Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 230411
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1111 PM CDT Wed Mar 22 2017

.SHORT TERM...(This evening through Thursday)
Issued at 326 PM CDT Wed Mar 22 2017

A band of mid level clouds moved eastward across Minnesota this
morning and will enter western Wisconsin later this evening. Radar
returns showed precipitation across western MN, but metars showed
only light precip and nothing measurable, so transitioned light
pops to flurries and sprinkles overnight.

On Thursday a large upper level low that is currently moving onshore
the California coast will move across the 4-corners and become
cutoff from the main flow. Low level theta_e advection will lead to
saturation in the lowest 700 mb of the atmosphere and forecast
soundings show enough lift to produce some light rain. Have pops
increasing throughout the day on Thursday, but again little
accumulation.

.LONG TERM...(Thursday night through Wednesday)
Issued at 326 PM CDT Wed Mar 22 2017

The main focus of the long term period is the system set to impact
our area from tomorrow through the weekend.  By tomorrow evening,
the cut-off upper low will be positioned over the four corners
region with surface cyclogenesis ongoing across eastern Colorado.
The warm front will be draped across southern MN/northern IA and
into central WI tomorrow night and will be the focus for the
rainfall development given the strong low level convergence.

The latest trends with the forecast guidance indicates the heaviest
rain potential across far southern MN and northern IA.  The outlier
is the Canadian model which is much farther north.  The latest ECMWF
run shifted its QPF southward this morning, more in line with the
GFS.  In addition, the GEFS members indicate less than a 50% chance
of seeing an inch of rain north of Mankato.  With high pressure
pushing into the great lakes from the north during this period, tend
to lean toward the southern consensus.

This low will slowly move east across northern Oklahoma into
southern Missouri before finally turning northeast toward Chicago by
Sunday.  With that, we could see light precip lift back into the
region during this period.

Beyond that, the pattern looks to remain active with continued waves
moving through the center of the country.  Possibly additional
strong cut off lows moving through late in the period.  In terms of
temperatures, we look to run near to slightly above normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1111 PM CDT Wed Mar 22 2017

Two concerns this TAF period are timing arrival of low cigs and
shower/thunderstorm potential Thursday afternoon. Downstream obs
lead to some hesitation with bringing in lower cigs too fast
Thursday, as MVFR cigs (015-020) are still way down in central OK.
Models have been way to fast in moistening the low levels
recently, so continued to go a bit slower than guidance with
bringing in low cigs. Lower cig chances look to increase
significantly Thursday night as a warm front pushes up to the
MN/IA border. We could certainly be lower with cigs than we
currently have at the end of the period, but at 20+ hours out,
was more conservative with how low to take things than what the
LAMP guidance has. As for precip potential, the NAM shows
1000-1500 j/kg of MUCAPE coming up Thursday, but ridging aloft
looks to create dry mid-levels and a capping inversion to keep
tsra activity in check. Looks like light rain should expand across
the area Thursday afternoon as the LLJ noses into southern MN.
Again, we may be too bullish with precip mention at this point
this taf period given the dry mid-level air.

KMSP...Very dry low level air remains in place and will be tough
to displace, so continue to run later/higher with cigs than LAMP
guidance. Also concerned we won`t see much in the way of rain
until Friday morning when deep moisture finally arrives.

/OUTLOOK FOR KMSP/
Fri...MVFR/IFR with -RA likely. Wind NNE 5-10 kts.
Sat...Chc MVFR -RA. Wind ENE 10 kts.
Sun...Chc MVFR. Wind ENE 5 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...JRB
LONG TERM...SPD
AVIATION...MPG



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