Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 220546 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1246 AM CDT SUN MAY 22 2016

.UPDATE...
Issued at 1245 AM CDT SUN MAY 22 2016

06z aviation discussion updated below.

UPDATE Issued at 822 PM CDT SAT MAY 21 2016

Only minor changes made to the evening forecast, mainly to slow
down the progression of warm air advection showers and
thunderstorms expected late tonight through Sunday morning. Still
pretty dry in the lowest levels /the 00Z KABR sounding indicates
850 mb dewpoint depressions at approximately 20 C/. Therefore
limited any POPs across the western CWA until after 06z...and
that may be too soon. Adjusted sky cover to match the advection of
stratus across the western CWA as well. Otherwise...remaining
forecast fields look on track.

UPDATE Issued at 656 PM CDT SAT MAY 21 2016

The aviation discussion has been updated below.

&&

.SHORT TERM...(This Evening through Monday Night)
Issued at 315 PM CDT SAT MAY 21 2016

The potential for severe storms late Sunday afternoon through Sunday
evening will be the main forecast concern.

a large upper level trough of low pressure over the Pac NW will
slowly lift northeastward into SC Canada by 0Z Monday. This
system...along with a surface low pressure and associated front
will slowly slide across the western Dakotas around 0Z monday.
This front will interact with a moist...albeit narrow boundary
layer where cape values should reach 2K J/KG. The best area of
cape is located along the Missouri River Valley. This is where
some hi-res models suggest strong to potentially severe
thunderstorm development. That said...both the NAM and GFS are
suggesting the Missouri River Valley could see stratus through
most of the day which should limit the convective potential. The
12Z NSSL WRF highlights limited convection fairly well. Somewhat
interesting...nearly all models suggest weak elevated showers
Sunday...which seems unlikely given 700 MB temps of plus 8C.
Overall...the severe potential Sunday looks rather limited.
Stronger storms are possible Sunday night as a healthy LLJ
develops. Hail and damaging winds will be the main threat. Locally
heavy rainfall will also be possible.

Additional strong storms are possible along and east of I-29 Monday
afternoon as the front will be slow to exit the cwa. Cape parameters
remain fairly high...and shear is decent enough to support strong
storms.

.LONG TERM...(Tuesday through Saturday)
Issued at 315 PM CDT SAT MAY 21 2016

A fairly active forecast is taking shape during the long term. A
very broad positive tilt trof is expected to exist from south
central Canada southwest into the extreme southwest CONUS. A wavy
but weak frontal boundary will persist on the southern edge of the
westerlies through most of the forecast time period. Every day or so
a surface wave will track northeast across the central
CONUS...producing scattered showers and thunderstorms over much of
the Central and even parts of the Northern Plains. Details in this
particular flow pattern are hard to pin down and thus a broad brush
approach will have to be used for pops/pcpn. Temperatures overall
should favor near to perhaps slightly below normal during the four
to seven day time period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1245 AM CDT SUN MAY 22 2016

Stratus continues to spread over parts of western and central South
Dakota and ceilings are expected to lower into the MVFR category at
the KPIR and KMBG TAF sites. Isolated showers and thunderstorms are
also forecast to move into the region after 9Z tonight.
Otherwise...expect southerly winds through the TAF period...becoming
gusty across eastern SD around 12z Sunday and persisting through the
afternoon.

A more significant threat for thunderstorms is expected along a
front late Sunday afternoon through Sunday night.

&&

.ABR Watches/Warnings/Advisories...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...Mohr
SHORT TERM...SD
LONG TERM...TDK
AVIATION...Mohr



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