Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 160337
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1037 PM CDT Wed Mar 15 2017

.SHORT TERM...(This evening through Friday)
Issued at 255 PM CDT Wed Mar 15 2017

Didn`t make any significant changes to the previous forecast. Main
changes were to try and fine tune chances for light precipitation
tonight and again Thursday night. In the big picture will see a
short wave ridge work through the area Thursday before a decent
trough drops southeast through the area Thursday night into
Friday.

Fairly robust warm advection looks to get some light precipitation
going over the area by this evening and into the overnight hours
as it shifts east. It`s mainly a question of how quickly things
saturate in terms of where any precipitation may fall, and amounts
look to be light regardless. However, given a warm nose aloft and
sub-freezing near ground temperatures, any precipitation could be
in the form of some light sleet, freezing rain, or freezing
drizzle, so a few slick spots are possible tonight, particularly
over the northeast and eastern portion of the forecast area. Some
lingering precipitation is possible over the east early Thursday,
then we should see things dry out before another chance for some
light precipitation works across mainly the northern portion of
the area Thursday night. That looks to develop on the northwestern
portion of a weak surface wave that will be moving through
Nebraska.

.LONG TERM...(Friday night through Wednesday)
Issued at 255 PM CDT Wed Mar 15 2017

After Friday the large scale pattern looks to change as much more
pronounced ridging develops over the western CONUS and shifts
eastward. That upper ridge will be centered over our area by
Sunday, then looks to flatten late Sunday into Monday as a strong
upper trough moves east across central and southern Canada.
However, upper ridging looks to re-establish itself over the area
by midweek. The guidance is in reasonably decent agreement on this
overall evolution of the large scale features, which results in a
more mild and mostly benign forecast for the area through the
period.

A nice ridge of high pressure looks to build across the region
from Friday through Saturday, before we start to get into return
flow Saturday night. Although there is decent warm advection
progged Saturday night into Sunday, and a frontal passage Sunday
afternoon/evening, there is minimal moisture return into the
region, so the period looks to be mainly dry. It`s possible later
forecasts may need to add some low PoPs for later Sunday into
Monday, but at this point the probability of occurrence for much
measurable looks to be minimal, so doesn`t look worth including.
High pressure will be in control again from Monday afternoon
through Tuesday, then better chances of widespread precipitation
look to arrive later Tuesday night and Wednesday. At that point,
we should see much better moisture return ahead of a period of
warm advection as surface troughing starts to develop in the High
Plains ahead of a western CONUS trough. Although beyond the
forecast period, the is reasonable model agreement that a system
will move northeast from the Central Plains into the Mid-
Mississippi Valley during the second half of the week, which could
make things more interesting for portions of the area, although
temperatures may be too warm for anything other than rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1026 PM CDT Wed Mar 15 2017

Main forecast issue ahead is the possibility of below 2000 foot MVFR
stratus at HON and FSD terminals during the 18z - 00z time frame
hinted at by some of the models. However, same guidance that
suggests stratus has been overdoing low level moisture, so have
left mention of stratus out of the TAFs.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...MPX
LONG TERM...MPX
AVIATION...Ferguson/JH



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