Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 151940
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
240 PM CDT Fri Sep 15 2017

.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 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 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1243 PM CDT Fri Sep 15 2017

KATY should see VFR conditions this afternoon, otherwise the
remainder of the area should continue to experience IFR/MVFR cigs
through the rest of the day and into tonight. The highest
probabilities for thunderstorms should be around the KATY region
through the evening.


&&

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

$$

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



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