Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 191817 AAB

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
117 PM CDT Mon Jun 19 2017

.SHORT TERM...(Today and tonight)
Issued at 217 AM CDT Mon Jun 19 2017

The short term concerns are the convective trends today and

Water vapor imagery showing a couple of short waves moving in the
northwest flow over the area. One is exiting to the east across
western Wisconsin. Isolated showers associated with this feature
and will hold those until about 12z. They second feature is
moving through eastern south dakota. A few showers and isolated
thunder associated with this short wave as well. Feel this will
gradually weaken during the morning as it moves in...but will have
to include isolated mention out west for a few hours this
morning. Then HIRES models continue to indicate redevelopment of
showers and isolated thunder late morning/early afternoon as
MUCAPE builds to around 750 J/kg mainly to the south. We will see
a corridor of showers develop into central MN early this
afternoon...but that should wane during the afternoon as the focus
redevelops to the southeast. We continued the scattered/isolated
mention with the activity today. With varying cloud cover we
should see temperatures warm close to yesterdays values most

During the night...another short wave drops into the cwa and will
spread more high end chance PoPs to the cwa. Instability is
lacking and we may tend to see diurnally driven convection move
into the area and weaken overnight. The wave does look potent
enough to continue the thunder chance longer into the night as it
moves through.

.LONG TERM...(Tuesday through Sunday)
Issued at 217 AM CDT Mon Jun 19 2017

The highlight of the extended period will be a sweeping cold front
due to pass through the region Wednesday night into Thursday
morning. With this front will come the best chances for organized
showers/thunderstorms for this week, including the potential for
severe weather.

The cold front will actually come onshore the west NOAM coast
during the day tonight into Tuesday morning and continue to press
eastward across the Rockies Tuesday night and Wednesday. The
system will be preceded by a flattening ridge and developing deep
southerly flow. This will spell an increase of deep moisture from
the southern CONUS in advance of this system and a more
progressive flow aloft. Increased jetting in the lower and middle
levels within a more unstable environment will aid in
strengthening shear for thunderstorm development. With MLCAPEs
growing to the 2000-3000 J/KG range with a diurnally weak (or no)
cap ahead of strong frontal lift, there is potential for
organized thunderstorm development Wednesday afternoon and
evening. The SPC Day 3 Outlook captures these details by
highlighting a Slight Risk area for portions of far southern MN
and the rest of the WFO MPX coverage area within a Marginal Risk.
With the warm-sectoring coming from this system, Wednesday will
be the warmest day of the week, but it still looks to have a
roughly 10-degree difference from northeastern to southwestern
parts of the WFO MPX coverage area. While central MN and western
WI will hit the mid- to-upper 70s, western and southern MN will
hit the low-to-mid 80s. The relative cold air advection behind
this system will not actually commence until Thursday, leaving
lows Wednesday night in the upper 50s to lower 60s.

Otherwise, ahead of the frontal system, Tuesday will be dominated
by surface high pressure and dry northwest flow aloft, producing
mostly clear skies with high temperatures in the upper 60s to mid
70s, which is about 5-10 degrees below normal. Behind the system,
Friday through Sunday will see a return of northwest flow aloft
but this time with a few upper level low pressure waves drifting
through from central Canada into the Great Lakes. This will make
for spotty showers from time to time Friday on through the
weekend, particularly on Saturday when the upper low itself looks
to move across MN into IL/IN. Temperatures will also become cooler
on the backside of the midweek system with highs within a few
degrees of 70 for the end of the week and the weekend.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 117 PM CDT Mon Jun 19 2017

VFR conditions through the period. Scattered showers and a few
storms will exit southern Minnesota by mid afternoon with a period
of dry conditions through most of the evening hours. Another
disturbance will drop south overnight, bringing another round of
scattered showers and a few storms. Skies clear again for Tuesday.

KMSP...It appears most of the SHRA are to the south and that`s
where they will stay today. Winds will become slightly more
westerly this evening before veering more northwesterly behind
another front Tuesday.

Wed...VFR. Chc -TSRA. Wind S 10 kts.
Thu...VFR. Chc -TSRA. Wind WNW 5-10 kts.
Fri...VFR. Wind NW 10 kts.




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