435
FXUS63 KFGF 150920
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
320 AM CST Fri Nov 15 2024

.KEY MESSAGES...

- Patchy to areas of dense fog across portions of eastern North
  Dakota and west central Minnesota this morning.

- Light rain is expected Saturday into Sunday morning for areas
  north of I-94, with light snow mixing in across portions of
  the Devils Lake Basin.

- Unsettled pattern mid next week, with predictability low on
  impacts and higher on widespread precipitation.

&&

.DISCUSSION...
Issued at 318 AM CST Fri Nov 15 2024

...Synopsis...

Ridging turns to southwest flow throughout day, with a deepening wave
moving out of the Rockies. Under the current ridge we have light
winds and patchy to areas of dense fog affecting portions of eastern
North Dakota and west central Minnesota. Winds remain on the lighter
side throughout the day, with skies becoming cloudy end of the
afternoon. Temperatures warm to the low to mid 50s for highs as warm
air advection shifts through the northern plains. A shortwave trough
will propagate through the Northern Plains over the weekend. This
shortwave will bring rain and a little snow to the northern portions
of the FA. Thereafter, a deep trough over the western US is pegged
to cross the plains midweek, bringing the potential for widespread
precipitation to parts of the Northern Plains and Upper Midwest.
While this pattern change is well advertised in all guidance, there
remains significant differences in the details, which will determine
the location, duration and potential impacts this system may bring.

...Patchy to Areas of Dense Fog...

Patchy to areas of dense fog continue to affect portions of eastern
North Dakota and west central Minnesota through the morning hours.
Winds have remained light, with dew point depressions at or near
zero. Satellite continues to show the widespread dense fog in
central Minnesota, that has the possibility to stretch further north
into west central Minnesota by morning. However confidence is low in
that occuring before sunrise. Short term guidance has struggled to
handle the fog and how far north it will develop in west central
Minnesota through the morning hours. We will continue to monitor the
fog and how large the coverage gets through the morning. An SPS is
out for Cavalier through Barnes counties for areas of dense fog
dropping visibility to a quarter of a mile. This runs through 6am
this morning.

...Weekend Rain and Snow...

A shortwave will propagate through the region Saturday into early
Sunday. The track of the associated surface low has not changed
significantly over the past 36 hours, which increases predictability
in the areal extent of precipitation and totals. Most precipitation
will stay north of the surface low in western ND into southern
Canada, but sprinkles/light rain may make it as far south as I94 in
eastern ND. Due to weakening frontogensis as the wave pushes
through, totals are not expected to be significant. Measurable QPF
will be highest in the Devils Lake Basin, where there is a 40%
chance of seeing a tenth of an inch or greater. Totals will taper
quickly to the south and east. A little snow is still anticipated to
mix in across the far northwestern FA on the systems backside.
Therefore, there is a 50% chance of seeing a Trace of snowfall
accumulate on grassy surfaces across the Devils Basin Saturday night
into Sunday morning.

...Active Pattern Midweek...

An upper level trough is expected to arrive in the Pacific Northwest
Sunday evening, propagating and digging over the Northern Rockies on
Monday. Simultaneously, a southern wave will be ejecting into the
Southern Plains. How these waves interact will dictate our systems
eventual evolution. Guidance has begun to cluster around a more
north/west track of the midweek low, tracking it from the Panhandle
region of Texas Monday afternoon into MN by Tuesday. There is still
a subset of ensembles that keep the low further south/east, however
the important takeaway here is that even further south and east
tracking scenarios produce precipitation over a large swath of the
FA. The result of the surface low tracking through MN/far western WI
is more QPF across this FA, with the added caveat of warmer
temperatures due to strong WAA. For example, the probability for at
least 1 inch of QPF is now as high as 70% in northeastern ND, with
all of the forecast area seeing probabilities over 50%. Snowfall
remains highly uncertain, as the further westward the low drifts,
the more likely it is for precipitation to stay as rain.
Additionally, if the low tracks as far west as northwestern MN,
which some members of ensemble guidance are showing, the systems dry
slot will become an issue Tuesday night into Wednesday. Overall,
there remains significant uncertainty in precipitation type and
totals, even if the general synoptic pattern is becoming clearer.
Continue to check back over the next several days as more details
become available.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1019 PM CST Thu Nov 14 2024

The question right now is how much fog will we see tonight and
how significant will it be. Ceilings for the most part have
risen to MVFR outside of DVL. There is a signal for ceilings to
fall once again to IFR after 06z, but confidence in this
scenario is very low, so for now we`ve decided to keep the
prevailing MVFR. Eventually stratus should become VFR in
preparation for the next system of precipitation, but given how
today went with stratus it may linger around longer than
expected once again.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

$$

DISCUSSION...Rafferty/Spender
AVIATION...Perroux