Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 240355

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1055 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 06Z TAFS through 06Z Friday night)
Issued at 1055 PM CDT Thu Mar 23 2017

Stable precip in the form of rain and drizzle has broken out north
of the 850mb warm front from western MN across the Twin Cities
into WI. This secondary warm front (the main surface warm front
was crossing I-80 at 11pm) is also the demarcation line for
IFR/MVFR cigs to the north and VFR south. It`s about as far north
as it is going to make it, with the ra/dz helping to reinforce the
clouds/boundary layer moisture, so will keep MSP/EAU MVFR or
lower. Thunderstorms have broken out across Neb and are quickly
spreading into NW IA. These storms though look to come up to
about as far NW as Mankato/Red Wing line, so removed TS mentions
from MSP/RWF. Rain will linger through much of Friday morning at
RWF/MSP/RNH/EAU, but precip the remainder of the period will
remain southeast of AXN, with STC on the northern fringe. Lower
confidence in cig improvements Friday afternoon. GFS/NAM soundings
though show low moisture cleaning out pretty aggressively at MN
terminals. Given extent of current low clouds, was hesitant to be
too quick in getting rid of them and was hesitant to go VFR all
the way to MSP.

KMSP...Looks like any thunder will remain south of the field,
though not by much. With dz/ra breaking out, think the VFR trend
that came up from the south will stop on the doorstep of MSP, with
MVFR becoming IFR cigs being dominant into Friday morning. We`ll
also keep light precip going through the morning before drying out
in the afternoon. For now, kept MVFR cigs going through the
morning, though the GFS/NAM would say MSP could go VFR around 00z.

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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