Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 161720 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1220 PM CDT Fri Apr 16 2021

Issued at 1214 PM CDT Fri Apr 16 2021

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 936 AM CDT Fri Apr 16 2021

Not really too many changes planned to the today period. Lower-end
pops remain throughout the day, mainly across the western half of
the CWA while weak mid-level energy tries to work southeast across
the region. Similar to yesterday, going forecast high temperatures
should pan out okay, unless breaks develop in the clouds again, in
which case, going highs may be 3 or 4 degrees off.


.SHORT TERM...(Today through Saturday Afternoon)
Issued at 407 AM CDT Fri Apr 16 2021

Precip chances and cloud cover will continue to remain the main
features to track today into tonight as our region remains under the
influence of some upper level features. Radar returns this morning
show light precip across our southern zones. Pierre has been
reporting light rain since late last evening. More scattered returns
across ND are moving southward into our northwest zones. And,
portions of the James valley are also seeing some scattered
activity. Area webcams in all these locales support these returns.
The upper flow pattern indicate a couple of upper lvl features to
watch today. One being the closed low across the Colorado Front
Range that is progged to shift ewd into the Plains and slowly open
up with time by late tonight. The other feature is an upper trough
that is forecast to slide sewd out of Canada into ND during the day.

These features will allow light precip to persist for this CWA
today. The activity should be confined from the James valley
westward across the Missouri valley. HiRes guidance more or less
depicts this scenario shifting the showers south to south-
southwestward through today. Any rain/snow mix or all snow chances
will be during the morning hours and accumulations of either rain or
snow will be minor. Cloud cover will again hang tough over most of
the FA today. There may be some brief thinning in our far east along
the MN border where temps could approach 50 this afternoon.
Otherwise, the majority of us will see highs once again in the 40s.
The upper trough will swing through the area tonight into Saturday
morning. Shower activity will persist through the overnight but
should be exiting this CWA closer to daybreak Saturday morning. A
drier airmass will filter in on Saturday and provide a better
opportunity to see more sunshine and warmer temperatures.

.LONG TERM...(Saturday Evening through Thursday)
Issued at 407 AM CDT Fri Apr 16 2021

The main mid-level pattern over the CONUS during the long term would
seem to favor general troffing over the middle and eastern part of
the country. N/NW flow aloft will lead to the passage of a front or
two. The main system will move through Sunday night into Monday. A
pv anomaly is expected to drop into the Northern Plains toward
Sunday evening, with a sfc front swinging through the CWA during the
afternoon/evening hours. Ahead of the front, a fairly mild airmass
will spread out or develop over the forecast area. Feel that model
blend is probably a touch too low for max temperatures, and thus
boosted temps a notch toward NBM 75th percentile. Post frontal pcpn
is also expected. The exit region of an H3 jet will spread
divergence/uvm across the area Sunday evening. Meanwhile, layer Q-
vectors also indicate synoptic scale lift over the region. Moisture
isn`t super plentiful per PWATs, but sufficient enough for light
pcpn. GEFS probs for at least 0.01 of measurable pcpn are fairly
high so sct/likely pops look good. Boosted model blend pops some as
they looked a bit low. Pcpn should start as rain, but then
transition to a mix or all snow later in the evening as colder air
makes its way south into the CWA. Only light snow accumulations
appear likely Sunday night. As for temperatures, they start off
above average for Sunday, but then transition to below normal for
the early part of next week, only to return to near normal by weeks


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1214 PM CDT Fri Apr 16 2021


MVFR/IFR cigs and perhaps some off and on light showery activity
are expected to persist regionwide through this evening. After 06Z
tonight, conditions are forecast to begin improving back to VFR
from west to east as low clouds steadily shift or clear off. KATY
may actually drop into IFR overnight before seeing conditions
improve there on Saturday back into VFR.




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