Area Forecast Discussion
Issued by NWS Twin Cities, MN

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531
FXUS63 KMPX 161007
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
407 AM CST Mon Jan 16 2017

.SHORT TERM...(Today and tonight)
Issued at 407 AM CST Mon Jan 16 2017

Wintry precipitation is sneaking northward toward south central
and southeastern Minnesota early this morning. The precipitation
shield will continue to expand northward today as the surface low
lifts toward southern Lake Michigan. A marked increase in
precipitation will occur between 21z and 03z as the coupled jet
structure (and attendant layer differential divergence) shifts
over the area. The precipitation gradient looks to be tight, and
likely to intersect the Twin Cities, given QPF differences ranging
from a couple hundredths in the northwest to a couple tenths in
the southeast (which makes a big difference in impact when we`re
talking wintry precip). Thermal profiles point toward
predominately freezing precip in our forecast area with a little
snow mixing in at times (especially during the evening). Given the
potential for icing, have inched the advisory a little farther
north to include Eau Claire (Interstate 94 in WI) and Red Wing,
but not the Twin Cities. Most locations in the advisory area can
expected around 1 inch of snow in addition to ice accumulations
ranging from a few hundredths to around one tenth inch along
Interstate 90 (Albert Lea).

Temperatures remain mild with highs right around the freezing mark
and lows tonight ranging from around 10 degrees in the northwest
near Alexandria, to the mid 20s in the southeast near Albert Lea
and Eau Claire.

.LONG TERM...(Tuesday through Sunday)
Issued at 407 AM CST Mon Jan 16 2017

Big story for the extended is the prolonged thaw and well above
normal temperatures we are still anticipating through next
weekend.

The reason for the dramatic turn toward warmer weather is the very
blocky pattern models are in good agreement in developing.  By
Thursday, a strong blocking high will have developed over Hudson Bay.
At the same time, anomalously low heights centered over Alaska will
build down the west coast of North America. The will result in very
mild air spreading across pretty much all of North America east of
the Rockies. In terms of h85 temp anomalies, we`ll see our warmest
air in the Wednesday through Friday time frame.  The two days we
have potential to significantly overachieve with temperatures will be
Wednesday and Thursday, as we will not be stuck under stratus and
low level winds will be out of a favorable SW wind direction for
warming. By Friday, as the western NOAM trough continues to push
east, this will push the warmest air to our northeast. In addition,
Friday we will see deep southeasterly flow develop from the surface
up to the jet level. This will signal the return of low stratus and
precip chances.  Still have high confidence in widespread highs
Wednesday through Saturday getting into the 40s. Beside highs
getting above freezing, we likely see lows for a lot of places
remain above freezing Thursday through Saturday as well, so it will
be a legit thaw. As for records, record highs this week are up
around 50, so seeing record highs seems unlikely at this point,
though we could certainly get up within 5 degrees a couple of days.
What is more likely to fall next week are record warm minimums.

So when does this mild pattern break?  Looking at GEFS h5 height
anomalies, the blocking ridge over Hudson Bay will be remaining in
place through the end of next week, so although we don`t look to be
as far above normal next week as we will be this week, this warm
pattern looks to stick with us until the final week of January.
There`s a good chance this warm stretch will keep the current run of
above normal temperature months in the Twin Cities, which currently
sits at 16, in place.

As for precip, though there is good agreement on the large scale
trough/ridge setup from west to east across North America, models
continue to struggle with how energy coming out of the mid Miss.
Valley will work up here at the end of the week into the weekend. It
looks like our fist surge of moisture will arrive Fri night/Sat,
with another quickly on its heels for Sun night/Mon. The first looks
to be a primarily rain event, with wave two being more of a rain
to snow scenario.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1113 PM CST Sun Jan 15 2017

Tricky aviation forecast with respect to hours 18-30 as the models
continue to shift the amounts of moisture and where the p-type
change begins. Latest models indicate greater moisture further
north along with the wintry precipitation so have adjusted the
TAFs for KMSP-KRNH-KEAU to indicate a greater likelihood of FZRA
in addition to SN. That said, there looks to be a tighter gradient
of where the precipitation shield ends, so have maintained the
remaining three TAFs dry. Have also reduced the flight condition
during and after the precipitation as MVFR for a longer duration.
Confidence is still shaky in these scenarios with such frequent
model changes so additional adjustments to p-type and timing in
later TAFs are certainly possible.

KMSP...Have added in FZRA starting tomorrow evening to reflect
latest thinking in the models and have also dropped flight
category deeper into MVFR. The best timing for precipitation looks
to come just at the tail end of the evening push but the
possibility is still there that precipitation may start during the
evening push tomorrow and would start more as FZRA than SN.
Ceilings may also be troublesome after the precipitation ends as
IFR ceilings are possible which could extend into the morning push
Tuesday.

/OUTLOOK FOR KMSP/
Tue...MVFR possible early then clearing. Winds NW bcmg W 5-10 kts.
Wed...VFR. Winds SW 5-10 kts.
Thu...VFR. Winds S 5-10 kts.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory from noon today to 6 AM CST Tuesday for
     WIZ024>028.

MN...Winter Weather Advisory from noon today to 6 AM CST Tuesday for
     MNZ077-078.

     Winter Weather Advisory until 6 AM CST Tuesday for MNZ082>085-
     091>093.

&&

$$

SHORT TERM...LS
LONG TERM...MPG
AVIATION...JPC



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