Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 240004

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
704 PM CDT Thu Mar 23 2017

.SHORT TERM...(This evening through Friday)
Issued at 304 PM CDT Thu Mar 23 2017

A complicated forecast ahead. A strong low pressure system is
developing on the lee of the rockies in eastern Colorado and will
take the next few days to deepen and evolve through Oklahoma and
turning northeast through the Midwest, affecting our local weather
all the way through Sunday. For the next 24 hours, the main
concern locally is the warm front set to lift into northern
IA/southern MN with widespread low stratus and rain likely north of
the front tonight.  Best LI`s becoming slightly negative this
afternoon and expanding northward tonight led to a mention of
thunder in the forecast across all of southern MN and west central

As the low ejects late tonight into tomorrow, it will dive southeast
into Oklahoma and eastward from there, hence pulling the moisture
and the front down as well with a high pressure area building in
across northern Ontario.  With this track, and the guidance coming
into a much better consensus, lowered QPF for much of central MN,
keeping the 0.5" and higher amounts south of the Twin Cities area.
As the system emerges and the front starts going south, we lose of
negative LI`s as well by tomorrow, so removed thunder from the
forecast for tomorrow during the day.  The heaviest QPF looks to
occur along I-90 and into northern Iowa and in an west to east
oriented fashion from there.  The main thing to note tonight with
the precip amounts is the behavior of the low level jet.  While
initially, a 50 knot LLJ pushes into southern MN, it will quickly
fold over to the east as the night progresses, limiting the
northward extend of the best rain producing cells.  By the end of
the day tomorrow, the low will still be down in Oklahoma, so moving
quite slow as it reached maturity and becomes vertically stacked.

.LONG TERM...(Friday night through Thursday)
Issued at 304 PM CDT Thu Mar 23 2017

With the surface low still in Oklahoma but the front continuing to
retreat south, continued to slowly work the pops southward out of
the forecast area tomorrow night through Saturday.  The vertically
stacked low will begin a trek northeast into Missouri Saturday but
will be weakening through the morning.  With a lack of a noticeable
jet, it will take its sweet time moving through MO and toward
Chicago.  By the time it reaches IL, we could see light QPF on the
back side of this system so continued to advertise chance pops
across western WI and into far eastern MN.

The next developing system will be quickly on its heels and finally
help push it east through the Great Lakes by Monday.  There are
certainly some noticeable differences in the handling of that next
system for early to middle of next week, and right now most of the
QPF looks to stay south of here but that could certainly change at
this stage.

Overall, the period continues to look active across the CONUS with
repeating waves and low pressure systems moving through.  Locally,
temperatures look to remain near or above normal.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 704 PM CDT Thu Mar 23 2017

Complicated forecast lies ahead as warm front currently in SW IA
moves north to about the MN/IA border tonight. Continued
saturation on southeast winds finally has IFR stratus expanding
across central MN, though at the same time we have an improvement
to VFR skies quickly moving north out of IA into southern MN with
the HRRR showing it may get as far north as MSP/EAU. In addition,
significant plume of elevated instability currently over Neb will
get advected northeast ahead of the warm front this evening, with
showers and thunderstorms expected to develop in the 4z-9z window.
RWF/MSP will be on the northern side of the TS most likely, but
will be close enough where we felt a TS mention was worthy.
Friday, NNE winds will be increasing in strength, which will help
advect drier low level air south. This will spell a clearing of
the low clouds for at least AXN, but could get farther south.

KMSP...IFR cigs are slowly expanding to our west and south, so
just a matter of time before MSP joins in on the fun, with earlier
than 3z certainly possible. Expect a WSW-ENE band of showers and
thunderstorms to develop north of the warm front between 5z and
9z. The HRRR is trending a little south of MSP for where the
storms develop, but will be close enough to warrant a vcsh mention
and will likely pose flight line issues for departing traffic.
After 9z, we will be stuck in a rut when it comes to the moisture
feed and like the idea of the GFSlamp where it`s on and off
-ra/-dz into Friday afternoon.

Sat...Chc MVFR -RA. Wind NE 5-10 kts.
Sun...Chc MVFR. Wind ENE 5 kts.
Mon...Chc MVFR Early. Wind N 5 kts.




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