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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
1257 am CDT Thursday Jul 31 2014

Updated for 06z aviation...
issued at 1248 am CDT Thursday Jul 31 2014

&&

Short term...(this evening through thursday)
issued at 234 PM CDT Wednesday Jul 30 2014

Tonight and Thursday...surface analysis continues to show extensive
high pressure over much of the north-central states. Aloft...the
pattern continues to be a trough East...Ridge west...with northwest
flow over central North America. Water vapor imagery shows a swath
of moisture rounding the western fringes of the eastern trough...
around a developing cutoff low within the center of the trough over
Ontario. As this moisture drops south into northern Minnesota and
Lake Superior...additional cloud cover can be expected over western
Wisconsin and far eastern Minnesota through the rest of the
afternoon and early evening hours. Going further west into
Minnesota...aside from diurnal pop-up middle-level cumulus clouds... no
significant weather is expected. However...for western Wisconsin...
this additional moisture is in response to another weak shortwave
disturbance aloft. Similar to yesterday...this disturbance will aid
in isolated shower/thunderstorm development for portions of western
Wisconsin. The shortwave for today is not as impressive as the one
experienced yesterday...therefore am expecting lesser coverage and
intensity of any storms that do form. Any and all activity is
expected to dissipate by sunset...allowing for clear skies
overnight. A similar story is then expected for tomorrow as yet
another weak disturbance aloft combined with the heating of the day
will make for isolated afternoon showers and thunderstorms over
western Wisconsin. As for temperatures...more of the same is
expected with no change in airmass. Highs on Thursday will be
similar to today...reaching the upper 70s to lower 80s. Lows tonight
will be similar to what was recorded early this morning...again
dropping to the middle 50s to around 60.

Long term...(thursday night through wednesday)
issued at 234 PM CDT Wednesday Jul 30 2014

The longer term outlook hasn/T changed much with things still
looking to become more active as we head into next week. The
eastern upper trough looks to lift northward as the western ridge
flattens some while expanding eastward over time. Of concern with
respect to active weather... particularly heavy rain potential...
is a cutoff upper low beneath the upper ridge which is prognosticated by
both the European model (ecmwf) and GFS to slide northeast/east into our area
during the first part of the week. This feature looks to be
accompanied by some monsoonal moisture... which helps to boost
precipitable water values over the region that will already be
increasing somewhat in situ from local/regional
evapotranspiration. The main time frame of concern looks to be
from later Monday through late Wednesday as the baroclinic zone
loiters in the area with the surface trough positioned to our
west. The GFS and European model (ecmwf) show the potential for several rounds of
precipitation/convection during that time frame... and produce copious
rainfall in our general vicinity... ranging from 2 to as much as 6
inches or so. The location and timing of each round of precipitation is
highly questionable at this time... and it/S possible the heaviest
activity could be just to our north or south. But... the overall
pattern is looking more favorable for some heavy rainfall in the
region... with confidence increasing a bit with each successive
series of deterministic and ensemble guidance. Prior to that...
we/ll have some occasional chances for scattered lighter precipitation as
shortwaves cruise through the area in the lingering northwest flow
and we maintain sufficient lapse rates for some rain showers and isolated
ts activity.

&&

Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1248 am CDT Thursday Jul 31 2014

VFR conditions throughout with light winds at all sites except
Keau which had a quarter inch of rain around sunset. This low
level moisture should cause fog to develop overnight...so have
LIFR conditions beginning around 08z. On Thursday expect light
northerly winds and scattered clouds at or around 4-5kft.

Kmsp...
VFR conditions throughout. A stray shower is possible Thursday
afternoon but coverage will be to sparse to include any mention in
the tafs at this time.

/Outlook for kmsp/

Sat...VFR. Winds variable 5 kts.
Sun...VFR with MVFR/thunderstorms and rain possible. Winds SW 5-10 kts.
Monday...VFR with MVFR/thunderstorms and rain possible. Winds SW 5-10 kts.

&&

Mpx watches/warnings/advisories...
Minnesota...none.
WI...none.
&&

$$

Short term...jpc
long term...999
aviation...jrb

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