Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 300850

Area Forecast Discussion
National Weather Service Aberdeen SD
350 AM CDT Thu Mar 30 2017

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 349 AM CDT Thu Mar 30 2017

Stratus deck continues to try advecting westward early this morning,
but has halted its progress somewhat with the leading edge from
around Victor, through Aberdeen and down to Pierre. Leading edge is
a bit ragged as well. On the edge of this stratus deck, still a
potential for some fog development over the next few hours. Drizzle
has also been noted off and on as well over the southeast CWA where
CIGs are lowest, especially in the Watertown area. The ATY ASOS
carried -RA for a short time a few hours ago, with VVV also
reporting -DZ. A few web cams also verify light precip. RAP
soundings support drizzle as well, persisting through the morning
hours. Have therefore added patchy drizzle to the forecast for the
southeast CWA this morning, mainly where the CIGs are lowest. Had to
make some rather significant changes to sky grids this morning and
through the day to account for more cloud cover with this stratus
deck. The big question though is just how far west it will expand,
with models varying in its westward expansion. This will also have
an impact on temperatures today, with cloudy areas staying cooler
than non-cloudy areas. MaxT grid for today reflects this, with
warmest temps around 60 degrees in north central SD, and cooler
readings in the upper 40s in the Watertown area. Temps overall today
look to be a few degrees cooler than yesterday.

The rest of the short term looks mainly dry, with just some small
precip chances along and south of I-90 on Saturday as a storm system
skirts us to the south. Temperatures will rise into the 50s for most
areas on Friday, with some lower 60s creeping back in by Saturday.

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 349 AM CDT Thu Mar 30 2017

An upper level pattern change is progged for next week. Instead of
split flow keeping energy contained to the southern stream, models
are trending toward a single, deep trough moving into the Plains
Monday through early Wednesday. The GFS is farther north than the
ECMWF which centers the stacked low over Nebraska and keeps the
ND/SD border a bit drier. Both models do bring some precip to the
region. One thing to watch will be the temp profiles. The GFS is
substantially cooler than the ECMWF on the back side of the low and
also carries more moisture. For now, it looks like precip will be
rain. Forecast highs in the 60s on Sunday will trend downward by mid
week into the 50s.


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1222 AM CDT Thu Mar 30 2017

VFR conditions are expected to prevail over the KMBG terminal
through Thursday evening. KATY is trending down through MVFR
conditions in lowering cigs, and will likely be down in IFR cigs
within the next couple of hours. KATY could perhaps be into some
sub-VFR fog by morning, too. Low clouds will stick around at KATY
for much of the next 24 hours. Satellite imagery trends and
changes in the latest short-range model guidance now bring this
area of sub-VFR stratus into the KABR and KPIR terminals prior to
12Z and keep it around at these two terminals for several hours
into Thursday before conditions begin to improve back into VFR




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