Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
336 PM CDT Tuesday Jun 2 2015
Short term...(this evening through wednesday)
issued at 320 PM CDT Tuesday Jun 2 2015
Convective development associated with an advancing area of low
pressure over the western Dakotas is the primary focus through
In the meantime...gusty southerly winds and increasing heights ahead
of the trough have facilitated a warming trend to above normal
temperatures today...with middle afternoon temperatures in the 75 to 80
degree range. A few showers leftover from nocturnal Dakotas
convection have held together enough to generate a few light radar
returns over west central Minnesota this afternoon. Really do not
expect to see much more than that until developing convection in the
Dakotas /closer to the surface low...more so in North Dakota north of
the middle level capping inversion/...spreads eastward into west
central Minnesota later this evening. Meanwhile...another area of
convection will likely develop over South Dakota this evening as a
shortwave presses in and the low level jet strengthens. This
secondary activity is then expected to move into the forecast area
after 09z...and spread eastward during the morning hours.
On Wednesday afternoon...the cold front will be moving across the
area. However...models do favor stratus cloud development during the
morning hours...and with the potential for convective debris from
the Dakotas activity...may have a tough time destabilizing. Deep
layer shear is also very marginal...so at this time the likelihood
of organized severe storms is low in our forecast area.
Long term...(wednesday night through tuesday)
issued at 320 PM CDT Tuesday Jun 2 2015
The first part of the extended period... Wednesday night through
Friday will be impacted by how far south the frontal boundary sags
to the south of our County Warning Area. The second half of the extended
period...Saturday through Tuesday...will be related to another
frontal boundary and upper long wave trough moving across Canada
and into the Great Lakes/northeast.
First...the mean upper level flow will hold from the west...and
west-southwest from Wednesday night...through Friday. Although this
is a relatively fast flow...both the GFS/ec have been held or even
slowed the frontal boundary position Wednesday night which may
lead to holding onto the precipitation longer into the evening
than expected. But...with the fast flow...you would expect a
faster solution and quickly moving out the frontal boundary and
associated precipitation field with it. I do like the ec/Gem
solutions which keeps the bulk of the precipitation field east/southeast
of our County Warning Area after 00z as the anticipated shortwave embedded in this
faster flow...moves east of our area. The second concern is
whether high pressure building southward Thursday/Friday will
allow for some drier air to filter in. The GFS is wetter and
further north then the ec/Gem which seems unrealistic due to the
drier east/NE flow developing. However...kept slight chance as far
north as the Twin Cities based on some differences in the wind
The second half of the extended period will be related to the
evolution of the upper low developing in the SW Continental U.S....and the
upper ridge building over Texas. This type of pattern will lead
toward warmer and slightly drier conditions if the upper ridge
builds further to the north across the upper Midwest. Will
continue with the blended scenario...but the best solution is to
hold onto chance probability of precipitation starting Saturday/Sunday as the mean flow from
both the ec/GFS becomes more northwest due to a stronger shortwave moving southeast
across central Canada late in the weekend.
There remains no real warm weather in terms of highs in the 80s or
even 90s based on the upper flow and mean ensembles 500 mb heights
past the middle of next week. The key for any substantial warm up
will occur once the long wave trough that has been persistent over
eastern Canada...slowly breaks down...or a long wave trough begins
to take over the western Continental U.S..
Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1259 PM CDT Tuesday Jun 2 2015
A few waning showers will affect kaxn and possibly kstc this
afternoon...but VFR conditions are expected area-wide into the
evening. Gusty southerly winds will also persist ahead of the
surface trough that will bring higher shower and thunderstorm
chances overnight and Wednesday. Expect thunderstorms that develop
over the Dakotas to advance eastward into the area after
05z...with additional development possible Wednesday afternoon as
the cold front moves across the area. MVFR cloud development is
expected on Wednesday morning as well...which could minimize
development of strong thunderstorms.
Kmsp...VFR conditions through tonight...with shower chances
arriving mainly after 09z...and thunderstorm chances after 14z.
Also expect MVFR clouds to develop by 18z.
/Outlook for kmsp/
Thursday...VFR with MVFR/IFR possible in thunderstorms and rain. Wind variable 5 kts.
Friday...VFR with MVFR/IFR possible in thunderstorms and rain. Wind east 10 kts.
Sat...VFR. Wind east-northeast 10 kts.