Scientific Forecaster Discussion
fxus63 kmpx 270349
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
1049 PM CDT Wed Jul 26 2017
issued at 1046 PM CDT Wed Jul 26 2017
Updated to include 06z aviation discussion below.
Short term...(this evening through thursday)
issued at 231 PM CDT Wed Jul 26 2017
Upper level ridging just west of The Rockies will build during the
next few days and our upper level flow pattern will go from a
westerly to a northwesterly pattern. Therefore we will dry out
for a few days with very typical Summer time temperatures.
A cold front/wind shift/drier airmass boundary extends from
Western Lake Superior to a low pressure area in central Kansas.
Showers and thunderstorms are associated ahead and along the
boundary. Behind the boundary clearing skies, northwest winds and
lower dew points are noted. As cooler air filters in this
afternoon a few scattered low clouds will form. Skies will clear
by evening in Minnesota with scattered clouds lingering in western WI.
High pressure will continue to build overnight and Thursday. Winds
will be light and variable over eastern WI which will lead to
patchy fog. Thinking is that winds will be just enough across most
of Minnesota to limit fog formation. A pretty strong wave moves through
Thursday afternoon coupled with steep lapse rates and as a result
will introduce chance for showers across north and east areas.
Scattered showers come to an end shortly before sunset and as the
wave moves off to the east.
Long term...(thursday night through wednesday)
issued at 154 PM CDT Wed Jul 26 2017
Consistent forecast for the long term period, with essentially no
changes made from the previous shift. The period looks relatively
quiet, and will likely see several dry days in a row for most
By tomorrow evening, there may be a fair bit of cloud cover around
as the shortwave dives southeast across Wisconsin. Those clouds
should gradually dissipate tomorrow evening as the wave moves away
and as we lose diurnal forcing. The following couple days will be
dominated by high pressure and northwesterly flow aloft. The same
disagreements still exist between the GFS and the European model (ecmwf) in terms of
whether we see thunderstorms develop overnight Saturday night
through Sunday. Tend to side with the European model (ecmwf) in this scenario as
forcing for ascent is very minimal. So, still forecasting a dry
weekend with highs in the low 80s and comfortable in terms of
humidity as dew points stay down around 60 degrees.
The European model (ecmwf) and the Canadian agree on keeping the weekend dry as well
as the first half of next week. In fact, a quick look at the run
total quantitative precipitation forecast off the 12z run of the European model (ecmwf) reveals that through next
Wednesday, much of our area is predicted to receive 0.00"
precipitation. The GFS on the other hand indicates closer to an
inch of precip with a round Saturday night, Sunday night, and again
along a frontal boundary Tuesday night into Wednesday. As of now,
tend to side with the drier European model (ecmwf) solution through the 7 days period.
Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1046 PM CDT Wed Jul 26 2017
VFR conditions expected to prevail throughout this taf set. High
clouds this evening through tomorrow morning then scattered mid-
level fair weather cumulus clouds to develop for tomorrow
afternoon. Some MVFR ground fog is possible, particularly at the
WI taf sites, during the pre-dawn hours Thursday morning. Lesser
chances at the outlying Minnesota taf sites but confidence is less so
will omit its mention at this point.
Kmsp...some patchy ground fog is possible near msp Airport,
particularly near bodies of water, but is not expected to roll
onto the msp Airport grounds. Otherwise, no significant weather
/Outlook for kmsp/
Fri...VFR. Wind east 5 kts.
Sat...VFR. Wind S 5-10 kts.
Sun...VFR. Wind SW 5 kts. Isolated shra/tsra.