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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
643 am CDT Sat Jul 26 2014

Updated for 12z aviation discussion...
issued at 629 am CDT Sat Jul 26 2014


Short term...(today and tonight)
issued at 318 am CDT Sat Jul 26 2014

Early morning water vapor imagery with gfs26.00 500mb heights and
winds showed a compact upper level low in southern Manitoba...and
an upper level ridge centered over northern Texas. This led to quick
zonal flow over the northern third of the Continental U.S....with a weak
shortwave located over central South Dakota. This shortwave was able
to fire off a few thunderstorms overnight. The leading edge of these
storms were falling apart...and the latest runs of the hires
models...including the hopwrf and hrrr show the developing
convection diving southeast over southwest Minnesota and northern
Iowa. Therefore have introduced a slight chance of probability of precipitation across the
far southwestern County Warning Area.

Later today instability will build along a weak surface
trough...with an upper level wave diving down from Canada. This will
support a few late afternoon showers and thunderstorms mainly across
northern Minnesota and WI. Forecast soundings show cin holding off
convection early in the afternoon...with deep mixing by late
evening. Increased the winds across western Minnesota to reflect this
boundary layer mixing. Continued precipitation chances across the northeast
overnight Saturday with cooler drier air moving in from the

Long term...(sunday through friday)
issued at 318 am CDT Sat Jul 26 2014

The upper low will rotate southeastward across western Wisconsin
Sunday. Scattered to numerous shower coverage expected across eastern
Minnesota and western WI...with isolated light showers or sprinkles expected
further southwest across western/southern Minnesota. Removed the thunder mention
due to poor lapse rates and little or no instability. This event
will be similar to the one about 2 weeks ago...except that this
one is a bit weaker and areal coverage of precipitation is not expected
to be as impressive.

Clearing skies will follow Sunday night which will mark the
beginning of a long stretch of mostly clear skies and seasonal or
slightly below normal temperatures. Not much to discuss beyond
Sunday...each day will more or less be a Carbon copy of the last.
The trough will remain parked over the Great Lakes with ridging
across The Rockies and the western Atlantic for the next week or
two. Removed probability of precipitation for late next week due to very weak forcing and
little or no instability. Thinking the widespread quantitative precipitation forecast over WI on
the GFS and European model (ecmwf) is much overdone and is likely a result of an
overestimation of evapotranspiration...and superadiabatic lapse
rates at the surface due to winds less than 3 knots.


Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 629 am CDT Sat Jul 26 2014

LIFR fog that had developed across western Minnesota earlier this morning
was gradually improving with the daytime heating. Expect VFR
condition to return by middle morning. Later this afternoon
instability together with favorable upper levels should support a
few widely scattered showers and even a thunderstorm. At this time
coverage will be to scarce to mention thunder in the tafs. VFR
conditions should prevail overnight as drier air moves across the

MVFR/LIFR fog has developed at the sites surrounding kmsp...but
expect conditions to improve as the morning progresses with VFR
conditions anticipated shortly. A few high based showers could
develop this afternoon...but coverage will be scarce. A few
showers are possible again on Sunday.

/Outlook for kmsp/
Monday...VFR. Winds north at 5kts.
Tuesday...VFR. Winds north at 10kts.
Wednesday...VFR. Winds north at 5kts.


Mpx watches/warnings/advisories...


Short term...jrb
long term...borghoff

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