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 641 am CDT Wednesday Apr 16 2014
Axn and especially stc will be most impacted by moderate to heavy
snow today. Stc looks to be very along the axis of heaviest
accumulation...with the greatest lift occurring middle day there. The
surface low will move east along the Iowa border and eventually
take a slight northeasterly track. A decent amount of dry air will
poke northward through the southern third of Minnesota this
morning...so delayed the precipitation until this afternoon at
msp. Rwf/msp/rnh/eau will also see temperatures warm enough for
mostly rain from this event...but snow will certainly mix in for a
time. This afternoon...the rain/snow line will setup just north of
the metropolitan...so will closely monitor this as it develops.
Kmsp...its possible a some very light snow comes down middle
morning...but dry air in the low levels will need to be overcome
quickly...otherwise the developing band of precipitation will
outrun the metropolitan before saturation occurs. Thinking there is a
decent shot of this...so just introduced vcsh for this morning.
By the time precipitation gets here midday...surface temperatures
will support rain...and stay that way until evening when snow
finally mixes it. Accumulation at msp is expected to be
minor...around an inch possible mainly this evening.
/Outlook for kmsp/
Thursday...MVFR ceilings may linger early...otherwise VFR. Winds north-northeast 10-15 kts.
Friday...VFR. Chance MVFR Friday night with rain/snow. Winds NE 5-10 kts.
Sat...chance MVFR with rain/snow. Winds east-southeast 10-15 kts.
Minnesota...Winter Weather Advisory until 10 PM CDT this evening for mnz041-
Winter Storm Warning until 4 am CDT Thursday for mnz042>045-
Winter Weather Advisory until 4 am CDT Thursday for mnz058-059-
Winter Weather Advisory until 10 PM CDT this evening for
WI...Winter Storm Warning until 4 am CDT Thursday for wiz014.
Winter Weather Advisory until 4 am CDT Thursday for wiz023.
Winter Storm Warning until 7 am CDT Thursday for wiz015-016.
Winter Weather Advisory until 7 am CDT Thursday for wiz025-027.