Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
942 am CDT Sat Oct 25 2014
issued at 942 am CDT Sat Oct 25 2014
High pressure continues to build into the region from the
west...and current observations are in line with the previous
forecast thinking. No changes are required for today...enjoy.
Short term...(today through sunday)
issued at 340 am CDT Sat Oct 25 2014
A quick shot of cold advection overnight behind short wave...but
this becomes more neutral by midday with warming taking place at
850 mb in eastern ND this afternoon. Main high pressure ridge to remain
west of the forecast area today moving over the area this evening and
then east Sunday. With the high to our west look for a west-
northwest wind 10-15 knots range. There is a ribbon of middle and high
level moisture that models arent having the best time depicting
from Glasgow Montana into far south central ND/NE South Dakota. This is expected
to dissipate somewhat this morning so should see a good deal of
sun all areas today. With cold advection weakening today and a
favorable west wind did up temperatures a tad in the Red River valley
with 60-65 reasonable...with 55-60 either side of the valley.
Coolest temperatures tonight in the eastern forecast area while return flow
sets up in eastern ND. Southeast winds increase a bit on Sunday as 850
mb warm advection occurs. Some weak lift and decent 850 mb Theta-E
advection into the Red River/northwest Minnesota Sun afternoon-evening should bring a low risk
of a few showers. Storm Prediction Center keeps any risk of thunder more over northern Minnesota
so moved thunder threat a bit east based on model prognosticated 850 mb
showwalters sun aftn-eve. But overall the instability at 850 mb is
pretty weak with focus more so in eastern Minnesota/Wisconsin 00z-06z Monday.
Long term...(sunday night through friday)
issued at 340 am CDT Sat Oct 25 2014
As threat for thunder shifts east...kept a low risk for a few
showers in northeastern-eastern forecast area through 06z Monday before
drying it out. Very minor event regardless. After this...a pretty
potent 500 mb short wave trough will move from the Montana/Saskatchewan
border at 06z Monday to near Grand Forks by 06z Tuesday. Weak surface
low associated with upper system stays just north of the international
border. Moisture with this system is quite weak and thus
precipitation coverage weak as well. Will maintain the low probability of precipitation
for showers mainly Monday afternoon-night with best chance in the cold
advection on the backside of the surface/upper low. Amounts once again
quite low. But definitely a brisk and cooler Monday night.
For Tuesday through Friday...
long wave pattern had a zonal flow across the region through the
period. Long wave trough remains off the West Coast of North
America and amplifies a bit through the period. Flat Ridge builds
slightly through the period over central North America. The
deterministic GFS and European model (ecmwf) were in reasonable agreement at 84
hours. However the GFS becomes progressively faster through day 8
than the European model (ecmwf). Models amplify the pattern by Friday. Will prefer the
slower European model (ecmwf).
Little change to temperatures on Tuesday. Wednesday and Thursday temperatures decreased a degree
or so. On Friday temperatures decreased one to four degrees from yesterdays
Aviation...(for the 12z tafs through 12z Sunday morning)
issued at 744 am CDT Sat Oct 25 2014
West to northwest wind will increase middle morning into the
afternoon averaging 10 to 20 kts over the area...a tad stronger
wind gusts possible in the northern Red River. High pressure moving in will allow
winds to diminish quickly near sunset and then turn light
southerly late tonight. Band of middle clouds near Williston to
Wahpeton thinning out some today with cirrus thinning out too.
This leaves the taf sites generally clear today-tonight. I threw
in sct250 to account for lonely cirrus.