Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
1016 am CDT Monday Aug 31 2015
issued at 1012 am CDT Monday Aug 31 2015
Cold front near a Hallock to just west of Grand Forks to about
Valley City line. Remaining showers lifting northeast toward
Cavalier. Otherwise got a band of middle/high clouds with front.
Models continue idea of pretty much drying up any precipitation as it
moves through. Will maintain very low probability of precipitation into the middle afternoon with
front into the Red River and far northwest Minnesota but after that dry as front
begins to wash out as main energy lifts northeast into Canada.
Short term...(today through tuesday)
issued at 330 am CDT Monday Aug 31 2015
Water vapor imagery early this morning showed a strong upper
shortwave trough over northern Montana. Showers and a few
thunderstorms were progressing northeast ahead of the wave over
eastern Montana through central North Dakota. The upper wave will
lift into Canada while a surface cold front slowly moves east today.
Much of the large-scale forcing will move into Canada with the
upper wave...just glancing parts of the Devils Lake basin this
morning. This area stands the best chance for showers/isolated thunder.
After this pushes through by mid-morning...expect mostly dry
conditions today. Did keep a slight chance pop with the boundary
as it moves east...but with weakening surface convergence and warm
middle-level temperatures...not confident in any precipitation. Most guidance is
dry. Temperatures will be slightly cooler than Sunday...but still several
degrees above average. Winds will be breezy from the southwest
ahead of the boundary into the afternoon.
High pressure will build over the area tonight into Tuesday...with
return southerly flow beginning during the day on Tuesday. Highs
on Tuesday should remain very warm in the low to middle 80s.
Long term...(tuesday night through sunday)
issued at 337 am CDT Monday Aug 31 2015
Southwest flow aloft continues Tuesday night into Wednesday. The GFS/European model (ecmwf)
continue to show the development of some convection overnight Tuesday
night within enhanced 700-850 mb warm/moist advection. The 00z
NAM shows around 2000 j/kg MUCAPE along with 20-30 kts of deep
shear over the area. However...placement and even initiation of
elevated storms in these warm advection regimes tends to be
difficult to nail down...so just kept low probability of precipitation Tuesday night across
the northern half of the area for now.
Wednesday will be very warm and moist as low-level southerly flow
becomes established underneath a building upper ridge centered
over the Great Lakes. Highs may reach near 90 in spots...nearly 15
degrees above average.
For Thursday through Sunday...expect an unsettled period beginning Thursday
night and continuing into next weekend. A broad southwest flow aloft
pattern will develop...and ample moisture will advect into the
northern plains by the end of the week. There will be several
shortwaves ejecting out of deep trough in the west. Expect several
chances for thunderstorms with severe weather possible depending on
timing and overall moisture/instability that appears sufficient at
times. Temperatures should start above normal and trend below normal by
Sunday behind a cold front.
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 651 am CDT Monday Aug 31 2015
VFR conditions expected through the taf period. A weak cold front
will push across the area today with southerly winds shifting
southwesterly and then westerly. The timing of the wind shifts
will need to be monitored. A few showers may impact kdvl over the
next few hours but otherwise precipitation chances appear too low to
mention at all other sites. High pressure will move overhead
tonight with winds becoming light.