Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Twin Cities/Chanhassen Minnesota
1155 PM CDT Tuesday Jul 28 2015

Short term...(this evening through wednesday)
issued at 213 PM CDT Tuesday Jul 28 2015

Early afternoon satellite imagery showed a mature middle latitude
cyclone centered over the US/Canadian border. A cold front was
entering western Minnesota. Dewpoints were in the 70s ahead of the
front...and 50s behind it.

Latest model trends continue to downplay the convective threat later
this afternoon and evening. The reason being residual cloud cover has
limited the instability across the region. Moreso h700 thermal ridge
was located overhead...which capped off any potential for deep
convection. Meanwhile...surface winds were beginning to veer with
time...which decreased the surface convergence. As a result...have
removed probability of precipitation across most of Minnesota...and have only chance probability of precipitation in
western WI.

Westerly winds will increase in the wake of the passing cold
front...with values close to Wind Advisory criteria. Forecast
soundings show 30kt mixing potential...but the best winds move
across the region early Wednesday opted not to go with
a Wind Advisory since 1) the timing is off and 2) its marginal.

Long term...(wednesday night through tuesday)
issued at 213 PM CDT Tuesday Jul 28 2015

Extended guidance still in general agreement through the end of
the forecast period... with predominantly dry northwest upper flow
prevailing across the area. There are just a couple chances for
precipitation as shortwaves and associated surface boundaries move through
the region... but nothing that appears significant at this time.
Surface ridge to our west will keep dry northwest flow over the
area Wednesday night through Thursday. A weak shortwave and
surface trough will move through the area Thursday night and early
Friday... but any precipitation associated with it looks to stay to our
North/East. Surface ridging then builds back in for Friday and
Friday night. Both the GFS and suggest a slightly stronger
shortwave will drop in on northwest upper flow Saturday and
Saturday night... although it is at that point that their
solutions begin to diverge a fair bit with the GFS showing a
better cold front and more upper troughiness in its wake in
comparison to the European model (ecmwf). Both have similar timing with respect to
precipitation chances... however... with chance probability of precipitation dropping in from
northwest to southeast Saturday and Saturday night... then things
drying out Sunday for all but perhaps the southeast portion of the
area on Sunday. Lingered some low probability of precipitation over the south Sunday night
through Monday with the baroclinic zone lingering in that area and
another weak upper shortwave dropping southeast across the region.


Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1155 PM CDT Tuesday Jul 28 2015

Other than high clouds streaming overhead into southeastern Minnesota and western WI
through early clear expected through the period. West
winds will remain 10-15 knots tonight...but will strengthen to 20-25
knots and gust to 30-35 knots by middle morning Wednesday. additional concerns.

/Outlook for kmsp/
Thursday...VFR. Wind west 10-15 knots.
Friday...VFR. Wind northwest 10 knots.
Sat...VFR. Wind SW at 5-10 knots.


Mpx watches/warnings/advisories...


Short term...
long term...jrb

National Weather Service Glossary of Abbreviations