Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Grand Forks ND
931 am CDT Monday Mar 30 2015
issued at 927 am CDT Monday Mar 30 2015
Weak shortwave will continue to propagate east-southeast across forecast area today.
Associated band of spotty rain showers focused in zone of 850mb
frontogenesis/warm advection. With ceilings mainly from 6-8k feet most
returns likely virga/sprinkles. Made some minor pop adjustments
through the morning with no other changes.
Update issued at 651 am CDT Monday Mar 30 2015
Some radar returns have started to develop in the northern County Warning Area but
nothing is reaching the ground so far. Think we will eventually
get some rain as the frontogenesis band strengthens. Middle and high
clouds have been moving across the area so increased clouds for
the rest of the morning.
Short term...(today through tuesday)
issued at 352 am CDT Monday Mar 30 2015
Precipitation coming in today will be the main challenge for the short
Northwesterly flow aloft has set up over the region...and WV loop
shows a weak shortwave trough moving through southern
Saskatchewan. This shortwave will dig down through southern
Manitoba into northern Minnesota during the day today. In response...a
weak surface low will move from southern Canada down southeastward
through our County Warning Area. There will be a good middle level temperature gradient
along with the low...and the models show some fairly strong
frontogenesis at 800mb mainly over our northeastern counties.
Bumped up probability of precipitation to likely for a short time in our northeast. Given
warm air upstream...think that rain is most likely although a few
flakes mixing in as the band moves in this morning is not
completely out of the question. Some of the model are putting out
nearly a quarter of an inch of rain but given recent performance think
this is overdone and kept top amounts just over a tenth. The
precipitation should push out to the northeast by afternoon.
Further south and west...there will be no precipitation and less cloud
cover...allowing for some good mixing of 30kt 925mb winds. Do not
think that Wind Advisory will be needed but it should be pretty
breezy in our western and southern tier. Behind the surface low winds
will be from the northwest but 850mb temperatures will be on the rise.
Kept highs in the west in the 60s while the northeastern counties
will stay mainly in the 40s to near 50.
Tonight should be fairly quiet as very weak surface high pressure
builds in behind the surface low. Mixing will decrease and skies
should be mostly clear but with a pretty warm air mass overhead
will keep lows close to the freezing mark. The warm trend will
continue into Tuesday as upper ridging moves briefly into the
plains and southerly winds kick in as low pressure develops over
the northern rockies. Highs should again reach the 50s to low 60s
with nice mixing from the southerly winds along with sunshine and
more warm air advection.
Long term...(tuesday night through sunday)
issued at 352 am CDT Monday Mar 30 2015
Tuesday night through Wednesday night...the next upper shortwave
moves from eastern Montana into the plains...although the track of
this system will be further north than our last strong trough. Q
vector convergence shows most of the lift will be north of the
international border...and the models have only a token amount of
quantitative precipitation forecast in our far northern counties as the surface low moves through but
we get the dry slot. Kept only some low probability of precipitation in the far north and
think that winds will be the main issue with this system as there
will be a pretty tight pressure gradient Wednesday behind the surface
low. 850mb temperatures in the warm sector of the low get up into the
upper teens c...so temperatures will be quite toasty on Wednesday. After
a fairly mild start in the 40s think we should get well into the
60s most areas. Cold air advection starts in for Wednesday night
and readings should drop back into the 30s.
Thursday through Sunday...models continue to show a deep low
pressure system moving across the region to start the period. As the
low departs the area...look for precipitation to mainly fall across
the northern part of the area. Expecting mostly snow with the wrap around
moisture as cooler air filters south out of Canada. Another wave is
forecast to cross the area for the weekend...with more chances for
light precipitation on Saturday...and a shot of reinforcing cool air for the
end of the period on Sunday.
Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 651 am CDT Monday Mar 30 2015
VFR conditions at all taf sites with mainly middle level clouds and
think this should continue throughout the period. A band of rain
may impact ktvf and kbji later this morning but there is still
uncertainty about how heavy. Will keep visible above 6sm and ceilings above
3000 feet. Winds will pick up from the northwest this afternoon
across the western taf sites...with some gusts over 25 kts at
times. Winds will quickly diminish again after sunset.