337
FXUS63 KABR 150554 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1154 PM CST Thu Nov 14 2024

.KEY MESSAGES...

- Temperatures will range 10 to 15 degrees above average
  through Monday, dropping to around normal Tuesday.

- A storm system could affect the region through the middle part
  of next week with a 30 to 60 percent chance of precipitation.
  The highest chances are over northeastern South Dakota into
  west central Minnesota.

&&

.UPDATE...
Issued at 1144 PM CST Thu Nov 14 2024

See the updated aviation discussion below for the 06Z TAFS.

Issued a Dense Fog Advisory last hour for some of our eastern
zones, mainly east of the James Valley...across parts of northeast
South Dakota and west central Minnesota. Fog has been developing
and shifting north into those areas with observed visibilities to
a mile or lower, and in some cases down to one quarter mile.
Guidance projects this to expand some through the early morning
hours and maintain until after sunrise.

UPDATE Issued at 947 PM CST Thu Nov 14 2024

Most of the evening so far has been relatively quiet weather
wise. However, have been keeping an eye on low stratus and fog
development across the southeast corner of South Dakota. It has
been shifting north-northwest the last few hours and now has
started to enter our far southeast zones; near Watertown and
points south. Beefed up the fog potential overnight across our
eastern zones earlier this evening. Localized visibilities could
become dense overnight and we`ll have to keep an eye on trends the
next 1-4 hours to see if a Dense Fog Advisory is needed.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 305 PM CST Thu Nov 14 2024

Upper level ridging will build over the region tonight and Friday
ahead of a trough digging down the west coast of the country. Will
begin to see a more southwesterly flow develop Friday night as the
trough becomes more positively tilted.

At the surface, a weak high pressure pattern will remain in place
tonight into Friday morning. In the far eastern part of the CWA
where rainfall occurred a day or so ago, conditions will be
favorable for fog development again late tonight into early
Friday morning. The high will then get pushed east ahead of an
approaching low pressure system, with the CWA remaining between
the high to the east and the low to the west Friday afternoon and
Friday evening. Will see the pressure gradient tighten up during
this time, with wind gusts of 20 to 30 mph possible, especially
across central South Dakota. The low will continue to track
eastward Friday night, with its associated frontal boundary
reaching the western CWA late Friday night. No precipitation is
expected in the near term period.

Low temperatures tonight will be in the mid 20s to lower 30s. High
temperatures on Friday will be in the upper 40s to mid 50s. Lows
Friday night will be in the 30s.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 305 PM CST Thu Nov 14 2024

Deterministic models and clusters show an upper-level trough
stretching from MT to the west coast of CA Saturday morning, which
pushes a surface low pressure through western and central SD during
the day Saturday. The jet along the westward side of the trough
starts to weaken, and by Sunday afternoon/evening it causes the low
pressure over AZ/NM to break off from the trough. This upper-level
low starts to move east/northeast as a shortwave with a surface low
pressure connected to it. The mid-levels move moisture over central
SD Saturday evening which helps surface precipitation to develop.
The deterministic models have precipitation forming around the
surface low pressure, however, only the Canadian show a small bit of
precipitation moving through north central SD, mainly Corson county.
The NBM has PoP values around 35% over Corson county Saturday
morning decreasing to 20% by the evening, with the clusters having
mean 24hr precipitation of 0.01 falling over north central SD. The
mid-levels have WAA occurring over south central SD, which leads to
surface temperatures Saturday and Sunday being 10-20 degrees warmer
than normal. These warmer temperatures are above freezing, which
will decrease the chance for snow (only a few ECMWF members show
snow potential), so the precipitation, if any falls, will likely be
rain.

Through the day Sunday into Monday, the clusters and models show the
upper-level shortwave move northeast, with variations in its
location and strength. The Canadian has a more northerly track,
while the ECMWF and GFS have a southerly track to the lows in the
upper-level and surface. The timing of the precipitation is very
similar, with it moving in Monday afternoon, give or take 6 hours,
with the heaviest precipitation occurring Monday evening and
overnight. The only difference comes in how widespread the
precipitation is over central and eastern SD. The location of the
upper-level trough following the precipitation Tuesday causes some
models and clusters to continue precipitation develop through
Wednesday and Thursday. NBM generally has PoP values between 30-60%
Monday evening through Tuesday, with values between 20-40% Wednesday
and Thursday. With Mondays temperatures being 10-20 degrees warmer
than normal, the precipitation looks to start as rain as it moves
into central and eastern SD, which the clusters and NBM agree on.
However, as the temperatures start to drop to around normal early
Tuesday, variations in the models and clusters start to occur in the
p-types as a few members start to show sleet and snow occurring
starting Tuesday evening/ overnight into Wednesday. Areas around and
to the west of the Missouri River have more members showing snow
than rain Wednesday, though less than 40% show any precipitation
occurring on the ECMWF. Areas to the east of the Missouri River show
an equal number of members with rain or snow, though it is still
less than 40% of members showing any precipitation occurring. The
clusters that have rainfall show mean rainfall amounts around 0.35in
occurring west of the James River Valley, with around 0.75in of rain
to the east of it. The members with snowfall have mean snowfall
amounts around 2in over central and eastern SD. The GFS and Canadian
0.5km model winds and lapse rates show strong winds over central and
eastern SD likely reaching the surface Monday evening into Thursday,
the NBM shows surface winds and gusts increasing overnight Monday
with widespread areas of 30kt gusts with pockets of 35kts. These
winds look to die back through the day Thursday. If snow does fall
during this time, it could become blowing snow and impact
visibilities.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1144 PM CST Thu Nov 14 2024

Terminals KABR,KATY,KPIR,KMBG

Low stratus and foggy conditions are setting in across parts of
northeast South Dakota, including the KATY terminal. LIFR/VLIFR
cigs and vsbys will likely prevail at this TAF site through the
overnight until about mid morning. IFR vsbys will be possible at
KABR, perhaps with a period of LIFR vsbys after sunrise before
conditions improve. VFR conditions will prevail at KPIR/KMBG
through this TAF set and return to KABR/KATY by late morning.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 10 AM CST Friday for SDZ008-011-019>023.

MN...Dense Fog Advisory until 10 AM CST Friday for MNZ039-046.

&&

$$

UPDATE...Vipond
SHORT TERM...Parkin
LONG TERM...Vernon
AVIATION...Vipond