Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 111741
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
1141 AM CST Sat Nov 11 2017

.UPDATE...
Issued at 1127 AM CST Sat Nov 11 2017

Fog and stratus has moved away from the Pierre area and has begun
to mix out. Main focus will be on a localized area of
precipitation that may develop over parts of south central South
Dakota this evening. Models continue to go back and forth on this
feature, with several CAMs and the operational NAM identifying a
localized area of higher QPF while the deterministic GFS no longer
represents this feature. Therefore confidence is lowish, however
we can see an upstream vort and there is an 80kt jet streak just
to its south, that will put our south central counties under the
left exit region. Some weak/elevated cumulus is already developed
over the badlands and this supports the above narrative. BUFKIT
profiles are warm (above freezing) but with such a dry layer below
7kft wet bulb effects suggest that precipitation may make it to
the surface as snow. The determining factor will be lift, with the
NAM at around 20 microbars within a broad dendritic growth zone
while the GFS is closer to 5. If the GFS is correct, then small
flakes will melt and we will get sprinkles, but if the NAM is
correct then brief (hour or two) but accumulating snow is
possible.

See update to aviation discussion below.

&&

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 308 AM CST Sat Nov 11 2017

A weak surface trough over the region this morning will gradually
push east today as high pressure begins building south into the CWA.
Warmer temps aloft across the area today should allow highs to rise
into the 30s and 40s for most areas, with the warmest readings over
southern areas. Will also be watching a weak mid level disturbance
passing across the region, which looks to clip the southwest CWA
with some scattered rain and snow showers this afternoon and
evening. Lower level moisture is lacking a bit, but soundings reveal
there should be enough saturation to get a few showers going by
later this afternoon. Hi-res models agree fairly well in bringing
some scattered activity into the southwest CWA later this afternoon
and through the evening hours. Initially, temps are warm enough for
rain, but as things cool off this evening, a switch to some snow
showers are possible.

High pressure centers itself over the area by 12Z Sunday. Air mass
is not overly cold, and models/soundings do suggest there could be
some scattered to broken cloud cover at this time. This suggests
temps won`t completely tank Sunday morning, but will likely drop
down into the teens over northern areas nonetheless. The high
pressure moves off to the east by Sunday afternoon with low level
warm air advection and southerly winds developing over the CWA.
Warmest air will reside across the southwest CWA where highs could
reach 50 degrees Sunday afternoon.

.LONG TERM...(Sunday Evening through Friday)
Issued at 308 AM CST Sat Nov 11 2017

Weak upper level ridging will be dominant over the area through much
of the extended period. The exception will be when a weak shortwave
trough moves through Tuesday night, and again when a stronger wave
moves through Thursday night into Friday morning.

At the surface, high pressure will be over the eastern part of the
area Sunday night, then gets pushed east on Monday as low pressure
digs down the lee of the Rockies. The boundary associated with the
low looks to track across the CWA Tuesday afternoon/evening, but
limited moisture will allow it to move through dry. High pressure
tracks across the area late Tuesday night and Wednesday, before
another low and associated frontal boundary move through Thursday
afternoon and Friday. With the strong upper wave overhead, will see
a better chance for precipitation with this system. For the most
part, the precipitation looks to be rain, but may mix with or switch
over to snow late Thursday night into the early morning hours on
Friday.

Temperatures will remain fairly mild through the period, with highs
mainly in the 40s and 50s. Friday looks to be the coolest day, with
highs in the 30s to mid 40s. Overnight lows will be in the mid 20s
to mid 30s.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1127 AM CST Sat Nov 11 2017

VFR conditions are anticipated for KABR/KATY/KMBG. Pierre area may
see some snow develop, but confidence is low as preferred
location for precipitation may be to the south. This may result in
some MVFR visby.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...Connelly
SHORT TERM...TMT
LONG TERM...Parkin
AVIATION...Connelly



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