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fxus63 kmpx 170915 
afdmpx

Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
415 am CDT Sat Aug 17 2019

Short term...(today through sunday)
issued at 325 am CDT Sat Aug 17 2019

The main concern in the short term is the chance for severe
thunderstorms tonight, the threat for which has increased
particularly across southern and western Minnesota. Strong
downburst winds, large hail, and even isolated tornadoes will be
possible.

As of early this morning, a large trough was moving slowly east
across the western half of Canada and is expected to deepen as the
day progresses. We'll spend the day in the warm sector well to
the east of the cold front that currently extends from Manitoba
southward into North Dakota. While this is the main feature of
concern, a shortwave trough will develop and intensify later this
afternoon to the south of the main upper trough. This feature will
move nearly due east to the north of the South Dakota/Nebraska
border, and reach southwest Minnesota this evening. So, two features to
keep our eyes on today and tonight as they approach, with the
southern shortwave arriving a few hours ahead of the main cold
front. The models are in good agreement that the main upper low to
the north will include an intensifying embedded shortwave rotating
through North Dakota toward Minnesota tonight, leading to the entire
system becoming negatively tilted and stronger than previously
expected. Storm Prediction Center increased the threat to a slight risk across much of
southern Minnesota and an enhanced risk across southwest Minnesota.

Temperatures will rise into the 80s and dew points will generally
be in the lower 60s locally. Southerly winds will increase this
afternoon ahead of the aforementioned cold front. This will lead
to MLCAPE values generally between 1500-2000 j/kg and combined
with deep layer shear around 35-40 knots, strong and severe
thunderstorms are possible. The initial shortwave may set off
scattered thunderstorms across the southern third of Minnesota by
evening. Meanwhile, storms should fire along the cold front
across the Dakotas this afternoon, likely growing upscale into
line segments. Strong cold pool development along these line
segments looks more likely, which would lead to an increased wind
threat as the line segments move from west to east across southern
Minnesota, including the Metro, late tonight and through the overnight
hours.

Once the cold front exits to the east mainly by tomorrow mid
morning, a few scattered showers may linger for a few hours, but
overall a drying and clearing trend is expected. Highs on Sunday
will be a little cooler behind the front, with mid to upper 70s
expected and dewpoints falling into the 50s for most by late
afternoon.



Long term...(sunday night through friday)
issued at 325 am CDT Sat Aug 17 2019

Overall the long term period will be fairly quiet. Monday night
still is our best chance at thunderstorms in this period, but
there is quite a bit of uncertainty at play.

By Sunday night, the main upper low will have moved east toward
Hudson Bay with the negative tilt to the south now extending
southeast toward the eastern Great Lakes. The upper low will
become quasi-stationary to begin next week over Hudson Bay with
deep zonal flow expected locally. This means temperatures will
rebound and should have no problem reaching the low to mid 80s
Monday and Tuesday. A subtle shortwave is still expected to
develop to our west as a ridge becomes more defined over the High
Plains. The path and strength of this shortwave is still
uncertain, so continued with a blended approach for pops which
yields about a 30% chance for storms Monday night.

An upper ridge will develop across western Canada in response to
another strong upper low approaching the western Canadian coast
by Tuesday. The Hudson Bay upper low will dive southeast and send
yet another cold front south through the northern plains Tuesday
night, leading to a slight cool down for Wednesday and Thursday as
Canadian high pressure settles in. Temperatures and dew points
look to be on the rise again though on Friday as the upper ridge
to our west begins encroaching on the local area as main upper low
continues pushing east.

&&

Aviation...(for the 06z tafs through 06z Saturday night)
issued at 1045 PM CDT Fri Aug 16 2019

Mid/high clouds will be on the increase Saturday, with a complex
of showers and thunderstorms expected to move across the area
late Saturday evening and overnight. Winds will be south/southwest
through Saturday afternoon, with afternoon gusts developing at Minnesota
sites. Saturday evening winds back to the southeast as the front
approaches.

Kmsp...showers/thunderstorms look the most probable between 06z-
12z Sunday.

/Outlook for kmsp/
sun...VFR with MVFR possible early. Wind northwest 5-10 kts.
Mon...VFR. Slight chc -tsra/MVFR late. Wind S 5-10 kts.
Tue...VFR. Slight chc -tsra/MVFR early. Wind S 5 kts.



&&

Mpx watches/warnings/advisories...
WI...none.
Minnesota...none.
&&

$$

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