Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1055 PM CDT Tuesday may 26 2015

Short term...(this evening through wednesday)
issued at 330 PM CDT Tuesday may 26 2015

A rather impressive wrapped up system continues to lift north into
Wisconsin this afternoon. A tropical and very efficient atmosphere
with slow moving cells embedded within the larger deformation rain
shield has led to heavy rainfall rates in areas today. Reports of 1
to 2 inches within 30 to 60 minutes have been received from the
metropolitan. Moderate to occasionally heavy rain will continue into the
evening across southern/eastern Minnesota and western WI before gradually tapering off.
The band of rain will essentially shrink from the west and east this
evening...leaving a good possibility of light showers continuing for
much of the night near the Minnesota/WI border per the consistent hrrr
reflectivity forecast and pattern recognition. Thunder has been
absent for the last few hours and not anticipating much given the
poor lapse rates and tropical airmass. Radar reflectivity does not
look particularly impressive...but rainfall rates will remain high
due to the high precipitable water values and above average atmospheric efficiency.

The system will pull away late tonight...although a weak disturbance
may rotate around it across northern Minnesota and WI Wednesday. A capless
atmosphere and the possibility of some cape...especially across northwestern
WI where surface dew points will be highest...may spark a couple
afternoon storms. The rest of the area will be mostly sunny. Highs
in the middle 80s still look good and all guidance supports those

Long term...(wednesday night through tuesday)
issued at 330 PM CDT Tuesday may 26 2015

The long term trend starts out with mainly dry conditions into
Thursday ahead of the next surface cold front which is forecast to
move into northwest Minnesota and eastern South Dakota by 00z
Friday. This will increase probability of precipitation over the western portion of the
area by that time. The east should remain dry until Thursday night
as the front moves into eastern Minnesota by 12z Friday. Expect organized
thunder...and there is some chance of severe weather associated
with it into Thursday night...mainly across the western County Warning Area.

This all shifts east into eastern Minnesota and western Wisconsin into
Friday afternoon/night. MUCAPE values increase to 2500 j/kg over
the western portion of the County Warning Area Thursday night...with similar
values ahead of the front Friday afternoon/evening over the
southeast third of the area. Precipitable water increases to 1.5
inches into Thursday night ahead of the boundary...although deep
layer shear is lacking. Heavy rainfall is a threat and
instability should be strong enough for at least an isolated
severe weather threat along the front.

Much cooler conditions arrive into the weekend in the wake of the
front. The cfsv2 plume outlook has indicated this trend for the
last few days. This will generate maximum temperatures some 10 to 15
degrees below the averages for that period. Warmer temperatures
arrive into early next week as an upper ridge builds over the


Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1055 PM CDT Tuesday may 26 2015

An area of showers...slowly decreasing in intensity and coverage
across wc WI...will diminish by morning. Only aviation concern is
MVFR...possibly IFR visibility in wc WI but with middle/high cloudiness
continuing leaning toward only low end MVFR
visibility/high end IFR visibility for both Keau/krnh. Otherwise...VFR conds
will continue with winds starting from the SW/WSW...then more
west/west-northwest Wednesday morning/aftn. Some gusts are possible in ec Minnesota/wc WI
during the afternoon.


Some MVFR visibility this early morning. other aviation
concerns with winds SW tonight...becoming west/west-northwest by Wednesday

/Outlook for kmsp/

Thursday...VFR. Chance afternoon -shra/-tsra. Winds S 10-15 kts.
Friday...MVFR/IFR ceilings/visibilities in shra/tsra. Winds SW 5-10 kts becoming
north-northwest at 10-15 kts.
Sat...VFR. Winds NE 10-15 kts.


Mpx watches/warnings/advisories...


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

National Weather Service Glossary of Abbreviations