Area Forecast Discussion
Issued by NWS Twin Cities, MN

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281
FXUS63 KMPX 242042
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
342 PM CDT FRI JUN 24 2016

.SHORT TERM...(This evening through Saturday)
Issued at 342 pm CDT Fri Jun 24 2016

This is a perfect scenario of calm weather before the storm in the
next 24-36 hours.

Slight adjustments were made for tonight, and Saturday afternoon
timing of the thunderstorms, but overall stuck close to previous
forecast.

First, a very strong and abnormally deep upper low for late June was
moving across the northern Rockies this afternoon. Models continued
a straight forward forecast with this upper low progged to move
along the Canadian border, from North Dakota, to southern Manitoba
by Saturday evening.

As with previous values of wind shear and instability, models
continued to depict a period that highlights both of these
parameters maximized between 19z Sat - 01z Sun across central
Minnesota early, and then moving southeast into east central
Minnesota, and west central Wisconsin by early evening. 0-6km wind
shear values initially are forecast to be around 25 kts, but are
expected to increase to 30-40 kts by early evening. MLCAPEs range
from 2000-3000 J/kg in west central and central Minnesota at 18z
Saturday, to 1500-2000 J/kg by 00z Sunday in east central Minnesota
and west central Wisconsin. Other severe weather parameters
including CWASP (Craven-Wiedenfeld Aggregate Severe Parameter on SPC
website) and Helicity also show the potential of organized severe
thunderstorms Saturday afternoon, into the early evening. Latest SPC
Day 2 outlook has portions of east central Minnesota and west
central Wisconsin in an elevated risk of severe thunderstorms.
Latest CIPS also support an outbreak with today`s run (12Z Friday)
leaning toward July 14, 2010 which was the Northfield, Lakeville,
Randolph tornado (EF-1). This tornado also affected west central
Wisconsin near Ellsworth that had an EF2 tornado.

In the short term, a few elevated instability showers or
thunderstorms are possible tonight, but latest CAMS do not show any
type of organization or consistency. Therefore, kept isolated or
scattered showers and thunderstorms in the forecast. The best chance
of more organized or scattered activity will occur in northern
Minnesota after midnight, and drift to the southeast into east
central Minnesota and west central Wisconsin toward sunrise. This
is also where some of the local RAP/HRRR convective elements show
some potential. However, if any storms do develop, the amount of
instability and shear is weak enough to limit severe potential.

.LONG TERM...(Saturday night through Friday)
Issued at 342 pm CDT Fri Jun 24 2016

Strong to severe thunderstorms will likely be in progress across
eastern MN and western WI at the start of the long term with ample
shear and instability in place. CWASP values are most favorable from
the Twin Cities on north and east. PWAT values at or above 2 inches
are indicated in various model solutions for these same areas.
This is above the daily max for the MPX sounding climatology,
leading to a flooding concern if the storms would begin to train.
The culprit is a strong low pressure system moving eastward across
south central Canada with a trailing cold front arching southward
across MN. The worst of the storms should east of our forecast
area by midnight Saturday night, if not a few hours earlier.

By Sunday, the low pressure system will be just north of MN with
the cold front well east and south of the local area. There will
be a breezy west wind on Sunday, especially across central MN,
but highs will still likely top out in the lower to middle 80s.
Thereafter, the flow aloft will become more northwest with high
pressure building in for Monday and Tuesday. Both days will be
quite pleasant with highs in the 70s along with dew points in the
45 to 55 degree range.

For the balance of the work week, Wednesday through Friday, we`ll
remain in a northwest flow but there will be a few short waves
moving through. Some instability showers and thunderstorms can not
be ruled out during this period. The day with the best chance for
a little precipitation is Thursday, when the strongest of the
waves moves through. High will slowly rise to around 80 by the
time we reach Friday afternoon.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1230 PM CDT Fri Jun 24 2016

Short term concerns are the MVFR ceilings in south central and
east central Minnesota. Later concerns deal with timing of
thunderstorms development, especially Saturday morning after 15z.

Latest regional satellite has the clouds slowly eroding across
southern Minnesota, with only an hour or two at best before the
MVFR ceilings lift or dissipate. Otherwise, VFR conditions will
continue this afternoon and evening with a very slight chance of
thunderstorms developing after 06z. The best and most concentrated
area of thunderstorms look to be across far east central Minnesota
and west central Wisconsin after 09z. Therefore, will continue
the prob30 in these areas. Otherwise, introduced VCTS after 15z
for most of MPX forecast area. Winds will remain from the south-
southeast today and tonight, and more south-southwest Saturday
morning.

KMSP...

Still some MVFR ceilings near the airport or an hour or two this
afternoon. However, these clouds should lift and dissipate by 20z.
Kept the prob30 in the taf for late tonight based on
uncertainties of convection expected to develop across northern
Minnesota and dive south-southeast toward east central Minnesota
after 09z. Better chances of VCTS will occur after 18z along with
the possibility of severe thunderstorms. Winds will remain from
the south-southeast this afternoon through tonight, and more
south- southwest Saturday afternoon.

/OUTLOOK FOR KMSP/

SAT EVE...MVFR/IFR Ceilings possible early. Southwest Wind 10-20 kts.
SUN...VFR. West wind 10-20 kts becoming northwest.
MON...VFR. Northwest wind 10-15 kts becoming east 5 kts or less.

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

$$

SHORT TERM...JLT
LONG TERM...RAH
AVIATION...JLT



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