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Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
537 am 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 east...so 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 12z tafs through 12z Saturday morning)
issued at 503 am CDT Friday Apr 18 2014
MVFR br with isolated LIFR fog developed over the eastern area this
morning. This will improve after 12z over east central Minnesota as
thicker clouds move in...and into west central Wisconsin after 14z
as more clouds move in there. After the fog...expect VFR middle
clouds much of the day as initial warm air advection pattern develops. May see a
brief -shra/-shsn over the western half of the area into the
morning...but believe as it travels east this afternoon...should
erode in the drier air. Some very light returns on radar
associated with the weak warm air advection into western Minnesota now. Pressure
gradient increases during the day...so east to southeast winds
expected to increase... mainly in the afternoon over the western
areas. This will continue into the night as well as the surface
front moves east over the Dakotas. It should remain dry over the
area through 06z Saturday. Will bring in MVFR ceilings and -shra
into kaxn after 06z and toward kstc by 12z Sat.
Kmsp...5sm br at the airfield will last an hour or two as thicker
clouds arrive. Will keep ceilings at or above 7k feet through the
morning...and middle/high level clouds over the area into tonight and
Saturday. Will keep things dry through this period. East to
southeast winds will increase into the afternoon...and could
become gusty. This will linger through the night and into
Saturday as the pressure gradient moves in ahead of the front.
/Outlook for kmsp/
Sat night...chance MVFR with -shra. Winds SW becoming northwest 5-10 kts.
Sun...VFR. Winds north-northeast 5-10 kts.
Monday...VFR. Winds SW becoming northwest 5-10 kts.