Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 152330 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
630 PM CDT Fri Sep 15 2017

.UPDATE...
Issued at 624 PM CDT Fri Sep 15 2017

See updated aviation discussion below.

&&


.SHORT TERM...(This Evening through Saturday)
Issued at 240 PM CDT Fri Sep 15 2017

Main concerns through Saturday are POPs and temperatures. Sfc low
in Nebraska will head northeast into the eastern part of South
Dakota this evening and overnight. Ahead of that low, it has
cleared off to some degree. This will likely lead to diabatic
heating and moderate MLcapes by late afternoon and early evening.
Low level and deep layer shear is pretty decent too. However,
pretty warm H7 temps and only moderate lapse rates from H7-H5
could be a limiting factor. Nonetheless, feel isolated storms,
maybe even severe, are possible along the I29 corridor and east
into the early evening hours.

For Saturday, sfc cold front moves into MN, taking with it the vast
majority of LLM and instability. However, decent looking wave per
PV anomaly charts will slide across the state for the first part
of the weekend. This chunk of energy should be able to kick off
post frontal sct showers over the forecast area Saturday into
Saturday night.

Temperatures will average out below normal for the entire weekend.


.LONG TERM...(Saturday Night through Friday)
Issued at 240 PM CDT Fri Sep 15 2017

Sunday: we open with the upper trough lifting north into southern
Canada. At the surface, a 1023mb high pressure builds overhead early
and continues southeast during the day. We initially will have weak
cold advection overnight, but that transitions as the surface high
moves south to warm advection in western counties.

Sunday night: Warm advection with a 30-40kt low level jet overhead.
There is a weak wave evident across North Dakota, but the reflection
of this is little more than a 12 to 15Kft cloud deck. Will leave
in the low chance for rain showers but no QPF.

Monday features zonal flow/weak ridging aloft as we are between two
upper lows.  We will remain in southerly flow as a lee low develops
to our west. Warm advection will return our temperatures to back
above average, with the warm up continuing into Tuesday as a
surface low deepens across Montana and the southwestern parts of
the Canadian Prairie provinces. Another low will develop across
the front range Tuesday afternoon. The inverted trough/cold front
in-between will pass across the CWA during the
afternoon/evening/overnight hours which is fairly consistent
between guidance. Ahead of this feature we can also expect strong
southerly winds. Depending on moisture return, this front could
provide the focus for thunderstorms thanks to an approaching
negatively tilted trough.

A cooler, much drier airmass moves in for Wednesday. Models diverge
on how to handle the rest of the extended, particularly when it
comes to chances for precipitation late next week/weekend.


&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday Evening)
Issued at 624 PM CDT Fri Sep 15 2017

Scattered showers, and a few thunderstorms, are possible this
evening across mainly the far northern and eastern portions of the
CWA. Periods of MVFR vsbys are possible with the precipitation.
IFR/MVFR cigs will be common across the area through the entire
TAF period, with occasional periods of MVFR vsbys in fog across
the north and east late tonight into early Saturday morning.

&&


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

$$

SHORT TERM...TDK
LONG TERM...Connelly
AVIATION...Parkin



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