Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 122027
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
227 PM CST Sun Nov 12 2017

.SHORT TERM...(This Evening through Monday)
Issued at 224 PM CST Sun Nov 12 2017

A ridge axis aloft is centered overhead and while this is squashed
by a weak wave over North Dakota the main effect of this feature
will be for some higher clouds to move across the forecast area
tonight and early Monday. Lower down we have southerly flow with
about a 10mb gradient at the surface. 1/2km winds peak around 30-
35kts across the southern tier of the CWA, migrating from south
central to southeast counties through the morning. Mixed winds in
the Coteau top out in the mid 20kt range once mixing starts. NAM
does show a shallow saturated layer through 2kft under the
inversion - though the GFS mixes this out. Based on timing of the
NAM it may not reach our area until after daytime heating starts
and has the potential to mix somewhat before arriving. At this
point, mixing to 900mb yields highs around 50s in the James and
40s to the east so will stick with something more akin to the
previous forecast highs compared to the blended guidance which is
lower thanks to the NAM/Canadian cooler temps due to less
mixing/stratus.

.LONG TERM...(Monday Night through Sunday)
Issued at 224 PM CST Sun Nov 12 2017

Little has changed in the overall trends in the out periods. Zonal
flow as the period starts is interrupted briefly Tuesday/Tuesday
night when a fast-moving pv anomaly scoots through the northern
plains. Still not much in the way of precipitation chances showing
up with this one. Then, a longwave ridge moves through, with dry
conditions in place all the way to late Thursday night before
precipitation chances show back up in the forecast. Keeping with
lower end chances for rain/snow Friday as the GFS/Canadian and ECMWF
have different ideas on timing/strength of the pv anomaly working
through the middle of the country at the end of the week.

Still looks like Monday night/Tuesday will be near to above normal
for temperature while a "warm" airmass is in place. A cold frontal
passage advertised for Tuesday will knock temperatures down Tuesday
night into Wednesday to around or just a tick below normal. But the
cold air is thought to be short-lived as models still advertise
another push of low level waa Wednesday night into Thursday before
the next cold frontal passage is expected late in the week. With the
current inconsistencies in the longer range output of the 12Z GSM
solutions, just let blended guidance take care of the max/min temps.

One target of opportunity that was collaborated and adjusted was an
increase to the winds on Thursday and Friday. Low level winds appear
to be rather strong out of the south Thursday/Thursday night
becoming strong out of the north-northwest on Friday, so loaded in
CONSMOS for those forecast periods.


&&

.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1125 AM CST Sun Nov 12 2017

VFR conditions are expected for all terminals. We will see low
level wind shear over the Pierre area tonight.


&&

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

$$

SHORT TERM...Connelly
LONG TERM...Dorn
AVIATION...Connelly



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