Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kfgf 180541 
afdfgf

Area forecast discussion
National Weather Service Grand Forks ND
1141 PM CST sun Nov 17 2019

Update...
issued at 1141 PM CST sun Nov 17 2019

The low clouds have now scoured out of Grand Forks. Tough call
overnight on cloud trends, so will maintain continuity for now.

Update issued at 739 PM CST sun Nov 17 2019

Even minimal amounts of mixed precipitation tonight would be
highly impactful, especially for the Monday morning rush. However,
just not seeing much happening upstream. Cloud heights are
actually rising west of Devils Lake to Jamestown line. Will still
keep an eye on observations this evening, but for now have removed
the mention of mixed precipitation overnight. The better chances
for some light precipitation look to be on Monday. This chance
for light precipitation arrives as surface temperatures also rise
back above freezing, so most of it would fall as light drizzle or
light rain.

Update issued at 553 PM CST sun Nov 17 2019

Main question for this shift will be the potential for any mixed
precipitation to develop. Currently, confidence is pretty low for
this to occur. Radar imagery shows a few echoes along the western
edge of the Red River valley and from Winnipeg to Brandon, in
Manitoba. However, nothing appears on surface reports or webcams.
For that reason, will remove any mention of mixed precipitation
until mid evening and see if anything develops by then.

&&

Short term...(this evening through monday)
issued at 257 PM CST sun Nov 17 2019

Confidence is growing for a couple of rounds of wintry mix to
move through portions of eastern North Dakota into northwest
Minnesota tonight through Monday night. This could impact travel
from possible light icing.

Several weak impulses are being observed upstream moving over the
Canadian rockies and prairie provinces. The first impulses will
be on the weaker side but still enough to produce lift aloft and
warm air advection from the west. This promotes a warm but dry layer (2-3c) near
700 mb-800 mb to move over the region ahead of a surface warm front. Deep
moisture a top this dry layer is expected to accompany the
synoptic lift and will be visually apparent by radar returns this
evening and tonight. Eventually this virga should eat away at
least some of the dry, warm layer with some hydrometeors making it
through to the surface. There still remains some uncertainty in
the magnitude of dryness in this 700 mb-800 mb layer and will dictate how
many hydrometeors succumb to evaporation before reaching the
ground. Hoping 00z upstream raobs will gage this layer better.
Surviving hydrometeors should acquire enough warmth to melt and
fall as liquid, at least partially. For this reason, there will be
the chance for light freezing rain late tonight within eastern
North Dakota will moving eastward into the Red River valley Monday
morning. Thus this potential for light freezing rain brings the
chance for light icing and hazardous travel conditions, especially
for the Monday morning commute. Further complicating things will
be surface temperatures suggested to be on either side of freezing
overnight. Those that see surface temperatures below freezing
will see highest potential for impacts due to icing.

Another, better strengthen impulse is expected to move into
northwest Minnesota Monday afternoon. This will bring another
chance for wintry precip in the form of snow, sleet, rain, and
freezing rain. This could also pose a threat to travel for
locations in northwest Minnesota, best chances reside north of US
Highway 2. The nbm ensemble system continues to suggest a loss of
ice nuclei aloft as this lift and moisture moves into northern Minnesota,
although further examination of forecast soundings across the
deterministic suite suggests otherwise. Thus, confidence is low in
the thermodynamic profile aloft and an equal chance of light
freezing rain, sleet, and snow for northwest Minnesota late Monday
into early Tuesday. Above freezing air temperatures will also
play a factor in determining p-type as well as surface
temperatures remain in this period as well.

High temperatures Monday will be getting well into the 40s around
midday excluding low where temps may linger in the low to mid
30s.

Long term...(monday night through sunday)
issued at 257 PM CST sun Nov 17 2019

The main impact for this period will be the midweek storm with its
snow and wintry mix. Temperatures vary throughout the period, but
most days will have temperatures near the climatological average.

Tuesday and Wednesday... a shortwave trough will be moving into the
northern plains/Canadian prairies Tuesday into Wednesday giving a
source of synoptic lift. Based on deterministic model guidance the
main forcing mechanism will a cold front passing through the
northern plains connected to a low near the Hudson Bay. With
temperatures near freezing both snow and a wintry mix are possible.
Gefs suggests mainly snow, with some chances for wintry mix. Nbm top
down though suggests a greater chance of wintry mix, especially in
southeast North Dakota and northwest Minnesota. Given these
different outputs there is still a lot of uncertainty when it comes
to precipitation type. Based on gefs plumes liquid quantitative precipitation forecast values range
from 0.0" to around 0.2" with most members at 0.1" inches or less.
So a high quantitative precipitation forecast event does not look likely, but if the precipitation
phase trends more in the freezing rain or freezing drizzle direction
then this could be a higher impact event. There is also a signal for
some frontogenetical banding along the front if snow ends up as the
main precipitation type so totals could be higher in localized areas.

Thursday to Sunday... after the shortwave passes we return to zonal
flow with no significant storms. There might be a few chances for a
few rain or snow showers by next weekend, but both ensemble and
deterministic model guidances vary significantly at this point so
confidence in details is not high at this point.

&&

Aviation...(for the 06z tafs through 06z Monday night)
issued at 1141 PM CST sun Nov 17 2019

Clouds have risen into VFR at kdvl and kgfk, and probably will
soon at kfar. Models struggling with these details. The rise in
clouds may yet make it to ktvf and kbji, but confidence is low,
so will hold off on that until later into Monday. There will be a
period of a few showers Monday from west to east, but think it
will fall as light rain for the most part as the wind switches to
the west.

&&

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

$$

National Weather Service Glossary of Abbreviations