Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 132040

Area Forecast Discussion
National Weather Service Aberdeen SD
340 PM CDT Wed Sep 13 2017

.SHORT TERM...(This Evening through Thursday Afternoon)
Issued at 338 PM CDT Wed Sep 13 2017

An upper ridge over the central CONUS has led to continued above
normal temperatures over much of the region today under a sunny
sky. As of 2pm, temperatures have risen into the upper 80s and
lower 90s, except over north central South Dakota, where thick
smoke has limited temperatures. At KMBG, temperatures have
struggled to rise into the lower 80s and visibilities have been
steady in the 1.5-1.75mi range throughout the day. The HRRR smoke
model and NWS Air Quality forecast have both picked up on the
near surface smoke well today. Using those tools as a guide, have
expanded the smoke into the morning hours tomorrow since winds
will be light and don`t expect much change in the conditions.

The light winds that are over the area are being caused by a
broad area of low pressure in the lee of the Rockies in WY/CO and
the dissipating cold front stretches from northeast to southwest
across SD and to the main low. As we have a series of shortwaves
move over the area through Friday, the surface low will gradually
shift east through southern SD tonight through Thursday. The
first wave is currently moving into the western Dakotas and are
already seeing some showers in southwest ND. Expect these high
based showers to move into central SD later this evening and
likely dissipate through the overnight hours. Lapse rate above
the cloud bases are very weak (only 5.5-6 C/km), so not expecting
much for thunder. If there are any stronger cells, the dry air
below 12kft may lead to gusty winds. Also, some hints in the high
resolution models (ESRL HRRR especially) for the potential for
heat bursts again tonight as the showers/storms weaken or

For tomorrow, there will likely still be isolated showers
continuing through the day, but largely over the northern part of
the CWA (where the best moisture above 600mb is located) as a
couple weak waves move through. At this point, thinking the best
chances will be in SE ND where the moisture/forcing are
co-located. Still expect a surface trough to be nearly stationary
over portions of the southeast CWA, although models still vary on
the location depending on the strength of a weak llvl jet tonight
over eastern SD. Confidence is very low at this time, but could
see some development along that trough where there is an increase
in convergence and some moisture pooling. Hi-res models haven`t
been too enthused with development at this point, so have shown
limited PoPs during the afternoon. If something does develop,
there would be enough shear/instability to produce a strong

.LONG TERM...(Thursday Evening through Wednesday)
Issued at 338 PM CDT Wed Sep 13 2017

The models agree real well with the upper level pattern from
Thursday night through Wednesday next week. The main issue during
this period will be the mean upper level troughing over the western
U.S. At this time, the most significant short wave trough to come
out of this western trough will be Thursday night through Friday
night. The models all agree that most of our CWA will have good
chances of showers with some thunderstorms southeast in the CWA. The
main upper low pressure trough out west will then kick out across
our region later Friday night through Saturday evening bringing more
chances of rainfall. One more quick moving short wave trough from
the west will bring more chances of showers/storms for Sunday night
into Monday. The models then show another large upper low pressure
trough digging into the southwest U.S. with upper level heights
building over our region from Monday into the middle of next week.

Temperatures will be cooling down from Thursday into Friday and
remaining below normal through the weekend as we remain on the north
side of the surface cold front with north winds. Highs should be
only in the 60s for both Saturday and Sunday. Temperatures are
expected to then warm up from Monday into Wednesday as winds become
south with upper level heights rising. Temperatures will be back in
the 70s and 80s.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1255 PM CDT Wed Sep 13 2017

For the very short term, smoke is the main focus for north
central SD. KMBG has been consistent in showing reduced
visibilities and ceilings from the smoke, so have stuck with
persistence due to the light winds and smoke upstream. Satellite
indicates this smoke nearing KABR and have introduced smoke into
the forecast their too. Surface smoke models are showing
conditions gradually improving tonight into Thursday, but will
need to monitor with future issuance`s.

Otherwise, a weak disturbance will likely produce some high based
clouds and showers as it moves across the area tonight and
tomorrow. Think the best opportunity is over central SD this
evening and early overnight and then for northern SD late tonight
into Thursday.




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