Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
307 am CST Friday Feb 12 2016
Short term...(today through saturday)
issued at 305 am CST Friday Feb 12 2016
Forecast challenges concern temperatures and snow event Saturday
night Sunday. Typical precipitation total differences at this point in time
otherwise models in reasonable agreement with snow event and will
follow National guidance.
Skies continue to clear from north-S as Arctic high pushes in. Along
with the clearing comes the temperature drop with the north half
below zero except in the immediate valley. Winds generally 5-10kts
and sufficient to produce sub -25 wind chills so will keep
advisory going. Cold advection levels off later this morning
however with cold airmass in place temperature recovery will be
modest at best. Unsure if current snow cover or lack of will have
an impact on temperatures.
Arctic high builds in tonight. With wind diminishing temperatures
will have no problem dropping off with sub 20 below readings
likely especially from the valley east. Although winds will be
real light wind chills drop back down so another headline will
likely be needed but will let later shifts handle that. Exception
will be over the western forecast area where return flow and clouds will
limit temperature drop.
Surface high will continue to shift east Saturday. Warm advection
and thickening clouds ahead of next wave will help with
temperature recovery all areas. Expected band of snow in enhanced
area of warm advection aided by upper forcing will reach areas
mainly west of the valley be late afternoon.
Long term...(saturday night through thursday)
issued at 218 am CST Friday Feb 12 2016
Snow will spread from west to east Saturday night into Sunday ahead
of wave and associated surface trough. Some model differences on
snow accumulation and where favored forcing will occur this
period. Current guidance suggest favored area would be roughly
across the south half of the forecast area. At this point with potential for
advisory level snowfall will issue an Special Weather Statement to heighten awareness.
Will also see 20 to 25 kts of wind which would further increase
potential for visibility issues in falling snow. With continued warm
advection will be seeing steady or even rising temperatures
Snow will diminish from west to east later Sunday with minimal
additional accumulations expected Sunday night. Depending on
cloud cover minimums not nearly as cold.
Monday-Thursday...seasonably mild temperatures expected to start the
period on Monday ahead of another northwest flow clipper system Monday night into
Tuesday. The 00z GFS/European model (ecmwf) show some differences with respect to
timing/location of this system...with the GFS slower and bringing
the snow band farther east into east ND. Surface high then drops southward
with cooler temperatures into mid-week. However...it appears that our area
will be on the western periphery of the colder air mass...and with
an expected return to more zonal flow by late in the period...the
cool down is expected to be short-lived. There is low confidence in
timing/placement of any weak progressive upper shortwave troughs and
associated light snow chances Tuesday night through Thursday.
Aviation...(for the 06z tafs through 06z Friday night)
issued at 1124 PM CST Thursday Feb 11 2016
Kgfk/ktvf have cleared out and kdvl/kbji look to be on the cusp so
they should also clear within the next hour. May take a few more
hours for the clearing to get to kfar. Winds are staying up in
the 5 to 10 knot range but should increase toward morning as the
pressure gradient tightens up. As the surface high builds in later Friday
these winds should die down again.
ND...Wind Chill Advisory until noon CST today for ndz006>008-015-016-
Minnesota...Wind Chill Advisory until noon CST today for mnz001-002-004>009-