Scientific Forecaster Discussion

Return to Local Conditions & Forecast
Area forecast discussion 
National Weather Service Grand Forks ND
333 am CDT Friday Apr 18 2014

Short term...(today through saturday)
issued at 330 am CDT Friday Apr 18 2014

Forecast challenges concern temperatures...wind today/evening and
precipitation chances/phase tonight-early Saturday. Models in reasonable
agreement through the period and will use model blend for
forecast.

Organizing low pressure over northern High Plains will increase
surface pressure gradient across region today. Mixed layer deepens to
around 850mb with 30 to 40kts at the top of the layer. Strongest
winds expected across western forecast area into southeast ND so will issue Wind
Advisory into early evening. Will see clouds today however with
mixing...warmer start and respectable warm advection temperatures
should be able to recover closer to average most areas.

Models in good agreement in tracking two surface lows...one in South Dakota
the other in Saskatchewan eastward and consolidating into main low north
of the international border by Sat morning. Associated surface
boundary will bisect forecast area by morning. This evening low level jet
increases to 50+ kts with best convergence with this feature
across the northern forecast area. Precipitable water values increase to nearly
an inch. With amount of moisture...short wave and low level jet
convergence looks like respectable rain potential and increased probability of precipitation
across the north tonight. Farther south rain potential along
boundary more uncertain as best forcing is farther north. Still
uncertain for thunder potential as very warm elevated layer but
with strength of low level jet and amount of moisture cannot rule
out a few rumbles. Main concern with this event will be mixed precipitation
potential across the far NE. Favored guidance keeps surface
temperatures just above freezing but this area will need to be
monitored closely for freezing rain potential. Will also have to watch wind
speeds this evening across southeast ND this evening as low level jet
Cranks up. Have advisory going to 7pm and hopefully winds will
diminish then. Mixing and forecast area in warm sector will keep
temperatures up overnight.

Column dries from west to east Saturday as precipitation winds down and
should clear the forecast area to the east by afternoon. Column cools some
during the day however with solar and brisk westerly flow
temperatures should remain mild.

Long term...(saturday night through thursday)
issued at 330 am CDT Friday Apr 18 2014

Looks like milder day Easter Sunday with warming column and light
return flow.

Maintained low probability of precipitation across the north Sunday night as short wave
tracks across S Canada.

Monday through Thursday night...GFS/ECMWF in good agreement through
00 UTC Thursday...diverging thereafter with the timing and strength
of the next eastern Pacific shortwave for the late week period. Some
light rain may skirt the Canadian border region Monday...but
otherwise remain dry as surface high pressure builds across the region.
Dry conditions will continue into Tuesday with high temperatures
both days from the middle 50s to middle 60s.

First wave of precipitation associated with next short-wave moves into the
forecast area Tuesday night into Wednesday. Wednesday will be windy
given tight surface pressure gradient. Surface low moves into central ND
Wednesday night with the GFS dry slotting the region... whereas the
European model (ecmwf) is still wet. This GFS/dry European model (ecmwf)/wet bias continues through
Thursday before the system begins to move out and wrap up across Minnesota
Thursday night. GFS is slower and stronger as the low exits...but the
European model (ecmwf) is faster and weaker. Thermal profiles remain warm enough for
all rain through Thursday with daily highs from the middle 40s to near
60 degrees. Will keep isolated thunder through the event given some
weak instability. All said...will maintain high chance all blend
probability of precipitation for the middle to latter half of next week...but model
differences preclude higher values at this time.

&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 1145 PM CDT Thursday Apr 17 2014

High pressure will gradually move east tonight with low pressure
approaching from the west. The lighter winds will gradually
increase overnight...and become windy on Friday. Ceilings will also
increase...but remain VFR. Lower ceilings and precipitation will be
possible Friday night (toward the end of this taf period)...but
confidence in these details remain low.



&&

Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&

$$

Short term...voelker
long term...Rogers/voelker
aviation...tg