Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1256 PM CDT Friday Apr 18 2014

Updated for 18z aviation discussion...
issued at 1240 PM CDT Friday Apr 18 2014


Short term...(today and tonight)
issued at 355 am CDT Friday Apr 18 2014

Short term concerns are the fog to the east and the threat of
rain/snow showers west today. Then focus turns to showers
developing ahead of front later tonight.

Areas of fog developing in the mainly clear east this morning.
Middle/high level clouds moving in from the west...will limit
widespread fog into eastern parts of Minnesota...into early morning.
May go locally dense in west central Wisconsin for a time...before
the clouds come in by 12z or so. Will mention areas of fog east
through about 14z. Then the other issue is the threat of an
isolated rain or snow shower into the morning over western areas.
There is some fgen moving into the west...and ceilings have dropped
to around 5k feet in some locations. There may be enough forcing to
generate some isolated -shsn/-shra through the morning. Pretty dry
farther to the do anticipate anything that does develop to
dry up as it moves farther east into the afternoon.

Then the next threat of weather arrives after midnight tonight to
mainly west central areas. Warm air advection and increasing 850 mb moisture
transport will help generate some rain showers ahead of the front. Pressure
gradient increases late Friday afternoon and into Friday night.
Gusty winds will develop west this afternoon...and spread east into
eastern Minnesota tonight. This along with the cloud cover will allow
temperatures to remain on the warmer side tonight...especially over

Long term...(saturday through thursday)
issued at 355 am CDT Friday Apr 18 2014

The front will continue heading east Saturday. Forcing along the
front weakens Saturday...but showers are still expected to
accompany it especially across central Minnesota due to strong warm air advection. Breaks
in the sunshine and temperatures warming into the 60s across
eastern Minnesota and western WI will bring a threat for thunder...but
severe weather is not expected. The front will sag south to
northern Iowa/southern Wisconsin and stall for Saturday night and
Sunday. This will keep the shower/storm chances going across far southern
Minnesota and portions of western WI.

Meanwhile...much drier air will encompass the remainder of the
forecast area Sunday with light winds. Dew points may end up being
a bit drier than currently forecast...but light winds throughout
the boundary layer may not completely mix out the moisture at the
surface as forecast soundings indicate. Abundant sunshine should
allow for steep low level lapse rates...easily tapping into the
warm air aloft and making for a rather mild day with highs in the
upper 60s to lower 70s.

Weak low pressure will track from North Dakota across northern Minnesota and
the northern Great Lakes Monday. Thermal ridging will be tamped
down late with the front and the surface high pressure building
south into the plains. Should still be enough time and available
sunshine to bring highs back into the 60s.

The ridge pushing across Minnesota will become elongated...stretching
from the Great Lakes northwest into northern Canada next week.
As low pressure becomes organized over the western High Plains and
northern rockies in response to a deepening trough down the West
Coast...a cool east/southeasterly boundary layer flow will
strengthen across the Midwest. Robust warm sector across the
plains and strong southwest middle level winds will spread the eml
northeastward into Minnesota/WI midweek. Low level warm air advection/moisture
advection on a potent low level jet will prove sufficient enough
to generate a band of showers and thunderstorms north of the warm
front. The spread amongst the global models has decreased enough
to raise probability of precipitation into the likely range during this time.


Aviation...(for the 18z tafs through 18z Saturday afternoon)
issued at 1240 PM CDT Friday Apr 18 2014
a low pressure system will develop and move across northern
Minnesota which will cause the east southeasterly winds to become
southerly later tonight and Saturday morning. A weak cold front
will move through the region which will bring a chance for light
showers. The best chance for rain will be at the northern sites.
Cloud bases have the potential to go down to MVFR during the
rain...but should generally remain above VFR the rest of the time

VFR conditions throughout. The best chance for rain will be north
and west of just have vcsh for now since confidence is
too low to include precipitation in the tafs.

/Outlook for kmsp/
Sat night...chance MVFR with -shra. Winds SW becoming northwest 5-10 kts.
Sun...VFR. Winds north-northeast 5 kts.
Monday...VFR. Winds SW becoming northwest 5-10 kts.


Mpx watches/warnings/advisories...


Short term...dwe
long term...borghoff