Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Grand Forks ND
703 am CDT Monday Apr 21 2014

issued at 700 am CDT Monday Apr 21 2014

No forecast changes this update period.


Short term...(today through tuesday)
issued at 340 am CDT Monday Apr 21 2014

Forecast challenges concern temperatures and upcoming precipitation
chances. By midweek models continue to show differences with upper
low track and where associated main rain band will set up. Held
pretty close to persistence in later periods.

For today cold front should be through forecast area by morning. Cooler
column in place with coolest air aloft across NE forecast area this
afternoon. Wrap around/cold advection stratus prognosticated by models
to drop through forecast area this morning. Main uncertainty will be how much
cloud cover will be across the forecast area this afternoon which will have
impact on temperatures. Will no doubt be quite a bit cooler today
but just how much is the question. Maintained maximum temperatures close
to inherited inherited values.

High pressure settles in overnight. Diminishing wind and mainly
sky clear should allow temperatures to drop off close to freezing.

Tuesday will see some thermal recovery with increased mixing and
warm advection.

Surface low associated with approaching upper low will propagate
to the western Dakotas by morning. Precipitable water values
increase to around an inch and as low level jet shifts east should
see areas of rain development...mainly after midnight.

Long term...(tuesday night through sunday)
issued at 340 am CDT Monday Apr 21 2014

As upper low wobbles into the forecast area looks like a respectable rain
event setting up Wednesday/Wednesday night. Models differ on upper low
track and this will have an impact on where main rain band sets up
but overall for now likely probability of precipitation look good spreading from west to
east during the period. As models come together later shifts will
be able to increase probability of precipitation accordingly. Not too impressed with
thunder potential until later Wednesday across the south half of
the forecast area.

Thursday to Sunday night...models continue to be in relatively fair
agreement with evolution of cutoff 500mb low pressure system to
traverse the northern plains midweek. Most of Thursday will be a
transition from the dry slot across east ND and the end of the warm air advection precipitation
band in northwest Minnesota to the deformation zone forming and dragging a rain
snow mix across the northern half of the forecast area Thursday night. Some
light snow or rain showers may continue early Friday with north
winds. Surface high on Saturday will bring a cool end of April weekend.
Temperatures for the period will be below end of April normals...40s and
50s for highs with lows in the 20s and 30s.


Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 700 am CDT Monday Apr 21 2014

MVFR/isolated IFR ceilings will slowly lift and scatter out late this
morning into the afternoon. Remainder of the period will be VFR.


Fgf watches/warnings/advisories...


short term...voelker
long term...jk/voelker